Food - Analytical Chemistry (ACS Publications)

Food Arthur K . Foltz, lames A. Yeransian, and Katherine G. Sloman, General Foods Technical Center, White Plains, N. Y. 7 0602

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the authors have attempted to provide a representative survey of the advances made in food analysis during the time span from the preparation of the previous review (28P),covering the period from October 1968, t o October 1970. Citations appearing in this review with dates prior t o this interval were included if they had not previously come to the attention of the authors in time for past inclusion. It has regrettably been necessary to eliminate many relatively minor changes reported in established procedures even though these are often useful. Where similar work is reported in both American and foreign journals, the domestic publications generally have been cited for reasons of availability and convenience to the authors while recognizing that excellent work is a1.o being reported elsewhere. .A number of texts have been recently published which pertain to food aiialyiis. One rather conipreheiisive treatise is the “Handbuch der Lebensmittelchemie” (12P), a multiple volume work which serves as a useful reference book for arialytical chemists. Also useful for food analysts is Herschdoerfer’s text (13P) dealing with quality control of foodstuffs. The new edition of Joslyn’s “Methods in Food Analysis” (14P) provides a welcome updating of an old standby. The second volume of the Swiss Food Book (31P) dealing with methods for evaluating foodstuffs and the proceedings of the 1969 Technicon International Congress (2P) also coiitain items useful to food analysts. The eleventh edition of the A.O.A.C. “Official Methods of Analysis” (19P) and the reprinting of the “Approved Methods of the American Association of Cereal Chemists” (3P) have also been pubI ished. s

I N PRIWIOUS REVIEWS,

ADDITIVES

Methods for the detection of the many different additives in foods continue to increase in the scientific literature. Antioxidants have been evaluated by Mueller (58A) using an oxidation reaction with indigo carmine dye. Spectrophotometry has been used by Vigneron et al. (82A) to determine antioxidants in oil after extraction with acetonitrile or ethanol. Extraction and column chromatography is suggested by Johnson (42A) for the determination of BHA as its nitrosoderivative in vegetable oils. A rapid gas chromatographic method for BHA and B H T in vegetable oils after dilution with carbon disulfide has 70R

been described by Hartmaiiii et al. (3612) and gas chromatography has also been used by Takahashi (76A) for these antioxidants in breakfaqt cereals. Gallic acid esters have been determined by Wachs et al. (84A) by gas chromatography after silylation. A scheme for phenolic antioxidant detection, proposed by Takeshita et al. (77.4) uses polyamide and silica gel column chromatography followed by polyamide thinlayer chromatography. Another thinlayer chromatography method (78A) has been applied to the separation of gallic acid and its alkyl esters. Ainew method for detection and quantitation of antioxidants in lipids such as BHA, B H T , tocopherols, etc, described by Glavind et al. (29-4) uses the stable free 1,l-diphenyl-2-picrylhydrazyl radical for detection. Thin-layer systems capable of detecting 1-2.5 pig of aiitioxidants have been studied by van Dessel et al. (l7.4), and by Daq et al. (16A). Silica gel thin-layer chromatography for antioxidant. has been proposed by Vioque et al. ( M A ) , and polyamide thin-layers have been used by Wang et al. ( M A ) , and Lee ( M A ) for antioxidants. Propyl gallate in lard has been determined by Latz et al. (52-4) by utilizing it. luminiwmt properties and Hurtubise (%A) has studied the luminescent properties of the common food antioxidants and developed analytical methods using these properties (S9A). Polarographic methods for the determination of the phenolic antioxidants have been proposed by Franzke et al. (24A) using a rotating graphite electrode and Kohler et al. (46A)use polarography after nitration for the determination of 6-tert-butyl-m-cresol. The ring oven technique has been applied by Sibalic et al. ( 7 l A ) to the semiquantitative determination of phenolic antioxidants. Methods for determination of preservatives are plentiful and varied. A method for sodium benzoate in the presence of sorbates proposed by Buglio (8A) uses isolation in benzene, hydrogenation of the sorbic acid, partition on diatomaceous earth, and UV measurement. A rapid screening procedure for the determination of benzoic acid and sorbic acid in fruit beverages described by Gantenbein et al. (26A) uses extraction into mixed ethers and UV measurement. Colorimetric methods for hexamethylenetetramine, benzoic acid, sorbic acid and p-hydroxybenzoates after isolation by steam distillation have been outlined b y Engst et al. (19A). A method of fractional extraction from

ANALYTICAL CHEMISTRY, VOL. 43, NO. 5, APRIL 1971

ether with basic solutioiis is the basis of a method described by Courtial (14A) for the UV determination of benzoic acid, sorbic acid, and p-hydroxybenzoic acid ester. Thin-layer chromatography on polyamide-silica gel has been proposed by Chiang (11A) for the separation of preservatives, and Grune et al. ( S O A ) use silica gel TLC for the same preservatives. Another T L C procedure, described by Prahl et al. (67d) is preceded by steam distillation for the isolation of the preservatives. Reversed-phase thin-layer chromatography has been used by Wang et al. (85A) to identify preservatives and artificial sweeteners in soft drinks. Reversedphase paper chromatography has been similarly used by Lee (54A) for the identification of sixteen preservatives. -i method for t,he determination of bromacetic acid and its ethyl ester proposed by Guyot-Hermann et al. (Mil) determines the difference between total and estractible bromine as these compounds. Dehydroacetic acid has been determined by Yamamoto et al. (89’4) by its reaction with the tris-(l,l0 phenaiithroline)-FeII chelate. Polarography has been applied by Arai et al. (2A) t,o the analysis of furylfuramide iri foods. Sorbic acid has been determined in foods by Spacu et al. (7SA) by its reaction with sodium chlorite, and by Alessaiidro et al. (1.4) by oxidation with potassium persulfat’e and then reacting the aldehyde with 2-thiobarbituric acid. Gas chromatography has been used by Kanno et al. (44A), I3andion et al. (SA), Tani et al. (80A), and Kuiiitake (50A) for the determinat’ion of diethyl carbonate in foods and beverages. Propionic acid in bread has been determined by Kaiiiio et al. (45.4) using liquid columii chromatography with a thermal conductivity detector. A survey of analytical methods for emulsifiers and st’abilizershas been compiled by Hibbert (37A), and RIurphy et al. (59A) have reviewed methods for synthetic emulsifiers. A study of a gas chromatographic method for sorbitan moiiostearate by Murphy et al. (604) indicates that unless the source of the emulsifier is known t’he method is only qualitative. Gravimetric procedures are described by Barcklom (4A) for the determinat’ion of polysorbate 80 in pickle products. Silaned silica gel T L C has been used by Gossele et al. (28A) to identify Spans and Tweens in pastry powders. Murphy et al. (61A) have used alumiiia columii clean up and thiiilayer chromatography to determine polyoxyethylene emulsifiers in foods.

Column chromatography followed by gas chromatography has been used by Neckermann et al. (65A) t o separate and determine monoglycerides and lactylated monoglycerides. A scheme for the detection of natural and foreign mono- and substituted monoglycerides in foods has been proposed b y Gernert (27A) utilizing thin-layer chromatography and identification of acids after hydrolysis. Methods for the identification of emulsifiers in foods b y Kroeller include methods for sorbitol mono- and tri-esters (48A) and for calcium stearyl lactate ( @ A ) . A procedure for the gas chromatographic analysis of sorbitan fatty acid esters has been described b y Sahasrabudhe et al. (69A). Lipids on the surface of dried fruits have been determined by Ristrow (68A) using twodimensional TLC. Synthetic surfactants used in the preparation of coffee have been identified by IR spectrophotometry by Charro Arias et al. ( I O A ) . A rapid screening method for brominated vegetable oils in soft drinks using X-ray fluorescence spectrometry has been proposed by Conacher et al. (12 A ) . Casein binder in meat products has been determined b y Freimuth et al. (25A) by colorimetry after polyacrylamide gel filtration. A procedure for the determination of sodium glutamate in foods described by Johnson et al. (21A ) involves colunin chromatography and formaldehyde titration of the separated amino acid. Ribonucleotides added to soups have been determined b y Carisaiio et al. ( 9 A ) using column chromatography and UV measurement. Stone (74A) has described a method for the detection of enzymic chill-proofing agents in beer by a turbidimetric procedure. Traces of ethanol in foods have been detected b y Lisle (55A) by oxidation t o acetaldehyde, formation of the 2,4-dinitrophenylhydrazone and T L C identification. The amount of isopropyl alcohol in fish protein concentrate has been determined b y gas chromatography b y Smith et al. (72A). Methyl salicylate, safrole, and related compounds in beverages have been determined by Larry (51A) using gas chromatography after distillation. A sensitive and selective method for the determination of borate with poly(vinylalcohol) and iodine has been tested b y Monte-Bovi (67A). A method for bromate in flour has been described b y Eosch Serrat et al. (6.4) using colorimetric reaction with 4 - dimethylaminobenzylidenerhodanine. E D T A has been determined spectrophotometrically in commercial fruit juices by Bruno et al. (7A) using the cobalt complex, and by Yamagata et al. (88A) using thin-layer chromatography. A simplified method for the determination of nitrate in food has been described by Stoya (75C) using Griess-Ilosvay reagent, and Berezina

et al. (6A) have used a similar reaction for nitrite in sausage. Nitrates and nitrites have been determined by Huynh et al. (40A) using polarography for the total nitrateafter oxidation, and uranium determination for original nitrate. A photometric determination for nitrite in pork described by Zunsunegui Perez (91A) uses the reaction with 2,3-dimethyl-1-phenyl-5 pyrazolone in sulfuric acid. Improved methods for sulfurous acid in foods have been used by Franzke et al. (23A) including distillation, trapping in tetrachloromercurate reagent and pararosaniline determination. Methods for the determination of dimethylpolysiloxaiies in foods proposed by Kea1 use low temperature separation ( @ A ) , or petroleum ether extraction (63A), and atomic absorption spectrophotometry for silicon detection. Column chromatography has been used b y Samuelson et al. (7OA) t o separate alditols from sugars in dietetic foods. Sorbitol in lemonade has been determined by van Os et al. (66A) using titration with periodate and LuffSchoorl titration t o correct for sugars present. Methods for xylitol in canned food have been proposed by Fiseris et al. (22A) and by Markh et al. (56-4) using measurement of the copper complex. Graham (31-4) has studied the determination of alginate in dairy products using pectinesterase to convert the pectin t o galacturonic acid, calcium precipitation of the acid and phenolsulfuric acid for the final determination. A clarification and detection method for carbosymethylcellulose in milk has been described by Hansen et al. (34A). Color and precipitation reactions of cellulose ethers have been described by Crossmanii et al. (15A) as a means of identifying these compounds in foods. For the detection of reducing substances in ergocalciferol, Guttmaii (32A) has used a tetrazolium blue reduction. Methods t o determine cyclamates in soft drinks have been proposed by Harrison et al. ( M A ) using barium chloranilate colorimetric determination of the sulfate released by nitric acid, and by Nagasawa et al. (62A) using degradation t o cyclohexylamine which is determined b y spectrophotometry or turbidimetry. Johnson et al. (43A) have determined cyclamates in canned fruits using hydrolysis t o cyclohexylamine and colorimetric determination of the amine with p-quinone. The separation of saccharin and cyclamate is achieved by DiPasquale et al. (18A) using estraction at controlled p H and the ferroin method for detection. Infrared spectrophotometry has been used by Coppini et al. (1SA) to determine saccharin and also cyclamates after conversion t o cyclohexene. A thin-layer chromatographic procedure for these sweeteners has been described by Woidich (87A). Dulcin has been determined by Eyrich

(20A) using the Jorissen reaction, b y Inoue et al. (41A) by the p-dimethylaminobenzaldehyde method or the diazotization method. A new fluorometric analysis procedure for dulcin has been proposed by Uchiyama et al. (81A), and a modification of the p-dimethylaminobenzaldehyde method has been described by Tanaka et al. (79A). Sodium saccharin has been determined by Yamamoto et al. (90A)by its reaction with tris-(1,lO phenanthro1ine)-iron(I1) chelate. Saccharin, P 4000, dulcin, and cyclamate have been separated and identified by thin-layer chromatography by Korbelak et al. (47.4). ADULTERATION, CONTAMINATION, DECOMPOSITION

Considerable athelition is being paid t o techniques and refinements for the detection of adulteration in various food commodities. Many authors have investigated ways to detect mixtures of fats and oils. Huygliebaert' et al. (73B) used gcs chromatography of the sterols from butter adulterant fats after separation by digitonin precipitation and acetate formation. Cerutt'i et al. (30B) chromatographed the corresponding TMS derivatives. Huyghebaert et al. (74B) employed TLC of the unsaponifiablc fraction to detect 2.570 foreign fat cont'ent. LaCroix (86B) employed the Katz and Keeney digitonin-celite column method and detected adulterat'ion of butterfat greater tliaii 5% b y the p-sitosterol found. T l i i h author (87B) also reported collaborative results for this method. Roos et al. (126B) described the removal of unkiiown uiisaponifiables from synthetic butterfat to aid sterol anal compared four methods for oil identification toward butterfat adulteration detection. A phytosterol acetate test for vegetable fat detection that' did not use digitonin precipitation was reported by Chatterjee et al. (3WB). 13achmann (7B) used TLC,' of unsnponifiables to detect 5% veget'able fat in butter. Steryl acetate chromatography, was used by Inoue et al. (76B) for the detection of foreign fats in bottled milk. F a t t y acid ratios enabled I3oniforti et al. (22B) t o evaluate German butters for authenticity. TLC of saturated triglycerides after random rearrangement enabled Chakrabarty et d . ( S I B ) t o ascertain the effects of various ghee adulterants. Aschaffenburg et al. (4B) detected cow milk in goat milk by gel electrophoresis of caseins. The interesterified fat portion of foreign fat in butterfat was detected by T L C of a monoglyceride baiid by Heiidricks et al. (66B). These authors (66B) further analyzed the monoglycerides by GLC to characterize them. Parodi et al. (I12B) detected tallow in but'terfat by trisaturated t'riglycerides. Infrared spectral characterization of Dutch


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butterfat provided a reference for adulteration analysis for D e Ruig (S8B). Roos et al. (125B)found D T A solidification curves useful for the same purpose. A combination TLC-GLC method for cholesterol determination allowed Thorpe et al. (141 B ) t o detect 2 to 3% of animal fat in vegetable oil and a collaborative study (140B) reported further results. Lauro (88B) measured fish oil in vegetable oil by a precipitation method. Multibranched fatty acid content provided a way for Wachs et al. (151B) t o detect hydrogenated marine oil as a n adulterant. The polyunsaturated triglyceride fraction, separated by TLC, and then GLC analysis provided a scheme for estimating seed oil adulteration in olive oil for Galanos et al. (59B). Dimoulas (S9B) detected the adulteration of olive oil with olive husk oil by T L C of unsaponifiables. Eionda et al. (19B) enumerated various means to determine cocoa butter adulteration. Uiino (18B) reported an I R method of determining the shell percentage mixed with cocoa bean. T L C of glycerides and fatty acids permitted Franzke et al. (48B)to detect foreign fat in castor oil and vice versa. The stigmasterol/campesterol rat’io and disterolein/dipalmitoleiii ratios provided bases for Ihacco et al. (ZCB)for measuring illipe butter used in cocoa butter adult,eration. Alkaloid detection by a color test detected argemone oil in edible oils for Rose et al. (ZSB). Soya-bean oil in sunflower seed oil was identified by T L C of its &tocopherol by Biernoth (16B). Eastijns (10B) reported on the influence of diets on lard fatty acids as it might affect adulteration judgments. I>TX analysis of glycerides crystallized by the Boenier method was investigated by Imamura et al. (75B) in a study of lard adulteration. A method for detecting adulteration in Concord grape juice, using paper chromatography, has been adapted to other dark juices by Fitelson (44B) and the collaborative study reported (45B). Circular paper chromatography detected soya-bean extract, in orange juice concentrates and beverage bases by its raffiiiose and stachyose for Benk and Krein (12%). Benk et al. (11B) studied browii pigment’s to try to detect juice from blood oranges in concentrates while Alberola et al. (2%) used GLC of amino acids and sucrose to detect citrus juice adulteration. Soybean protein and caseinate in meat products were identified by disk electrophoresis by Thorson et al. (14bB). Guenther (61B) found foreign proteins in meat by an immunoelectrophoretic technique. Freimuth et al. (52%) detected egg white and soy protein (51B)in hot sausages by polyacrylamide gel electrophoresis. A difference in microscopic refractive patterns enabled Freeman (50B) to identify cod meat substituted for crab-

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meat. Barley in wheat flour has been determined using polyacrylamide gel electrophoresis by Silano et al. (1SZB) and by immunodiffusion by Liuzzi et al. (92B). Multiple radial immunodiffusion was investigated to quantify food adulterants by Lietze (90B) and utilized to measure wheat in supposedly “wheat free” bread by him ( 9 f B ) . Invert sugar added to honey was detected by its 5-hydroxymethylfurfural UV absorbance by Inoue et al. (77B). Harwalker (6SB) found differences in the electrophoretic protein patterns of eggs adulterated with incubator rejects. Doum palm nut in powdered coffee was identified by its lauric acid contribution by Foschini et al. (47B). The addition of compounds to vanilla extracts mas studied using GLC and TLC by Bonnet (2dB). Pepper adulteration was studied by gel electrophoresis of protein extracts by hlicco et al. (1OOB). hlycotoxins and other potent food contaminants are still a cause for concern. Ayres et al. (6B) presented a review about their detection in foods. Fischbach (4ZB)reported on current research in the field of aflatoxin analysis. Fishbeiii et al. (4%)reviewed the chromatography of mold metabolites. Teng and Hanzas (138B) described a new developer for aflatoxin TLC. Stubblefield et al. ( f S 7 B ) published their technique for improved resolution. Pons et al. (115B, 116B) evaluated aflatoxin resolutioii by scanning plates with a fluorescence densitometer. Twodimensional T L C gave a n improved separation of 131, Bz, GI, and Gy for Peterson et al. ( I l Z B ) . Engstrom (41B) described three new solvent systems for aflatoxin TLC. A rapid confirmatory test by spore growth inhibition appeared by Clements (SSB). Rapid screening for cottonseed aflatoxin contamination by the fluorescence of bhe fibers and sticks was found possible by W’hitten (156B). Stoloff et al. (1S6B) recommended methods to achieve uniform sample preparation for assay of nuts, and Tiemstra (145B) studied peanut sampling variability. A rapid detection method for aflatoxins in peanuts using millicolumii chromatography was described by Holaday (68B). Waltking et al. (15ZZB) claimed their improvements halved the time for assays as compared to official procedures. Mayura et al. (97B) employed differential separations to avoid ambiguity from interferences. Scott (129B) removed theobromine and thus avoided difficulties in analyzing cocoa beans for aflatoxins. An interfering fluorescent component was resolved by hlchleans et al. (98B) in their cottonseed hull and meat assays. Masri et al. (94B)reported a method for aflatoxin hI in milk and later reported a modification (96B). Levi (89B) presented the results of a collaborative study of aflatoxin B1 in green coffee. A


TLC isolation method for B1, was published by Hanna et al. (6ZB). Bullerman et al. (27B) described a method suitable for aflatoxin analysis of meat. A metabolite exhibiting TLC behavior similar to aflatoxin B1, but not similar toxicity, was reported by Crowther (S5B). Owens et al. (108B) analyzed for kojic acid, terreic acid, and terrein by GLC. Schmidt et al. (l27B) determined byssochlamic acid in juices by TLC. A method for aflatoxin, ochratoxiii, and steriginatocystin in cereals and groundnuts was proposed by Vorster (149B) after he and Purchase (150B) determined the sterigmatocystiii in grain and oilseeds. Trace levels of other carcinogenic type materials, especially polynuclear aromatic hydrocarbons, are still pursued by methodology studies. A chapter iii “Residue Reviews” (118B) deals with their occurrence in smoked foods. Howard and Fazio (70B) reviewed their distribution in various foods. Biernoth (15B) adapted the T L C method of Grimmer and Hildebrandt to give more rapid results. 3,4-Benzopyrene in cereals by TLC was studied by Rohrlich ( f Z 4 B ) . Fritz (58B) reported the solubility characteristics and resultant dist’ributioii of polyaromatics during boiling and preparation of coffee and coffee substitutes, and he also (5SB) described their formation during roasting. This author (55B) also gave a method for detecting the formation of 3,4-benzopyrene in thermally treated foods and during the baking of bread and biscuits (56B). Fritz (54B) also found this compound in margarine and mayonnaise and investigated its level in frying oil (5‘7B). Calzolari et al. (28B) studied the effect of decaffejnation on polycyclic formation during roasting. Biernoth (17 B ) analyzed fats and oils for the compounds possibly extracted from clarifying carbon. Used frying oil was assayed for 13 polynuclear aromatics by Berner et al. (1SB). Roasted peanuts and their shells were analyzed by Ballschmieter ( 8 B ) . Contamination of food with antimicrobial agents and drugs has also been reported. Raible and Mohr (119B) used a bromphenol blue method to detect quaternary ammonium compounds in beer. Phenolic disinfectants in raw milk were measured by Puerschel et al. (117B) using Gibbs reagent. Palmer et al. ( f f O B )utilized bacterial inhibition on paper disks to detect traces of penicillin in milk. Sulfonamides were determined in milk by ion exchange and colorimetry by Houston and Gmstead (69B). Havlova et al. (64B) assayed milk for inhibitors, including penicillin, using triphenyltetrazolium chloride, Hydrocortisone in milk was measured colorimetrically with phenylhydrazinium chloride by Truck-

sess et al. (146B). Jolles and Terlain (79B) employed T L C with bioautography or anisaldehyde-HzS04 spray t o identify antibiotic residues in spiramycin-fed chickens. Blakely et al. (20B) analyzed for chlortetracycline in fish by paper chromatography and bacterial inhibition. Colorimetry after steam distillation allowed Kroeller (8SB) to assay for residual morpholine on citrus peel. Residues of ethylene oxide have been detected in wheat by a carbon-14 labeling technique by Pfeilsticker et al. (1ISB) and in bread, as ethylene chlorohydrin, by Manchon et al. (9SB) using gas chromatography. Oguma et al. (106B) analyzed fats and oils for propylene oxide residues. The presence of solvent residues from various stages and types of food processing has been shown in a number of publications. Menzonnet et al. (99B) investigated trichloroethylene and methylene chloride residues in decaffeinated coffee using GLC and pyrolysis. Urandenberger et al. (26B) also measured residual trichloroethylene using microcoulometric and electron capture GC detection. Dichloromethane in hop extract was detected by a headspace GLC procedure by Kruger (84B). A solid sampler was employed by Dean et al. (S7B)to detect a variety of residual solvents in oils and oleoresins by GLC. Fore and Dupuy (46B) found dimethylformamide the best solvent to extract residual acetone and hexane from oilseed meals and flours prior to gas chromatography. A headspace analysis to detect volatile solvent residues in spice oleoresins was described by Labruyere et al. (85B) and Roberts (I2SB) determined chlorinated solvent residues in them by microcoulometry after separation on Porapak Q. Pagington (109B) chromatographed aqueous solutions on Porapak to detect and measure chlorohydrins. Ress et al. (122B) reviewed methodology for chick edema factors. The identity of solvent used in spice extraction has been confirmed by an IR gas cell technique by Schwartzman et al. (128B). Kroeller (82B) described a method for determining acrylonitrile contamination in foods. Ackman et al. (1B) extracted and chromatographed isopropyl alcohol residues in fish-protein concentrate. The determination of cyclohexylamine has been performed by Howard et al. (71B) using distillation, extraction, and flame ionization GC; by Weston et al. (16SB) using electron capture detection after reaction with l-fluoro-2,4-dinitrobenzene, and by Bradford e t aZ. (25B) colorimetrically after complex formation with l-chloro2,4,&trinitrobenzene. Czuczy (36B) identified p-sulfamoylbenzoate as a saccharin impurity using paper chromatography. Modifications t o the original method for methylmercury compounds in foods

have been reported by Westoo (154B) and the applicability of the methods was studied (155B). Woggon et al. (169B) tested foods for migration of 3-aminocrotonic acid from plastics. Uhde et al. (147B) analyzed edible oil for hydroxyphenylbenzotriazoles to determine their transfer from plastic utensils. Uhde et al. (146%) also examined oil for contamination with 4,4’-thiobis(64ertbutyl-m-cresol) after storage in polyethylene. Reichle and Tengler (221B) determined the uptake of some synthetic rubber plasticizers by milk. Ostromow and Hofmanii (107B) investigated the extraction of rubber additives into milk from dairy equipment. Monomeric plasticizers from poly(viny1 chloride) tubing were determined in milk by Wildbrett et al. (157B). hlayrhofer and hlohler (96B) found additional T L C confirmation necessary after GLC in a method for N-nitrosodimethylamine and N-nitrosodiethylamine because of solvent impurities. Howard et al. (72B) described a method for extraction and GC-thermionic measurement of N nitrosodimethylamine in smoked fish. Dimethylpolysiloxanes (silicone oils) were determined in food by atomic absorption by Kea1 (10SB) in tile presence of silicates. Methods for detection and confirmation of extraneous matter in food are still undergoing slow refinement. Thrasher (14SB) reported a light filth method applicable to high bran flour. Thrasher et al. (144B) also recommended nheptane as a superior flotation solvent with alcoholic and water extraction. Carson and hlartinez (29B) described characteristics for identifying ten fly species in food contamination. A differential staining technique reported by Stein et al. (1S5B) allowed the distinction of plant tissue from true contaminants. Sen (1SOB) determined uric acid by urate oxidase as an index of insect infestation in flour. Freeman (49B) reported the non-applicability of a urea test to dry milk for detecting rodent urine due to normal urea content. Flotation and calcium analyses were used to determine the bone content of comminuted chicken by Kamm and Coffin (80B). Bone particles in meat were weighed after sample solubilization and solvent separation by Hill et al. (67B). Shell in chocolate by a spiral vessel count method has been studied collaboratively and reported by Jackson (78B). Guarino (60B) identified microorganisms in foods by headspace GC analysis. Free gossypol in cottonseed was determined in a method modified by Smith (1S4B). Many authors have provided methods to ascertain damage or decomposition in foodstuffs. Barnes (9B) used the flour maltose value to measure aamylase activity from weather damage.

Susceptibility to bacterial a-amylase attack was used by hudidier el al. (5B)to indicate damaged starch while Williams et al. (258B) determined damage by the color formed with an iodine reagent. Cooks et al. (S4B) correlated the appearance of fluorescent compounds with mold damage in wheat flours. Oil from sunflower seeds was found to contain oxygenated fatty acids after storage by Mikolajczak et al. (101B). Nawar et al. (IOdB) recovered alkanes and alkenes from fats subjected to irradiation. The nonacidic volatile decomposition products of hydrogenated cottonseed oil used for deep fat frying were identified by Reddy et al. (120B). Hydroperoxides in oils were determined by Niederstebruch and Hinsch (104B) by a polarographic method. Herring oil rancidity was measured via the pentane and other hydrocarbons present using GLC by Kiesvaara et al. (81B). Plakhotin et a l . (114B) suggested the use of a chemiluminescent analysis to study meat curing. A titrimetric method was used by Shelef et al. ( f S 1 B ) to assess fresh beef bacterial spoilage. Isovaleric acid, among other unidentified substances, was reported by Uethea et al. (14B) in decomposed eggs. The freshness of fish was estimated by Ehira et al. (40B) using nucleoside phosphorylase and xanthine oxidase. Trimethylamine content of fish meat as determined by GLC was correlated with freshness by Konaka et al. (105B). The amounts of methyl ketones and o-aminoacetophenone in stored sterilized concentrated milk were measured and related to flavor deterioration by Arnold et al. (SB). Sloan et al. ( I S S B ) identified compounds produced in heated strawberries. CARBOHYDRATES

I n the field of carbohydrate analysis, in addition to the improvements in total sugar and starch analysis, many analysts are turning to chromatographic and enzymatic techniques as a means of determining specific sugars and polysaccharides. The glucose oxidase method for glucose has been automated by Scobell et al. (632)and applied to the analysis of glucose in corn syrups. Fructose has been determined by de Mucciarelli et al. (41C) using mercuric acetate and zinc dust treatment followed by reaction with thiobarbituric acid with a sensitivity of 0.02 Fmole per ml in urine. Methods for the determination of fructose in the presence of glucose have been described by Nakamura (42C)using cysteine-sulfuric acid, and for fructose and glucose using anthrone or phenol-sulfuric acid ( 4 S C ) , the determination is achieved by Tschersich et al. (7JC) by the use of enzymes, and by Terentev et al. (71C) who combine optical rotation and reaction with sodium tetrahydroborate.


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The combination of glucose, fructose, and sucrose in potato tuber juice has been analyzed by Samotus et al. (51C) using dinitrophenol and anthrone methods. Methods for the determination of invert sugar in the presence of sucrose include an amperometric method after reaction with periodic acid described by Todt et al. ( B C ) , a turbidimetric procedure using mercuric iodide by Ludwikowska (S7C), and the use of colorimetry with 3,6-dinitrophthalic acid described by Emmerich (19C). Sucrose and glucose present together have been determined by Terent'ev et al. (70C) using sodium tetrahydroborate to reduce glucose t o optically inactive sorbitol and measuring optical rotation before and after the reduction step. Tateo (6SC) has used the different reactions to inversion, and saccharification to determine maltose, glucose, and sucrose with a colorimetric picric acid procedure. Gas chromatographic procedures for the specific reducing sugars and polysaccharides include the use of trimethylsilyl derivatives by Shaw (56C) for the analysis of potato sugars, by Clapperton et al. ( I S C ) and Otter et al. (46C) to analyze carbohydrates in wort and beer, by Davison et al. (14C) using myoinositol as internal standard for free sugars in plants, by Rumpf (49C) who suggests an improved silylation procedure, and by Martin et al. (S9C) who use this technique for the determination of sugars in distilled spirits. Chlorosilyl derivatives have been used by Capella et al. (9C) to determine the sugars in wine. Trifluoroacetyl poly01 derivatives of sugars have been prepared by Shapira (55C) and eliminate the problem of multiple peaks for each sugar and also provide derivatives with improved stability and volatility. Permethylated sugar alcohols and permethylated methyl glycosides are suggested by Ovodov et al. (47C) as derivatives for sugar analysis by gas chromatography. Cayle et al. ( I l C ) describe the use of trimethylsilyl derivatives of the sugar alditols to prevent the formation of anomer peaks; the procedure has been applied to corn syrup. Thin-layer chromatography has been applied to monosaccharides partially methylated with alkaline methyl sulfate by Vas'kovskii et al. (76C). Separations of galactose, glucose, and fructose from sucrose have been obtained on thin-layers of cellulose by Berger et al. (7c). Low temperature (-18 "C) thin-layer chromatography has been used by Avigad et al. (SC) to separate anomeric forms of monosaccharides. Studies of the thin-layer electrophoresis patterns of carbohydrates have been described by Stefanovich (6SC). A new dipping reagent for paper chromatograms using malonic acid and aniline has been proposed by Zentner (8UC), and

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the extraction of sugars from paper chromatograms and their determination by a n ultrasensitive ferricyanide method has been described by Guinn (2SC). An improved ion-exchange system for saccharides proposed by malborg et al. (77C) uses boric acid-2,3 butanediol buffers. Samuelson et al. (62C) have separated aldehydes, polyols, and sugars by a combination of two ion-exchange chromatographic techniques. Polarography of simple sugars after reaction with o-phenylene-diamine has been studied by Takagi et al. (66C). The UV absorption of sugars after reaction with strong sulfuric acid has been investigated by Houle et al. (26C), and the sensitivity of the procedure improved. Chandra et al. (1%') have proposed a new titrant, a potassium copper tellurate, for sugars. The ceric sulfate method for reducing sugars has been found by Bayonove ( E )to give different results on wine from those obtained by the Bertrand method. Nicol (44C) has derived a n equation relating boiling-point elevation to sucrose concentration in solution. E p y m e analysis has been used by Hoff maim (25C) to determine lactose in cagein compositions. Lactose in cheese hab been determined by Sutherland et al. (65C) using column chromatography and phenol-sulfuric acid colorinietry, and by Taylor (69C) using enzyme hydrolysis to glucose which is detected by the glucose oxidase method. The effect of clarifying agents on the determination of carbohydrates in milk has been exhaustively studied by Vizintaite (76C). The total sugar in confectioneries has been determined by Lur'e et al. (3%') using a dichromate colorimetric procedure. A study of methods for the total sugar in orange juice by Lifshitz et al. (36C)indicated that all five methods studied gave substantially the same results. When borate is present in a sugar solution Lin et al. (S6C) suggest that the standards used for colorimetry should also contain borat,e. Gas chromatography of mono- and oligosaccharides in potato tubers has been described by Kimura et al. (SSC), in starch hydrolysates up to maltoheptaose by Beadle (6C), and in beer, wort, and brewing syrups up to 15 glucose units by Otter et al. (46C). Levoglucosan in corn syrups has been determined by Kheiri et aE. (392) by gas chromatography and may serve as an index of the method of manufacture of the syrups. Thin-layer chromatography has been used by Washuettl (78'2) t o identify and determine u p t o trisaccharides in barley grain. A thinlayer procedure for maltooligosaccharides has been described by Shannon et al. (54C) using serial development in different solvents, and another system for these compounds has been described


by Haytko et al. (24C). Column chromatography using polyacrylamide gel has been used by John et al. (28C), and Dellweg et al. (15C) to separate monoand oligosaccharides. An automatic analyzer is used to monitor the column effluent. Turbidimetric and colorimetric estimations of polysaccharides i n flours have been found useful by Deschreider (16C) for analysis of commercial flours and irradiated flours. The trisaccharides of honey have been isolated and characterized by Siddiqui et al. (57C). A review by van der Bij (74C) covers the use of IR spectrometry and gas chromatography in the analysis of starch derivatives and hydrolysates. The use of enzymes for starch determination has been described by Donelson et al. (I7C, I8C) for wheat and maize fractions. Pancreatic a-amylase has been used by Stoll (64C) to analyze for starch in apples. Sal0 et al. (6OC) have used glucoamylase to determine starch in agricultural products. Corn, wheat, and starches have been analyzed by Libby (S4C) using dimethylsulfoxide solubilization and glucoamylase. Starch in grains and other foods has been determined by Friedemann et al. (2OC) using Rhozyme-S to hydrolyze the starch. As a n alternate to acid hydrolysis, Adkins et al. (IC)suggest the use of dextrin-1,6-glucosidase for starch hydrolysis. Calcium chloride extraction and measurement of optical rotation after precipitation of proteins is described by Roofayel (48C) for analysis of starch in grains. Bose et al. (SC) have proposed a formamide extraction and iodine-blue method for starch in sugar. A semimicro method for starch in a single cereal grain described by Banks et al. (4C) uses calcium chloride extraction and enzyme hydrolysis. Juliano et al. (SOC) report that low values are obtained on high amylase starches when analyzed by a starchiodine test. Amylose in starch has been determined by Hsieh et al. (27C) using descending paper chromatography with 35% perchloric acid. A spectrophotometric method for the hydroxypropyl group in starch ethers has been described by Johnson (&'9C), and a rapid N M R method for these ethers has been reported by Stahl et al. (6%'). The purification and identification of the hemicelluloses of milled rice have been described by Cartano et al. (IOC). The optical rotation of soya-bean-hull cellulose has been used as the basis of a method for crude fibre in dehulled soya beans by Anderson et al. (bC). Carbohydrates of the glycopeptides of whole milk have been analyzed by Sinkinson et al. (59C) using gas chromatography. Sugar phosphates have been separated on a cellulose ion-exchanger by Funasaka et al. (21C). An improved

method for the determination of the end point for the saccharification time of malt has been suggested by Silbereisen e t al. (58C) using a gypsum plate impregnated with iodine as a n outside indicator. Chitin in food is determined by its glucosamine content in a method proposed by Wieckowska (79C). Analytical procedures for gums in foods are discussed by Glicksman (22C). Thin-layer chromatography has been shown by Takeo e t al. (67C) to be useful for the identification of cyclodextrins. Improvements in the assay of dextran in cane sugar materials have been suggested by Keniry e t al. (31C ) . A rapid method for the determination of the total pectin in citrus product's has been proposed by Monselise (40C) using volume measurement of precipitated pectic acid. Methods for the determination of available and unavailable carbohydrates in foods have been outlined by Southgate ( 6 0 2 , 61 C) ; these procedures include soluble carbohydrates, celluloses, and lignin. COLOR

Thin-layer chromatography systems have been evaluated by Wrolstad (540) in the study of the anthocyanins of fruits using various adsorbents and solvent systems. Anthocyanin pigments in eight varieties of sour cherries have been examined by von Elbe e t al. (21D) using paper electrophoresis. Paper chromatography and densitometric measurement have been applied by Fuleki e t al. (230) to the analysis of the anthocyanins in cranberry products. Methods of characterizing and estimating anthocyanin compounds in black currant juice are described by Morton ( 3 9 0 ) . Paper chromatography has been used by Casoli e t al. ( 8 0 ) to determine the anthocyanins in eggplant. Anthocyanins in grape variet'ies have been separated by Conradie e t al. (140) and Schmidt-Hebbel e t al. ( 4 5 0 ) using thin-layer chromatography and by Lee et al. (330) using paper and thin-layer chromatography. Cellulose thin-layers have been used by Nybom (410) t o analyze the anthocyanins in black raspberries. Extraction, thin-layer chromatography and quantitation procedures are described by Hetmanski e t al. (290) for the analysis of the anthocyanins in rhubarb. Procedures for the detection of leucoanthocyanins in defatted soybean flakes described by R a n g e t al. ( 6 2 0 )use ethanol extraction, column clarification, and paper chromatography. Wildfeuer e t al. ( 5 3 0 ) have proposed methods for the determination of carotenoids in bakery products and raw materials using solvent extraction, spectrophotometry, and column chromatography. A rapid method for the determination of carotenoids in orange juice products has been presented by Bernath e t al. ( 5 0 ) using

extraction on a special chromatographic column. Methods for the determination of pigments in vegetable oils have been proposed by Box e t al. ( 6 0 ) using column chromatography and spectrophotometry, and by Srour (47D) using similar techniques. Sims et al. ( 4 6 0 ) have recorded specific constants for the calculation of pigments in wheat flour, and determined the absorptivities of the true pigments, lutein, and its esters. Methods for the determination of flavonoids in foods include the use of thin-layer chromatography and colorimetry described by Jablonowski e t al. (SOD),for analysis of sorrel, parsley, and lettuce; paper chromatography has been used by Szotyori e t al. ( 5 0 0 ) for the analysis of flavonoids in fruit juices; while Duggan (200) has described isolation, two-dimensional thin-layer chromatography and gas chromatography for examination of flavonol glycosides in apples, pears, and strawberries. Tea flavonols have been analyzed by gas chromatography of their trimethylsilyl derivatives in a procedure described by Pierce et al. ( 4 4 0 ) . Plant pigments have been fractionated by Johnson e t al. (310 ) using isoelectric focussing with various p H gradients. Pigments and pectin substances in tomatoes have been determined by colorimetry after extraction and clarification by Kurdzliieva e t al. (S2D). A study of methods for the determination of polyphenols in wort and beer by de Clerck e t al. (1SD) summarizes and describes procedures for thePe compounds. A system for the examination of the tannins of grain sorghum has been described by Bate-Smith e t al. (3D). Tannins in red wine have been analyzed by Diemair e t al. (170) by Sephadex chromatography. Counter-current dialysis of infusions of black tea has been used by Millin e t al. (380) to separate and classify the brown pigments, while Crispin e t al. (15D)have used acetylated Sephadex t o analyze the pigments in black tea extracts. A semiautomated method for the evaluation of tea infusions has been adapted by Casson et al. (9D) for the determination of polyphenols and color. A study of thc thearubigens by Brown e t al. (7D) has identified these compounds as polymeric proanthocyanidins. Sugar color has been fractionated by Gross ( 2 7 0 ) into fourteen fractions using paper electrophoresis, ion-exchange, membrane dialysis, and gel filtration. Paper electrophoresis covering a wide pH range has also been used by Greenshields e t al. (260) for the study of caramels. A procedure for separating and identifying nonforeign coloring agents in mayonnaise has been described by Benk e t al. ( 4 0 ) . T h e solid state infrared spectra of 55 synthetic food colors have been compiled by Evans e t al. (220). Procedures for the separation of

water-soluble synthetic food dyes have been described by Lehmann et al. (340, 351)). T h e estimation of coal-tar dyes in foods has been accomplished by Banerjee e t al. (20) using isolation on polyamide powder and paper chromatography. Paper chromatography has been used by Arino Espada e t al. (1D) to identify dyes in carbonated beverages. Dobrecky e t al. (180) have used radial paper chromatography to separate food dyes permitted in Argentina, and twodimensional paper chromatography for dyes permitted in the U.S.A. (19D). Circular paper chromatographic methods have been applied by Haiisens et al. ( 2 8 0 ) to the determination of water-soluble dyes, and by Luise ( 3 6 0 ) to t'he determination of oil-soluble synthetic dyes. Thin-layer chromatography has been used by Paris ( 4 2 0 ) to detect natural and artificial dyes after adsorption on white wool flocks or on fiber bands. The differentiation of some permitted and nonpermitted blue coloring chemicals has been described by Chapman e t al. (10D) using thinlayer chromatography. Polyamidesilica gel thin-layer chromatography has been described by Chiang for red food dyes (11D) and for yellow food dyes ( I Z D ) . Thin-layer chromatographic techniques have been used by Davidek et a l . (16D) for fat-soluble and watersoluble food dyes, and by Graham et al. ( 2 4 0 ) for synthetic food dyes. The use of polycarbonate-coated foils for use in the chromatography of food dyes was also invest'igated by Grahani et a l . (25D). Water soluble food colors have been identified by Perry et al. (43D) using thin-layer chromatography and cliff erent solvent systems, and by Takeshita e t al. (51D ) using microcolumii clironiatography with DEAE-Sephadex as well as thin-layer chromatography. For the examination of the food dyes alone, hlarmioii (37D) has described a method for 4-formylbe1izenesulfonicacid in FD 8: C Violet KO. 1, RIoteii e t al. ( 4 0 0 ) have determined 6-hydrosynaphthalene-2 sulfonic acid in color additives, and Stein has detected subsidiary colors in F D & C Blue No. 1 (480), and in Citrus Red No. 2 (490). ENZYMES

A sizeable review by Shipe and Uredderman (31E ) is coiiceriied with determining enzyme activity in foods and consumer products. Amnion ( 1 E ) investigated dehydrated media as models for frozen food enzyme behavior. Perten ( M E ) reported collaborative results for three a-amylase methods for cereal grains and flour. X viscometric method utilizing gelatinized potato st,arch mas employed by Tipples ( S S E ) to measure a-amylase activity in small samples. Purr et al. (28E) colorimetrically determined milk acetyl-esterase using indoxyl acetate and Kiermeier and


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Gull (19E) measured its 8-glucuronidase with phenolphthalein. Hirayama et al. (It%’) tested milk for alkaline phosphatase with a colorimetric disodium p-nitrophenylphosphate reagent. Copius-Peereboom et al. (9E) differentiated native and renatured milk alkaline phosphatase by TLC. This same author (8E) used agar-gel electrophoresis to survey various dairy products for phosphatase isoenzymes. Gunther and 13urckhart (IOE) reported a rapid colorimetric method for egg alkaline phosphatase. Cohen (“E) correlated residual acid phosphatase activity to canned ham cooking temperatures. Schormuller et al. (SOE) separated oat phosphatases on C M Sephadex C-50. Winter (S5E) described a simple gasometric method for catalase activity and applied it to several vegetables. Janzen et al. (15E) used a syringe to quantitatively measure oxygen evolved in a simple milk catalase procedure. Oxidase in seeds and flour was determined colorimetrically by Barber0 ( S E ), Bakowski et al. (2E) used the color method of Morris to give a contact test for perosidase activity in blanched vegetables. Winter ( M E ) measured the same by rate of guiacol color formation on paper. Ota e t al. (25E) reported variation of polyphenol oxidase activity in tea leaves as it affected quality. Buzun et al. (6E) purified polyphenol oxidase and galloylesterase from tea leaves using extraction and sephadex separation, A qualitative test for residual lipase activity ill oat products was given by Kazi et al. (18E),while Saito et al. (29E) determined milk lipase by the p H stat method. Lee and Wiley (21E) measured and partially characterized pectinesterase in apples. 130~11et al. (5E) evaluated dried pomace by determining its polygalacturonase viscometrically and a modified iodometric method was utilized by Mannheim et al. (22E) to survey fruit from Israel for this enzyme. Electrophoretic separation of fractions of isoenzymes of glutamic-oxalacetic transaminase allowed Visacki et al. (34E) and Stalder (S2E) to distinguish fresh and thawed meat. Meat heat treatment effects were studied using a carbesterase test by Pfeiffer e t al. ( 2 7 E ) . Gunther et al. (11E) used the 2,4-DNPH color to measure aspartate aminotransferase in egg yolk. Koji proteinases were estimated with a technique involving photographic film by Nakayama et al. (bSE,24E). Lawrence and Sanderson (2OE) modified Cheeseman’s method to provide a micromethod for rennet and other proteolytic enzymes. Starch-gel electrophoretic separation followed by nigrosine staining enabled Kaminski et al. (I7E) to detect wheat proteases. Joshi and Ganguli (16E) reported a rapid turbidimetric 76 R

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method for proteose-peptone, proteose, and peptone in milk. Janicek et al. (14E) used Folin’s reagent to follow trypsin inhibitor destruction through soybean debittering and Belitz et al. (4E) studied its thermal stability in peas and beans. Hochstrasser et al. ( I S E ) isolated and characterized plant protease inhibitors from potatoes. FATS, OILS AND FATTY ACIDS

A review of rapid methods for determining the total fat in foods is given by Smith ( I S S F ) and Schroeder (118F) reviews both the properties and typical test methods for shortenings and other food fats. A general survey of chromatographic applications to lipid analysis is given by Viswanathan (14%’) and methods of separating isomeric and natural mixtures of triglycerides by TLC have also been critically examined

(147~). Comparisons of methods are reported for determining fat in various milk products ( f S F , 44F) and Konev and coworkers (84F,85F) and Butov (25F, 16F) have made use of a fluorochrome (phosphine 3R) to measure the fat in milk products by fluorimetry. Aegidius (1F) was issued a patent for a system wherein fat in milk is measured by relating light transmission to concentration after first adding a Versene solution to chelate the casein micelles and homogenizing a t a constant pressure. A commercial instrument incorporating the principles embodied in the above patent was compared against the Babcock method in a collaborative study reported by Shipe ( I S I F ) . D e Toni ( S 9 F ) reports the use of turbidimetry for measuring the fat in milk with a continuous flow automatic system which incorporates ultrasonic energy to effect homogenization and Ashworth ( 9 F ) presents the relationship of turbidity per unit fat as it is affected by the degree of homogenization. Changes are tabulated in the relation between these two properties over the wavelength range of 375 t o 875 mp. Glass et al. (60F) describe a gas chromatographic method for simultaneously determining the fat and fatty acid composition of as little as 30 milligrams of milk by a procedure incorporating extraction, centrifugation, preparation of methyl esters, and GLC using methyl tridecanoate as an internally added standard. An indirect micromethod for determining milk fat by centrifugation is reported (537) which makes use of standard micro-hematocrit equipment. Free and bound lipids of hazelnuts, walnuts, and almonds have been extracted and chromatographically analyzed by Kaic and Tadic (80F) and the effects of the drying process on lean pork and chicken meats with respect to extractability of fat with various sol-


vents is reported by Kopecky et a1. (86F), with the highest yields of fat being obtained by extraction of freezedried meat with chloroform-methanol. A rapid refractometric fat determination is described for fish (12°F) and a semimicro gravimetric method for determining the total lipids in fish meal was developed ( 4 F ) which is reported to have similar accuracy to the A.O.A.C. method 22.037 while requiring much less time to perform. A slight decrease in ether extractable lipids has been found in coffee after decaffeination and roasting processes (29F). This is accompanied by other quantitative changes in fat composition. The use of complexometric reactions has been applied in determining fats in various foods. Bosch et al. (22F) report a method for determining fat in olive cakes by saponification, precipitation of the fatty acids with an excess of standard BaC12 solution, and titration of the excess barium with standard E D T A solution. A similar technique (56F),using an excess of magnesium ion in place of the barium, gave results for oil in olives and arachis oil in seeds (54F) which are reported to be more precise than those obtained by Soxhlet extraction. The complexometric titrations have the advantage of being applicable to wet samples. Magnesium complexometry has also been applied to the determination of oil in soybeans (58F). Use of excess Pb(K03)2solution with subsequent E D T A titration was used in similarly determining fat in fried potatoes and maize ( 5 r F ) , oil in olive marcs (55F), and for a variety of vegetable oils (91F , 928’). Bentz et al. (1I F ) have evaluated uqe of differential scanning calorimetry (DSC) for determining fat solids and present comparisons with dilatation and N M R methods for soft and hard fats. Use of DSC was also appraised by Miller et al. ( 1 0 I F ) for lard, soybean oil, and tallow. Wettstrom (148F) describes use of wide line N M R for the determination of the solids-to-liquid ratio of hydrogenated fish oil and K M R has also been applied ( S F ) to the determination of the oil content of maize samples and as a rapid and nondestructive procedure for estimating the iodine values and average molecular weight of oil in individual corn kernels (35F). Bosin and hfarmor (23F),also report use of N M R for determining the solids content of fats and state that the method described is more rapid, accurate, and universally applicable than the determination of the Solids Fat Index by dilatometry. The use of differential thermal analysis as a control instrument in the monitoring of the hydrogenation of edible fats is described (136F) and recommended for producing consistent product. A semi-automated thiocyanate method for determining per-

oxide values of !ipids was developed involving use of a n AutoAnalyzer (135F) and applied to salmon and menhaden oils. Gmcian el nl. (62F) report on the use of near-infrared spectrophotometry to determine the hydroxyl number of the unsaponifiable fraction of olive oil and olive oil cake. The method given is recomrnendcd for routine use as being faster and as accurate as chemical acetylation. Use was made of I4C by Seher and Josephs (13OF) to follow the behavior of methyl oleate through gas chromatographic analysis. It was reported t h a t anywhere between 5 and 2,501, of this ester is retained on a GLC column, depending on the polarity of the stationary phase. No holdup, however, was found for esters of saturated fatty acids. Radiochemistry was also used to advantage to determine the theoretical triglyceride content of vegetable oils (95F, 96F) by labelling samples with I4C tagged tripalmitin and analyzing the specific activity of eluates after chromatographic isolation of triglycerides on alumina columns. Refining losses were determined using this technique. Smits et al. (134F) describe a device for measuring the oxygen uptake by a n oxidizing fat based on compensation of oxygen used by electrolysis of water. Also described is a fluorescent light device which permits irradiation of oil samples by selected parts of the spectrum. Storage effects on the oil of milled maize fractions were measured (192;”) by a gas chromatographic technique with a relationship being established for content of soluble oil to storage time, temperature, particle size, and the atmospheric oxygen content. Use was made (28F) of the 2-thiobarbituric acid test t o classify the quality of olive oils into different grades of rancidity and a T L C method was reported for the rapid determination of fat rancidity using silica gel on aluminum foil (368’). T h e spectrometric determination of butterfat rancidity was directly related t o its absorbance at 280 mp (94F) and McManus (100F) used gas chromatography t o rapidly determine the oxidative stability of confectionary fats and oils. This was achieved by direct injection and comparison of fresh us. rancid samples. Artman et al. ( 7 F ) report on the chromatographic isolation and spectrometric characterization of substances produced at low levels in hydrogenated soybean oil by heating after first converting the oil t o ethyl esters, distilling and removing the urea adduct material. Use of refractive index is described (88’)as a means of objectively evaluating rancidity in fats and oils and Bishov et al. (18F) report a gas chromatographic method for continuous accelerated study of oxygen uptake in fats. A micro-titrimetric method for the determination of the

oxirane functional group has been developed (3OF) using quaternary ammonium halide and perchloric acid to determine compounds with about 2 microequivalents of available oxirane content. Fioriti et al. have determined the epoxy glycerides of Veronia seed oil by GC (4°F) after conversion t o 1,3dioxolane derivatives and also in conjunction with picration-TLC after isolation by column chromatography (46F). Karstens (82F) reports on a comparison of four methods for determining the epoxide-oxygen of fats and oils and concludes t h a t the method involving the potentiometric back titration of excess added collidine hydrochloride with AgN03 gives the highest accuracy of the methods tested. Franzke et al. (502;”) report a modification of the Fioriti spectrophotometric method claimed to reduce reaction time and increase sensitivity 30 to 40-fold. A system is given by Hammond (68F) for the complete analysis of complex triglyceride mixtures involving separation of the triglycerides into classes, forming diglycerides, fractionation of the diglycerides into classes, and analyzing these by their stereospecificity. Piretti and Strocchi (115F) report on the determination of triglycerides in dietary fats by direct gas chromatography on Chromosorb W HP coated with 3y0 OV-1. Persmark et al. (114F) describe a method for determining saturated triglycerides in fats by preliminary separation on argentated T L C plates, extraction of spots located with 2’,7’-dichlorofluorescein and then converting the glycerides into corresponding methyl esters for analysis by gas chromatography, An interesting innovation in the TLC-GC approach is given b y Kaufmann et al. (83F) wherein the T L C is performed on the inner surface of a quartz tube coated with Kieselgel. This tube, after effecting separation of lipids, is incorporated as part of the inlet system to the gas chromatograph and a moving zone oven is used to effect volatization and entry of individual components into the instrument. Separation is reported ( H F ) of saturated triglycerides by high resolution liquid chromatography on columns packed with cross-linked polystyrene beads and a method is described (149F) for the quantitative reaction of glycerides with ethanolamine, recommended as a means of estimating the lipid content of foodstuffs for serial analyses. Oette and Doss (1108’) described micromethods for rapid transesterification of lipids on T L C plates to prepare methyl esters for gas chromatographic analysis and use of pancreatic lipase is described (COF, 98F), achieving selective hydrolysis of olive oil for elucidation of the mean composition of f a t t y acids in the 2-position of the glycerides. A stereo-specific analysis

for some triglycerides is described (125F) which incorporates use of pancreatic lipase (to determine acids in the 2position) and G. candidum lipase (which specifically hydrolyzes oleic acid residues). Phosphatidylphenols are formed from the resulting diglycerides after T L C separation and use is then made of phospholipase A on these materials (specific for the residue in the 1-position of a 2-phosphatide). Products obtained are determined by GLC of their methyl esters and results are used to calculate the stereospecific location of the acid residues. Rajiah et al. (119F) describe the determination of glycerol after saponification by gas chromatography of its trimethylsilyl ether and Watts and Dils (146F) have also determined the mono- and diglycerides of lecithins from egg and bovine brain by gas chromatography of trimethylsilyl derivatives. Berner (12F) reports a TLC method for the specific determination of mono-, di-, and triglycerides by extracting and saponifying separated spots and then applying an enzymatic method to the determination of the liberated glycerol. A comparison is made (14F) of enzymatic glycerol determination with chemical methods and the former was judged to be more reproducible and selective. Biernoth (16F) describes the use of TLC and densitometry to quantitate glycerides in a method using multiple solvents for separation and S02C12vapor for locating spots. Blum et nl. (20F) describe a gas chromatographic procedure used to determine the glycerol, mono-, and diglycerides in emulsifiers, shortenings, and other materials after conversion t o the trimethylsilyl derivatives and measuring peaks against a cholesteryl acetate internal standard. Franzke and Strandt (518’) describe and critically examine several titrimetric methods of determining mono-, di-, and triglycerides. Litchfield (90F) reports on the analysis of Ephedra nevadensis seed fat by consecutive liquid-liquid partition and gas chromatography, listing the isolation of 30 triglycerides and the identification of 16 fatty acids from these triglycerides. Bandyopadhyay (10F) details a method for estimating saturated triglycerides in fats by argentation thin-layer chromatography and Harrison et al. (“OF) report on the determination of the fatty acid composition of chocolate fats by GLC. A urea fractionation procedure is proposed (7°F) for concentrating those esters of cocoa butter with similar GLC retention times in separate fractions for determining minor components. The main components of the hydrocarbon and oxygen containing fractions of hop oil in wort were identified by GLC (13%’) and Wood (1502;”)has applied temperature programmed GLC to the trimethylsilyl derivatives of wheat flour lipids t o

ANALYTICAL CHEMISTRY, VOL. 43,

NO. 5 ,

APRIL 1971

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investigate the changes occurring during bread making. Silver nitrate thinlayer chromatography was used (318’) as a vehicle for detecting rearrangement reactions of triglycerides and use of preparative TLC is described by Clayton e t al. (34F)for the identification of wheat flour lipids. Graveland (6SF, 64F) presents a combined TLC-GLC method which is applied to the quantitative analysis of lipids from as little as 3- to 9-mg samples of wheat flour and dough. I n order to minimize degradation, methods have been developed (99F) for low temperature anaerobic extraction of free and bound lipids from wheat flour. Privett e t al. (11827) describe the results of analysis of the lipids from various milk products by extraction, TLC, column chromatography, I R spectrophotometry, and liquidliquid partition. Brewington e t al. (248’) describe the application of combined GC-AIS analysis to the identification of new components in milk fat and a rapid technique for preparing milk fat methyl esters is given ( S S F ) which employs an essentially nonalcoholic solution. DeMan (37F) reports that traces of moisture in milk fat may prevent preparation of methyl esters by the sealed tube method, which is described, and he also reviews methods and results (38F) which have been applied to analysis of milk fat fractions. Hadorn and Zuercher (66F) describe the systematic development of a universal method for the gas chromatographic analysis of edible fats and oils and present an application in determining milk f a t in fat mixtures. Luddy et al. (9%’) present a rapid technique for the quantitative preparation of methyl esters of butter fat and other fats and Matsui e t al. (97F) describe the GLC analysis of triglycerides in milk products. The latter place residues from an ammonia-solvent extraction directly in the 400 “C glass inlet of a gas chromatograph and then perform the analysis with the column temperature programmed to 320 “C. Fricker (5”) reports on the fatty acid composition of lipids in potatoes as determined by GLC of the methyl esters, with independent data given for peel and flesh. Golodova (61F) proposes a method for determining the fatty acid composition of vegetable oils with the aid of potentiometric hydrogenation, showing a dependence of the amount of absorbed Hz throughout the course of catalyst potential change on the iodine value of the respective oil. Gas chromatography is employed in the determination of fatty acids of brandy and wine after formation of the ethyl esters (65F) and for determining the free fatty acids in cheese (7dF) after extraction, neutralization, and lyophilization with the GLC step being performed on the corresponding methyl 78R

esters. The lyophilization step is reported to improve recoveries of C&, acids. A comparison of methods to determine the free fatty acid content of butter is reported (74F) and Inkpen e t al. (75F) report on the determination and comparison of extractable and “bound” fatty acids in wheat and wheat products. Iverson (76F) describes a programmed temperature GLC technique for analyzing trace amounts of fatty acids, outlining principles to be followed rather than presenting a generally applicable method and a correlation of fatty acid structure with preferential order of urea-complex formation is also given (78F). A single step photometric micromethod has been developed ( S 2 F ) for the determination of f a t t y acids in lipids using rhodamine 6 G reagent in benzene solution, and Dudzinski (41F) describes a spray sequence for reagents for detection of free fatty acids separated by TLC. A rapid method described for the detection and determination of free fatty acids and other organic acids on TLC plates (41F) was applied to a lipid extract from mushrooms. A chromatographic method for separating and determining the higher fatty acid monoglycerides of oils according to chain length and unsaturation is reported ( I 08F) wherein mixtures of monoglycerides obtained by high temperature glycerolysis were separated by reversed-phase partition paper chromatography. Durocher e t al. (437) describe a rapid column chromatographic method for separating long chain fatty acids from neutral lipids and Franzke e t al. (49F) describe a simple method for converting the P-keto-fatty acids of milk to the corresponding methyl ketones prior to analysis by paper chromatography as the dinitrophenyl hydrazones. Arkima ( 6 F ) reports on the application of gas chromatography in determining fatty acids steam distilled from bottom fermented beers and stouts and a combination of silicic acid chromatography with gas chromatography was used ( I F ) to obtain the fatty acid distribution in cod fish lipids. Horvat e t al. (718’) have analyzed the acids formed from the autoxidation of methyl linoleate by combined GC-MS. The determination of nonpolar dimeric fatty acids in fats and oils was accomplished using T L C on Silica gel G to separate methyl esters which were then quantitated by densitometry (178’). Studies with I4C labelled fatty acids showed this method to be capable of recoveries of about 90%. Use of catalytic hydrogenation is reported (67F) as a n aid to the identification and determination of unsaturated fatty acids by GLC. The establishment of double bond positions in monounsaturated fatty acids was accomplished (6F) by combined GC-MS analysis using a packed column and a


He separator. A method is given (137F) for the separation and identification of the geometrical isomers of octadeca-9,ll-dienoic acid in food lipids by GLC and parameters are also reported for the GLC analysis of propane1,2-diol fatty acid esters in shortenings containing mono- and diglycerides (1,948’). Use of mass spectrometry is reported for location of double bonds in ethylenic acids ( 1 4 I F ) , establishing double-bond position in poly-unsaturated fatty acids (107F) and for analysis of isomers of monounsaturated fatty acids of vegetable oils (162F). Strocchi et al. (1S8F) have devised a GLC method for separating and identifying geometrical isomers of linoleic and linolenic acids for use on vegetable oil lipids using an Apiezon L coated glass capillary column and Pohl and coworkers (116F) describe a micromethod for separation and oxidative cleavage to identify polyene fatty acids by TLC and GLC. Privett et al. (117F) make use of high vacuum fractional distillation for separating complex mixtures of methyl esters of polyunsaturated fatty acids, employing a mixture of long chain acetates as a carrier to reduce artifacts through a spinning band column and monitoring distillate with GLC. The fatty acids in yeast heads were determined ( l 2 Z F ) by forming their p bromophenacyl esters after isolation b17 counter-current distribution. Korver and coworkers (87F) present a n improved version of the alkaline isomerization method for determining the linoleate and linolenate in edible oils and use of the salts of cobalt, copper, nickel, and mercury is described as spotting reagents in the paper chromatography of fatty acids (1408’). Huang et al. (73F) describe a procedure for determination of dimers and polymers in heated fats and oils by sublimation after formation of methyl esters from the fat and a GLC method is given for determining the nonglyceride esters present in sansa olive oil (104F). A method for analyzing gasliquid chromatograms of silylated monoglycerides and lactoylated monoglycerides is given by Neckermann e t al. (106F) and Montedoro e t al. (102F) describe methods for determining the phenolic antioxidant materials present in olive oil by TLC on Kieselgel G-50 plates. Vilicic e t al. (142F) have determined the phenolic antioxidants present in sunflower seed oil by TLC, with the spots developed by use of 2,6-dichloroquinonechlorimide being extracted with ethanol and measured spectrophoto.metrically. The GLC determination of lactones in heated pork fat (1458’) and in various meat fats through processing (144F) is described. GLC is also used in the analysis of long chain f a t t y alcohols in fats and oils after formation of their trifluoroacetyl and trimethyl-

silyl derivatives (79P). Isolation and analysis of hydroxy compounds in milk lipids as their pyruvyl ester 2,6-dinitrophenyl-hydrazones is given (1S9F) and Wurziger et al. (151F) report on the T L C separation and colorimetric determination of 8 phenolic substances obtained from “coffee wax” found on the surface of coffee beans. The analysis of isoprenoid hydrocarbons and fatty acids by a combined GC-MS technique is described (45F) and Hansen (69F) reports on the isolation and identifiration of 4,8,12-trimethyltridecanoic acid from butterfat. GLC was used t o determine cyclopropenoid fatty acids in Sterculia foetida oil (126F) and various other seed oils (120F) and Rosie et al. (12%’) describe a titration method for determining cyclopropenoid acids using hydrogen bromide. Gelpi and Oro (59F) report a method of analyzing isoprenoid hydrocarbons and fatty acids in shark liver oil products as determined by combined GLC-MS. Karleskind (81F) describes the application of T L C to the fractionation of nonsaponifiable matter employing oversize plates and horizontal movement using a special apparatus. T L C is also used to analyze the products obtained in the “degumming” of corn sprout oils (48F) and for analyzing the unsaponifiable matter of butter (88F) by two-dimensional TLC. Sterol acetates isolated from vegetable oils were analyzed by a T L C procedure (129F) and Mordret ( I O S F ) describes a procedure for the direct analysis of sterols in rapeseed oil by GLC. Capella et al. (27F) report on the analysis of rapeseed oil unsaponifiables by combined GLCMS and the chromatographic determination of free and esterified sterols from various wheat lipids has also been reported (15F). Renkonen (121F) describes the analysis of lecithin from herring b y fractionation on T L C after hydrolyzing with phospholipase C and acetylating to give the diglyceride acetates. Parsons and Patton ( I 1 S F ) report the analysis of polar lipids from milk by two-dimensional T L C , and T L C is also applied ( 1 1 2 F ) to the identification and quantitation of phospholipids in cocoa beans. Parinov (111F) gives a method for extraction and photometric determination of choline containing phospholipids in foodstuffs, and the phospholipids of corn and oat grain have been determined by T L C on silica gel plates (109F). Nakanishi et al. (105F) describe the analjrsis of milk fat phospholipids and T L C and column chromatography were used by Lepage (89F) to determine the phospholipids of white potato tubers. FLAVORS A N D VOLATILE C O M P O U N D S

A review and discussion of gas chromatographic applications to the analysis

of food odors is presented (186G). Teranishi (169G) and Scott (149G) describe recent advances in chemical and instrumental methods of flavor analysis. Weurman (185G) reviews techniques used for isolation and concentration of volatile compounds in food and discusses the important variables t o be controlled. Solms (156G) reviews flavor compounds with emphasis on those determined in meats and vegetables and Pilnik (1SOG) reviews the technology of aromatic and flavoring substances isolated from fruits and margarine. Dastoli and Price (SbG) describe a n objective method for measuring bitterness or sweetness by extracting and solubilizing portions of papillae from animal tongue tips (“sweet” chemoreceptors) and palate regions (“bitter” chemoreceptors). These are then reacted with the material to be tested and intensity is monitored by measuring the refractive index of resulting solutions. Strocchi et al. (167G) have followed the transformation of flavor during food dehydration and storage and describe a column chromatographic method for separating volatile compounds. Measurements made during the drying of liquid foods (115G) established factors determining aroma retention and Saravacos and Moyer (I4SG) measured the volatility of some flavor compounds through freeze drying in order to define optimum conditions for maximum flavor retention. A desiccator method is described by Maier (104G) for determining sorption curves of volatile aroma constituents in foods. A gas chromatographic method (1OSG) is presented for determining the heats of sorption of volatiles on selected food components and a spectrometric study is reported (102G) of the sorption of volatile substances on thin films of food. Issenberg (78G) describes a gas chromatographic apparatus used to measure sorption isotherms at low water activities and suggests the method for measuring interactions of volatiles with noiivolatile food constituents. Gottauf (66G) describes a n improved head space technique for the determination of aroma substances in food, and analysis was made (74G) of the pyrolysis products of a number of carbohydrates, proteins, and amino acids. Practical observations were given on the use of mass spectrometry for flavor research, particularly in conjunction with gas chromatography (77G, 7‘9G) and Miethke (117G) describes the use of automatic head space GLC in food control analysis. A procedure for effecting separations of volatiles from solids in the injection port of a gas chromatograph is described (96G) and Nelson et al. (120G) describe the use of paraffin oil for the extraction and collection of volatile microconstituents in foods. A technique is described (6G) which details the application of direct spectrophotometry to the analysis

of paper chromatograms for quantitating flavor volatiles. A critical examination of the use of porous polymers (Porapaks) was made (111G) as applied t o the gas chromatography of some volatile components from fruit aromas, and use of GLC is described (176G) for determining allyl hexanoate in pineapple aromas, essences, and other foods. Volatile components of Smooth Cayenne pineapple were determined (56G) by GLC-MS, after extraction of pineapple essence with isopentane, using large-bore opentubular columns and a membrane-type interface. Ton (17bG) describes a method used to monitor the aroma of pears by GLC as i t varied during maturation and Creveling et al. (SOG) have determined volatile components of Bartlett pears by GLC in combination with IR, MS, UV, and N M R spectrometry; microozonolysis was used to establish positioning of double bonds. D o et al. (S5G) have analyzed the volatiles of peach fruit by GLC and compare the differences in volatiles of treeripened fruit with fruit t h a t was artificially ripened. Techniques are described (174G) for collecting banana volatiles and concentrating them prior to GLC separation and subsequent identification, and Romanenko (1S8G) describes a paper chromatographic method for determining naringen in grapefruit. Rymal et al. (140G) make use of low temperature distillation and methylene chloride extraction to obtain volatile extracts from canned orange juice for analysis by GLC and J R . This was done to monitor the juice for changes in volatile flavor constituents through storage at two temperatures. The components of coumarin derivatives from expressed lime oil responsible for its luminescence have been isolated and identified (94G) and the characteristics of lime oil of different geographical origins are compared. The nionoterpenes in the terpene fractions of tangerine and mandarin oils were separated and identified by GLC followed by I R spectrophotometry of the eluates condensed a t -76 “C (9G). Comparisons were made of these and other citrus oils. A rapid GLC analysis of the headspace over citrus juice was used in determining ethanol in fresh and stored samples (SSG) with a wide variation found between varieties and even between individual fruits of the same variety and harvest. Dougherty (S6G) presents a method for determining the water soluble volatile constituents of citrus products by distillation t o obtain the oil-free volatiles and then oxidizing these and determining the chemical oxygen demand. Differences in the composition of genuine lemon oil, fresh commercial oil, and one-year old commercial oil were established by GLC (52G) and MacLeod (101G) describes the rapid


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analysis of natural essences (such as lime oil, distilled peppermint oil, and expressed grapefruit oil) by combined flow-programmed and temperature-programmed capillary gas chromatography. A paper electrophoresis method was used by Maier et al. (105G) t o reveal the presence of limonin monolactone which is described as the nonbitter precursor responsible for delayed bitterness in certain citrus juices when (in time) i t is lactonized t o a bitter dilactone, limonin. A specific TLC assay method is also described (106G) for the determination of as little as 0.5 ppm of limonin in citrus fruit tissues and juices. Paillard (123G) has performed an analysis of apple aroma by GLC of the volatile constituents after first concentrating them on active carbon and Barrera Pinero et al. (13G) describe a procedure for concentrating fruit aroma carbonyls for gas chromatography by vacuum distillation followed by formation of the 2,4-dinitrophenylhydrazones and give results obtained by this technique for apple juice. The GLC determination of phenolic amines in fruit juices is described by Coffin (27G) and applied to orange and apple juices (found only in the former, not the latter). A comparison was made (S7G) of the headspace method with liquidliquid extraction for the handling of apple flavor components for GLC analysis and it was concluded that parameters of the latter technique were easier to control for achieving quantitation. GLC was also used (38G) to monitor the flavor compounds in apples during growth and storage with studies made of 121 substances from five apple varieties. Fang-Yung et al. (48G) describe a spectrophotometric method for determining hydroxymethylfurfural in apple juice, with its presence described as being possibly due to the reaction of fructose with amino acids during heat treatment of commercial, pasteurized juice (none is found in fresh juice). A GLC-RZS combination was used (65G) to identify 66 components from Gravenstein apple essence with two types of separators being tested (ix., sintered glass and membrane types). Gasco et al. (60G) report that approximately 300X concentrations of fruit juice aromas (apple, pear, or blackcurrant) could be effected without modification by use of vacuum distillation a t room temperature and present GLC data to support this view. A method (71G) is given for the GLC determination of maltol and ethyl maltol in apple juice, both directly and by use of the corresponding trimethylsilyl derivatives, using 2,6-dimethyosyphenol as an internal standard, and GLC has also been used for demonstrating the presence of hexyl 2-methylbutyrate in aroma from Golden Delicious apples (81G). X a r t i n Mira (11OG) describes a system 80R

used to establish differences between two apple varieties by GLC, using 4 columns of different polarity after first concentrating the juice by “flash” distillation. The GLC-MS identification of sixteen volatiles from Evergreen blackberries is described (146G) following extraction with ethyl chloride and a similar investigation used in conjunction with sensory methods sufficed to identify the 3 major aroma constituents of bilberries (179G). It was established that a solution of these 3 compounds produced odors similar to the original bilberry juice. The aromas of American cranberries (5G) and lingonberries (4G) were also examined by GLC-MS analysis with 43 components identified from the former and 44 from the latter. Kuusi et al. (92G) have measured and characterized the aromas of blackcurrant varieties and their juices by aroma number and GLC analysis in consort with organoleptic evaluations and concluded that the quantity of aroma can only be reliably evaluated for those cases where the quality of aroma is similar. Ferretti et al. (50G) have made use of GLC combined with I R and MS data of isolates to identify forty compounds produced by browning reactions in a lactose-casein model system after extraction of products in CH2C12. Wong et al. (189G) describe a method for the extraction of flavor compounds from cheese, using acetonitrile, which does not extract interfering fat and describe use of same on Cheddar cheese, Blue cheese, and heated milk fat. An enzymic determination of acetaldehyde in starter, yogurt, and butter is given (177G), and GLC was used to identify the volatiles contributing to harsh flavor in peanut butter ice cream (168G). Scanlon and Lindsay (147G) present a sensitive electron capture GLC procedure for determining the diacetyl content of milk, reporting t h a t the method was found to be rectilinear from 0-160 parts per lo9. Capillary gas chromatography was used by Siek et al. (154G) for the semiquantitative analysis of fresh sweet-cream butter neutral volatiles (49 compounds identified and estimated) and approximately 100 volatile compounds from milk-fat steam distillates were identified by preparative GLC and MS after a vacuum steam distillation and ether extraction of the distillate (15SG),with heated and stored samples found to have more volatile compounds than did fresh cream. Compounds associated with the “gluey” flavor of stored casein were identified by Ramshaw et al. (134G) using GLC-MS techniques, and Parks et al. (126G) have also identified 6-trans-nonenal as being the compound responsible for the offflavor of foam-spray-dried milk (flavor threshold reported to be less than 0.07 ppb in fresh whole milk). Liebich et al. (97G) describe the GLC-MS


analysis of volatile flavor components of two types of Cheddar cheese and Cheddar cheese powder, and a technique is given (88G) for the separation of volatiles from steam deodorized milk fat into lactones, free fatty acids, and nonacidic compounds. An illustration of the effectiveness of this technique is given by use of GLC before and after separations have been effected. Kinsella (86G) reviews the flavor chemistry of milk lipids, and a GLC method is given (63G, 64G) for determining the volatile amines of salmon caviar and cheeses (62G, 65G). Forss (57G) presents a review of recent advances in analysis of flavors of dairy products and Metwally (116G) describes a GLC method for use both in determining carbonyl compounds and for measuring the effect of spray drying on the flavor of cheese. The carbonyl compounds of ghee flavors have been isolated and characterized (80G)by TLC after steam distillation and formation of the 2,4D N P derivatives and Ciblis (24G) has described headspace GLC determinations of diacetyl and acetoin as these relate to flavor, keeping quality and microbiology of ripened cream butter. The identification and determination of Z-furaldehyde in sterilized concentrated milk samples by a GLC-1LIS technique is described (8G) and related to storage and flavor data, and Poznanski et al. (131G) have defined the free fatty acids of Edam cheeses of different qualities by GLC analysis after preparation of their methyl esters. Palo et al. (125G) have described the determination of the C2 to C18 fatty acids of milk and milk products by GLC without esterification using a column packed with 10% polyoxypropylene glycol adipate and 1% Hap04 on Celite 545. Smith and Brown (155G) describe a GLC method for determination of isopropyl alcohol in solid fish protein concentrates wherein the dry sample (4-10 mg), sealed in a melting point tube, is heated a t 180 “C in the flash heater of a gaschromatograph and Sasaki e t a l . describe techniques for determining the volatile hydrocarbons (144G) and volatile, neutral, noncarbonyl oxygenated compounds (145G) of dried bonito by extraction and GLC separation. A colorimetric method for the determination of capsaicin in the fruit of Capsicum annum L . is given ( l G ) , employing a modified Buchi and Hippenmeier method and Jonczyk (8dG) critically compares five methods for determining capsaicin in capsicum fruit. Morrison (118G) presents a GLC method for determining capsaicin and suggests from data obtained t h a t there is a possible correlation between these data for various samples and the organoleptic Scoville Heat Value. A T L C method is given for the determination of capsaicin in spice paprika (167G),

and a colorimetric method is described (150G) for determining trace amounts of the pungent constituents of black pepper (piperine, chavicine, and piperettine). Stahl and Wagner (168G) make use of a thermomicro separation and application technique (TAS procedure) and T L C to separate and identify the characteristics of saffron, and a combined GLC and T L C sequence is described (159G) for differentiating the geographic origin of spices. Lawrence (96G) has applied a T L C technique t o determine the botanical origin of the cinnamons of commerce. A qualitative GLC study of isothiocyanates in rapeseed mustard grains is described by Rigolier (ISGG), and Kojima et al. (87G) have also used GLC to determine the aromatic components of wasabi (Japanese horseradish). Buttery and coworkers (17G,2OG) describe a vacuum steam-distillation-continuous extraction technique which was used to isolate volatile components of bell peppers for subsequent identification. Gas chromatography has been used to characterize steam volatile constituents of carrots (16G) and potatoes (19G) with subsequent identification being made using mass and IR spectrometry. Deck (S4G) has determined the identity of 53 potato chip flavor volatiles by use of GLC retention time data, IR, and mass spectrometry, and the isolation and identification of 6,10,14-trimethylpentadec-5,9,13-trien-2-one (18G) and 2,6- dimethylundeca - 2,6 - dien - 10 -one (15G) from tomato volatiles is also described. Guadagni and coworkers (69G, TOG) describe a statistical relationship which indicates the possibility of using MesS analysis as a n indicator of aroma intensity in canned, heat-processed tomato juice. N’elson et al. (121G) describe the measurement of tomato volatiles partitioned into oil, stripped with a n inert gas, and trapped at low temperature. These were then analyzed by GLC-LIS techniques and effects of variety, processing, and storage were studied. T h e composition of tomato aroma has also been analyzed by other workers using GLC (178G) and GLC-MS (14SG). Balboni et al. (10G) describe a n apparatus for the direct collection of volatiles from meat with recoveries ranging from 86 to 95y0 and Grosch (67G) describes a n analytical procedure based on chromatographic methods (gas, column, and thin-layer) to determine the carbonyls of food after formation of 2,4-DNP derivatives. “Catty” odors in foocls are reported to be due to the presence of 4-mercapto4-methylpentan-2-one (127G), detected and identified by use of GLC-MS, and Champagne et al. (21G) have used a similar approach in the identification of the volatile components of beef and pork fats. Watanabe et al. (182G)

describe the extraction and identification of volatile acidic compounds in heabdegraded pork fat, and Chang et al. (22G) describe the GLC analysis of 2,4,5-trimethyl-3-oxazoline and 3,5dimethyl-lJ2,4-trithiolane in the volatile flavor of boiled beef. Column and thin-layer chromatography were used by Mabrouk et al. (99G) in sequence to isolate the intramuscular polar lipids of nonaqueous beef flavor with identifications being made by use of Rf values, specific staining reagents and IR. Work was also performed in the extraction and Sephadex fractionation of beef flavor precursors (98G) with comparisons made of the precursor content of different muscle tissue. Yamato et al. (192G) describe the analysis of volatile carbonyl compounds from heated beef and a comparison of methods (44G) for isolating free aldehydes from autoxidized triolein, trilinolein, and trilinolenin supports the Lea and Swoboda vacuumdistillation method as the most useful A paper chromatographic method. method for separating and determining alkyl methyl ketones in fats is described (58G), and Sandoval and Salwin (142G) report on their use of headspace GLC to monitor effects of decomposition and freeze-drying on aromas of beef and strawberries. Hobson-Frohock (75G) reports on the use of molecular sieve 5.4 in the separation of the flavor volatiles of cooked chicken prior to analysis by GLC-&IS. A procedure is described (9SG) for the separate measurement of the volatile and nonvolatile “mustard oils” from cabbage with isolation of individual compounds achieved by paper chromatography and Freytag and Ney (59G) report on their work in the extraction and T L C analysis of asparagus aroma , demonstrating the occurrence and origin of dimethyl sulfide. A spectrophotometric method for the determination of oleuropein in olives is reported (29G), and the analysis of canned onion flavor by GLC (2SG) and onion oil by T L C (12G) is also reported. The formation of volatile carbonyl compounds with strong odors was established as being produced in peas by enzyme activity on linoleic and linolenic acids, using GLCM S for analysis of the 2,4-DNP derivatives (68G). Tolboe (171G) describes a technique for separation of volatile oxidation products in edible fats using vacuum distillation at 80 “C and 10-5 mm. The recovered volatiles are determined colorimetrically after collection in a cold trap. The frying of moist cotton balls was used as a procedure (19SG) to produce decomposition of frying oils under controlled conditions prior to analysis of developed acidic components and Evans et al. (47G) describe a technique for monitoring edible oil quality by GLC measurement of the thermal release of pentane.

Zanin (194G) suggests a method for evaluating vinegar quality by IR analysis on extracted flavor and colorimetric procedures are given (113G) for the determination of diacetyl and acetylmethylcarbinol in vinegars. The volatile flavor substances in some clover species have been analyzed by Honkanen et al. (76G) by GLC-MS and various polyphenols present in vinegars have been elucidated ( 1 4 G ) by paper chromatography. Ethyl vanillin isomers were determined by gas chromatography (165G) and a T L C method is described for the detection of p-hydroxybenzyl alcohol in vanilla (1S2G). Trachman (173G) describes a GLC method for determining alcohol in beer and Sterk (161G) presents an NMR method for determining ethanol in aqueous solutions and methanol in ethanol. Owades et al. (122G) describe a direct colorimetric method for determining aldehydes in alcoholic beverages, and the estimation and identification by colorimetric analysis of phenols in malt from peat-fired kilns is reported by Macfarlane et al. (100G). Colorimetric analysis is also applied to the estimation of nonflavonoid phenols in wines (QIG), and to the determination of 5-hydroxymethyl-2 furaldehyde in sherry and grape concentrates (114G). GLC analysis was applied to determining phenethyl alcohol in beer (45G), to determining volatile sulfur compounds in beer (4SG), in determining t h e phenolic compounds in beer after formation of the trimethylsilyl derivatives (SIG),and in analyzing the flavor aroma compounds of beer (7G, 4OG-42G). Techniques for concentrating volatiles in beer for further analysis were examined (124G) and T L C procedures are described for identification of carbonyl compounds in beer (139G). Steffen (160G) describes a colorimetric procedure for simultaneously determining H2Sand volatile thiols in beer, and Zenz et al. (195G) make use of GLC for determining the differences produced by irradiation of beer. Engan (46G) describes a GLC procedure for distinguishing between different types of malt, Aitken et al. (ZG, SG) describe the T L C analysis of beer bittering substances, and Hartley (7SG) used GLC to determine volatile hop constituents in wort. A technique employing trichlorofluoromethane for extraction and concentration of volatiles from ethanolic solutions is presented (72G) and Reinhard (1S5G) describes the analysis of cider by GLC. The determinations of volatiles in tequila and mescal (IOi‘G), of ethanol in spirits (229G), and of fusel oil in alcoholic distillates (84G) were also performed by use of GLC techniques. Kahn el al. (83G) have determined the composition of volatiles from whiskey by GLC-MS. AConway diffusion method is described (17OG) for the determina-


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tion of acetaldehyde in wine, and 140 volatile compounds were identified (39G) from grape musts and wines by GLC examination and measurement of retention times using 7 different packed columns. GLC was also used to determine the composition of muscat aroma (184G), the volatiles of Concord grape essence (162G) and the volatile components of wine distillates, wines, and grape juices (ISSG). GLC-MS techniques were used to determine the butaneboronate ester derivatives of hop constituents (151G) and for comparing the differences in aroma composition for Grenache juice and Grenache Rose wine (163G). A review of the chemistry of coffee aroma is given by Gautschi et al. (61G), and Winter et al. (188G) review thc volatile components of coffee aroma and the analytical methods used for isolation and identification of same. Other reviews of coffee aroma are given (55G, 180G, 185G). Stoffelsma et al. (164G) list 158 components of roasted coffee which they have isolated by GLC and have identified by spectral means. Pellizzari (128G) makes use of GLC-RIB techniques to identify plant phenolics (many found in coffee) as their trimethylsilyl derivatives, and Feldman et al. (49G) make use of analytical data obtained for green coffee in a n attempt to account for changes occurring during roasting. Methods for separation and analysis of nonvolatile flavor components are reviewed. A combined, stepwise GLC-TLC procedure is given (54G) for the analysis of constituents of coffee aroma. GLC has been applied to the analysis of teavolatiles from black tea (90G, 14lG), green tea (190G), teas grown in different terrains (191G), and for determining the volatiles from tea shoots (85G). Two ionone type compounds were isolated by repetitive GLC from tea (119G) and were then identified by spectral data. Steam volatile compounds of roasted cacao beans were determined by GLC (276G) and a review of chocolate flavor is given by Rohan (157G). Soybean milk volatiles were identified (41 positively) by GLC-MS (187G) including ethyl vinyl ketone which is reported (111G) to contribute to the raw bean odor and flavor. Manley etal. (108G) describe the GLC-XIS analysis of the basic fraction of hydrolyzed soy protein (identifying 10 pyrazines) . Streuli (166G) discusses and reviews roasting and baking aromas with respect to their isolation and identification and paper chromatographic methods are given for the determination of volatile carbonyl compounds in breads (89G, 109G). The volatiles occurring during breadmaking were trapped and determined by a GLC-&IS procedure (18G) after lyophilization and EtCl extraction. An isotopic dilution technique is de82 R

scribed for quantitation of flavor compounds in roasted peanuts (15G, 26G) and a relationship was shown to exist between GLC values obtained for the isobutyraldehyde produced in the roasting gases from peanuts and the roasting temperature used (11G). Major basic volatile components of roasted barley were analyzed by GLCMS (181G) and GLC was also used to separate the volatile moiiocarbonyl compounds of roast barley, followed by column and TLC purification and spectral identification (152G). Trace components of the flavor fraction of maple syrup were also separated and identified using GLC followed by LIS, with the identification of a number of previously unreported compounds (51G). IDENTITY

Data on the composition of foods, on the detection of foods in foods, and methods for establishing the genuineness of foods continue to increase in the literature. This section lists those studies which appear to be of general applicability. A method for identifying aperitifs described by Bouscharain et al. ( 1 5 1 ~lists ) the combinations of colors in the particular aperitifs. Samples of brandy have been examined gas chromatographically by Reinhard ( 6 1 H ) and differences between classes have been established. The probability of determining the source of illicit spirits by means of neutron-activatioii analysis, atomic absorption, and gas chromatography has been assessed by Hoffman et al. ( 3 6 H ) . Characterization of whiskey samples by Schoeneman et al. (6511) uses gas chromatography and UV extinction. A thin-layer chromatographic-fluorometric micromethod for sugar alcohols, invert sugar, and glycerol in beverages described by Tanner et al. (75t1) has been applied to wines and fruit juices. Franzke et al. (1811) have determined the theobromine and theophylline in matC, kola, and cocoa. Methods for the determination of the geographical origin of cassia and cinnamon have been developed by Voelker et al. ( 8 1 H ) , using thin-layer chromatography and differentiation of certain types of these spices has been achieved by Stahl et al. (71H) using a sedimentation procedure. The effects of sample aging on the validity of an electrophoretic method for the determination of casein in mozzarella cheese have been studied by Albonico et al. ( 1 H ) , who found an increase in interferences which causes a decrease in the sensitivity of the method. Charro Arias et al. (2ZH) have studied the fatty acids in fat from cheeses and noted differences between cheeses from cow, sheep, and goat's milk.


Computer methods have been used by I3iggers et al. (1111) to differentiate between Coffea arabica and Coffea robusta by means of gas chromatographic profiles. Chemical studies of coffees have been made by Derbesy et al. (2SZi) on the green coffees of Angola, by Pereira et al. (57H) on green and roasted coffees from Angola, and by ilvila Salazar et al. (311) on coffees in Ecuador. The effects of decaffeination on the carbohydrate components of coffee have been studied by Calzolari et al. (18H) and by Coassini-Lokar et al. (22H). The polycyclic aromatic hydrocarbons in decaffeinated coffee have also been studied by Calzolari et al. (19H). The theobromine and theophylline content in raw coffee and tea has been determined by Franzke et al. (2711). A comparative study of normal coffee beverage and Italian soluble coffee has been undertaken by 13arbera et al. ( 5 H ) , and the differences noted. Stauffer (72H) has reported new values by t'he digitonin method for the sterol content of eggs, flour, and semolina, and Wojtowicz et al. (84H) have tabulated values for the sterol content of durum flour and semolina for the calculation of egg in egg noodles. I n studies on the chemical composition of whole egg, Parkinson has studied the protein fractionation patt'erns of raw and pasteurized whole egg (53H), and the effect of staling and freezing (54H). The egg content of noodles has been determined by Silano et al. (6811) by quantitative analysis of egg proteins by disk electrophoresis. The determination of amino sugars has been used by Mueller et a l . (46H) to detect egg white in sausage products. Egg-white content in liquid egg-yolk has been determined by Ney (48H) by paper electrophoresis and measurement of the ovalbumin band. New factors for the determination of egg yolk conbent in egg liquids have been reported by Pelz et al. (56H). The variations in the ion-exchange chromatographic peaks from heated, frozen, and spray dried egg yolks have been studied by Seideman et al. ( 6 6 H ) , as have the species differences between chicken, turkey, and goose (67H). Sterol ester comparisons have been used by Bernaerts et al. ( 1 0 H ) to detect fresh wheat in edible egg pastes. Typical values and indexes of fatty acid ratios have been described by Lokar et al. (43H) for butter. The determination of butter fat in a fat mixture has been achieved by Phillips et al. (58H) using gas chromatography and butyric acid content. Differential thermal analysis has been used by Niiya et al. (49H) to detect foreign fats in butterfat. Tests for the purity of cacao butter described by Franake et al. ( d 9 H ) include detection of fat from shell by the reaction with 4-dimethylaminobenzalde-

hyde. A quality estimation of cocoa butter by the use of ultraviolet difference spectra has been given by Hadorn et al. ( S 5 H ) . Urea fractionation and programmed temperature gas chromatography has been used by Iverson et al. ( 4 0 H ) to determine the fatty acid composition of cacao-butter oil. The specifications of fatty components of eleven oilseeds have been compiled by O'Connor et al. (51H) for consideration by the Codex Committee 011 F a t s and Oils. Wolff (83H) has discussed the application of the analysis of the unsaponifiable matter to the determination of the composition of fats and fat mixtures. A thorough study of the chemistry and analysis of olive oil has been published, by Graciaii Tous ( S Z H ) including characteristics, analytical techniques, and minor constituents. Purity of sesame oil and olive oil and the response of these oils to cooling and heating D T A has been studied by Niiya et al. (5OH). Sesame oil in petroleum et'her has been found by I3ose (1411) to give a green color with hydrochloric acid. Vegetable oil (olive oil) in fish oil has been determined by Wurziger e t al. (85H) by cholesterol and sitosterol evaluation. A simplified electrophoret'ic method of identifying fish species has been described by Mackie (44H)depending upon the species-specificity of the separation patterns of the muscle proteins. Qualit'y indexes for fish and fish products proposed by Valencia et al. (791i) mention the measurement of hypoxanthine content as the most valuable index. A review of methods of estimat'ing fruit content in processed fruit products, and for detecting adulteration has been published by Kefford (#HI. Authentic data on the composition of several varieties of berries have been presented by Boland et al. ( I S H ) . Twelve samples of fresh elderberries have been analyzed by Taylor et al. (74H) for chemical constituents. The effect of irradiation on the chemical constituents in fruits and vegetables has been studied by Maxie et al. (46H). Studies on the composition of lemon, juices by Guenther et al. ( S 4 H ) show no differences due to origin of t8hejuice, but some changes are caused by processing. T h e analytical composition of authentic Florida orange juice has been reported by Floyd et al. (26H). ,4 method for the detection of blood orange juice in orange-juice concentrate has been described by Benk et al. ( Q H )using paper chromatography, and Sephadex separation. Pentosan content has been used by Benk (8H)to detect pulp and peel extract'ives in orange juice, and he also described a method for soya-bean extract in orange-juice concentrate ( 7 H ) . T h e nitrogen constituents of orange juice have been examined by

Beilomo ( 6 H ) on fresh samples and on storage and treated samples. The precipitin test and gas chromatographic investigation of the fat has been used by Castledine et al. @OH) to aid in the identification of meat in meat products. Wurziger et al. (86H) have examined the polyunsaturated acids of meats and shown that these may be used to identify the nature of the meat. A further study of lipids by Hubbard et al. (39H) includes analysis of the fatty acids of bovine, porcine, ovine, and avian species and a discussion of their usefulness in identification. A review of methods for the assessment of meat freshness by Pearson (55H) includes the suggestion that free fatty acids, total volatile nitrogen, and extract-release volume provide the best correlation with organoleptic findings. Characterization of meat proteins by polyacrylamide electrophoresis has been described by Skaare et al. (7OH) as a means of identifying meat from whale, bear, and horse. Studies of the detection of soya-bean protein and caseinate in meat products using disk electrophoresis have been made by Thorsen et al. (7513, 7 6 H ) . Thin-layer chromatography has been used by Tsvetkova (78H) for the detection of sodium caseinate in meat products. I n another method for casein and soya-bean protein described by Olsman e l al. (5211),separation is obtained by urea-starch gel electrophoresis. The orotic acid content of milk has been used by Brieskorn et al. (17H) as a measure of the milk content of milk containing foods. Electrophoresis on thinlayer polyacrylamide gel ha,s been used by Bret (16H) to identify pure milk, and milk mixtures of cow, sheep, and goa't milk, Gel electrophoresis ha,s been used by Aschaffenburg et al. ( Z H ) to detect one per cent cows' milk in goats' milk, and a similar technique has been used by Freimuth et al. (SOH) to detect goat milk in cow milk or in human milk. Indicators of the presence of ground cashew nuts or ground peanuts in ground almonds are suggested by Houlbrooke et al. (37H) to be calcium content and the clouding point of the oil. The effect of heat on the characteristics of oil and proteins from peanuts has been investigated by Varma et al. (SOH), and t,he effect of roasting on the stability of peanut proteins has been studied by Xeucere et al. ( 4 7 H ) . The free amino acids in potatoes have been determined by Bancher et al. ( 4 H ) using thin-layer chromatography after fractionation on Sephadex; characteristic patterns have been found for potato varieties. The amino acid composition of rice and rice by-products has been obtained by Houston et al. (38H). Characteristic differences in glucose syrups due t o manufacturing processes have been found by Trenel et al. (77H)

by gel chromatography. Analytical profiles of sorghum-cane and sugar-cane syrups have been studied by Johnson et al. ( 4 1 H ) , and identification in blends is not easy. Binard ( 1 2 H ) has summarized the various components in teas. A specific authenticity test for vanilla extracts has been described by Prat et al. (6011), using detection of resins and pigments by thin-layer chromatography. Amino-acid analyses have been obtained by Ewart ( 2 4 H ) on wheat, rye, barley, oats, and maize. h ratio of two protein components, determined by electrophoresis, has been shown by Garcia-Olmedo et al. ( 3 1 H ) to indicate the percentage of common wheat in a mixture. h disk electrophoretic method has been presented by Fabris et al. (2511) which differentiates durum wheat by-products and soft wheat byproducts. Different varieties of wheat have been characterized by various contents of proteins and gluten in the grain by Pokrovskaya et al. (59H). Electrophoresis using 7 -5% polyacrylamide gel has been shown by Silano et a / . (6911) to isolate an albumin fraction which is specific to soft' wheat. Disk electrophoresis has been used by Resmini (6211) to detect winter and summer wheat, and t o detect soft wheat products in hard wheat products ( 6 9 1 ) . Soft and hard wheat have been differentiated by gas chromatographj- by Vogel et al. (8WH). Soft wheat has been detected by the presence of sitosterol palmitate, and hard wheat has been found to contain cholesterol palmitate only in a method described by Salvioni (6411). Thin-layer chromatography has been used by Gruener et ala ( S S H ) to estimate the addition of soft wheat t o hard wheat by the determination of the sterol esters. INORGANIC CONSTITUENTS

Emphasis 011 instrumental methods of analysis for inorganic constituents of foods continue t o increase for reasons of speed, specificity, and sensitivity. This is especially so recently in light of the rising attention given to the role of trace element's in the diet from both the detrimental and essential points of view. The removal of the bulk of organic material without losing or obscuring the trace material of interest continues to be an analytical problem. Wendt ( 9 6 J ) suggested some improvements toward better speed and precision when ashing maple syrup. IlullerMangold ( 7 2 5 ) found that he could ash resistant carbon residues from starch using ammonium nitrate. Bowen ( I f J ) used a mixture of potassium and sodium nitrates to rapidly decompose samples with good recovery of most of the A flow-t'hrough elements tested. oxygen flask allowed Relisle et al. ( 7 5 ) to apply the Schoniger combustion to 10-gram samples. Fujuwara et al. ( 3 4 5 )


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showed the construction of an oxygen bomb for sample destruction. A digestion mixture employing sodium molybdate was found necessary by Harrison and Andre ( 4 0 4 to digest sugar beet leaves for mineral analysis. Frei (32J) used T L C to separate and analyze for trace metals in cereals. A rotatingdisk technique of direct reading spectrochemical analysis enabled Coeteer (19J) to measure Zn, B, Mn, Cu, Al, Fe, K, P, Mg, Na, and Ca in plant ash. Schiweck et al. (86J) described a polarographic method for heavy metals in sugars and other foods. A procedure for Mg, Mn, Fe, Cu, and Zn in marine shrimp was published by Knauer ( 5 4 4 . The use of an absorption tube by Hosogaki et al. (485) permitted measurement of 0,2-1 ppm of As in food by using atomic absorption. Lunde (665) analyzed marine oil phospholipids for arsenic with a neutron activation procedure. McLellan ( 6 8 4 claimed results superior to atomic absorption for barium using emission from a N20 flame and scanning in the assay of plant material. Melton e t al, (70J) proposed an atomic absorption method for boron useable down to 3 ppm in plant material. Boron in caviar was identified and measured with TLC and circumin colorimetric techniques by Brunstad ( 1 4 4 and the ensuing collaborative. study ( 1 S J ) reported. nerkh et al. ( 8 4 used a modified carmine method for boron in refined foods. An automated azomethine H procedure for boron WRS given by Basson et al. ( 6 4 . Calcium was determined by flame photometry with interferences suppressed by a radiation buffer by Lehmanii and Zook ( 6 d J ) . Foss e t al. ( S I J ) used atomic absorption for Ca in modified vegetable oils and calcium driers. The AOAC method was compared to a liquid ion exchange electrode for feed analysis in a study by Allen e t al, (2J). Calcium ion activity in milk was measured using selective electrodes by Muldoon et al. (715) and Kraemer et al. ( S S J ) , Cobalt was determined by oscillopolarography after dithizone extraction by Fabry et al. (285). The distribution of natural copper in milk was ascertained using neutron activation analysis by Samuelsson (84J). Burke et al. (15J) employed atomic absorption in a method for Cu and Ni in tea. Zn dibenzyldithiocarbomate reagent provided the basis for a colorimetric Cu method applicable to soya-bean oils for List et al. (65J). Popov e t al. (79J) and Deck et al. (21J) investigated colorimetric Cu methods for oils. A carotene interference in the colorimetric determination of Cu in milk was reported by Armstrong et al. ( 4 4 . Lead traces were isolated and concentrated from food with strontium sulfate by Flann and Bartlet ( 3 0 4 and Hoover et al. ( 4 7 4

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and quantified with colorimetry and atomic absorption, respectively. Okada et al. (’754 used bomb combustion and an absorption tube for lead traces in rice and tea. Intonti et al. ( 4 9 4 looked at P b traces in meat ash by emission spectrometry. Spark source mass spectrometry gave a detection limit of 2 ppb for mercury in apples in a method by Tong et al. (9OJ). An automated mercury determination by substoichiometric radioisotope dilution was reported by Rueicka e t al. (82J). Lidums e t al. ( 6 4 4 described the preparation of a homogeneous sample solution from heterogeneous materials such as fish prior to H g analysis. Kosta and Byrne (67J) gave their scheme for activation analysis of Hg a t the nanogram level. An oxygen bomb combustion prior to colorimetry gave Fujita et al. ( 3 3 4 good mercury recoveries. A radiochemical method for vegetables rich in calcium permitted Newburger et al. ( 7 3 4 to use neutron activation analysis for Mo and Wo. Ssekaalo et al. (895) developed a routine method for molybdenum in biological materials involving wet ashing and a, 2-amino-4chlorobenzenethiol color reaction. Hoffman e t al, ( 4 5 4 , Olson (76‘4, and Hall et ul. ($85) as well as Dickey et al. ( 2 2 4 with a ring oven procedure reported methods for traces of selenium utilizing fluorescence of the 2,3-diaminonaphthalene adduct. Colorimetry a t two wavelengt’hsavoided imi~urityinterferences in a method for selenium with 3,3’-diaminobenzidine hydrochloride by nomenech (83J). Rot’h and Gilbert ( 8 1 4 measured down to 3 p g of Ag per liter in wine using atomic absorption after a dithisone concentration. Flame photometric methods were compared to a sodium electrode for measurements in foods by Cameron and Delaney (I7J). Konrad (56J) found that CuCll gave the clearest milk sera for sodium and potassium flame photometry, Silicone compounds were analyzed in a n organic matrix using atomic absorption by Paralusz (775). A long T-shaped absorption tube allowed Okada et al. ( 7 4 4 to detect 0.1-1 ppm tin in canned fruit juices with this technique. Hayashi (425) also analyzed this range using square wave polarography. Stilbazo reagent was employed by Kobayashi et al. ( 5 5 4 for tin while Kirk et al. ( 5 1 4 used quercetin in his colorimetric method. The addition of citric acid permitted Mee and Hilton (69J) to analyze sugar products directly for zinc with atomic absorption. Bromide residues in vegetable foodstuffs were determined by Kretzschmann and Engst (59J, 6 0 4 as bromphenol blue. Brochon (125) described a bromide method producing eosine from fluorescein. A silver indicating electrode was used in a potentiometric


NO. 5, APRIL 1971

chloride titration for feeds by Sharpe (87J). A chloride specific ion electrode gave results agreeing with the Volhard titration for cheese samples for Holsinger et al. ( 4 6 4 . Vander Werf e t al. (93J) reported good results using iiQuantabsJ’ to monitor chloride in meat, fish, and cheese. Distillation and titration, with their own modifications, were used by Henry ( 4 3 4 and Klemm e t al. ( 5 3 4 in their fluoride analyses. A fluoride electrode measurement was recommended by Torma e t al. (91J) and Tusl (92J) for feeds. 13ernatonis e t al. (10J) described a kinetic method for measuring microquantities of iodine in milk, while Johansen et al. ( 5 1 4 used neutron activation analysis. Hanssen et al. ( S U ) studied conditions for H C N distillation from foods, and Gyorgy et al. (3YJ) measured cyanide with a selective electrode. Voogt (945) demonstrated the feasibility of select’ively determining nitrate in spinach suspensions with a selective electrode. Nitrate and nitrite in milk and its dry products were measured spectrophotometrical1y after a diazotization reaction by Manning et al. ( 6 7 J ) . Lembke et al. (635) reported a sensitive colorimetric method for nitrite in cheese. Elemental phosphorus has been directly determined using gas chromatography and a selective flame photometric detector by Addison et al. ( I J ) . Hashizume e t al. ( 4 1 4 formed the TMS derivative of orthophosphate prior to GLC analysis. Estrin et al. (ZSJ, $ 7 4 reported on phosphorus methods for fruits and the subsequent collaborative study. Phosphine has been measured using GLC and microcoulometric, thermionic, and flame photometric modes of detection b y Berck et al. ( Q J ) . A flame spectrophotometric micro method for sulfur in proteins was published by Gersonde (865). Trace sulfur in fat was combusted and ultimately determined as H2Sby Pippen et al. (78J), Cesium-137 in milk was counted after filtration through an ammonium phosphomolybdate bed by Jankowska (60J) and after Prussian blue coprecipitation by Wiechen (97J). Saiki et al. (83J) described a method for iodine-131 in milk. Manganese-54 in foods was determined by Davis et al. (20J). Sanderson ( 8 5 4 measured radium-226 and thorium-228 in food, soil, and ash by multidimensional coincident gammaray spectrometry. Radio strontium methods were described by Porter et al. ( 8 0 4 and Lahoud et al. (61J) capable of tolerating large excesses of calcium and zinc, respectively. Methods for carbon dioxide were reported for wine and champagne by Drawert ( 2 4 4 and for still and sparkling wines by Capt et al. (18.J). Hydrogen peroxide in milk was the subject of methods by Gilliland (36J) using horse-

radish peroxidase, and Ferrier e t al. (WQJ)employing TiCL and colorimetry. Free oxygen in foods and containers was determined coulometrically by Shvabeiiskii ( S S J ) . A modified Kipphan met’hod for oxygen in bottled beer wa8s given by Hiefrier and Burwig ( 4 4 4 . Dissolved and headspace oxygen were measured using a Clark electrode by Burroughs (16 J ) in a method for bottled juices, and using paramagnetic susceptibilit’y and polarography by Becker ( 6 J ) for preserves. Nitrous oxide and other canned food headspace gases were analyzed using GC with molecular sieve and Poropak Q columns by Elkins e t al. ( 2 5 J ) . Arikawa e t al. (SJ) studied optimum time ranges and ion effects in determining sulfite by the method of West and Gaeke. Zugravescu et al. (98J) prepared a test paper to estimate SOz in acid samples such as fruit juices. The determination of SO2 in soft drinks was automated by Walkley et al. ( 9 5 4 . MOISTURE

A review of methods for measuring the equilibrium relative humidity of candy products is given by Cakebread ( S K ) along with a discussion of the advantages and disadvantages of each method. White (19K) presents a critical review of chemical and physical methods for determining moisture in honey, and the results of a collaborative study ( 1 I K ) are given for determining soluble solids in tomato products b y refractive index after first treating them with a pectic enzyme preparation and filtering. A comparison is made (12K) of a direct GLC method for the estimation of water in st’arch with a n indirect method in which 2,2-dimethoxypropane is reacted with water, the acetone thus produced permitting the use of a flame ionization detector. Kuroi (IOK) provides a comparison of the Karl Fischer titration using formamide-methanol with the film method for determining moisture in caramel and sugar candy. I n the film method, a small bag of high density polyethylene is used with the drying then achieved in a vacuum oven. The bound water in dough was measured ( Q K ) by determining the water removable by ultracentrifugation and subtracting this from the total water. The bound water was found to decrease with increasing age of the dough. Spiess e t al. (16K) report on the measurement of water vapor adsorption isotherms for a number of dried foods and the adsorption rates of moisture by wheat flours have been related to physical, chemical, and baking characteristics by Cdani e t al. (17 K ) . Pelhate (1SK) describes a method of determining the thermodynamic state of water in wheat grains in order to predict its suitability for storage and Bosin et al. ( 8 K ) describe modifications made

to relative humidity equipment which reduce the time required for obtaining moisture equilibrium data. Results obtained using a commercial dried fruit moisture tester (employing the measure of conductance as it varies with moisture content) are compared ( 1 K ) with the A.O.A.C. oven method in measuring the moisture in prunes, and a statistical examination is given ( 6 K ) of data obtained by toluene distillation US. that of the Karl Fischer method for determining water in whole milk powder. A selenium dioxide hygrometric probe is described (16K) which is intended for use in measuring equilibrium relative humidities of foods in small containers and the use of a differential scanning calorimeter is applied ( 4 K ) for measuring the “freeeable” (Le., “free”) water in doughs. The possibilities of using near-infrared measurements at 0.977 micron for measure of water in liquid transparent foods are reported ( 7 K ), and a procedure is given for applying this to the measure of water in beer ( 6 K ) . Near-infrared spectrometry was also employed for determining water in dairy products ( 8 K ) after methanol extraction and on glycerides (18K) dissolved in chloroform. -4 study (14K) of numerous extractants for determining water by near-infrared spectrophotometry resulted in the recommending of dimethylphthalate as being the most suitable for food products t h a t will not react with this solvent. ORGANIC ACIDS

As in the past, all of the chromatographic techniques as well as distillation and extraction have been employed to separate acids from foods where a complex mixture of them usually exists. Gierschner (IYL), after study of alternative procedures, recommended distillation from a modified Woidich apparatus for increased recovery of formic acid from fruit juice. Sarudi (47L) also modified a distillation procedure to complete the process in one hour instead of four to five when he analyzed fruit syrups. Ledford (SQL)measured acetic, propionic, and butyric acids directly using GLC on porous polymer beads. Antonini et al. ( I L ) separated propionic and butyric acids from cheese b y T L C of their ethylamine salts. An automated enzymatic method for lactic acid determination was reported b y Cameron et al. (7L). Salwin and Bond (46L) determined lactic and succinic acids in foods by GLC of their propyl esters and Staruszkiewicz (61L, 5%) reported the results of the collaborative study of the method. Steinhauer et al. (6SL) employed their butyl esters t o determine them in frozen whole eggs. I n addition t o lactic and succinic, pyruric, fumaric, and citric acids were analyzed by GLC after reaction with

methanol-BFP in a paper b y Hautala and Weaver (2IL), Bethea (SL) used GLC measurement for free succinic acid extracted from eggs. Jurics (25L) used paper chromatography and densitometric measurement for succinic acid in fruits. Mayer et al. (341,) reported an enzymic method for lactic acid applicable to wine. Rebelein (4SL) described the effect of acetaldehyde combined with sulfur dioxide on a colorimetric measurement of lactic acid in wine. Moehler et al. (56L) separated fourteen acids from wine using Kieselgel column chromatography. These authors (S7L) also reported paper chromatographic separation of wine acids subsequent to column chromatography and they (S8L) also identified angliceric acid in wine. Patschky (COLI removed interfering pigments from red wine before applying the eiizymic citric acid method of Mayer and Pause. A simplified procedure for citric acid in wine and grape must was published b y Rebelein (4SL). A new fluorimetric method for micro quantities of cit’rateb y Guyon and Marks (19L) was based on quenching. Bruemmer (6L) investigated the utility of commercial T L C plates for determining organic acids important in baking. Fitelson (1%) detected fruit juice acids b y paper chromatography after P b precipit’at’ion and H1S regeneration. Bourzeix et al. (4L) used cellulose T L C to analyze for individual acids in grape juice and wine. Many authors have explored the GLC of volatile acid derivatives after preliminary separation from the food by P b precipitation. Li et al. (32L) precipitated a i O % methanolic estract and then regenerated with HzS before methylation and chromatography. Fit’elson et al. ( I S L ) formed the ThlS derivatives directly from the P b salts when analyzing vanilla extracts. Fernandez-Flores et al. (111,) employed a similar technique for fruits, and Johnson et al. (24L) for table syrups. Newly found carboxylic acids of brewed coffee were identified using GLC and spectrometric techniques by Woodman et al, (57L). Methyl esters of aliphatic and aromatic acids were formed by in situ pyrolysis of tetramethyl ammonium salts in a chromatographic inlet by Bailey (WL). Non-isomerized hop extracts were analyzed for CY and p acid distribution by Rigby and Stoffer (45L). Rehberger and Cuzner (44L) described spectrophotometric methods of analysis for CY and p acids in commercial hop extracts. Likens et ai. ( S S L ) recommended the inclusion of pyridine in the conductimetric measurement of hop CY acids to improve the end point,. Poe et al. (41L ) reported a colorimetric procedure for aconitic acid in sorghum juice, and Gupta, et al. (18L) modified the decarboxylation procedure of Ro-


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berts and Ambler to agree with polarography in the analysis of molasses. Trop et al. (55L)deteriniiied a-hydroxy acids in foods by TLC separation and manometric gas measurement aft,er separation. Schwartz et al. (49L)isolated and characterized vicinal diols, epoxides, and a-hydroxy acids by reaction on a periodate column and D N P H formation. The esters of 3-oxo-acids were quantitatively converted int'o alkyl methyl ketones prior to analysis as 2,4D N P H derivatives by Franzke et al. (I&). Individual a-oxo-acids in beer were methylated aiid separated by GLC by Harrison and Collins ( $ 1 ~ 5 ) . Sasaki et al. (48L) reported a simplified colorimetric method for levulinic acid in shoyu. Scopoletin was isolated from raw coffee by column and T L C and s h o m to fluoresce strongly, but has a different Ri value from aflatoxin according to Thier et al. (54L). Moellering et al. (89L) described ail enzymic determination of D-gluconic acid utilizing gluconokinase, Residues of branched decanoic acids in cot.tonseed and its products were detected by T L C after methyl ester formation of all other acids b u t sterically-hindered neodecaiioic acid in a paper by Mizaiiy (35L). The occurrence of 5-oxopyrrolidine-'2carboxylic acid in sterilized tomato juice was investigated using paper chromatography by Jacoreyiiski et al. (25L). Harms et al. (SOL) showed the existence of the 5-hydroxytryptamides of arachidic, behenic, and ligiioceric acids iii coffee. Gellerman et al. '(15L) gave a simplified method for aiiacardic acids in cashew nut shell extract. The orotic acid content of milk was iiivestigated by Brieskorn et a,l. (5L) who used it to estimate milk solids in food and by Kiermeier et al. (26L) who suggested modifications to improve reproducibility. An automated chlorogenic acid procedure applicable t80 coffee was developed by Sloman and Panio (50L). Corse et al. (8L) isolated chlorogenic acid, neochlorogenic acid, aiid Band 510 from roasted coffee. Lehmann et ai. (SIL) determined chlorogenic acid in coffee by absorption and elution from polyamide micro columns followed by UV spectrophotometry. Lehmann and Hahn (SOL) measured both chlorogenic acid and trigonelline with the same polyamide columns. Kung et al. (2%) separated and measured mono- and dicaffeoylquinic acids in coffee by GLC of their TMS derivatives. h combination of poly(vinylpyrro1idine) column chromatography and GLC enabled Wilson et al. (56L) t o det,ermine chlorogenic acid in plant tissue. Dallos and Koeppl (10L) identified nonvolatile phenolic acids in beer by gas chromatography of their trimethylsilyl derivatives. Kusnawidjaja et al. (28L) employed two dimensional paper chro86 R

*

matography to establish the occurrerice of vanillic, ferulic, a,iid caffeic acids in vegetable food products. Giannessi (16L) detected phthalic acid in oils after methylation and GLC analysis, and Covello et al. (9L) accomplished the same with TLC and deusitometry. PROTEINS, AMINO ACIDS, AND NITROGEN

Improvements in a,ll types of analyses for nitrogen-containing compounds coiitinue to increase in the literature. Viifortunately many minor changes in methodology could not be included in this review because of lack of space or similaritmyto other proposed improvemeiits. More rapid analysis for total nit'rogen has been achieved by Sutton et al. (71111) working with fish products, by Schulz (6531) working with milk, and b y Deschreider et al. (12d1) working with flour, by the use of automatic analysis techniques. An iiivest'igat'ion of the application of neutron actmivation by Doty et al. ( I S X ) to the determiiiation of nitrogen in feeds has shown good correlation between this method and the Kjeldahl technique. Ultraviolet measurement has been used by Iwaida et al. (3261) and Saito (6331) t o determine the probeiiis in milk after staiidardizat'ion against Kjeldahl nitrogeii determiiiatioiis. X colorimetric adaptation of t'he Foliii phenol procedure by Potty (60;l) has been applied to the determination of proteins in the presence of phenols and pectins. Dye-binding and biuret techniques have been compared by Parial et al. (5631) with Kjeldahl for the determination of protein i n brown and milled rice and found satisfactory. Grueiier et a1 (8831)have described a dye-binding met'hod for protein in wheat flour, and recommend the use of Orange G. A colorimetric procedure for prot'ein in dried meat' which uses the xanthoproteic reaction has been developed by Krivenkova et al. ( S S l l l ) , The use of enzyme preparation has been suggested by Hang et al. (2531) to improve the filterability and estractabi1it.y of the iiitrogeii constituents of beans. Conditiolis for the determiiiatioii of wheat-flour proteins by the biuret reaction have been studied by O'Hara (52211) wit'h special emphasis 011 the effect of reducing sugar. A spect'rophotometric method for the determination of protein in sausage products described by Kroylova et al. (4Od1) uses the react,ion with copper sulfate. Mota ( 5 1 N ) has studied the effect of crumb roasting on the determination of milk protein in milk chocolate aiid concludes that the AOAC method does not give reliable results when heated crumb is present in the product. The need to standardize the extraction procedure for protein in frozen fish has been shown by Ravesi et al. ( 6 M ) in a study of the various factors involved. A review by Menden


et al. ( 4 8 X )covers procedures for amino acids and v o t e i n quality, Methods for the determiiiatioii of casein in milk have been described by Kirchmeier (56,lI) using the isoelectric nature of casein in a t8itrationprocedure, and b y Vietti-Rlichelina et al. (8031) using colorimet'ry with fruct'ose and cysteine hydrochloride. Another rapid method for casein in hydrolyzed lactalbumin by de Hoog et al. ( 2 0 N ) utiliaes t8hecolor reactioii of casein with bromcresol purple while set in an agar gel, The isolat8ion and charact,erization of a wat'ersoluble wheat-flour protein has been described by Fish et ai. (1651) using ionexchange aiid Sephadex separations. Isoelectric focussing has been used by Cateimpoolas et al. (S!lf) t'o separat'e soj-beaii whey proteins using focussing from p H 3 to 10. Cooniassie Brilliant Blue was found b y Fish et al. ( I b X ) t,o provide good detection of 11-hey protein bands after disk elect,rophoreeis. A darch-gel electrophore,sis procedure described by Ganguli et al. (21Af) uses Petri dishes as gel coiit,ainers. Mack0 et al. (447l1)have mapped the proteins of potatoes using electrofocussing and elect'rophoresis, and found differences between varieties. A mass spectrometric procedure for amino-terminal sequence analysis of proteins has been described by Gray et al. (30111) using acetylatioii and protease digestion. Chromatographic and electrophoretic methods have been used by Rohrlich et nl. (6aN) to separate and identify peptides from the peptic hydrolysate of wheat. gliadin. A turbidimetric method described by Joshi et al. (33~11)uses specific precipitants to determine proteose-peptone, proteose, and peptone in milk. Uayer et al. (261)have presented a gas chromatographic-mass spectrometric method for the sequence analysis of polypeptides. Nethod8 of determining total volatile nitrogen i n meat aiid fish have been discussed by Pearson et al. (56J1, 5731). Methods for the determination of amnionia include colorimet'ric methods described by Wasilewski e! al. (8551) for meat', a microdiffusion technique applied by Vyiicke (82-$1)to fish, aiid discussions of distillation and diffusion techniques by Thaler et al. ('74&-76A11). .A simple method, using periodate, has been described by Galanos et al. (2051) for the determinat,ion of a-hydrosyamino nit'rogeii. Many approaches have been made to the problem of determining protein thiol groups. Suzuki et al. (72iTf) have used atomic absorption spectrometry determination of the mercury bound to the protein after reaction with mercuric chloride or p-chloromercuribenzoate. A gel-filtration met'hod has been applied to protein mercapto group determinations by Erwin et al. (14M) usillg chloromercuribeiizoate labeled with carbon-

14. A spectrophotometric method described by Hamm et al. (%4M)uses the decrease in UV reading of p-chloromercuribenzoate after reaction with thiol groups. A colorimetric procedure for these groups ha,s been suggest,ed b y Sakai et al. (64M) using the reaction with mercury orange. Spectrofluorimetry has been used b y Vakaleris et al. for t,he determination of mercapto groups in cottage cheese (7'8.11)1 and for sulfhydryl and disulfide groups in milk A polarographic proteins (79Jf). method has been described by Hird et al. (,%?,If) for low-molecular-weight thiols and disulfides in flour using a silver-silver chloride reference electrode. The use of ascorbic acid as reducing agent has been recommended by Michel (4Q.W) for the Rosen method for the determination of amino acids. Applications of amino-acid analysis to food research have been discussed by Davies ( I O M ) . A method for the removal of humins in plant hydrolysates by ionexchange chromatography has been suggested by Larseii et al. (43.U'). Aqueous dimethyl sulfoxide has been found by Moore (60X)t o be a better solvent for ninhydrin reagent for amino acid analysis. Gas chromatography of the sulfur-containing amino acids described by Shahrokhi et al. (67M) requires the use of several eilylating a g e n t . ~ for the twelve acids studied. Taiinenbaum et al. (73JI) have presented evidence t'hat the formation of met'hioriine sulfoxide is not apparent when the acid is determined by the N-trifluoroacetyl methyl ester gas chromatographic procedure. Aliphatic amino acids have been oxidized by ninhydrin to the aldehyde and then determined b y gas chromatographic headspace analysis in a procedure described by Olsen (63M). The use of N-trifluoroacet'yl methyl esters has been used by Kurosky et al. ( 4 2 X ) for the analysis of amino acids in beer and wort. Amino acids have also been determined by gas chromatography of their methyl esters in a procedure described b y Gee (2BJI). Improved ion-exchange chromatography of amino acids has been used by Denic ( I l d 1 ) to analyze individual maize kernels. 4 better hydrolysis procedure, which reduces the variability in results for tyrosine has been applied b y Kohler et al. (36Jf)to the analysis of wheat products. d versatile lithium buffer elution system has been described b y Perry et al. (6866) for single-column automated aminoacid chromatography. Thin-layer chromatographic techniques have been applied by Clark (931) to the quantitative determination of 17 amino acids, and by Hashnii et al. (2631) t,o 20 amino acids using preliminary electrophoresis followed by circular thinlayer chromatography. Arginine in prawns has been determined by Appanna ( 1 M ) using the

enzymes argiiiase and urease. Methods for cysteine include a, spectrophotometric determination using nitrilotriacetatoferrate(II1) in the presence of 1,lO-pheiianthroline described b y Bydalek et al. (6M). An ion-exchange procedure has been used by Friedman et al. (18111) to determine cystine and cysteine residues after reduction to sulfhydryl and alkylation with 4-viiiylpyridine. h direct spect'rophotometric method for cysteine described by Gaitoiide (19M) uses an acid ninhydrin reagent. Inglis et al. ( 3 1 N ) have used dithiothreitol and sodium t,etrathioiiate to convert cysteine to S-sulfo-cysteine which can be determined by ion-exchange chromatography. A thin-layer electrophoretic procedure has been described by Freimuth et al. ( l 7 M ) to determine glutamic acid in foods. Hydroxyproline has been determined in sausages and meat prcducts by Benger et al. (3~11')by oxidation with chloramine T and color development' with dimethylaminobeiizaldehyde. Studies on the determination of available lysine include a procedure for non-X-terminal lysine by Illatheson (46Ji') and a detailed study of this method (47J1). A rapid survey hydrolysis procedure for lysine analysis has been described by Palter et al. (6411) using ion-exchange chromatography. Excellent recoveries have been obtained by Villegas et al. (8I1l1) for the determination of lysine by using a triplicate-sample method on a n automated amino-acid analyzer. Colorimetric determination of methioniiie has been automated b y Ussary et al. (77JI). A detailed study of the reaction of tryptophan with glyoxylic acid carried out by Brieskorn et al. (6JI) has shown that halogen or cyanide cause high results. Hydrolysis with barium hydroxide and with 5N sodium hydroxide has been found suitable by Sternkopf (70111) for the determination of tryptophan in leguminous seeds. Hydrolysis with barium hydroxide and Sephadex G-25 column chromatography have been used b y Slump et al. (69M)to determine tryptophan in foods. An enzymatic determinatioii of glutathione in wheat, flour has been described by Kuninori et al. ( 4 1 M ) using glutathione reductase. Creat'inine has been determined in soups by ion-exchange chromatography in a method b y Carisano et al. ( 7 M ) . Cation-exchange-resin paper has been used b y Katayama et al. (34M)in a method for ethanolamine in plant, tissues as the dinitrophenyl derivative. Histamine has been determined in cheese by D e Koniiig (37111) by a fluorometric met'hod and in wine by paper and thin-layer chromatography using Pauly reagent by Illaier (45AI). The presence of diethylnitrosoamine in some foods has been confirmed b y Hedler et al. (27X) using thin-layer chromatography. Kroller (3QJf)has described a

method for the gas chromatographic and thin-layer chromatographic detection of nitrosamines in foods. After preparative thin-layer chromatography nitrosamines in flour were furt'her identified by Petrowitz (5964) by gas chromatography. A rapid procedure for. the separation of nucleot'ides by ionexchange chromatography has been described by Shimizu et al. (68.U). Fluorometric and gas Chromatographic methods for the determination of tyramine in foods have been described by Sen (66M). A paper chromatographic method has been used by Blackwell et al. ( 4 M ) for the det'ermination of histamine and t,yramiiie in yeast. VITAMINS

Deutsch ( 6 N ) reported the results of a collaborative study comparing methods for determining Vitamin C: utilizing 2,6-dichlorophenoliiidophenol, 2,4-dinitrophenylhydrazine, and o-phenylenediamine and recommended the last. as more specific. llueller-Mulot ( 1 8 N ) developed a specific test for ascorbic acid based on a reaction betweeii dehydroascorbic acid and glycine. A formaldehyde condensation with ascorbic acid provided a hlaiik titration in a 2,6-dichlorophenolindophenol method for evaporated milk by Pellet'ier (21X). Schubert et al. (25iY) determined ascorbic acid in apples by polarography. Iliffereiit' reducing agents t o determine dehydroascorbic acid in fruit were compared by Pribela et al. (22A:). N o hammad et al. (17'Sj eliminated .sulfite interference in the ~~--bromosucciiiimide method for food product,s. Carisaiio et al. ( 4 N ) used ion exchange to eliminate metallic ionic interference from canned juices. Weeks and Deutsch (28") separated and assayed (-)ascorbic and (+) isoascorbic acids from fruit beverages on glass fiber paper. Schmidt (23N, %&Y) conti~iucd his investigation of tocopherol coiitent on heat oxidation of arachis and soya-bean oils using TLC and colorimetry. Linow and Pohl (15Xj adapted l'arodi's method for t,otal tocopherols to yegetable oil. Niederstebruch et al. ( 2 0 s ) analyzed for tocopherolquiiionw by derivative polarography and, after osidation, also for tocopherols. n'elsoii et al. (19iY) gave a method using GLC and applicable to soya sludges and residues. Hall aiid Laidman (gLV) determined tocopherols and isoprenoid quinones in wheat grain and seedlings by a procedure involving gradient column elution and then GLC or colorimetry. An automat,ed method by Honnold et al. ( 1 1 N ) based on the Emnierie-Enpel manual method measured tocopherols in deodorized soya, but also included any other reducing agent. Eisses et al. ( 7 N ) simplified t,he Jones method for vitamin D in evaporated milk by substitut,iiig an aluniina column. A TL('


87 R

method for ergosterol and vitamin D using SbC19 detection and applicable to yeast food products was described b y Blasovich and Gabor ( S N ) . Baba et al. ( 8 N ) made use of spectrophotometry following molecular sieve analysis for vita,min D in fermented seafood. Slover et al. (26N) formed the trimethylsilyl ethers of tocols and tocotrienols and performed GLC analysis after a preliminary T L C separation. A collaborative study of extraction methods for fluorimetric riboflavin assay was reported by DeRitter ( 6 N ) . Hildenbrand ( I O N ) fixed riboflavine and quinoline yellow from foods on wool fibers prior to chromatography and UV absorbance and fluorimetry spectrophotometry. An adaptation of the AOAC fluorimetric method by Woodrow et al. (SON) eliminated the autoclaving step for dried milk products. Markman et al. (16N) investigated the use of polarography to determine riboflavine in milk. Recovery of thiamine from modified milk powder was improved b y a protease treatment b y I t o et al. ( I 2 N ) . Added thiamine in vinegar and wine was determined with a modified Dragendorff reagent by Giannardi et al. (8N). A simultaneous estimation of thiamine and thiamine pyrophosphate utilizing the thiochrome method after sephadex G25 separat,ion was reported by Wildemann ( 2 9 N ) . Janicki et al. ( I S N ) modified the cyanobromide method for vitamin PP in cereal and cereal products after studying color development conditions. Adrian et al. ( I N ) assayed for vitamin PP in corn using Lactobacillus Arabinosus after a chemical extraction. Vitamin Be components were determined by paper chromatography followed by photography of fluorescent spots and subsequent photometric measurement on the film by Kraut and Imhoff ( I 4 N ) . Vakil et al. (%'Ar) reported a faster microbiological disk assay method for folic acid in milk, cheese, and other foods. MISCELLANEOUS

The role of analytical instrumentation as it applies to the food industry has been reviewed by Ulrich (32P,33P). A review of the application of general chromatographic methods to food analysis is given by Cerma et al. ( 6 P ) ,while Gorbach ( I I P ) reviews the use of microchemical paper and thin-layer chromatographic techniques. Applications of T L C t o cereal analysis (4P) are also reviewed, and Lawrence (16P) has prepared a bibliography of T L C applications to foodstuffs. A general review of work done on tea and coffee covering about a decade (29P) provides a useful reference for the analyst working in this field. A spectrophotometric method previously reported for use with coffee was applied to the determination of caffeine in non88R

alcoholic cola beverages (2W)and in tea ( d I P ) by Polsella, The potentiometric determination of caffeine in both decaffeinated coffee (1UP)and green coffee (6P) is given which employs a titration using perchloric acid in a nonaqueous medium. Newton (18P) describes a gas chromatographic determination for caffeine in instant tea employing a KC1 thermioiiic detector. A chromatographic-spectrophotometric method for caffeine has also been reported to be applicable to cola chocolate (2QP). Schulta et al. (27P) describe a procedure for determining caffeine and theobromine in cocoa and cocoa products which employs a chromatographic purification followed by spectrophotometric determination. The caffeine content of decaffeinated coffee extracts have been determined (SQP)by flame ioiiiaat,ion gas chromatography using microglass beads coated with Carbowax 20 M. Small amounts of caffeine have also been determined spectrophotometrically in kola nuts (S6P) by a method employing both a prior esbraction and chromatographic purification step. The polarographic determination of the alkaloids solanine and demissine in the leaves of potato plants is described (2OP) along with the polarographic behavior of several such alkaloids found in the leaves of both wild and cultivated potato plants. The purine alkaloids of liquid cola extract were determined (SOP) gravimetrically by pharmacopoeial methods and individually by various methods including separation by T L C on silica gel plates. Silica gel T L C was also used (36P) in conjunction with anion exchange chromatography as a means of fractionating soy bean saponins and Rogers (25P) describes a comparison of data obtained for the deberniination of betaine in natural and synthetic orange juice samples using an ion eschange-colorimetric method. Salminen and Koivistoinen (26P) describe a scheme for the simultaneous determination of free amino acids, organic nonamino acids, sugars, nitrogen, and pectic substances in plant materials employing combinations of extraction, ion exchange column chromatography, and gas chromatography. Aaulene is used as a spotting or location agent for various chromatographic methods used in the analysis of aromatic and heterocyclic aldehydes, carbohydrates, and other aldehyde precursors (9P). Application of infrared milk analyzers are described ( I P , 8P) for determining the protein, fat, and lactose of milk along with typical data and comparisons of same with that obtained by conventional and more often used methods. The simultaneous determiiiat.ion of protein and fat in milk by spectrophotometry is described by Nakai et al. (17P). Ponomarenko et al. (2SP) report t h a t t,he chemiluminescence reac-


NO. 5 ,

APRIL 1971

tions of meat decrease as storage time increases and give the optimum conditions for observing these. A method for determining the size of sugar dust particles is described (YP)b y measuring sedimentation rates of the particles in cyclohexanol-cyclohexanone and Mohler et al, describe an enzymatic method for determining acids, carbohydrates, and glycerine in wine (16P). LITERATURE CITED Additives

(1A) Alessandro, A,, Dal Piaz, V.,Tendi, E., G. M e d . Mil., 119, 360 (1969); Chem. Abstr.. 72. 88953h (1970). (2A) Arai, S.: Gatsuda, 'T,, 'Nzppon Suisan Gakkaishi, 32, 655 (1966); Chem. Abstr., 60, 105119 (1968). (3A) Bandion, F., Kain, FruchtsajtInd., 14, 50 (1969); Chem. Abstr., 71, 111500y (1969). (4A) Barcklow, P., J . Ass. Ojic. Anal. Chem., 50, 1265 (1967). (5A) Berezina, E., Kholodnova, O., Myas. Ind. SSSR, 39, 21 (1968), Chem. Abstr., 70, 36467s (1969). (6A) Bosch Serrat, F., Corral Diaz, F., An. Bromalol., 21, 261 (1969); Anal. Abstr., 19, 3375 (1970). (7A) Bruno, E., Calapaj, I

Food - Analytical Chemistry (ACS Publications)

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