97.2
INDUSTRIAL AND ENGINEERING
added that, when present in the leaf to the extent of 1 per cent or more, chlorine tends to impair the combustibility. Although heredity plays a part, aroma in tobacco apparently is governed chiefly by soil and climate, but the specific factors involved and their mode of action are not known. However, the heavy fertilization of cigar tobaccos with nitrogen appears to be partly responsible for the decided difference between these and the cigarette tobaccos in the character of the aroma produced when the leaf is smoked. The differences in resin content shomm in Table I are hardly sufficient to indicate definite correlation with the aromatic properties of the different types of leaf, although the two most aromatic types, cigar filler and flue-cured, also have the highest content of resins. The sugar content of the flue-cured type is a factor of importance in the distinctive character of its aroma. The physiological strength of tobacco is largely measured by its nicotine content, and available information indicates that increased production of nicotine is favored by use of heavy soil types, heavy nitrogen fertilization, wide spacing and low topping of plants, dry seasons, and advanced maturity a t time of harvest. I n this connection i t should be stated that. in the heavy fermentation to which cigar filler leaf is commonly subjected, a half or more of the nicotine may disappear, so that, while the leaf must be classed as strong when in the freshly cured state, it is to be regarded as comparatively mild when ready for manufacture.
COIWLUSIOSS From the data presented it may be concluded that the marked difference in quantity of fertilizer nitrogen applied to the cigarette and the cigar types constitutes a highly significant factor in the sharp contrast which exists between these two classes of tobacco with respect to the nitrogen carbohydrate ratio and associated differences in composition of the leaf. Certain commercially important distinctions in properties or qualities in the two classes of leaf, including color,
CHEMISTRY
Vol. 26, No. 9
elasticity, grain development, aroma, and, in part, combustibility, are correlated with these differences in chemical composition. Difference in soil types and details of culture employed in growing t'he crop are important factors in the less pronounced contrasts in properties existing between the cigar binder and the cigar filler types, both of which are highnitrogen products. In this instance the contrasts in properties are not so clearly reflected in the organic constituents of the leaf although there are significant differences in composition of the ash. As betTveen the two cigarette tobaccos, bot'h of which have a high content of total carbohydrate, the reason why the Maryland type possesses an especially high content of pectin and cellulose instead of the high content of sugar and starch found in the flue-cured type has not been determined, although apparently a soil factor is involved. The distinctive method of curing commonly employed materially influences the chemical and physical characteristics of the flue-cured type. LITERaTURE
CITED
(1) h i e s , J. JV., and Boltm, G . E . , Ohio .Igr. Expt. Sta., Bull. 285 (1915). (2) =\nderson, P. J., Swanback, T. R., ant1 Street, 0. E., Conn. Bgr. Expt. Sta., Bull. 334 (1932). (3) Bailey, E . M., and Anderson, P. J.,Ibid., Tobacco Station Bd1. 10 (1928). (4) Garner, W.W., Racon, C . W., Bowling, J. D., Jr., and Brown, D. E., U. 9. Dept. Agr., Tech. Bull. 414 (1934). ( 5 ) Haley, D. E., Longenecker, J. B., and Olson, Otto, Plant Phyaiol., 6, 177 (1931). (6) PatterJon, H. J., Md. Agr. Expt. Sta.,Bull. 26 (1894). (7) Vickery, H. B., and Pucher, G. W., C'onn. d g r . Expt. Sta., Bull. 352 (1933). (8) 1-ickery, Pucher, Wakeman, and Learenworth, Carriegie Inst. Wmh. Pub. 445 (1933).
RECEIVED June 2 , 1934. The d a t a presented were obtained i n part in connection with tobacco production investigations conducted by the Bureau of Plant Industry in codperation with the North Carolina Department of Agriculture a n d Agricultural Experiment Station and the Maryland .igricultural Experiment Station.
Formaldehyde in Canned Marine Products GULBRANDLUNDEAND ERLING MATHIESEX Research Laboratory of the Sorwegian Canning Industry, Stavanger, Norway
T
HE problem of the natural occurrence of formaldehyde in fish and canned marine products is of considerable interest t o those engaged in food analysis. Kawahata and Kamba (6) h a r e shown that smoked meats contain formaldehyde. Ishio and Saki (5) found formaldehyde in twenty samples of smoked meat in concentrations varying from 1 part of formaldehyde to 10,000 to 50,000 parts of meat. Dill and Clark (3) obtained positive tests for formaldehyde in a commercial pack of canned herring (Clupea paZorsii) and in canned rock cod (Sebastodes species). They failed to find formaldehyde in an experimental pack of smoked sardines (Sardinia caerula). Ishida (4) found that fresh crab meat gave a weakly positive result when tested for formaldehyde. After canning and storage for 8 months, the crab meat gave a distinctly positive test. The results of Ibhida were confirmed by Dill and Clark who obtained formaldehyde from canned Crustacea in amounts of 1 in 30,000 to 1 in 200,000. Tankard and Bagnall ( 8 ) report positive results for formaldehyde in fresh fish when using phenylhydrazine hydrochloride with potassium ferricyanide according to the method of Schryver ( 7 ) . They conclude that the results are probably due to the natural occurrence of trimethylamine in the flesh of the fish.
Shipments of kippered herring have been condemned in the United States on the claim that formaldehyde was used as a preservative. The use of any preservative was strenuously denied by the Korwegian packer, and i t is certain that no Sorwegian canning factory is using formaldehyde or any other preservative in any of its sterilized canned products. The present TT-ork was begun with the object of investigating the extent of the natural occurrence of formaldehyde in canned marine products. METHODSOF ASALYSIS In determining formaldehyde, the general procedure and tests of the Association of Official Agricultural Chemists (1) were followed: Two hundred grams of the sample were ground with water in a mortar and transferred t o a distillation flask, and water was added until the mixture weighed about 450 grams. Seventy-five grams of phosphoric acid were added; the flask was connected with a condenser, and 50 ml. of distillate were collected. The distillate was tested for formaldehyde by the phloroglucinol and the Hehner tests. In certain cases the gallic acid test of Barbier and Jandrier ( 2 ) , the phenylhydrazine hydrochloride test, and the test using phenylhydrazine hydrochloride with sodium nitroprusside were also employed. The amount of formaldehyde
September, 1934
present was estimated by comparison with standardLzed solutions of formaldehyde in waher. Only a portion of the formaldehyde actually present is recovered in the fist 50 ml. of distillate. When additional 20-ml. fractions were examined, the first gave a positive arid the second a trace of the reaction for formaldehyde. Dill and Clark have shown that even with a 6-hour distillation only one-third to onefifth of the formaldehyde which they added t o salmon was recovered. Further experiments have shown that the figures given here should be at; least three times as high to show the actual amount of formaldehyde present in the food.
RESULTS When the fish flesh of herring was examined as described above, the distillate was negative to the phloroglucinol test and only slightly positive to the gallic acid and the Hehner tests. When this flesh mas canned and examined after being stored for 3 days, all the tests were distinctly positive. Fresh kippered (smoked) herring was examined and gave positive results, the amount of formaldehyde being less than 1 in 200,000. The quantity of formaldehyde in the kippered herring was not as high as in the canned kippered products. Smoked haddock gave a much stronger reaction, corresponding to a concentration of about 1 part of formaldehyde in 20,000 parts of distillate.
TABLE h Q E OF
111. FORMALDEHYDE IH STORED KIPPERED HERRING
KIPPERED HERRINQ Years 1.5 1.5 2.5
H C H O IN FIRST DISTILLATE Parts 1 in 75,000 1 in 100,000 1 in 25,000
the samples were positive. The concentration of formaldehyde found in the first distillate was 1 in 200,000 or less. Samples from ten commercial packs of different factories were examined after 21 months of storage. All of the samples were positive and t'he amount of formaldehyde present in the distillate varied from 1 part in 75,000 to 1 in 150,000. ExaMIXvarrIoN O F SMOKED AND CAiTNKD AND
BRISLING
S O . OF
S4MPLES
1 2 1
1 1
1 1 11
10
DESCRIPTION
AGE Years
Smoked small herring before canning Smoked brisling before canning Canned unsmoked herring in oil Canned smoked herring in 011 Canned smoked herring in oil Canned smoked herring in oil Canned smoked heiring in oil in aluminum container Expel. pack of smoked herring Commercial pack of smoked herring
..
..
2 5 5
..
HERRING
HCI-IO IN FIRST [)ISTILL?LTE
Parts Positive Positive 1 in 200,000 Negative 1 in 200,000 Positive
1
..
Negative 1 in 200,000
1.75
1 in 75,000 to 1 in 150,000
EFFECT OF CONTAIKER.As it was thought that the formaldehyde might be formed by a reaction between the container and the fish, several samples were canned in tin plate and aluminum, and after various periods of storage these were compared. The results shown in Table I1 indicate that there is little or no difference in the amount of formaldehyde formed when packed in aluminum or tin. TABLE 11. FORMALDEHYDE IN HERRINQ CANNED CONTAINERS HERRING
CONTAINER
Fresh Fresh Kippered Kippered Kippered lppered
'rln plate Aluminum Tin plate Aluminum Tin plate Aluminum
AGE Months 14 14 9 9 20 20
I N hlETAL
H C H O IN FIRST DIBTILL4TE P zrts 1 in 50,000 1 in 100,000 1 in 50,000 1 in 100,000 1 in 100,000 1 in 7'5,000
EFFECTOF STORAGE. It was thought that aging of the product might result in an increase in the amount of formaldehyde. I n order to solve this problem, the case samples of kippered herring which had been in storage for various lengths of time were tested. The results shown in Table I11 indicate that the amount of formaldehyde present is not dependent on the age of the product.
AGE OF
KIPPERED HERRING Years 2.5 4.5
10.5
HCHO
IN
FIRST
DISTILLATE Parts 1 in 50,000 1 in 50,000 1 in 200,000
FORhL4LDEHYDE IS COMMERCIAL PRODUCTS. AS analysis showed that formaldehyde occurred naturally in Sorwegian kippered herring, the experiment was extended to determine to what extent i t was present in commercially canned products of the Clupea and similar families produced in other countries. The results shown in Table IV indicate that it is of common occurrence. Analyses of several cans of crab and lobster are also included.
TABLE Iv. FORMALDEHYDE IN CANNED HERRING, SARDINES, TUNA, AKD Crustacea FROM VARIOUSCOUKTRIES HCHO PRODC-CT
ORIGIX
IN
FIRST
DISTILLATE
Parts
Sardines in cottonseed oil (Clupea harengus) EXAMIXATION OF AN EXPERIMEKTAL AND COMMERCIALSardines in olive oil (Clupea harengus) Sardines in oil (Clupea harengus) PACKOF CANXEDKIPPERED HERRING.Kippered herring Sardines in olive oil ( S a r d i n i a caerula) Dilchards in tomato sauce were packed in enameled cans and sterilized. After 12 Smoked ( S a r d i i i a caerula) Sardines in olive oil (Clupea pilcharmonths of storage, eleven samples were examined. All of
TABLEI.
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INDUSTRIAL AND ENGINEERING CHEMISTRY
dus)
Sardines in oil (Clupea pilchardus) Sardines jn oi! (C1vpea pilchardus) Sardines in olive oil (Clupea sprattus) Sardines in olive oil (Clupea sprattus) Sardines in olive oil (Clupea sprattus) Sardines in sesame, soy-bean, and mustard oils Herring in tomato sauce Herring in tomato sauce Tuna in oil Crab (Cancer magister) Crab Lobster (Homarus d m e r i c a n u s )
Maine, U. S. Maine, U.S. Maine, U. S. California, U . 6.
Positive Negative Doubtful Negative
California, U. S.
Negative
Portugal Portugal France Great Britain Fin!and Spain
Positive Positive Negative Positive Positive Positive
Latvia Germany Great Britain France Norway Japan Canada
Positive Positive Positive Positive 1 in 200,000 1 in 75,000 1 in 100,000
DISCUSSION OF RESULTS After having found that many canned marine products contain small amounts of formaldehyde when tested by the usual methods, an effort was made to determine the nature of its origin. Since all of the cans examined were sterile, it was evident that the formaldehyde was not formed as a result of bacterial activity. I n order to determine whether i t was possible that the formaldehyde was formed by oxidation during distillation, a sample of canned herring was steam-distilled, and, during the distillation, air was passed through the flask. The color reaction of the distillate from this sample was found to be the same as that from a n equal portion of canned herring which was distilled in a n atmosphere of carbon dioxide. This indicated that the formaldehyde was not formed by oxidation during the distillation process. Tests were then made to determine the presence of formaldehyde without distillation. Portions of the canned fish were mixed with distilled water, vigorously shaken in a glassstoppered bottle, and centrifugalized, and the milky liquid mas used for the tests. Tankard and Bagnall have shown that Schryver's test gives positive results in the presence of trimethylamine, It was found that all of the tests using phenylhydrazine as a reagent were positive to trimethylamine and therefore could not be applied directly to an aqueous extract of the fish. Of the remaining methods, only the Hehner test proved to be specific and sensitive enough for use. By means of this test the amount of formaldehyde present in the aqueous extracts was estimated, by comparison with known formaldehyde solutions, to be 1 in 100,000 to 1in 200,000. Yanagisawa, Horii, and Xshiura (9) are of the opinion that
INDUSTRIAL AND ENGINEERING CHEMISTRY
976
the formaldehyde found in the distillate from crab meat is formed during distillation with phosphoric acid by decomposition of histidine. As formaldehyde is found in the aqueous extract of canned fish Tvithout distillation, it is the authors' opinion that the amount found in the distillate is really present in the canned fish. Since formaldehyde, added as a preservative, is prohibited in most countries, the fact that it may occur naturally in canned marine products is of considerable importance. Formaldehyde must be present in quantities of at least 1 in 25,000 (possibly even more in smoked products), before i t can be stated with certainty that it has been artificially added.
Vol. 26, No. 9
aqueous extract of the fish. All the tests can be used upon the distillate from an acid distillation. Formaldehyde has been detected in the distillate from fresh and canned herring, crab, and other marine products. The amount found in the canned food is somewhat higher than in the fresh fish. The formation of formaldehyde in canned fish appears to be independent of the nature of the container and does not increase during long storage. The formaldehyde is not formed during the distillation process, as i t can be detected in a n aqueous extract of the fish by means of the Hehner test.
LITERATURE CITED SUMMARY Canned marine products frequently give a positive reaction when tested for formaldehyde by the official tests of the Association of Official Agricultural Chemists. The official tests where phenylhydrazine hydrochloride is used as a reagent cannot be applied directly to liquid foods or aqueous extracts of foods which may possibly contain trimethylamine. The trimethylamine naturally present in fish foods causes a positive reaction with these tests. Of the other tests used, only the ' Hehner test could be satisfactorily applied directly to an
(1) Assoc. Official Agr. Chem., Methods of Analysis, 3rd ed., pp. 340-2 (1930). (2) Barbier and Jandrier, Ann. chim. anal. chim. appl., 1, 325 (1896). (3) Dill and Clark, J . Assoc. OficiaZ Agr. Chem., 9, 117 (1926). (4) Ishida, J.Pharm. SOC. Japan, 422,300 (1917). (5) Ishio and Aoki, Ibid., 443, 20 (1919). (6) Kawahata and Namba, Ibid., 432,95 (1918). (7) Schryver, Proc. Roy. SOC.(London), B82, 226 (1909). (8) Tankard and Bagnall, Analyst, 51, 565 (1926). (9) Yanagisawa, Horii, and Nishiura, J . Pharm. SOC.Japan, 52, 74 (1932).
RECEIVPD June 29, 1933.
Hydrocarbon Oils Molecular Weights by the Cryoscopic Method and from Thermal Data M. R. FENSKE,W. B. MCCLUER,AND M. R. CANNON Pennsylvania State College, State College, Pa.
T
may have a high value for its Average molecular weights of complex highmolal freezing point lowering and for determining molecuboiling hydrocarbon mixtures have been obtained satisfactory solution characterislar weights is based on by a method based o n heats of vaporization. tics. Table I summarizes the the equation: This permits a n independent check o n the cryodifferences of opinion that exist dT - = RT2 _ scopic method of molecular weight determinain the literature. dx AH In this paper are given the tions. Using six different oils, the greatest where AH = heat of fusion of the results obtained b y c a r e f u l l y pure solvent at temperadifference between the two methods was found to measuring the molecular weights ture T be 7 per cent. The average molecular weights x = mole fraction of the of six pure compounds and six solute of fourteen different hydrocarbon oil fractions h y d r o c a r b o n oils with cyclohave been determined satisfactorily by the hexane as the solvent. MolecuIntegrated forms of this equalar weights of these six oils, as tion have been used to measure method involcing heats of vaporization. These well as those of eight other oils, molecular weights of hydrocardata have been correlated o n the basis of viscosity were also obtained from measurebon oils, but there seems to be index and 37.8" C. (100" F.) Saybolt viscosity ments of their heats of vaporizaconsiderable disagreement by the following equation: tion, This permits an indeamong the various investigations 100" F. viscosity pendent check on the molecular as to the a c c u r a c y of the re32,310 loglo weights of the oils. Cyclohexane sults obtained. In particular it 28.0 was chosen as the solvent because Mol. wt. = 240 has been shown (4) that, when 305 - viscosity index of its large freezing point condifferent solvents are used in stant. d e t e r m i n i n g t h e molecular weight of definite chemical compounds, the results obtained EXPERIMENTAL RESULTS BY CRYOSCOPIC METHODS differ considerably from the true molecular weight. SpecifiThe cyclohexane as well as all the solutes listed in Table cally, i t was found (4)that, when benzene was used as the reference solvent, ethylene dichloride gave results 5 per cent I1 were of a very high purity. The cyclohexane had a freeztoo high, stearic acid gave results 15 per cent too low, and ing point of 5.68 * 0.05" C.; and, using a value of its heat of carbon tetrachloride gave results 5 per cent too low. In fusion of 7.41 * 0.01 calories per gram as measured by Parks, general, the opinion appears to prevail that molecular weights Huffman, and Thomas (IO),the purity was calculated to be of extremely complex high-boiling hydrocarbon mixtures can- 99.8 per cent, I n Figure 1 the apparent molecular weights not be determined by the cryoscopic method with an accuracy of the substances are plotted against the freezing point lowexceeding approximately 5 per cent, even though the solvent ering, AT, in order to give the basis used to extrapolate to
,HE cryoscopic method
+
