New Test for Fat Aldehydes Resulting from Oxidation of Fats and Oils

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204

ANALYTICAL EDITION

carbohydrates present in a 2-gram sample. The water extraction may be omitted with all chemical pulps and the alcohol benzene may be omitted with alkaline-cooked pulps. If large quantities of lignin are prepared at one time, i t is difficult to control the temperatures developed during the mixing of the acid and the sawdust. It is advisable, therefore, to use a lower concentration of acid and mix i t with the sawdust at a lower temperature than specified above. Sherrard and Harris (4) have found that a 70 per cent sulfuric acid mixed with sawdust a t 10’ C. is satisfactory. Results obtained from lignin determinations in several woods according to the foregoing revised method are recorded in the last column of Table I, The effect of tempera-

Vol. 4, No. 2

ture on the lignin yields may be noted by comparing columns 1 and 2; the effect of hot-water extraction, by Comparing columns 2 and 3.

LITERATURE CITED (1) Bray, M.W., Paper Trade J.,87,5943 (1928). ENQ.CHEM.,14, 933 (2) Mahood, S. A.,and Cable, D. E., J. IND. (1922). (3) Oat, H., and Wilkening, L., Chem.-Ztg., 34,461 (1910). (4) Sherrard, E. C., and Harris, E. E., IND.ENQ. ORRIM.,24, 103 (1932). RECBIVED October 1, 1931. Presented before the Division of Celluloae Chemistry at the 82nd Meeting of the American Chemical Society, Buffalo, N. Y., August 31 t o September 4, 1931.

New Test for Fat Aldehydes Resulting from Oxidation of Fats and Oils HELGESCHIBSTED, The Borden Company Research Laboratory, Syracuse, N. Y. Oxidation of edible fats and oils leads to talXIDATION of fats and amounts of oxygen are absorbed oils leads to the developby butter fat at a temperature lowy flavors and odors. These are considered to ment of tallowy odors of 95” C. It would not be quite be due to the formation of various aldehydes. and flavors whose measurement safe to a s s u m e that the same A new test for f a t aldehydes has been developed, is exceedingly difficult, being quantitative reIationships exist and experimental data are presented to show the subject to the senses of smell a t lower t e m p e r a t u r e s and best composition of the new reagent and the and taste which vary greatly during the early stages of oxidain different people. Numerous tion. method of procedure which will give the optimum attempts h a v e been m a d e to Powick (6) and later Muncolor eflect. The new rosaniline reagent is over measure the degree of oxidation dinger (5) in G e r m a n y have twenty times as sensitive as the Kreis test or the by determining the products of done a great deal of work on the Schiff reagent. It is speciJic for fatty glyceride oxidation. Kreis test. Powick applied the aldehydes. The results of the new test are exThe most widely used test for test to a large number of compounds found in oxidized fats tallowiness in fats, including pressed in arbitrary speciJic color units which f a t t y oils, is t h e Kreis test. and oils. The only one which are called ‘Ifat aldehyde values.” Special apg a v e t h e characteristic color This test depends on a color plications are given. Oxidation tests with butter with phloroglucinol was epihyreaction between phloroglucinol fat at 50” C. gave correlation between the amount a n d t h e oxidized f a t . A drinaldehyde. T h e formation of oxygen absorbed and the f a t aldehyde value. known amount of fat is shaken of this aldehyde from oleic acid bv a comDlicated s e r i e s of vigorously for 30 seconds in a Perhaps the fact that test tube with concentrated hydrochloric acid. A 0.1 per reactions is suggested by P;wick. cent solution of phloroglucinol in ether is added and the the color reaction of the Kreis test depends on the presence of mixture is again shaken. It is then allowed to stand. If the one special aldehyde explains why this test is often unreliable. Richardson (7), as chairman of a Kreis test committee, fat is tallowy, a red or pink color appears in the acid layer. Kerr (4) stated in 1918 that the Kreis test is only roughly reports on the use of the test on wintered cottonseed oil. He proportional to the rancidity. He agrees with Winkel (9) that prepared six samples of this oil with varying exposures to the it is too delicate and not specific. The expression “rancidity” air. These samples were sent to three different laboratories is used by these investigators in a broad sense which covers to be tested according to Kerr’s directions. The conclusion other flavors than those due to oxidation. This has led to was that the average grading of the samples by this method confusion among other workers who have tried to apply the failed to disclose any correlation between intensity of the Kreis test and rancidity as judged by flavors. Kreis test to all types of deterioration in fats and oils. Von Fellenberg (1) in Switzerland and Inichof and SchoschI n recording the results of the Kreis test, it has been customary to designate each as positive or negative. This is ine (3) in Russia used the Schiff reagent as a test for aldehydes not entirely satisfactory, for it fails to take into account the in fats and oils. The Schiff reagent was the customary yellow fact that the same degree of oxidation in different fats and oils solution which is made by adding a sodium sulfite or bisulfite may result in the formation of oxidation products widely solution and hydrochloric acid to a fuchsine solution. Von differing in character, with corresponding variations in flavor Fellenberg’s modification is the least acid and also the most and odor. It is therefore important to judge each type of fat sensitive. Mundinger states that the von Fellenberg test is or oil on its own merits. I n comparing flavor scores with the better than the Kreis test, but neither of these is as sensitive readings of any test for oxidation products, it is important as an organoleptic test when applied to butter fat. to have for each fat or oil an individual scale, varying according EXPERIMENTAL PROCEDURE to the use for which the fat or oil is intended. The purpose of the present investigation is to develop a Holm and Greenbank (2) have shown that the Kreis test can be applied in a quantitative way when relatively large sensitive and reliable test for measuring fat aldehydes. The

0

‘

April 15, 1932

INDUSTRIAL AND ENGINEERING CHEMISTRY

205

400m-T-nl

DAY 5

FIGURE1. EFFECTOF SOJ CONCENTRATION

FIGURE 2. EFFECTOF IMPURITIES IN PETROLEUM ETHER

Schiff reagent seemed the most promising starting point. Oxidation of fats undoubtedly produces aldehydes, which will to some extent respond to the Schiff reagent. A tallowy colorless sample of butter fat which had absorbed about 0.7 cc. of oxygen per gram of fat was used. One g a m was dissolved in 100 cc. of petroleum ether (b. p. 50' to 100" C.). When this fat solution was shaken with the ordinary yellow Schiff reagent, a color reaction took place which changed the aqueous solution from yellow to orange-red. The petroleum ether solution was also colored yellowish red, but not so much as the aqueous solution. A very heavy dark red emulsion formed which took a long time to clear, leaving a dark-colored substance floating on the surface of the Schiff

43 0 0 r 7 - 7 - 7 - 7

~g

200

I

I

I

I

I

1w 2 IO0 a I-

i5

20 __

40

60

80

yo ALCOHOLB Y VOL.

FIGURE3. EFFECTOF ALconoL CONCENTRATION

reagent. This substance undoubtedly was an addition product formed by an aldehyde of high molecular weight and the Schiff reagent. It was insoluble both in the aqueous layer and the petroleum ether layer. The addition of ethyl alcohol from 30 to 50 per cent by volume entirely eliminated it, and the color intensity of the petroleum ether layer was enormously increased. The explanation of this effect is probably that the alcohol causes a dehydration of the rosaniline hydrochloride resulting in an increased solubility of the reaction product in petroleum ether. The addition of alcohol, however, changed the color of the Schiff reagent from yellow to red, particularly when the sulfurous acid concentration was reduced far below the quantity required for the ordinary Schiff reagent. This red coloration of the yellow Schiff reagent might possibly have been caused by the presence of aldehyde impurities in the alcohol, but the same intensity of red color was also developed when carefully purified alcohol was added to the yellow Schiff reagent. Apparently the color must be due to the dehydrating effect of the alcohol, which causes the reappearance of the quinoid form of the rosaniline hydrochloride with its characteristic red color. The addition of alcohol entirely changes the character of this reagent so that it can no longer be called "Schiff reagent?? The new red alcoholic reagent can be used only as a test for aldehydes readily soluble in petroleum ether.

.-

I

A number of factors such as the concentrations of sulfur dioxide, alcohol, and rosaniline hydrochloride were found to influence the color intensity of the petroleum ether layer when using the new reagent. A series of tests was therefore undertaken to study these various factors, and to determine the best composition of the new reagent giving the optimum color intensity and the conditions under which optimum and reproducible values are obtained. I n preparing the usual Schiff reagent it is ordinarily recommended that fuchsine in amounts of 1 to 5 grams per liter be used. After comparing several commercial grades of fuchsine it was decided to use rosaniline hydrochloride. This compound is considered to be the main constituent of the ordinary fuchsine. It crystallizes with 4 molecules of water (17.57 per cent). The commercial product, however, contains only about 9 per cent of water. Hereafter rosaniline hydrochloride is referred to in several places as R. A. HC1. I n making up the usual yellow Schiff reagent, it was found possible to reduce the prescribed amount of hydrochloric acid, thus markedly increasing the color reaction. When the reduction was carried too far, the fuchsine precipitated. When 50 per cent alcohol was added, the acidity could be decreased further without causing precipitation of the fuchsine. On standing, a crystalline precipitate, due to the presence of sodium salts, formed, but, by using an aqueous solution

A .6 -8 1.0 *)h R.A.HC1 FIGURE4. EFFECT OF R. A. HCl CONCENTRATION .2

of sulfur dioxide, the sodium salts were eliminated. A very marked optimum color value was obtained with 0.45 mole SO2 per mole rosaniline hydrochloride when using a 1 per cent solution and 50 per cent alcohol by volume, as shown in Figure 1. Petroleum ether of commercially purified grades has a tendency, on standing, to reduce the aldehyde content of a tallowy fat solution, undoubtedly owing to the presence of certain unsaturated hydrocarbons which react with the fat

Vol. 4, No. 2

ANALYTICAL EDITION

206

aldehydes. Figure 2 shows this effect and also the effect of various methods of purification. Figure 3 shows the effect of alcohol content on the color value. Fifty per cent alcohol by volume 'gave the optimum color intensity for all three concentrations of rosaniline. I n making up the reagent as described below, the alcohol content will be slightly below 50 per cent by volume but, as the curve is rather flat at this point, this should have very little effect. The relationship of concentration of rosaniline hydrochloride to color value is shown in Figure 4. One per cent was adopted as most suitable. By varying the fat concentration, it was found that the fat aldehyde value decreases with decreasing fat concentrations, or decreasing color value. When using a 1per cent rosaniline reagent, the fat aldehyde value reaches a maximum at a color value of about 600, after which it remains constant.

holding the reagent, or to divide the freshly made reagent into several small bottles which should be completely filled and well stoppered. PREPARATION OF REAQENTAND COLOR STANDARD. Twenty grams of pure rosaniline hydrochloride on the anhydrous basis are placed in a 1000-cc. volumetric flask with about 600 cc. of absolute alcohol. The flask is then shaken vigorously until all is dissolved, after which the flask is filled to the mark with absolute alcohol. The solution is now allowed to stand for several days during which a dark-colored sediment forms, consisting of organic impurities and nearly all of the salt. Five hundred cubic centimeters of the clear, filtered, 2 per cent solution are pipetted into a 1000-cc. volumetric flask to which are then added 133 cc. of 0.1 M aqueous solution of SO2 (6.4 grams of SO2 per liter) or its equivalent and distilled water to the mark after cooling to room temperature. The strength of the SO2 solution is best determined by adding 0.1 N iodine in excess and titrating the excess back with 0.1 N thiosulfate. A 0.001 per cent cresol red solution buffered to a pH value of 8.3 was used as a color standard. The buffer solution was made up as follows:

............ Boric acid.. ............................ Sodium chloride.. ....................... Sodium borate (decahydrate).

IA.

I

2

4

6

8

IO

c c R.A.HC1 SOLUTION

FIGURE5. EFFECTOF VARIATION IN AMOUNT OF

REAGENT USED

Several types of containers were tried out. The results varied widely, the highest values being obtained with test tubes. These should be large enough to allow room for mixing and preferably should measure 22 by 175 mm. The manner of shaking was studied and it was discovered that a gentle rotation at a rate of 30 r. p. m. gives a much higher color than a vigorous shaking. Rotation is accomplished by placing the test tubes in a basket in such a way that when the basket is fastened to a vertically rotating disk the tubes are inverted as the disk rotates. The time of rotation giving the optimum color value was found to be 4 minutes. The proportion of rosaniline reagent to the fat solution is also important. Five cubic centimeters of the rosaniline reagent with 25 cc. of fat solution were found convenient and gave the maximum color value, as shown by Figure 5. If the colored petroleum ether solution is allowed to stand in contact with the rosaniline reagent after rotating, the color intensity will increase about 10 per cent during the first 3 hours and then remain constant for several hours. As the kind of glass used and the condition of its surface affect the color value on standing, it is recommended that the major part of the colored petroleum ether be pipetted into clean test tubes soon after rotating. Under these circumstances, the color value will drop slightly during the first hour, but then remain practically constant for several hours, This procedure, although it results in a lowering of the color intensity, was adopted solely for the purpose of obtaining uniformity. Temperature has some effect on the color value. From 5" to 25' C. it is practically constant, but drops about 15 per cent a t 37 "C. It is therefore advisable to avoid such high temperatures. It is recommended that the rosaniline reagent be kept in a brown bottle, since light, particularly direct sunlight, is found to be detrimental. As oxygen slowly oxidizes the sulfur dioxide, it is advisable to exclude oxygen from the bottle

Grams 7.6477 7.6044 1.7696

These were dissolved in distilled water and made up in a volumetric flask to 1 liter. One-tenth gram of cresol red on the anhydrous basis was weighed into a 100-cc. volumetric flask and dissolved in the above buffer solution and the flask finally filled to the mark with the same. From this solution 5 cc. were pipetted accurately into a 500-cc. volumetric flask and the buffer solution added up to the mark. This standard color solution matches fairly closely the shade of the fat aldehyde rosaniline color. Both the rosaniIine hydrochloride and the cresol red used were the National Medicinal Products. L

40 80 I20 160 TIME OF HEATING, HOURS

200

FIGURE 6. PROGRESS OF OXIDATION OF BUTTER

FATAT 50"

c.

Several grades of petroleum ether were tried and, of these, the most satisfactory was Eimer & Amend's Benzine (Petroleum) Purified, b. p. 30" to 100" C. It is necessary to purify it further by shaking four or five times with concentrated sulfuric acid, 250 cc. per 2 liters of petroleum ether. The acid should be only faintly yellow after the last shaking. After that the petroleam ether is refluxed over 100 cc. of a 50 per cent caustic solution for 2 hours and finally distilled over 100 grams of calcium oxide. The higher fraction, boiling between 50" and 100" C., is collected separately to be used for the aldehyde test. DETAILSOF TEST. The fat or oil is dissolved in purified petroleum ether to a suitable concentration varying from 0.05 to 10 grams per 100 cc. of solution, depending on the aldehyde

April 15, 1932

INDUSTRIAL AND ENGINEERING

content. The color value, after rotating with the rosaniline reagent, should preferably be between 50 and 200. If the first test does not come within this range the test should be repeated, using a greater or less amount of the fat to bring the color value within the above range. If the solution is not quite clear, it should be filtered before making up to volume. Twenty-five cubic centimeters of the clear fat solution are pipetted into a test tube (22 by 175 mm.), and 5 cc. of the rosaniline reagent are then added with a pipet and the test tube closed firmly with a No. 4 rubber stopper covered with tin foil. The test tube is then rotated as described above for 4 minutes and, after standing for a short time, about 20 cc. of the purple petroleum ether are pipetted into a clean test tube which may be closed with the same rubber stopper covered with tin foil. A colorimetric measurement is made after standing for 1 to 2 hours, using the cresol red color standard with an arbitrary color value taken as 100. The color value of the test solution is thus measured in terms of arbitrary color units. The aldehyde content of fat is expressed in these color units on the basis of a 0.1 per cent fat solution, and these specific color units are called "fat aldehyde values." The fat aldehyde value is calculated according to the following formula : A =

where A

R, Rt P

=

= = =

100 X R, X 0.1 Rt X P

fat aldehyde value reading of color standard in mm. reading of test solution in mm. percentage of fat or oil in test solution (grams of fat per 100 cc. of solution)

EXAMPLE : P = 1.0 (1 gram of fat per 100 cc. of solution) R. = 10.0mm. Ri = (5.4-5.5-5.5-5.5) average, 5.48 mm. A = loo lo = 18.2 (fat aldehyde value) 5.48 X 1

APPLICATIONS Various kinds of fats and oils were tested for fat aldehyde values according to the new method as described above. It is interesting to note that invariably the older samples gave a higher value than the fresh ones. All these samples of fats and oils gave practically an identical color shade with the new reagent, indicating that the aldehydes formed in various fats and oils are quite alike in respect to this react,ion. TABLEI. RESULTS OF TESTSON VARIOUS FATSAND OILS SAMPLE Coconut oil Palm oil Whale oil Cod-liver, oil Peanut oil Soy bean oil Linseed oil Cocoa butter fresh Cocoa butter' old Olive oil, fresjl Olive oil old Cottonse'ed oil fresh Cottonseed oil: old Corn oil, fresh Corn oil, old Butter oil fresh Butter oil: exposed to air Suet, fresh Suet, old

.

ORQANOLEPTIC FATALDEHYDE VALUE TEST Good 1.7 Good 1.4 Fishy 9.5 Relatively good 5.1 Somewhat rancid 46.5 Somewhat rancid 28.0 Bitter 2.6 1.8 Good 4.7 Good 14.3 Good Rancid 71 Good 20.0 Rancid 132 Good 5.5 Rancid 104 Good 0.5 Tallowy 10.3 Good 5.0 Tallowy 360

OXIDATION TESTS Ten-gram samples of pure butter fat with an original aldehyde value of 1.5 were heated in glass-sealed Pyrex flasks which contained about 126 cc. of air, or about 26 cc. of oxygen. The flasks were rotated at 50" C. for various lengths of time and the volume of absorbed oxygen calculated from data compiled regarding temperature and pressure before and after heating. The fat aldehyde values of these more or less

CHEMISTRY

207

oxidized butter-fat samples were determined as described above. I n Figure 6 are plotted the cubic centimeters of oxygen absorbed per gram of fat against time of heating. Figure 7 shows the correlation between oxygen absorption and the fat aldehyde value. I

.IO

.20

10

1

.46

Oe ABSORB€D PER GRAM OF F A T FIGURE7. CORRELATION BETWEEN OXYGEN ABSORPTION AND FAT ALDEHYDE VALUEOF BUTTERFATAT 50" C. cc

The following calculations are an attempt to correlate the oxygen absorption or the equivalent theoretical aldehyde formation with the fat aldehyde value as determined by the new method. It is assumed that the color intensity of the rosaniline hydrochloride, when combined with a fatty glyceride aldehyde through the SO2 linkage and dissolved in petroleum ether, is not materially different from that of the equivalent rosaniline hydrochloride dissolved in absolute alcohol. 24,000 cc. 02 (20' C.) = 1 mole fat aldehyde = 1 mole rosaniline hydrochloride (R.A.

HCl) = 338 grams R. A. HCI 1 cc. O2 e 0.0141 gram R. A. HC1 Color value of alcoholic rosaniline hydrochloride solution: 0.00046% R. A. HCl = 109 color units (color standard = 100) 0.000422%R. A. HCl = 100 color units

By comparing 1 liter of rosaniline hydrochloride solution with 1 liter of a 0.1 per cent fat solution containing 1 gram of fat, the following relationship is found: 1 liter of 0.000422%R. A. HCl with color value of 100 contains 0.00422 gram of R. A. HCI 1 - z0042 0.30 cc. of oxygen == 100 color units 0.014 1 cc. of oxygen per gram fat + 333 color units

From the curve in Figure 7 are taken the following figures: TOTAL RANGE OF OXIDATION OBSERVED: 1 gram butter fat absorbed 0.39 cc. 02,acquiring a fat aldehyde value of 33.2 Increase in fat aldehyde value: 33.2 - 1.5 = 31.7 color units 0.39 cc. 0 2 = theoretically 333 X 0.39 = 130 color units 31'7 'O0 = 24% of theoretical value 130

By making a similar calculation for different sections of the curve in Figure 7,values in Table I1 are obtained. TABLE11. OXYGEN-FAT ALDEHYDECORRELATION THEORETICAL% OF 0 2 INCREASECOLOR VALUE TBEOE Q U I ~ . RETICAL ABSORBED IN FAT TO 0 2 PER GRAM ALDEHYDE COLOR OF FAT VALUE ABSORPTION VALUE

cc.

0.39 0.03 0.22 0.14 (0.113)

31.7 5.0 4.3 22.4 (33.2)

130 10 73 47 (38)

24 50 6 48 87

RANGEOF OXIDATION Total Beginning Niddle Last part End (tangent)

ANALYTICAL EDITION

208

The low value for aldehyde formation during the middle part of the oxidation is quite significant in that it shows that during this period of decolorization of butter fat the major part of the oxygen absorbed is probably used up by the carotin contained in the butter fat, and relatively little aldehyde is formed. A lower color value than is expected theoretically could also result from a reaction between the fat aldehyde and free sulfurous acid, which undoubtedly is present in the rosaniline reagent through dissociation of the rosaniline sulfite. Further tests with more oxygen absorption might possibly give results which would agree even better with the theoretical values. I n order to prove that extreme oxidation of fats can result in low fat aldehyde values, a series of samples of butter fat was exposed to air at 100' C. for varying lengths of time. The results, which are given in Table 111, show that the fat aldehyde value reaches a maximum of about 950 in 15 hours, after which it drops rapidly and then more slowly to below 50 a t the end of 35 hours. The oxygen absorption seems to slow down after 20 hours' exposure. It is therefore probable that the reduction in fat aldehyde value during the last hours of heating is due mainly to formation of condensation products rather than to further oxidation of the aldehydes. An old sample of corn oil, which had been exposed to air a t room temperature for about 6 years, gave a fat aldehyde value as low as 0.1, 'This sample was exceedingly off flavor. The absence of aldehydes is undoubtedly due to condensation. A similar case was found in the surface butter fat of a very old sample of whole milk powder, which had been exposed to air for 7 years. TABLE111. OXIDATIONOF BUTTERFAT AT 100' C. 08 DURATION ABSORRED FAT OF PER GRAM OF ALDEHYDE HEATINQ BUTTER FAT VALUE cc. Hr. 0 1.2 0 14 740 5 20 890 10 30 965 15 257 38 20 258 .40. 25 106 30 38 35

RE~MARKS

~~

Maximum

Vol. 4, No. 2

0

HzC-0I

I

e

0

-( CHJ:d-CH3

/I

8

0

H~-O-(!!-(CHZ)~-CHO

b

Hz -O--C-(

Several simple aldehydes, such as butyraldehyde, heptaldehyde, cinnamaldehyde, and vanillin, do not develop any color in the petroleum ether layer when rotated with the new rosaniline reagent. Neither did samples of oleic and linoleic acid, which had quite a tallowy odor. All of these products, however, gave more or less of a color reaction with the yellow Schiff reagent. The solubility of the yellow compound decreased with increasing molecular weight. This indicated that the aldehydes which produce the color in the petroleum ether when tested with the new rosaniline reagent must have a high molecular weight, and an affinity for petroleum ether sufficient to overcome the adverse effect of the attached rosaniline group, It is reasonable to assume that these aldehydes are glyceride aldehydes formed when unsaturated acid radicals of fats are oxidized. If the oxidation proceeds according to the reaction formula which follows, then there should be formed also a t the same time a simple aldehyde of low molecular weight, such as nonylaldehyde. This reaction may possibly go through an intermediate peroxide stage, as suggested by several workers. When tested with the usual yellow Schiff reagent, a tallowy butter fat develops relatively little of the water-soluble color which is caused by simple aldehydes. It has been shown (Figure 2) that the high acidity in the yellow Schiff reagent greatly depressed the color reaction. It is likely that the intense odor of tallowy butter fat is due to the presence of low-boiling simple aldehydes.

I1

+ CHI-(CH&-CHO

CHa)ie-CHa

0

Fatty glyceride aldehyde

Simple aldehyde

The coloring of the yellow Schiff reagent by aldehydes depends, according to Wieland and Schening (€9,on an overbalancing of the rosaniline molecule when two molecules of aldehyde are linked to one rosaniline molecule, with the result that the leuco form is changed to the quinoid form with loss of SO2. The reaction with a fat aldehyde probably combines in molecular proportion through the amino-sulfurous linkage with the rosaniline hydrochloride. This is already present in the colored quinoid form which apparently is preserved in the reaction product. The color shade of the reaction product is somewhat changed to a grayish purple as compared with the pure purple color of the rosaniline reagent. It is very likely that other basic dyes would react in a similar manner. Table IV gives a comparison between the various reagents for fat aldehydes, and shows that the new improved reagent is over twenty times as sensitive as any of the other reagents, I n extraction of fats from various food products, difficulties are sometimes encountered in obtaining the total fat aldehydes present. This problem will be discussed in a later paper, TABLEIV. COMPARISON OF VARIOUSREAQENTS FOR FAT ALDERYDES COLOR VALUE so1

..

DISCUSSION

+ 02 +

H C-O-C-(CH2)rCH=CH-(CHg)7-CHa H&-O-C-(CHI)IB-CHB I

___

-

PER

WT'FFT

FUCH-MOLE FREE 0.1% RELABINE FUCH- HC1 TALLOWY TIVE OR SINEOR PER BUTTERCOLOR R. A. R.A. MOLE FAT INR E A Q ~ N T HCl HCl FUCHSINESOLN. TENSITY REMARKS % Mole Mole Improved rosani1.0 0.45 0 213 100 Purpleline reagent red 0.5 3.2 0.35 10.6 5.0 YellowSwissSohiff reagent, van Fellenorange berg 0.1 18.2 22.0 7.3 3.4 YellowRussianSchiffreagent Inichof and orange Schoichine Kreis reagent, Kerr . . .. . . 10.5 4.9 Orange

.

..

ACKNOWLEDGMENT The author wishes to thank Miss W. H. van Wieren for making numerous colorimetric measurements and for offering valuable suggestions.

LITERATURE CITED (1) Fellenberg, von, Mitt.Lebensm. H y g . , 15, 198-208 (1924). (2) Holm, G. E., and Greenbank, G. R., I N D . ENQ. CHEM.,15, 1051-3 (1923). (h Inirhof ~., ----- - and Schoschine. Bull. Russe. No. 64. 159-73 (1926). (4) Xerr, R. H., J. I N D .E N G .CHEX.,10,471-5 (1918). (5) Mundinger, E., Milchwirtschaft. Forsch., 7,292-331 (1929). (6) Powick, W. C., J. Agr. Research, 26, 323-62 (1923). (7) Richardson, A. S., e t al., Oil & Fat Ind., 6,28-9 (1929). (8) Wieland H., and Schening, G. S., Ber., 54B,2627-55 (1921). (9) Winkel, M., Apoth. Ztg., 20, 690-2 (1905). .

I

RECEIVEDApril 15, 1931. Presented before the Division of Agrioultura and Food Chemistry at the 8lst Meeting of the American Chemioal Society, Indianapolis, Ind., Maroh 30 to April 3, 1931.