Showing papers in "Journal of the American Oil Chemists' Society in 1969"

Kinetics of linoleate oxidation in model systems

Abstract: Oxidation of methyl linoleate, trilinoleate and linoleic acid has been studied in model systems based on various solid supports. Oxidation was followed by measurement of oxygen absorption, peroxide values and products of oxidation as a function of moisture equilibrium relative humidity. Effects of various metals, histidine and the antioxidants propyl gallate and butylated hydroxytoluene were studied. The results indicate: (a) at 50 C oxidation of protein increases with increasing moisture content and the protein interacts with peroxides changing the overall oxidation rate; (b) increasing moisture content shows the same inhibitory effect on oxidation of trilinoleate as it does on methyl linoleate; (c) the effectiveness of antioxidants is increased with increasing humidity but some chelating agents complexed with metals become catalytic at the higher moisture content; and (d) at moisture contents in the region of capillary condensation, mobility of reactants is enhanced since the rate of oxidation increases significantly.

Factors affecting initial foam height in the Ross-Miles foam test

Abstract: A study has been made of the relationship between initial foam height, H, as measured by the Ross-Miles test, and such factors as surfactant concentration, critical micelle concentration (CMC) of the solute, surface tension (γ) of the solution, surface area (A) of the foam, and the work involved in the production of the foam surface. The initial foam was remarkably constant in character for the systems studied and there was a linear relationship between H and A. For five of the six solutes used, the work of producing the foam surface fell within a narrow range at concentrations in the neighborhood of the CMC, indicating an inverse relationship between A and γ. For these solutes, H≈(1000/γ)−3.6. The maximum in H occurred in the neighborhood of the CMC.

Lipoxidase deactivation to improve stability, odor and flavor of full‐fat soy flours

Abstract: Oxidation of soybean lipids catalyzed by lipoxidase was prevented by heat treatment of soybean meats, which were then ground to give a full-fat soy flour free of rancid odor and flavors. Our previous studies showed that lipids in cracked, dehulled, soybeans rapidly oxidized after the lipoxidase system was activated by increasing moisture content to 20%. A series of experiments are reported in which various heat treatments were evaluated for effectiveness of lipoxidase deactivation. Dry heat to 212 F, steaming, or both, deactivated lipoxidase to give flours that had low values of peroxide, conjugated diene and free fatty acid and had good flavors after 2 years’ storage. Wet heat alone was also an effective treatment, whereas wet heat preceded by dry heat at 180 F gave poor flavor stability after 2 years. Gas liquid chromatography studies gave evidence that the rapid formation of volatiles in full-fat soy flours was catalyzed by an enzyme system. A 10 member taste panel was able to detect significant flavor and odor differences between oxidized and nonoxidized samples.

Homogeneous catalytic hydrogenation of unsaturated fats: Group VIB metal carbonyl complexes

Abstract: Carbonyl complexes of Cr, Mo and W have been studied as soluble catalysts for the hydrogenation of methyl sorbate and of methyl esters from soybean oil. With methyl sorbate, relative catalytic activity decreased in the approximate order: mesitylene-Mo(CO)3, cycloheptatriene-Mo(CO)3, cycloheptatriene-Cr(CO)3, bicyclo (2,2,1) hepta-2,5-diene-Mo(CO)4, chlorobenzene-Cr(CO)3, methyl benzoate-Cr(CO)3, mesitylene-W(CO)3, benzene-Cr(CO)3, toluene-Cr(CO)3, mesitylene-Cr(CO)3, and hexamethylbenzene-Cr(CO)3. Order of catalytic activity was related to thermal stability of the complexes during hydrogenation. With mesitylene-M(CO)3 complexes, selectivity varied in the order Cr>Mo>W. Under certain conditions the mesitylene complexes of W, Cr and Mo reduced methyl sorbate respectively to methyl 2-, 3-, and 4-hexenoates as main products.

Vitamin E in foods: determination of tocols and tocotrienols.

Abstract: A method is described for the analysis of foods for the forms of vitamin E. Detailed procedures are given for extraction, saponification and partial purification by thin layer chromatography. The individual tocopherols (both tocols and tocotrienols) are identified and estimated as their trimethylsilyl ethers by gas liquid chromatography on SE-30 or Apiezon L at 235 C. Retention ratios are also given for separations on OV-17. Response factors relative to didecyl pimelate as an internal standard and overall recoveries were determined for α-tocopherol, β-tocopherol, γ-tocopherol, δ-tocopherol, β-tocotrienol and α-tocotrienol. Sample sizes depended on tocopherol content and were usually chosen to contain 3–50 µg of the individual tocopherols. Data for a number of seeds and oils are given. The greatest variety of forms was found in barley, which contains all the forms listed above, plus γ-tocotrienol.

Breeding rapeseed for oil and meal quality

Abstract: Significant variation in fatty acid composition occurs within the seed oils of theBrassica genus, which includes the mustards and rapeseed. Research into the inheritance and biosynthesis of fatty acids has shown that at least two biosynthetic pathways exist in the developing rapeseed and some of the steps are under direct genetic control. The plant breeder has the basic knowledge in this oilseed crop to produce seed oils with defined fatty acid composition, and a practical example is the commercial development of Canbra oil, the rapeseed oil from which erucic acid has been eliminated.Brassica seed meals contain thioglucosides which may cause metabolic disturbances when fed to certain classes of livestock. The major thioglucosides in rapeseed meal are those giving rise to 3-butenyl and 4-pentenyl isothiocyanate and 5-vinyl-2-oxazolidinethione. Partial success in eliminating these compounds has been achieved by breeding strains of turnip rape (B. campestris) which do not contain the glucosides of 4-pentenyl isothiocyanate and oxazolidinethione, and the identification of aB. napus variety with very low levels of all three glucosides. These findings suggest that complete removal of these sulfur compounds may be possible through plant breeding.

Edible oil quality as measured by thermal release of pentane

Abstract: As part of their thermal decomposition products, fatty hydroperoxides produce normal hydrocarbons The extent of hydrocarbon formation can be measured and associated with the quality and potential stability of an oil Edible oils containing linoleic acid develop 13-hydroperoxy-9,11-octadecadienoic acid as one product of autoxidation On thermal decomposition this hydroperoxide yields pentane; the amount released has been correlated with the flavor scores of fresh and aged soybean and cottonseed oils and with the peroxide values of these oils The quantity of pentane released has an inverse linear relationship to flavor score and a direct linear relationship to peroxide values Edible oils exposed to light exhibit a different relationship between flavor score and thermally derived pentane than do the same oils when autoxidized in the dark

Hydroformylation of unsaturated fatty esters

Abstract: Unsaturated fatty esters and vegetable oils were hydroformylated with H2 and CO (3500–4600 psi) and Co2(CO)8 to give fatty aldehydes at 100–110 C and fatty alcohols at 175–190 C. Yields of distillable C19 oxo products varied from 42% to 84%. Distilled products contained from 50% to 90% branched isomers and from 4% to 16% linear isomers. The proportion of linear isomers increased at higher reaction temperatures and in the presence of tributylphosphine-cobalt carbonyl complex. Linear and branched hydroxy products were separated by silicic acid column, thin-layer, and gas-liquid chromatography. The linear hydroxy product (from oleate and linoleate) was identified as methyl 19-hydroxynonadecanoate by nuclear magnetic resonance and mass spectrometry. Isomeric branched products were analyzed by mass spectrometry as the diester derivatives. They were identified as a mixture of 5- to 13-carbomethoxy methyl octadecanoate.

Theoretical investigations into the accuracy of sampling shelled peanuts for aflatoxin

Abstract: Within a population of shelled peanuts, aflatoxin may be concentrated in less than 0.5% of the peanuts. Those peanuts containing aflatoxin might have concentrations up to 1,000,000 µg of aflatoxin per kilogram of peanuts. Because of the distribution pattern, sample means vary widely, and the true average level of aflatoxin in the population is difficult to estimate. The objective of this study was to determine the effect of sample size, N, on sampling accuracy. The negative binomial distribution of aflatoxin since it allowed for a high probability of zero counts along with small probabilities of large counts. Using both the Monte Carlo technique and a direct computation method, the effect of sample size on sampling accuracy was quantitatively described.

Lipids of maturing grain of corn (Zea mays L.): I. Changes in lipid classes and fatty acid composition.

Abstract: The total lipids of the grain from three strains of corn were compared throughout the growing season. The Illinois High Oil stock and the two inbreds, H51 and K6, represented high, intermediate and low oil-producing lines. In all three strains lipid synthesis was most active between 15 and 45 days after pollination. The lipids were extracted from the grain with a mixture of chloroform, methanol and water and were separated into classes by silicic acid and thin layer chromatography. Triglycerides constituted 10–17% of the total lipids at 10 days after pollination and increased to 75–92% at 75 days. Polar lipids at 10 days represented 70–72% and at 75 days 4–21%. Fatty acid compositions of the triglycerides and polar lipids changed as the grain matured, but the fatty acids of the polar lipids were more saturated than those of the triglycerides throughout the sampling periods. The major polar lipids were digalactosyl diglyceride, monogalactosyl diglyceride, phosphatidyl choline, phosphatidyl inositol and phosphatidyl ethanolamine.

Refractive index as an objective method for evaluation of rancidity in edible oils and fats

Abstract: Common edible oils and fats (refined peanut oil, seasame oil, safflower oil, and butter oil, ghee) were exposed to direct sunlight, fluorescent light and Schaal Test. Data collected on refractive indices (N D 25 ) show an increase of the order of 0.001±0.0003 at the stage of development of perceptible rancid odor. The pattern of changes in refractive indices and peroxide values of these edible oils, autoxidized at 100±5 C, show that refractive indices indicate more precisely the termination of the induction periods than peroxide values.

The formation of 1-octen-3-ol in soybeans during soaking

Abstract: The soaking of soybeans in water as a pretreatment for soy milk manufacture was found to result in the production of significant quantities of 1-octen-3-ol. The amount of this compound formed at a soak temperature of 50 C increased with length of soak time and reached a maximum after approximately 6 hr. The rate of formation had a pH optimum of 6–7. A pure fraction of 1-octen-3-ol, isolated by a preparative GLC technique, was found to be levorotatory ([a] D 17 = −11.7; [a] D 13 = −11.8). Based on these findings, the mode of formation of 1-octen-3-ol in this case is presumed to be enzymatic. The flavor threshold of 1-octen-3-ol in soy milk was determined to be between 0.5 and 1.0 ppm.

Precursors of alk-2,4-dienals in autoxidized lard

Abstract: Evidence suggested that the low proportions of C10 alk-2,4-dienal found in mildly autoxidized linoleate or lard was basically due to a selective scission mechanism of the 13 and 9 conjugated linoleate hydroperoxide isomers. Spontaneous scission tended to be at the carbon linkage between a double bond and the hydroperoxide group. Thus the 13 hydroperoxide isomer produced the typically predominant amounts of hexanal. The 9 hydroperoxide isomer formed little C10 dienal and scission between the 9 and 10 carbons possibly led to some C9 alk-2-enal. Earlier studies of free aldehyde formation by autoxidized oleate, linoleate, linolenate and arachidonate support such a scission mechanism. Autoxidized linoleate was decomposed by dilute acid to C6 alkanal, some C9 enal and no dienal. Under different stress, such as heat, alkaline conditions and Cu++, large proportions of C10 dienals were formed. This appeared due to a shift in the point of scission to the saturated side of the hydroperoxide group.

Modification of quantity and quality of safflower oil through plant breeding

Abstract: Less than 20 years have passed since safflower was established commercially in the southwestern area of the United States. Already hybrid varieties are available, oil and protein contents have been raised greatly, and oil quality has been modified sufficiently to constitute another oil crop for American agriculture. It is hoped that the next 20 years will be equally productive in terms of improvements and modifications of the oil and protein of this crop.

New process for the production of better quality rapeseed oil and meal: II. Detoxification and dehulling of rapeseeds — feasibility study

Abstract: Feasibility studies have shown that a white, bland, defatted, thioglucoside-free flour can be prepared from rapeseed. The thioglucosides, the precursors of toxic principles, present in rapeseeds are removed by aqueous extraction. The key operations, boiling of the seed followed by wet-grinding and aqueous extraction, help in the removal of seed coat from the rapeseed. Although aqueous extraction results in the loss of solids, the quality of the end products is good and may offset the loss.

Reaction of gossypol with amino acids and other amino compounds

Abstract: The reactions of gossypol with certain amino acids and other amino compounds have been studied spectroscopically with respect to the effect of time and pH in the range from 5.7 to 7.5 at 37 C. The rate of reaction of gossypol with amino acids increases with increase in pH and has been shown to be related to the distance of the amino group from the carboxyl group within the molecule. Reaction products of gossypol with amino acids and other amino compounds were subjected to various purification procedures and analysis to determine combination ratios. In addition to the expected gossypol-to-amino compound ratio of 1:2, dictated by the formation of Schiff base-type bonds with the two aldehyde groups of gossypol, compounds with ratios of 1:3 and 1:4 were isolated. These results indicate that each of the two aldehyde groups of gossypol can react with two amino groups under the conditions studied.

Structure of unsaturated vegetable oil glycerides: Direct calculation from fatty acid composition

Abstract: Composition and structure of unsaturated glycerides of vegetable oils can be calculated directly from the fatty acid composition of the oil. Fatty acid distribution on the 2 position as normally determined by lipase hydrolysis is calculated from the composition of the whole oil by applying the following three rules in their respective order: Saturated fatty acids and those with chain length greater than 18 carbons are first distributed equally and randomly on the 1 and 3 position of the glycerol moiety; oleic and linolenic acids are treated equally, or as a unit, and distributed equally and randomly on all three glyceride positions with any excess from the 1 and 3 position being added to the 2 position; and all remaining positions are filled by linoleic acid. Remarkably good agreement between the calculated and experimentally determined fatty acid distributions is shown for soybean, linseed, safflower and many other vegetable oils whose compositions are reported in the literature. An association between oleic and linolenic acid within the glyceride structure of some vegetable oils is evident.

Kinetic rate constants determined by a digital computer

Abstract: The difficulty of determining rate constants for complex reactions has been overcome with the development of a general digital computer program that can determine up to 10 rate constants in any reaction scheme which can contain as many as 10 components. A given reaction to which the experimental data are to be fit is described to the computer in a short one-step integration subprogram, which solves the differential equations representing the scheme. Only this subprogram needs to be rewritten to change the reaction scheme. Special features of the program and length of calculations are discussed. A copper-chromite hydrogenation of a mixture of linolenate and conjugated linoleate demonstrates what the program does and what is a typical output.

Variation in composition of sunflower oil from composite samples and single seeds of varieties and inbred lines

Abstract: The seed oil of eight sunflower varieties grown at 10 locations in 1964 and 14 locations in 1964 showed highly significant differences between varieties and between stations in mean values for percentage of stearic, oleic and linoleic acids but no significant difference for palmitic acid. The same observations held for oleic and linoleic acids in three varieties common to eight stations in the two years. The only significant interaction appearing in these studies was between years and stations. Varieties requiring the same time to mature differed significantly. Oil from composite samples of inbred lines showed large differences in composition, e.g., the ranges in 56 lines grown in one season at one location were: palmitic 4.7–8.2%; stearic 1.7–9.1%; oleic 13.9–40.3%; and linoleic 47.9–76.4%. Single seeds within inbred lines also showed striking variation. The greatest variation occurred in lines inbred for one to three generations and the least in lines inbred for eight to nine generations. Pairs of lines with identical or similar flowering date differed significantly in mean values of all four acids. Variation between seeds within varieties were relatively narrow in Armavirec and Advent, but wide in Peredovik where the range was: palmitic 4.5–9.4%; stearic 2.5–12.4%; oleic 14.8–46.4%; and linoleic 34.3–75.5%. The results show that genetic control of oil quality, independent of flowering or maturity date, exists in sunflowers. The wide range in composition suggests that altering oil quality in the crop by breeding is a practical objective.

Reaction of cysteine and methionine with malonaldehyde

Abstract: Malonaldehyde (M), a product of polyunsaturated fatty acid oxidation, reacted with the sulfhydryl as well as with the amino groups of cysteine (cys) The cys-M product had an absorption maximum at 310 mµ, and the extinction coefficient at pH 70 was 23 × 104 Elementary analysis of the cys-M product agreed with a structure in which 2 moles of cysteine had reacted with 3 moles of malonaldehyde The molecular weight of cys-M preparations increased on storage and the UV absorption changed from 310 to 315–320 mµ, with a consequent shift to longer wavelength in the visible

A rapid method for the determination oftrans unsaturation in fats and derivatives

Abstract: Thetrans unsaturation present in samples of unsaturated fats and derivatives may be determined from measurement of the infrared absorbance at two wavelengths, one due totrans configuration of a double bond and the other due to the ester or acid group. The ratio of the two absorbance values has a linear relationship with thetrans unsaturation content. Thus, a drop of sample is diluted with CS2 and the infrared absorbance measured at 10.36 µ and at 8.5–8.6 µ if esters and 10.7 µ if acids. To calculate the per cent isolatedtrans double bonds in the sample, the ratio of the two absorbance values is substituted into the linear equation which was developed from known samples. The method is rapid since the sample need not be weighed nor made up to a known volume and thus may be applied to samples such as those collected from a gas chromatograph or after thin layer chromatography.

Selective hydrogenation of soybean oil: IV. Fatty acid isomers formed with copper catalysts

Abstract: Two samples of soybean oil hydrogenated with copper-containing catalysts at 170 and 200 C were analyzed for their natural and isomeric fatty acids. Methyl esters of the hydrogenated oils were separated into saturates, monoenes, dienes and trienes by countercurrent distribution between acetonitrile and pentane-hexane. Monoenes were further separated intocis- andtrans-isomers on a silver-saturated resin column. Double bond location in these fractions was determined by a microozonolysis-pyrolysis technique. The diene fraction was separated with an argentation countercurrent distribution method, and linoleate was identified by infrared, ozonolysis and alkaliisomerization data. The double bonds in thecis-monoenes were located in the 9-position almost exclusively. However, the double bonds in thetrans-monoene were quite scattered with 10- and 11-isomers predominating. About 86% to 92% of the dienes consisted of linoleate as measured by alkali isomerization. Other isomers identified as minor components includecis,trans andtrans, trans conjugated dienes and dienes whose double bonds are separated by more than one methylene group.

A simple photometric method for microdetermination of fatty acids in lipids

Abstract: A single step photometric micromethod for determination of fatty acids in lipids in benzene solution, using rhodamine 6G reagent, has been developed. The method eliminates the disadvantage of formation of a biphasic system and is applicable in the presence of glycerides, sterols, epoxy compounds, hydrocarbons and long chain hydroxy compounds such as long chain fatty alcohols. The long chain fatty acids from C12 to C22, both saturated and unsaturated, can be determined with reasonable accuracy in the concentration range of 0.08–0.25 µmole/ml. The method is simple, rapid, and requires relatively inexpensive chemicals.

Fat oxidation at lwo oxygen pressure: II. Kinetic studies on linoleic acid oxidation in emulsions in the presence of antioxidants

Abstract: Earlier reported kinetic studies on the dependence of lipid oxidation on oxygen pressure in emulsions were continued by studying this relationship in the presence of antioxidants. The substances tested represented two types of antioxidants, phenolic inhibitors (α-tocopherol, BHA, PG) and amino acid-retarders (glycine, alanine, histidine, tryptophane). The inhibiting effect of the first mentioned group, i.e., the formation of an induction period was, in general, not dependent on oxygen pressure, while the retardation caused by amino acids was stronger at low oxygen pressure than in air. The effect of lowering oxygen pressure was practically the same, when phenolic inhibitors were added as without such addition. It was, however, enhanced by the addition of amino acid-retarders. When representatives of these two types of antioxidants were added in combination, their synergistic effect was considerably enhanced at low oxygen pressure.

Hydrocarbons of dogfish and cod livers and herring oil

Abstract: Dogfish and cod liver oils and the oil from the whole herring were saponified and the hydrocarbons concentrated by chromatography of the unsaponifiable portion over alumina followed by silica gel treatment of the resulting fractions. Temperature programmed gas chromatography employing a 3% SE-30 packing was applied to the analysis of hydrocarbons of C14 to C32.5. The paraffins comprised two or more groups. Dogfish liver oil gave rise to 7.62% unsaponifiables and pristane, other saturated types, squalene and an additional group, high in unsaturated components, were 193, 325, 308 and 200 mg% in this portion or 15.7, 24.8, 23.5 and 15.3 mg%, respectively, in the oil. Cod liver oil yielded 1.0% unsaponifiables of which the above hydrocarbons in the order stated amounted to 0.30%, 1.15%, 3.29% and 2.27% or 3.0, 11.5, 32.9 and 22.7 mg% in the liver oil. The unsaponifiable material of herring oil (1.35%) was prominent in paraffinic hydrocarbons, the levels of the above specified components being 16.34%, 3.51%, 0.99% and 1.41% as stated or 221, 47.4, 13.4 and 19.1 mg% in the oil. The sterol and alcoholic contents were ascertained for the three marine oils and the glyceryl ether levels found to be highest for dogfish liver oil.

High oleic oils by selective hydrogenation of soybean oil

Abstract: High oleic (monoene) oils were obtained from soybean oil by selective hydrogenation with copper catalysts. A mixture of nickel and copper chromite catalyst had activity suitable for producing the high monoene oils. A new catalyst (copper-on-Cab-O-Sil) prepared in the Laboratory was more active than commercial copper catalysts. Hydrogenated oils contained 61–72% monoenoic and 14–24% dienoic acids, and there was essentially no increase in stearic acid. Thetrans-isomer content of these oils varied between 17% to 32%. Double bonds in the monoene were distributed along the molecule from C6 to C15, but were located preferentially in the C9 position for thecis-monoene and in the C10 and C11 positions for thetrans-monoene. When the iodine value of these high monoene oils was about 90–95, they remained liquid above 28 C. Citric acid treatment reduced the copper content of hydrogenated oils to a level that was comparable to that of the original soybean oil.

Identification of some acids from autoxidation of methyl linoleate

Abstract: The acids from autoxidation of methyl linoleate have been analyzed as their methyl esters by combined capillary gas chromatography-mass spectrometry (GC-MS) The principal components were hexanoic, trans-2-octenoic, suberic and azelaic acid Minor components included formic, pentanoic, heptanoic, trans-2-heptenoic, octanoic and nonanoic acid In addition,trans-2,3-epoxy-octanoic acid was isolated as its methyl ester by preparative GLC and was identified by means of NMR, high resolution MS, IR and by conversion to a known derivative

Evaluation of the differential scanning calorimetric method for fat solids

Abstract: Denison et al. (1) recently reported a method for measuring the per cent solids in fats using the Differential Scanning Calorimeter (DSC). The present work evaluates that method using the Perkin Elmer DSC-1, compares it with nuclear magnetic resonance (NMR) and dilatation methods, and extends it to hard butters. Although the method gave excellent interlaboratory agreement with soft fats, extension to hard fats led to greater experimental variance than SFI. The DSC method provides greater speed (one hour elapsed time) and additional information (thermal “fingerprint” of the fat). Thus, the DSC determination of fat solids overall compares favorably with the NMR method, as well as the SFI dilatation method. The DSC method is readily adaptable to quality control use.

A dimeric oxidation product of γ-tocopherol in soybean oil

Abstract: A dimeric oxidation product (5-γ-tocopheroxy-γ-tocopherol) has been isolated from soybean oil and identified. The dimer content in extracted oil was increased by elevating the moisture level in raw soybeans. With moisture increase, no change in the quantity of α-tocopherol was observed, but γ- and δ-tocopherol contents were greatly decreased and two kinds of dimer were formed from γ- and δ-tocopherols. When the moisture level in moistened beans was lowered, these dimers reverted to their corresponding original tocopherols. The same results were obtained by treating pulverized soybeans with various reducing agents. γ-Tocopherol added to autoxidizing soybean oil was oxidized more easily in the presence of oxidation products derived from tocopherols and turned into the dimeric product.