Dietary fat composition and tocopherol requirement: II. Nutritional status of heated and unheated vegetable oils of different ratios of unsaturated fatty acids and vitamin E

In studies conducted on male and female rats and involving evaluation of growth, reproductive and lactation performances and of lipid peroxidation, no evidence could be found for the need for added vitamin E (a-tocopherol) over and above that naturally present as tocopherols in the vegetable oils investigated. These oils are in common usage in industry, i.e., liquid nonhydrogenated cottonseed oil, a lightly hydrogenated cottonseed oil and a hydrogenated soybean oil shortening. The ratio of polyunsaturates to total tocopherol in the test oils varied from 640:1 to 9:1. Even those oils obtained from a commercial frying operation after a steady state had been attained contained sufficient vitamin E to meet dietary requirements. Results of in vitro peroxide hemolysis tests conducted on the red blood cells of the test animals did not correlate well with biological performance.     

Long-term responses of rats to heat-treated dietary fats: IV. Weight gains,food and energy efficiencies,longevity and histopathology

Representative cottonseed salad oils, corn oils, lards and hydrogenated vegetable shortenings, and portions of the same fats heated at 182 C for 120 hr were fed as 20% of nutritionally adequate diets to weanling albino rats in longevity studies. Differences in the responses of rats fed diets containing the unheated and heated fats were generally small with respect to rates of gain, 12 th week and adult weights, efficiencies of utilization of absorbed energy, incidences of grossly detectable diseases and longevities. There were no indications that the feeding of the heated fats had shortened survival times in comparison with the comparable unheated fat. Animals fed hydrogenated vegetable shortening, heated or unheated, survived the longest. However, gains were slightly slower with the heated cotton-seed oil diets, and food efficiencies were slightly lower with the heated cottonseed oil and heated lard diets because of decreased digestibilities of these fats. The usual disabilities of old age such as nephritis, respiratory disease and periarteritis were present in all groups. The incidence of mammary tumors was high but did not differ significantly with the kind of fat, heaated or unheated. Tumor incidence other than mammary was similar in both sexes and there was no significant difference between fresh and heated fats. Absence of adverse effects attributable to the heated fats during the life span of the rats in further evidence of the safety of these fats of the quality customarily consumed by the human population.     

Nutritional and toxicological evaluation ofHibiscus sabdariffa oil andCleome viscosa oil

Mesta seed oil (Hibiscus sabdariffa), like cottonseed oil, contains cyclopropenoid fatty acids (2.9%) and epoxy fatty acids (2.6%) in addition to normal fatty acids found in vegetable oils.Cleome viscosa (Capparidaceae) seed oil is rich in linoleic acid (70%) and free from any abnormal chemical constituents. Nutritional and toxicological evaluations of these two oils were done by multigeneration breeding studies by feeding the respective oils and groundnut oil as control at 10% level in a 20% protein diet with adequate vitamins and minerals. These studies revealed that rats fed mesta oil had inferior growth and reproductive performance and also had altered liver metabolism. Rats fedC. viscosa oil did not show any abnormal growth or reproductive performance or altered liver lipid levels. Thus, these studies indicate that raw or refined mesta oil may not be suitable for human consumption whereasC. viscosa oil can be used safely by humans.     

Flavor evaluation of copper-hydrogenated soybean oils

The use of copper catalyst to reduce selectively the linolenate in soybean oil improves its flavor stability. As previously shown, the copper must be removed or properly inactivated to obtain an oil of high initial quality. In oven and heat tests, odor and flavor development in the hydrogenated soybean oil samples correlate surprisingly well with actual levels of linolenate, but there were some differences in overall responses among cottonseed oil, copper-reduced (0.0% linolenate) and nickel-reduced (3.0% linolenate) soybean oils. The taste panel generally scored the last three oils in the following order: cottonseed oil, copper-reduced and nickel-reduced soybean oil. One of 10 papers to be published from the Symposium “Hydrogenation”. presented at the AOCS Meeting, New Orleans, April 1970. No. Utiliz. Res. Dev. Div., ARS, USDA.     

Detection of adulteration of cottonseed oil by gas chromatography

To detect adulterant vegetable oils in cottonseed oil, soybean, rapeseed, and ricebran oils were mixed into cottonseed oil extracted experimentally from seeds. These adulterated oils and the component oils were analyzed for sterols, fatty acids, and triglycerides by gas chromatography. In sterol analysis, stigmasterol was determined for adulteration with soybean and ricebran oils. Brassicasterol content seemed to be reliable as the indicator of adulteration for rapeseed oil. In fatty acid analysis, erucic acid for rapeseed oil and linolenic acid for soybean and ricebran oils were proof of adulteration. Triglyceride analysis was not so reliable as sterol analysis for detecting contamination, except that triglycerides with carbon-58, 60, and 62 indicate adulteration with rapeseed oil. Rapeseed oil (5%) and soybean and ricebran oils (10%) were the limits of detection for adulteration in cottonseed oil. Analysis of cottonseed oil from six refineries did not show positive indications of adulteration.     

Effects of fresh and used hydrogenated soybean oil on reproduction and teratology in rats

Groups of 25 pairs of two generations of male and female rats were fed diets containing 15% of either fresh hydrogenated soybean oil (iodine value, 107), a similar fat used 56 hr for deep frying or an unhydrogenated mixture of fats and oils with a fatty acid composition similar to the hydrogenated soybean oil. The first two litters of each generation were permitted to be born naturally. During the third pregnancy of each generation, one-half of the females were sacrificed on day 13 of gestation and inspected for early embryonic death. The remaining females were sacrificed on day 21 of gestation, and the fetuses were examined for either skeletal or softtissue abnormalities. There was no evidence of any deleterious effects on the reproductive parameters nor any teratogenic effects due to either hydrogenated soybean oil, a similar oil used for frying foods for 56 hr or an unhydrogenated mixture of fats and oils.     

Effects of fresh and used hydrogenated soybean oil on reproduction and teratology in rats

Groups of 25 pairs of two generations of male and female rats were fed diets containing 15% of either fresh hydrogenated soybean oil (iodine value, 107), a similar fat used 56 hr for deep frying or an unhydrogenated mixture of fats and oils with a fatty acid composition similar to the hydrogenated soybean oil. The first two litters of each generation were permitted to be born naturally. During the third pregnancy of each generation, one-half of the females were sacrificed on day 13 of gestation and inspected for early embryonic death. The remaining females were sacrificed on day 21 of gestation, and the fetuses were examined for either skeletal or softtissue abnormalities. There was no evidence of any deleterious effects on the reproductive parameters nor any teratogenic effects due to either hydrogenated soybean oil, a similar oil used for frying foods for 56 hr or an unhydrogenated mixture of fats and oils.     

Exacerbation of heart and liver lesions in rats by feeding of various mildly oxidized fats

Groups of 40 male Charles River rats were fed diets containing cottonseed oil, olive oil, corn oil, soybean oil, coconut oil, chicken fat, beef fat, butter oil, lard and saturated medium chain triglycerides. The fats were fed fresh and after 40 hr aeration at 60 C, which hardly changed peroxide values. In addition, fresh and aerated soybean oil and lard were fed to W/Fu rats. Body weights and life span were significantly influenced by the kind of fat fed, but not by aeration. Many hearts exhibited unspecific focal myocarditis and focal fibrosis. The latter was graded in a blind test, which revealed highly significant differences in the incidence of severe lesions; those fed corn oil had the most, followed by cottonseed oil, soybean oil, olive oil, beef fat, saturated medium chain triglycerides, butter, chicken fat and lard, in that order. Feeding of aerated fat resulted in an increased incidence with six of the eight fats. The W/Fu rats had lower incidences, but those fed soybean oil had more than those fed lard, and aeration led to a higher incidence. Some heart sections stained with Light Green SF Yellowish revealed areas of muscle fibrils that did not accept the stain, probably as a consequence of cellular damage. Higher incidences of this lesion were associated with the same fats as was severe fibrosis, and feeding of aerated fats led to higher incidences. Many livers revealed marked proliferation of bile ducts. The groups fed cottonseed, soybean, olive and corn oils had higher incidences of severe lesions, and feeding of the oxidized oils led to still higher incidences. None of the results appeared to be associated with the fatty acid composition of the fats, which suggested that these long term effects may have been due to minor constituents in the individual fats. One of seven papers presented in the symposium “Biological Significance of Autoxidized and Polymerized Oils,” JOCS-AOCS Joint Meeting, Los Angeles, April 1972.     

Biological evaluation of hydrogenated rapeseed oil

A 91-day feeding study evaluated soybean oil, rapeseed oil, fully hydrogenated soybean oil, fully hydrogenated rapeseed oil, fully hydrogenated superglycerinated soybean oil and fully hydrogenated superglycerinated rapeseed oil at 7.5% of the diet in rats; a 16-wk feeding study evaluated soybean oil and the three rapeseed oils or fats at 15% of the diet. Each fat was fed to 40 rats as a mixture with soybean oil making up 20% of a semi-synthetic diet. No significant differences in body weight gains or diet-related pathology were seen in the 91-day study although the rats fed liquid rapeseed oil had slightly heavier hearts, kidneys and testes than the others. The rats fed the four fully hydrogenated fats ate more feed and had lower feed efficiencies than those fed oils but no differences were seen among the four hydrogenated fats. In the 16-wk feeding study, no pronounced pathology related to the diet was seen although the rats fed liquid rapeseed oil had a slightly higher incidence of histiocytic infiltration of cardiac muscle than the rats in the other groups. The female rats fed the three rapeseed oil fats gained significantly less weight and the females fed liquid rapeseed oil had enlarged hearts compared to the other groups. The absorbabilities of the six fats were measured in the 91-day study when fed as a mixture with soybean oil and as the sole source of dietary fat in a separate 15-day balance study. The four fully hydrogenated fats were poorly absorbed and the absorption of behenic acid from the two hydrogenated rapeseed oils was found to be 12% and 17% in the balance study and 8-40% in the feeding study. The adverse biological effects of unhydrogenated rapeseed oil containing erucic acid as reported in the literature do not occur with fully hydrogenated rapeseed oil. In addition, the low absorbability of the fully hydrogenated rapeseed oil is an added factor in its biological inertness.     

Antipolymerization activity of oat extract in soybean and cottonseed oils under frying conditions

A methanolic extract of Noble oat (Avena sativa L.) was tested for its antipolymerization activity in soybean and cottonseed oils heated to 180°C for 10 h per day for 10 d and for its carry-through properties in fried bread cubes. The soybean and cottonseed oils containing 0.005 or 0.007% oat extract (based on total phenolic content) formed significantly lesser amounts of polar compounds with high molecular weight than did the oils containing 0.02% tertiary butyl hydroquinone (TBHQ), 1 ppm dimethylpolysiloxane (DMS) and oils containing no additives (control) as measured by high-performance size-exclusion chromatography. Fatty acid composition, also monitored, showed that oils with either level of oat extract maintained a significantly higher linoleic-to-palmitic acid ratio (18∶2/16∶0) than did the other treatments. Oil extracted from bread cubes fried (180°C) in oils containing TBHQ and oat extract and then stored at 60°C in the dark for up to 14 d had significantly lower (P≤0.05) peroxide values and higher (P≤0.05) 18∶2/16∶0 ratios than did oil extracted from cubes fried in oil containing DMS and in the control oil.     

The effect of dietary erucic acid on cardiac triglycerides and free fatty acid levels in rats

Male Sprague-Dawley rats, 3 weeks of age, were fed semisynthetic diets containing test oils at 20% by weight for 3 days, 1 week, and 16 weeks. The test oils contained up to 22.3% erucic acid. Growth retardation was evident in rats fed rapeseed oil high in erucic acid, and soybean oil and Tower rapeseed oil diets containing about 5% erucic acid. Cardiac triglyceride accumulation was found in rats fed diets containing about 5% erucic acid but not in rats fed Tower rapeseed oil which contains 0.2% of this acid. The cardiac free fatty acid levels were low, 50–100 μg/g of wet heart tissue, and were not affected by feeding diets containing about 5% erucic acid. Feeding a diet containing a high erucic acid rapeseed oil did result in higher free fatty acid levels but only at 3 days and 1 week; the level at 16 weeks was similar to the other oils. The fatty acid analysis of cardiac triglycerides and free fatty acids showed high percentages of erucic acid at 3 days and 1 week; at 16 weeks these levels had declined significantly. The results indicate that the accumulated erucic and eicosenoic acids, at 3 days and 1 week, accounted for the increase in cardiac free fatty acids when rats were fed the high erucic acid rapeseed oil. There appears to be no evidence that the early cardiac triglyceride or free fatty acid accumulation is related to the formation of the long term myocardial lesions. Contribution No. 739 Animal Research Institute.     

The relationship of polymorphism to the texture of margarine containing soybean and cottonseed oils

Summary A correlation of the organoleptic and physical properties of hydrogenated soybean oil, blends of this oil with hydrogenated cottonseed oil, and their corresponding margarines has been made by comparing samples crystallized under tempered and essentially untempered conditions. Margarine, which is usually processed under the latter condition and which contains a high percentage of hydrogenated soybean oil, will at times show a strong tendency to develop grain. This graininess was characterized by the presence of high meltingbeta polymorphs, formed by a slow rate of crystal growth. Thus the difference in the polymorphic behavior of highly hydrogenated cottonseed and soybean oil observed by Bailey still prevails in the partially hydrogenated oils but to a lesser extent. The tendency for hydrogenated soybean oil to formbeta crystals can be reduced or eliminated by conditions which promote faster crystal growth and/or the incorporation ofbeta prime stable triglycerides, which control crystal growth through mixed crystal or solid solution formation.     

A comparison of wesson loss and cup refining loss analyses of crude cottonseed and soybean oils

Wesson loss and cup refining loss were determined on 100 samples of crude cottonseed and soybean oils produced in different sections of the country. The Wesson method gave more reproducible results than the cup method. Wesson loss results were found to be closely indicative of the total neutral oil content of crude oils. The average ratio of cup loss to Wesson loss was 2.3 for crude cottonseed oil and 1.7 for crude soybean oil. The ratio varied considerably for individual crude oils of a given kind, or type within each kind, or a local producing section. Therefore, no real useful correlation between the results of the two methods was found to exist.     

Comparison of Soybean and Cottonseed Oils upon Hydrogenation with Nickel,Palladium and Platinum Catalysts

There is current interest in reducing the trans fatty acids (TFA) in hydrogenated vegetable oils because consumption of foods high in TFA has been linked to increased serum cholesterol content. In the interest of understanding the TFA levels, hydrogenation was carried out in this work on soybean oil and cottonseed oil at two pressures (2 and 5 bar) and 100 °C using commercially available Ni, Pd, and Pt catalysts. The TFA levels and the fatty acid profiles were analyzed by gas chromatography. The iodine value of interest is ~70 for all-purpose shortening and 95–110 for pourable oil applications. In all cases, higher hydrogen pressures produced lower levels of TFA. In the range of 70–95 iodine values for the hydrogenated products, the Pt catalyst gave the least TFA, followed closely by Ni, and then Pd, for both oils. For all three catalysts at 2- and 5-bar pressures and 70–95 iodine values, cottonseed oil contained noticeably less TFA than soybean oil; this is probably because cottonseed oil contains a lower total amount of olefin-containing fatty acids relative to soybean oil. Approximate kinetic modeling was also done on the hydrogenation data that provided additional confirmation of data consistency.     

A simplified process for the elimination of the halphen-test response in cottonseed oils

Since certain biological effects have been ascribed to the cyclopropenoids that give a positive response to the Halphen test, processes were explored to eliminate this response from cottonseed oils. Heating alkali-refined, Halphen-positive cottonseed oils in a modified laboratory deodorizer in the presence of cottonseed oil fatty acids, capric acid, citric acid, or phosphoric acid was found to be an effective method of eliminating this response. These treated, Halphen-negative cottonseed oils, the untreated Halphen-positive cottonseed oil, and a corn oil control were incorporated into rations fed to different groups of laying hens. Hens that ingested either the Halphen-negative cottonseed oil or the corn control produced normal eggs, whereas hens fed the Halphen-positive cottonseed oil produced eggs with pink whites, decreased pH of whites, and increased pH of yolks on storage, and lower ratios of oleic acid to stearic acid in the yolk lipids. The simple processes presented—particularly the use of cottonseed oil fatty acids—appear to offer a practical means of inactivating the cyclo-propenoids in cottonseed oil and thus eliminating the biological effects attributed to them. Presented at AOCS Meeting in Houston, 1965. Honorable Mention, Bond Award Competition. So. Utiliz. Res. Dev. Div., ARS, USDA.     

The use of thiobarbituric acid as a measure of fat oxidation

Summary An evaluation of thiobarbituric acid (TBA) as an agent for the measurement of fat oxidation was made by the application of several empirical procedures to animal and vegetable fats. An extraction procedure was used for removing the products of oxidation. The reaction with TBA was conducted in a boiling water bath to produce a red color, which was then estimated spectrophotometrically. Fats stored at −20, 0, 72, and 100°F. (−29, −18, 22, and 38°C.) and fats oxidized by the active oxygen method (A.O.M.) and by ultraviolet irradiation were examined. It was found that the TBA test might be of value in following the course of oxidation of cottonseed oil and soybean oil in the A.O.M. apparatus. Higher TBA values were obtained for soybean oil than cottonseed oil at comparable peroxide values. This is of interest because of the greater tendency of soybean oil to develop oxidized flavors. The volatile reaction products of oxidation were collected in toluene, and a comparison of the TBA values at comparable peroxide values of lard, cottonseed and soybean oils showed that the soybean oil volatiles developed the greatest intensity of color. Presented at the 27th Fall Meeting of the American Oil Chemists’ Society, Chicago, Ill., Nov. 2–5, 1953. This paper represents research undertaken by the Quartermaster Food and Container Institute for the Armed Forces and has been assigned No. 450 in the series of papers approved for application. The views and conclusions contained in this paper are those of the authors. They are not to be construed as necessarily reflecting the views or indorsement of the Department of Defense.     

Amino-hexose-reductones as antioxidants. I. Vegetable oils

Summary Amino-hexose-reductones were evaluated as antioxidants in soybean, cottonseed, and corn oils and were shown to be highly effective by all oxidative and chemical tests. The activity of the eight different reductones was approximately the same in any one substrate. Slightly higher activities were given by reductones of lower molecular weight. Activity was demonstrated at concentrations as low as 0.001% and was shown to be a linear function of the concentration up to 0.02%, the approximate limit of solubility. Out-standing features of the reductone-treated oils were long induction periods, slow absorption of oxygen, and low rates of peroxide development. Reductones are believed not to react directly with peroxides but to prevent peroxide formation by reacting with some precursor. The combination of reductones with other antioxidants showed synergistic effects in only one sample of corn oil. The activity of combinations in soybean and cottonseed oils was for the most part strictly additive. In soybean oil, citric acid-reductone combinations with each at the 0.01% level gave a slight improvement over the expected activity. Oils stabilized with multiple-component, antioxidant mixtures in which an amino reductone replaced propyl gallate showed less peroxide development and were equally acceptable according to organoleptic scores. Aged oils did not show the organoleptic improvement that would be expected from the marked improvement observed in the oxidative stability. Significant improvements in flavor stability could be observed with reductones only when they were used in combination with an-other antioxidant. Reductone-treated soybean and cottonseed oils did not show an appreciable improvement in flavor stability. Only the di-n-butylamino-and diallylamino-reductones contributed foreign flavors to the oil. Atypical flavors are believed associated with the amine moiety of the reductone. At high temperatures and at higher concentrations of reductones a brown melanoid color develops in the oil. The anhydro derivatives developed more color than the normal reductone. The reductones do not withstand oil deodorization conditions. Presented at the meeting of the American Oil Chemists' Society, Chicago, Ill. September 23–26, 1956.     

Effect of dietary palm oil and its fractions on rat plasma and high density lipoprotein lipids

Male Sprague Dawley rats were fed semipurified diets containing 20% fat for 15 weeks. The dietary fats were corn oil, soybean oil, palm oil, palm olein and palm stearin. No differences in the body and organ weights of rats fed the various diets were evident. Plasma cholesterol levels of rats fed soybean oil were significantly lower than those of rats fed corn oil, palm oil, palm olein or palm stearin. Significant differences between the plasma cholesterol content of rats fed corn oil and rats fed the three palm oils were not evident. HDL cholesterol was raised in rats fed the three palm oil diets compared to the rats fed either corn oil or soybean oil. The cholesterol-phospholipid molar ratio of rat platelets was not influenced by the dietary fat type. The formation of 6-keto-PGF_1α was significantly enhanced in palm oil-fed rats compared to all other dietary treatments. Fatty acid compositional changes in the plasma cholesterol esters and plasma triglycerides were diet regulated with significant differences between rats fed the polyunsaturated corn and soybean oil compared to the three palm oils.     

Cardiopathogenicity of soybean oil and tower rapessed oil triglycerides when fed to male rats

The triglycerides of soybean oil were purified by molecular distillation and those of Tower rapeseed oil by molecular distillation and adsorption chromatography. The original oils and the purified triglycerides were incorporated in semisynthetic diets at 20% by weight and fed for 16 weeks to weanling male Sprague-Dawley rats to compare the nutritional and pathological effects of the oils and their triglyceride fractions on rats. The study was carried out at two independent laboratories. No significant differences were observed between the results of the two establishments. The incidence of myocardial lesions was significantly higher in rats fed Tower rapeseed oil than in those fed soybean oil. Purification of the triglycerides by molecular distillation and adsorption chromatography appeared to have no major effect on the incidence of myocardial lesions. This supports our previous findings that the cardiopathogenicity of the test oils to rats resides in the triglycerides of these oils. Contribution No. 832 from Animal Research Institute and No. I-78 from Engineering and Statistical Research Institute.     

Flavor score correlation with pentanal and hexanal contents of vegetable oil

Samples of commercially processed soybean, cottonseed, and peanut oils were stored under controlled conditions then evaluated for flavor by a 20-member trained, experienced oil panel and for pentanal and hexanal contents by direct gas chromatography. The oils, which contained citric acid and/or antioxidants, were either aged from 0 to 16 days at 60 C or exposed to fluorescent light for 0 to 16 hr. The simple linear regressions of flavor score with the logarithm of pentanal or hexanal content in aged soybean oil gave correlation coefficients of −0.96 and −0.90, respectively; for cottonseed oil, −0.60 and −0.85; and for peanut oil −0.74 and −0.75. Addition of peroxide values to the linear regressions increased the correlation coefficients. Flavor scores of cottonseed and peanut oil can be predicted from pentanal and hexanal contents, but the technique is slightly more reliable for soybean oil based on the treatments used for these oils. Presented at the AOCS Meeting, Chicago, September 1973.