Color index for cottonseed oils

The color index determined by the area under the absorption curve in the region of 400–500 millimicrons is preferred over the A.O.C.S. photometric method in research on cottonseed oil color because the color index gives the more accurate measure of the relative chromogen concentration in cottonseed oils. The evidence that the color index method is more retiable includes: (a) a demonstration that the area under the absorption curve may be used in place of absorbance in the Beer-Lambert equation; b) a panel score for cottonseed oil color intensity that agrees with the color index better than it does with the photometric color; and c) sources of error in the photometric method that do not occur in the color index method, including those contributed by the high emphasis on absorption at 550 and 670 millimicrons. Presented at the 51st Annual Meeting, American Oil Chemists’ Society, Dallas, Tex., April 4–6, 1960. One of the laboratories of the Southern Utilization Research and Development Division. Agricultural Research Service, U. S. Department of Agriculture.     

Elimination of the halphen response of cottonseed oils in conjunction with deodorization

Two simple but effective pilot-plant processes were developed to produce Halphen-negative cottonseed oil. Both involve treatment of the oil with cottonseed fatty acids in a conventional batch type of deodorizer in conjunction with deodorization. In one process, in which the acids were added to the oil, the cyclopropenoids were inactivated in as short a time as 5 min after the oil reached the maximum temperature of 450–455 F. In the other, in which the acids were generated in situ, the oil did not become Halphennegative until about an hour and 45 min after it reached maximum temperature. The excess acids produced by both methods were readily removed during conventional deodorization. In contrast, deodorization alone reduced the cyclopropenoid content of the oil to a low level (0.02%) but did not render it Halphen-negative even after 3 hr at maximum temperature. These new processes are directly applicable for use by refineries that have the batch type of deodorizers. For refineries that operate continuous or semicontinuous deodorizers, it should be relatively simple to design preheating vessels or heat exchangers to inactivate partially or completely the cyclopropenoids before deodorization. Presented at the AOCS Meeting, New Orleans, May 1967. So. Utiliz. Res. Dev. Div., ARS, USDA.     

A simplified procedure for the determination of aflatoxin B1 in cottonseed meals

A simplified procedure for the detection of aflatoxin B₁ in cottonseed meals has been developed. The procedure substantially reduces the time and cost of aflatoxin analysis. A single chromatographic column of celite is used to concentrate and purify the aflatoxin fractions. A new solvent system of ether-methanol-water (96:3:1) improves separation of aflatoxin fractions on TLC plates. This improvement permits measurement of B₁ spots in one sweep of the plate with a densitometer using a 10–15 mm slit. The number of samples which can be screened for aflatoxin contamination on one TLC plate is doubled by re-use of the plate. The use of technical reagents and stainless steel beakers also helps reduce the time and cost of analysis. The procedure is sensitive to about 5 μg of B₁ per kg of meal. Presented at the joint meeting of the AOCS-AACC April, 1968, Washington, D.C.     

Bleaching of off-colored cottonseed oils

The adsorption of fixed red pigments from refined off-colored cottonseed oil by several adsorbents is described by the empirical Freundlich adsorption isotherm. Numerical values for the coefficient and the exponent in the Freundlich equation were determined for several oils and several adsorbeuts. Activated alumina was found to be a superior adsorbent for removing the red color bodies. It was observed that the variations from oil to oil in the numerical values of the coefficient and the exponent of the Freundlich equation were smaller for the several aluminas than they were for the other adsorbents studied. The particle size and moisture contents of the alumina, and the temperature of activated adsorption were of importance in determining the effectiveness with which the red color bodies were removed from the oils. The conditions required for optimum bleaching with alumina had no detectably adverse effect on oil quality. Presented at the 51st Annual Meeting of the American Oil Chemists’ Society, Dallas, Texas, April 4–6, 1960. One of the laboratories of the Southern Utilization Research and Development Division. Agricultural Research Service, U.S. Department of Agriculture.     

Improved method for determining gossypol in crude cottonseed oils

Summary The p-anisidine method for the determination of gossypol in crude cottonseed oils has been reinvestigated and modified to make it applicable to all crude oils obtained by the newer methods of processing cottonseed. The modifications included a change in the composition of the solvent, a higher reaction temperature, and the use of a more concentrated panisidine reagent. The modified method was found satisfactory where different colorimeters and spectrophotometers were used for measuring the color developed. Comparison of aniline and p-anisidine as reagents for the analysis of gossypol pigments showed that the presence of modified gossypol in some crude oils resulted in an over-correction for background absorption and led to significant errors when aniline was used as the color development agent. One of the laboratories of the Southern Utilization Research Branch, Agricultural Research Service, U. S. Department of Agriculture.     

The pigments of crude cottonseed oils. I. The inhibition of color reversion in crude cottonseed oils

Summary Treatment of freshly prepared crude cottonseed oils withp-aminobenzoic acid and subsequent removal of the di-p-carboxyanilinogossypol formed makes it possible to store the oils at a relatively high temperature (37–38°C.) and for an extended period of time (30 days) without incurring any adverse changes in the refining and bleaching properties of the oils. In addition, a considerable decrease in the refining loss of the crude oil is obtained, and the stability of the bleached oil is not affected by the treatment. Spectrophotometric studies made during all phases of the chemical treatment and during the refining and bleaching procedures show that thep-aminobenzoic acid removes almost completely the gossypol-like pigments which are present in the crude oils and yields oils having the characteristic carotenoid spectrum. One of the laboratories of the Southern Utilization Research Branch, Agricultural Research Service, U. S. Department of Agriculture.     

Evaluation of peanut and cottonseed oils for deep frying

A comparative study of cottonseed and peanut oils for frying of potato chips was undertaken. Industrial scale frying was conducted for 5 days with cottonseed and 5 days with peanut oil and frying oils and chips were sampled twice a day. Frying oils and oils extracted from stored chips were analyzed for ultraviolet absorption (A₂₃₂ and A₂₆₈), peroxide and acid values. Tocopherol and tertiary butylhydroquinone levels were determined by high performance liquid chromatography. Chips stored at room temperature for 12 weeks were organoleptically evaluated. During the first 20 hr frying the A₂₃₂, free acid and peroxide values of cottonseed oil increased rapidly, exceeding that of peanut oil, which increased moderately. For both oils, constant values were attained during the next 80 hr period, followed by moderate increases during the last 23 hr. Peanut frying oil lost 55% of its tocopherols and 54% of its tertiary butylhydroquinone during frying (103 hr), whereas cottonseed frying oil retained these compounds at the original levels. Tocopherols were also better retained in chips fried in cottonseed oil than in peanut oil. The fatty acid patterns of frying oils and oils extracted from chips did not show significant changes due to frying and storage, respectively. These results, therefore, suggest that cottonseed oil is sufficiently stable to be used as a substitute for peanut oil in deep frying.     

Present status of the filtration-extraction process for cottonseed

Summary Improvements and refinements in the process for filtration-extraction of cottonseed resulting from further pilot-plant development studies are described as well as their adaptation to the first commercial plant. These improvements which depict the present status of the process for cottonseed include principally certain modifications in the method of conditioning of the meats or flakes prior to cooking and in the procedure for crisping; selection of best conveyor type for conveying cooked material over relatively long distances without objectionable comminution; selection of filter medium combining the desired properties of durability, non-fouling, and low fines retention; determination of optimum filter-cake thickness; and development of a method for clarification of the product miscella by continuous recycling through the formed cake on the filter. Also discussed is the quality and color stability of the oil produced from comparable lots of cottonseed by the filtration-extraction process, as compared with that by hydraulic pressing, and by solvent extraction of uncooked flakes. Presented at the 45th annual meeting of the American Oil Chemists' Society, San Antonio, Tex., April 11–14, 1954. One of the laboratories of the Southern Utilization Research Branch, Agricultural Research Service, U. S. Department of Agriculture.     

Gaseous ammonia as a refining agent for cottonseed oils

In this investigation the application of gaseous ammonia to cottonseed oil refining was explored. The ammonia reacted quantitatively with the free fatty acids in the oil; its solubility in coftonseed oil was determined as a function of pressure. In “degumming” it was more efficient in removing phosphatides than other agents. A reduction in refining loss resulted for oils refined with gaseous ammonia as outlined and compared with the standard AOCS cup loss analysis. However, the oil colors were substantially higher even though the ammonia treated oils were re-refined with caustic solution. Results using cottonseed oil-hexane “miscellas” containing less than 70% oil showed low refining losses, but the colors were estremely high. Above 70% oil content the losses were higher, but the colors were lower. The colors never equalled “standard cup” results. This study was sponsored by the Texas Engineering Experiment Station and the Cotton Research Committee of Texas.     

A simplified gas liquid chromatographic determination for vitamin E in vegetable oils

A simple and rapid procedure has been developed for the isolation, concentration, esterification, and gas liquid Chromatographic (GLC) quantitation for the Vitamin E content of vegetable oils. Vitamin E is determined by saponification of the oil, ether extraction of the saponified mixture, drying and evaporation of the extract, followed by closed tube esterification and quantitation of the butyrate ester using a gas Chromatograph equipped with a hydrogen flame ionization detector. This technique eliminates the conventional thin layer Chromatographie isolation of Vitamin E normally used prior to direct or trimethylsilyl (TMS) derivative GLC quantitations. Oils fortified with Vitamin E in the 5 to 40 milligrams per 100 grams range showed recoveries of 93.4 to 98.6%.     

Gas chromatographic analysis of cyclopropenoid acids in cottonseed oils

A gas chromatographic method of analysis for cyclopropenoid acids in cottonseed oil, as the methyl esters, is described. With a glass column packed with a methyl silicone substrate on an inert support, methyl sterculate and methyl malvalate can be chromatographed without decomposition. Although methyl malvalate was not well resolved from methyl linoleate, it could be quantitated accurately at concentrations as low as 0.03% by a peak-height method. Quantitation can be done manually with an internal standard, or with a data system without an internal standard. The method does not require calibration with a cyclopropenoid acid standard, i.e., it is a primary method. Results compare favorably with those obtained by HBr titration. Less than 1 mg of oil is required for an analysis. Retired.     

Characterization of oils from low-gland and glandless cottonseed

New varieties of cotton which contain few or no gossypol pigment glands are being developed. Commercial production of such varieties should contribute to improving meal quality and reducing the color problems encountered with cottonseed oil. Samples of gland-containing, low-gland, and glandless seed grown in California were obtained, and the oils were extracted and characterized. With regard to the over-all characteristics the oils from the low-gland and glandless seed were indistinguishable from regular cottonseed oil. Iodine values, contents of unsaponifiables, cloud- and pour-points, response to the Halphen test, and similar characteristics resembled those of commercial cottonseed oil. No differences were found in behavior during winterization. Determination of the component fatty acids by gas chromatography showed the fatty acid composition of the oils to be typical. Determination of the positions of the double bonds in the unsaturated acyl groups showed no differences between the oils from gland-containing, low-gland, and glandless seed. Ultraviolet, visible, and infrared spectra of the oils revealed no differences other than the presence of gossypol in the crude oil from the gland-containing seed. The infrared spectra of the unsaponifiable fractions obtained from the oils showed some differences, which were not believed to be important. Presented at the fall meeting, American Oil Chemists’ Society, New York, N.Y., October 17–19, 1960. Trainee, Institute of International Education, UNESCO (present address: Union of Burma Applied Research Institute, Rangoon, Burma). One of the laboratories of the Southern Utilization Research and Development Division, Agricultural Research Service, U.S. Department of Agriculture.     

Reactivation of alumina used in bleaching of off-colored cottonseed oils

Spent alumina recovered from bleaching cottonseed oil with activated alumina can be reactivated by simple incineration at 400–700°C. and remoistening to at least 10% moisture content. The cycle of bleaching and regeneration may be repeated indefinitely with only nominal mechanical losses of alumina. Losses of refined oil by entrainment in activated alumine need be only 0.5%. One of the laboratories of the Southern Utilization Research and Development Division of the Agricultural Research Service, U. S. Department of Agriculture.     

Antioxidant activity of oat extract in soybean and cottonseed oils

A previously published method for extracting antioxidants from Noble oats with methanol was modified to improve the antioxidant activity. The extract was tested in soybean and cottonseed oils held at 30 and 60°C in the dark and at 30°C in the light. During storage, the peroxide values (PV) of the oils were generally significantly lower (P≤0.05) with the addition of the extract than was the control (no additives), and the PV were slightly higher than for oils containing TBHQ. In addition, the extract was added to emulsions of the same oils and held at 30°C in the light and at 60°C in the dark. The PV of the emulsions containing the extract were significantly lower (P≤0.05) than were the PV of those containing tertiary butylhydroquinone and the control.