A modified method for determining free fatty acids from small soybean oil sample sizes

A modification of the AOCS Official Method Ca 5a-40 for determination of free fatty acids (FFA) in 0.3 to 6.0-g samples of refined and crude soybean oil is described. The modified method uses only about 10% of the weight of oil sample, alcohol volume, and alkali strength recommended in the Official Method. Standard solutions of refined and crude soybean oil with FFA concentrations between 0.01 and 75% were prepared by adding known weights of oleic acid. The FFA concentrations, determined from small sample sizes with the modified method, were compared with FFA percentages determined from larger sample sizes with the Official Method. Relationships among determinations obtained by the modified and official methods, for both refined and crude oils, were described by linear functions. The relationship for refined soybean oil had an R ² value of 0.997 and a slope of 0.99±0.031. The values for crude soybean oil are defined by a line with R ²=0.9996 and a slope of 1.01±0.013.     

Ozonization of soybean oil. The preparation and some properties of aldehyde oils

A polyaldehydie product called aldehyde oil was prepared by the ozonization of soybean oil, followed by reductive decomposition of the ozonolysis products. Reductive decomposition by chemical means gave 85–90% yields of carbonyl in the aldehyde oil. Catalytic reduction gave 75–80% yields. Partially-hydrogenated soybean oil gave more efficient results than did unhydrogenated oil. The polyfunctional aldehyde oil was found to undergo condensation reactions with phenolic compounds, urea, amines, and polyols to give cross-linked polymers. Presented at annual meeting, American Oil Chemists' Society, St. Louis, Mo., May 1–3, 1961. This is a laboratory of the Northern Utilization Research and Development Division, Agricultural Research Service, U.S. Department of Agriculture.     

Effect of autoxidation prior to deodorization on oxidative and flavor stability of soybean oil

Summary Oxidation prior to deodorization was shown to be detrimental to the flavor and oxidative stability of soybean oil. The increase in the nonvolatile carbonyl content of freshly deodorized oils was proportional to the peroxide value of the oils before deodorization. Rate of loss of flavor and oxidative stability of the oil were related to the extent of carbonyl development. All oils, whether or not they had been submitted to any known oxidation, contained some nonvolatile carbonyls. The loss in stability was not due to a loss of the antioxidant tocopherol. Oxidized soybean oil methyl esters were shown to develop nonvolatile carbonyl compounds upon heating at deodorization temperatures. The addition of isolated methyl ester peroxide decomposition products to deodorized soybean oil reduced its flavor and oxidative stability in proportion to the amount added. The results obtained were parallel and similar to those obtained by oxidizing soybean oil prior to deodorization. Flavor deterioration and undesirable flavors were typical of aging soybean oil whether or not the oils were oxidized before deodorization or whether an equivalent amount of nonvolatile thermal decomposition products was added to the oil. These oxidatively derived, nonvolatile carbonyl materials are believed to enter into the sequence of reactions that contribute to flavor instability and quality deterioration of soybean oil. The structure of these materials is not know. This work indicates the importance of minimizing autoxidation in soybean oil particularly before deodorization to insure good oxidative and flavor stability. Presented at fall meeting, American Oil Chemists’ Society, October 20–22, 1958, Chicago, Ill. This is a laboratory of the Northern Utilization Research and Development Division, Agricultural Research Service, U. S. Department of Agriculture.     

Evaluation of SafTestTM methods for monitoring frying oil quality

The feasibility of applying methods developed by Safety Associates, Inc., to monitor oil degradation products, including malondialdehydes (AldeSafe^TM), FFA (FASafe^TM), and peroxides (PeroxySafe^TM), in fresh and heat-abused deep-fat frying oil was evaluated. Based on performance qualification studies, the AldeSafe method was the most suitable SafTest^TM assay for monitoring the quality of frying oil because of its high accuracy, precision, linearity, and reproducibility, and low detection/quantitation limits. A strong correlation (r=0.924) between the AldeSafe method and its counterpart, AOCS Official Method Cd 19-90, also supported the suitability of the SafTest method for monitoring oil quality. Moreover, the FASafe method had a moderately strong relationship with AOCS Official Method Ca 5a-40 (r=0.761). Our studies suggest that this test can be applied for monitoring frying oil; however, certain method performance limitations must be considered for routine analysis purposes. In contrast, the PeroxySafe method probably should not be used to monitor heat-abused oil without further development because of high variability, low accuracy, and low correlation (r=0.062) with the AOCS Official Method Cd 8-53 assay.     

Adaptation of the AOCS official method for measuring hydroperoxides from small-scale oil samples

An adaptation of the American Oil Chemists' Society Official Method Cd 8–53 for determining peroxides in fats and oils using a 0.5-g sample is described. Comparisons of the Official Method and the small-scale method were performed by analyzing soybean oil samples spiked with t-butyl hydroperoxide and autoxidized soybean oil samples. A linear relationship between the Official Method and the small-scale method was obtained with an R ² of 0.998. The small-scale method is sensitive, precise, and suitable for small sample sizes and uses only about 10% of the chemicals necessary for the Official Method.     

The flavor problem of soybean oil. I. A test of the water washing-citric acid refining technique

Summary The future of the soybean oil industry depends in part upon increasing the flavor stability of edible soybean oil. A procedure, which is reported to have been used by the German soybean oil refiners for combating flavor instability, has been tested on laboratory scale and appears to have distinct merit. Oils subjected to a particularly thorough degumming operation and to the subsequent addition of a small amount of citric acid during deodorization possessed a significantly higher flavor stability than did those subjected to a conventional type of refining. One of the laboratories of the Bureau of Agricultural and Industrial Chemistry, Agricultural Research Administration, U. S. Department of Agriculture.     

Determination of moisture in peanut butter

Summary and Conclusion The moisture and volatile content of whole peanuts has been determined by A.O.C.S. Official Method Ab 2-49 and has been compared with the moisture content of the sliced peanuts determined by a toluene distillation procedure described by Tryon (5). For practical purposes the results obtained by these methods are in agreement. Moisture of peanut butter has been determined by an over loss-in-weight technique corresponding to the conditions of A.O.C.S. Official Method Ab 3-49 for “second” moisture, and by the toluene distillation method. The results indicate that less dehydration was attained by A.O.C.S. Official Method Ab 3-49 than by the toluene distillation procedure. Losses in weight of peanut butter samples have been determined in vacuum and forced-draft ovens at 130° C. No differences were observed which would indicate that the conditions of A.O.C.S. Official Method Ab 3-49 produce low results because of oxidation. It can be concluded that the toluene distillation procedure, using apparatus described by Tryon (5), is suitable for determining the relatively small amounts of moisture present in peanut butter. The unique features of this apparatus seem to make the method particularly adaptable to peanut butter. This information is presented to provide the peanut butter industry with an additional method for use in problems involving determination of small amounts of moisture and for comparison with other prevailing methods. One of the laboratories of the Bureau of Agricultural and Industrial Chemistry, Agricultural Research Administration, U. S. Department of Agriculture.     

Comparison of FTIR and capillary gas chromatographic methods for quantitation oftrans unsaturation in fatty acid methyl esters

A computer-assisted method has been developed for estimation of isolatedtrans unsaturation using the peak area of thetrans absorbance band at 966 cm-1from FTIR spectra of fatty acid methyl esters. Peak areas were used to determine thetrans content of weighed standards containing from 0 to 100% methyl elaidate and of hydrogenated soybean oil samples containing up to 36%trans unsaturation. These data for percenttrans by FTIR were compared to corresponding data obtained by capillary gas chromatography and the AOCS Official Method 14-61. Determination of isolatedtrans composition in oils using peak areas gave values with the smallest standard deviation for weighed standards and values within 4% of those obtained by capillary gas chromatography and the AOCS Official Method for hydrogenated samples. Presented at the AOCS meeting in Phoenix, AZ in May 1988. To whom correspondence should be addressed.     

Bauer mill operation and its effect on the percentage of oil found in soybeans

Summary and Conclusions A Bauer Mill officially approved by the A.O.C.S. for grinding samples of soybeans to be used for oil determinations was used to grind duplicate series of the 10 check samples of soybeans sent out each year by the Smalley Foundation Committee. When the mill was operated at high temperature and forced to grind at its maximum rate, the 10 samples averaged 18.03% of oil. A duplicate series of 10 samples ground in a water-cooled mill at about one-half the maximum possible rate of grinding for the mill averaged 17.57% oil. Improper operation of a Bauer Mill when preparing soybean seed samples for analysis can cause abnormally high oil percentages. A simple mechanical device to reduce the rate of feed is suggested for use with the mill. A Bauer Mill is satisfactory for use in grinding samples of soybeans for oil analysis when it is properly operated. Division of Forage Crons and Diseases, Bureau of Plant Industry, Solis and Agricultural Engineering, Agricultural Research Administration, U. S. Department of Agriculture. Publication No. 234 of the U. S. Regional Soybean Laboratory, Urbana, Illinois.     

Evaluation of “Hysoy” in exterior paints

Conclusions Hysoy and blends of Hysoy and soybean oil can be used successfully in the formulation of white exterior paints. Such paints compare favorably in outdoor weathering tests with similar paints made with linseed and soybean oils. The principal advantage shown by paints formulated with Hysoy is a decrease in drying time. Presented at the Fall Meeting of the American Oil Chemists' Society, Oct. 11–13, 1954, in Minneapolis, Minn. The mention of firm names or trade products in this article does not imply that they are endorsed or recommended by the Department of Agriculture over other firms or similar products not mentioned. One of the Branches of the Aricultural Research Service, U. S. Department of Agriculture.     

Solvent effects on the products of soybean oil extraction

Summary Ethanol, isopropanol, isobutanol, ethylene dichloride, trichloroethylene, carbon tetrachloride, and hexane (b.p. range 30° to 60°C.) were used as solvents for the extraction of soybean oil and the comparative effect of the solvent on the color and other properties of the oil, meal, and isolated protein was measured. Ethanol extraction gave the best results with respect to the color of oil, meal, and protein, and it also served as a debittering agent for the soybean meal. One of the laboratories of the Bureau of Agricultural and Industrial Chemistry, Agricultural Research Administration, U. S. Department of Agriculture.     

Search for new industrial oils. IV

Summary Chemical screening of seed oils continues to reveal nature's diversity. This work provides leads to numerous species which warrant further research to investigate their oil and meal in greater detail, to appraise their crop potential, and to assess their practical value for providing new oilseeds. This is a laboratory of the Northern Utilization Research and Development Division, Agricultural Research Service, U. S. Department of Agriculture. Agricultural Research Service, U. S. Department of Agriculture.     

Continuous hydrogenation of soybean oil in a trickle-bed reactor with copper catalyst

Continuous hydrogenation of soybean oil with a stationary copper catalyst bed was performed at 110–180 C, 30–75 psig hydrogen and Iiquid hourly spaced velocities (LHSV) of 0.25–0.6 cc/hr/cc catalyst. In contrast to batch, continuous hydrogenation was achieved at a lower temperature with no need to postfilter the product. The soybean oil products from the continuous and batch processes hydrogenated to 0% triene were similar in fatty acid composition,trans content of 29% and linolenate selectivity of 5. Biometrician, North Central Region, Agricultural Research Service, U.S. Department of Agriculture, stationed at the Northern Regional Research Center, Peoria, IL 61604.     

Toxic protein from trichloroethylene-extracted soybean oil meal

Summary Fractionation studies have been carried out on a specially prepared undenatured toxic trichloroethylene-extracted soybean oil meal to determine which component of the meal is associated with the toxicity. Calf-assay of the samples indicated that the toxic factor is associated with the protein. The toxic factor associated with the protein is labile to strong acid hydrolysis. Measurable destruction of the toxic factors occurs when the protein is treated with alkali at pH 11–12 at 60°C. Because destruction of the toxic factor occurred when the neutral protein dispersion was autoclaved for 1 hr. and was followed by an alkaline treatment simulating the pH conditions encountered in tryptic digestion, it was not possible to evaluate the effect of tryptic digestion upon the toxic factor. Analyses of the toxic protein failed to indicate the nature of the reaction of trichloroethylene with the protein to produce the toxicity. Presented at the fall meeting, American Oil Chemists' Society, Chicago, Ill., September 24–26, 1956. Investigation conducted jointly by the Northern Utilization Research and Development Division, Agricultural Research Service, U.S. Department of Agriculture and the Veterinary Medical Research Institute and Agricultural Experiment Station, Iowa State College. Journal Paper J-3054, Iowa Agricultural Experiment Station, Ames, Project 814. A report of work done, in part, under contract with the U. S. Department of Agriculture and authorized by the Research and Marketing Act. Contract supervised by Northern Utilization Research and Development Division, Agricultural Research Service.     

Synthetic oils from residual dimerized fat acids

Summary Synthetic oils have been prepared from residual dimerized fat acids with soybean and linseed fat acids by esterification with polyalcohols, and with or without maleic anhydride or phthalic anhydride. Preliminary evaluation indicates that these oils give films which dry faster and are more resistant to water and alkali than linseed oil films. This enhancement of water and alkali resistance may result from an increase in C-C bonds present in the films. Ester gum varnishes made from these oils were not markedly superior to similar varnishes made from linseed oil. The Northern Regional Research Laboratory is one of four Regional Laboratories authorized by Congress in the Agricultural Research Act of 1938 for the purpose of conducting research to develop new uses and outlets for agricultural commodities. These Laboratories are administered and operated by the Bureau of Agricultural and Industrial Chemistry, Agricultural Research Administration, U. S. Department of Agriculture.     

Citric acid: Inactivating agent for metals or acidic synergist in edible fats?

Oxidative stabilities of soybean oil and lard are improved by the addition of either sorbitol or citric acid. Sufficient sorbitol gives enough improvement in stability so that added citric acid gives no increased stability. Unless sorbitol acts as a neutral synergist, forms a powerful acidic synergist in trace amounts or a new antioxidant, the antioxidant activity of citric acid appears to come from its inactivating capacities for metals. Presented in part at the 125th American Chemical Society Meeting, Kansas City, Mo., March 24–April 1, 1954. This is a laboratory of the Northern Utilization Research and Development Division, Agricultural Research Service, U. S. Department of Agriculture.     

Determination of the Unsaponifiable Matter in Fatty Acids by a Rapid Column Method

A rapid, quantitative method for determining the unsaponifiable matter (USM) of commercial fatty acids is described. The fatty acid samples are saponified with a mixture of potassium hydroxide and Celite 545 ground together then heated for a short period. The resulting granular powder is transferred to a glass chromatography column containing a short section of CaCl₂/Celite mixture, and the USM is eluted with dichloromethane. Samples were analyzed in 2 separate laboratories by the new method with slight variations. Good agreement between duplicates and between laboratories was obtained for all of the acids examined. Samples were also analyzed by Official Methods, and the results were uniformly somewhat higher by the proposed method. Agricultural Research Service, U.S. Department of Agriculture.     

Germination and free fatty acids in seed stock lots of cottonseed

Summary The relationship of the free fatty acid content in the oil to the percentage germination for 254 samples of cottonseed of different varieties indicates that the free fatty acid content may be used as a practical screening index for use in selecting lots of cottonseed to be reserved for seeding purposes and subsequent testing for germination. The percentage germination decreases in general with increasing free fatty acid content. The mathematical probability that a given lot of seed will exceed a specified minimum germination value decreases markedly as the free fatty acid content of the oil increases. Insofar as practical, it is suggested that cottonseed reserved for seeding have a low free fatty acid content, less than 0.75% in the oil if at all possible. One of the laboratories of the Bureau of Agricultural and Industrial Chemistry, Agricultural Research Administration, U. S. Department of Agriculture. In cooperation with the Production and Marketing Administration, U. S. Department of Agriculture, under Marketing Act of 1946.     

Color characteristics and chemical analyses of oil from frost- and weather-damaged soybeans

Summary Frosted soybeans and oils from frost-damaged soybeans were obtained from the farm and commercial sources. All soybeans used were classed as inferior, according to the Handbook of Official Grain Standards of the United States, with respect to both green and weather damage. Localities represented were Oklahoma, Mississippi, Illinois, and Iowa. Spectrophotometric measurements and visual comparisons were made to establish the green grades. If the necessary quantities of oils were available, the samples were refined and bleached; otherwise only the chemical analyses, green grading, and spectrophotometric measurements were made on the crude oils. Iodine values and free fatty acid were determined also. If a spectrophotometric method for the green grading of soybean oil were to be adopted, present indications are that the boundary between grades 1 and 2, comparable to the present N.S.P.A. grading system, should be at optical density 0.45 at 700 mμ, as measured in a 21.8 mm. I.D. tube in a Coleman Model 6B instrument, and that between grades 2 and 3 should be at optical density 0.58. It is recommended that duplicate systems of green grading be avoided. Presented at the American Oil Chemists' Society Spring meeting, San Antonio, Tex., April 11–14, 1954. One of the Branches of the Agricultural Research Service, U. S. Department of Agriculture.     

Fluorescence as a measure of brown substances in soybean lecithin

Summary The fluorescence of soybean lecithin increases in a linear fashion with an increase in brown substances. Since the measurement of fluorescence is simple and rapid, this measurement should prove a useful index of browning. The term “lecithin” is used throughout this paper to refer to the mixtures of phosphatides, oil, etc., known in the trade as soybean lecithin. It does not refer to phosphatidylcholine. Presented at fall meeting of American Oil Chemists' Society, October 11–14, 1954, in Mineapolis, Minn. One of the branches of the Agricultural Research Service, U. S. Department of Agriculture.