The centrifugal acetone foots test applied to crude soybean oil. II. Rapid method compared with other measures of phosphatides content and refining loss

Summary Comparisons are made between eight methods of grading crude soybean oil with respect to a laboratory refining loss determination which closely simulates commercial wash kettle practice. This list of methods includes the five analysis factors, acetoneinsoluble, HCl heat break, centrifugal foots, phosphorus and ash contents, each combined with percentage of ffa and moisture and volatile. It includes the official A.O.C.S. cup loss, the Wesson loss, and the chromatographic absorption loss determinations. On 12 crudes on which laboratory wash extraction loss and losses determined from centrifugal foots values, from acetone-insoluble contents, and from HCl break values were available, the centrifugal foots values best predicted the refining loss. The standard deviations of each method from the wash extraction loss were, respectively, 0.21%, 0.27%, and 0.29%. On seven of these crudes on which all nine determinations were available, acetone insoluble content showed the best correlation, followed by centrifugal foots and HCl heat break. The centrifugal foots test generally gives zero or trace results on degummed oil. By use of this method however the refining loss grade of crude soybean oils may be estimated in as little as one hour of elapsed time, and it requires only 5 to 10 minutes of the operator's time.     

Investigation of methods for determining the refining efficiency of crude oils

Conclusions Various methods for estimating the neutral oil content, or conversely the loss constituents of crude cottonseed oil and soybean oil, have been explored. Of those techniques studied the International Chemical Union chromatographic procedure seemed most appropriate because it was found to be reasonably accurate and most reproducible, was easy and rapid to carry out, and required no special, elaborate, or expensive equipment. The chromatographic method has been successfully applied to a variety of crude cottonseed and soybean oils and to a few vegetable oil residues containing high percentages of loss constituents. The results obtained with this technique would appear to be eminently suitable for evaluating the efficiency of plant refining processes. Indications are that the method might ultimately prove useful for establishing the value of the various lots of crude cottonseed oil and soybean oil which normally change hands in commercial channels. The last-mentioned application will probably have to wait for the development of a suitable companion, semimicro, or chromatographic bleach test and the adoption of an adequate acceptable standard spectrophotometric method for measuring oil color. Presented at annual fall meeting, American Oil Chemists' Society, Chicago, Oct. 31-Nov. 2, 1949     

A comparison of the cup refining loss and neutral oil determinations for evaluating crude soybean oil

Data from 833 non-degummed and degummed soybean oil samples, which were analyzed by both the neutral oil loss and cup loss methods, were examined, and it was found that the total premiums paid under the cup loss method and the proposed National Soybean Processors Association Technical Committee’s neutral oil analysis were the same. However, better quality oils would have received a higher premium, while poorer oils would have been penalized more heavily under the new procedure. Presented at the AOCS meeting in Toronto, Canada, 1962.     

A rapid alkali-wash method of refining cottonseed oil for refined color determination

Summary A very simple, rapid, reproducible method of refining crude cottonseed oils, for refined color measurement, has been developed. The results can be used to predict the colors of these oils when refined by the American Oil Chemists' Society Cup Method. The method has the advantages of rapidity and use of simple equipment and techniques and requires only small quantities of oil. Furthermore variations in results because of the amount and strength of lye and of “break” are not encountered since uniform conditions are employed. Because the method is used when it is desired to measure refined color without determining refining loss, it is not a substitute for the official cup refining method. The oil color research described in this paper was conducted as a cooperative project of the Texas Engineering Experiment Station and the Cotton Research Committee of Texas.     

Determination of refining loss in oil of pistacia seeds

The laboratory refining loss and the neutral oil content of the crude oil of Pistacia seeds are determined by the Wesson, acetone-insoluble and chromatographic methods and the results are compared. For a variety of samples with a different free fatty acid content, the refining loss by the chromatographic method is determined and an expression for the relationship between laboratory refining loss and free fatty acid content of Pistacia oil is proposed.     

A colorimetric method for determining small amounts of trichloroethylene in vegetable oils

Summary An accurate method for determining small amounts of trichloroethylene in vegetable oils has been presented. The method employs a distillation procedure to separate the trichloroethylene from the oil and a colorimetric procedure based on the Fujiwara reaction to determine the trichloroethylene in the distillate. The method has been tested on known samples of crude and refined soybean and cottonseed oils varying in trichloroethylene content from 0.001% to 0.6% with excellent results.     

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.     

Removal of chlorinated pesticides from crude vegetable oils by simulated commercial processing procedures

Crude soybean and cottonseed oil were processed using simulated commercial processing procedures to determine if oil processing would remove chlorinated pesticide contaminants of either natural or spiked origin. Two crude oil lots were spiked with endrin, DDT, DDE, aldrin, dieldrin, heptachlor and heptachlor epoxide before processing. Representative samples of crude oil and products following each processing step were analyzed for pesticide contamination. Results indicated that alkali-refining or subsequent bleaching did not reduce chlorinated pesticide contamination. Hydrogenation prior to deodorization reduced endrin contamination. Deodorization, with or without hydrogenation, eliminated chlorinated pesticides. The results of this study indicate that normal commercial processing of crude vegetable oils for human consumption effectively removes any chlorinated pesticides which may be present in crude oils. It is hypothesized that chlorinated pesticide removal is achieved by volatilization during deodroization, which is supported by known volatilization characteristics, similarity of behavior in pesticides studied, and absence of the pesticide or its conversion products in the finished oils, or both.     

Variables affecting the yields of fatty esters from transesterified vegetable oils

Transesterification reaction variables that affect yield and purity of the product esters from cottonseed, peanut, soybean and sunflower oils include molar ratio of alcohol to vegetable oil, type of catalyst (alkaline vs acidic), temperature and degree of refinement of the vegetable oil. With alkaline catalysts (either sodium hydroxide or methoxide), temperatures of 60 C or higher, molar ratios of at least 6 to 1 and with fully refined oils, conversion to methyl, ethyl and butyl esters was essentially complete in 1 hr. At moderate temperatures (32 C), vegetable oils were 99% transesterified in ca. 4 hr with an alkaline catalyst. Transesterification by acid catalysis was much slower than by alkali catalysis. Although the crude oils could be transesterified, ester yields were reduced because of gums and extraneous material present in the crude oils. Presented at the American Oil Chemists’ Society annual meeting, Chicago, May 1983.     

Gossypol content and refining losses on crude cottonseed oil

Summary 1. Gossypol has been found to be almost universally present in hot pressed crude cottonseed oils from all of the important cotton growing sections in the United States. 2. The average amount found in crude oils from 62 scattered mills was 0.05 per cent. The highest percentage found in a hot pressed oil was 0.210. Only 7 out of 124 oils failed to show the presence of gossypol. 3. Since gossypol content was not found to be proportional to deviation from average refining loss, it was concluded that at least a portion of the gossypol occurs in the oil in the bound state, associated with protein fragments.     

Spectrophotometric estimation of soybean oil in admixture with cottonseed and peanut oils

Conclusion A spectrophotometric method has been described for the determination of soybean oil in admixture with cottonseed oil. The method provides a simple and rapid means of detecting gross adulteration of one oil with another and permits an accurate determination of linolenic acid for use as a criterion of the economic value of an oil mixture and as a guide in oil processing. The factor limiting the precision of the method is variation in composition of the cottonseed and soybean oils in the mixtures to be analyzed. Variations in composition affect the proportion of measured triene conjugation, due to the linolenic acid content of the soybean oil and the apparent linolenic acid content of the cottonseed oil. Thus, for unknown mixtures only average value corrections can be made for apparent linolenic acid content and the accuracy of a particular analysis will depend upon how well the composition of the oils in the particular mixture follows those of the average mixture. The method described can be extended to mixtures other than those of soybean and cottonseed oils. Thus, soybean oil may be determined in admixture with a peanut oil. In general, any oil which has an unsaturated fatty acid capable of producing triene conjugation upon alkali isomerization can be determined in the presence of any other oil containing no appreciable quantity of unsaturated fatty acids which can produce triene conjugation by such treatment. Presented before The American Oil Chemists’ Society, New Orleans, Louisiana, May 10–12, 1944. One of the laboratories of the Bureau of Agricultural and Industrial Chemistry, Agricultural Research Administration, U. S. Department of Agriculture.     

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.     

A new method for determining gossypol in cottonseed oil by FTIR spectroscopy

A new method was developed to determine the gossypol content in cottonseed oil using FTIR spectroscopy with a NaCl transmission cell. The wavelengths used were selected by spiking clean cottonseed oil to gossypol concentrations of 0–5% and noting the regions of maximal absorbance. Transmittance values from the wavelength regions 3600–2520 and 1900–800 cm⁻¹ and a partial least squares (PLS) method were used to derive FTIR spectroscopic calibration models for crude cottonseed, semirefined cottonseed, and gossypol-spiked cottonseed oils. The coefficients of determination (R ²) for the models were computed by comparing the results from the FTIR spectroscopy against those obtained by AOCS method Ba 8-78. The R ² were 0.9511, 0.9116, and 0.9363 for crude cottonseed, semirefined cottonseed, and gossypol-spiked cottonseed oils, respectively. The SE of calibration were 0.042, 0.009, and 0.060, respectively. The calibration models were cross-validated within the same set of oil samples. The SD of the difference for repeatability and accuracy of the FTIR method were better than those for the chemical method. With its speed (ca. 2 min) and ease of data manipulation, FTIR spectroscopy is a useful alternative to standard wet chemical methods for rapid and routine determination of gossypol in process and/or quality control for cottonseed oil.     

Referee chemists and official methods

The need for Referee Chemists was recognized more than 50 years ago. Currently the Examination Board of the American Oil Chemists’ Society issues certificates to commercial laboratories in the name of qualified representatives who are members of the AOCS. A total of 79 chemists presently hold Referee Certificates in categories of cottonseed, soybeans, peanuts, cottonseed oil and other cup refined oils, soybean oil and other neutral oil loss oils, tallow and grease, protein concentrates, and cellulose yields. Referee Certificates have also been issued to a few chemists in Japan and Canada. The National Cottonseed Products Association, National Soybean Processors Association, etc., publish listings of their Official Chemists, who must first obtain AOCS referee certificates. Laboratories holding certificates must use Official Methods of the AOCS wherever applicable. The AOCSOfficial and Tentative Methods is one of the leading sources of standard methods for the fat and oil industries in the world. The origin of the present edition of AOCSMethods is described, and the roles of the Uniform Methods Committee, various technical committees, and the editor in the development, publication, and distribution of the methods are discussed.     

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.     

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.     

Quantitative measure of geometrical isomerization during the partial hydrogenation of triglyceride oils

A mathematical model has been developed using a digital computer for the calculation of the isomerization index for partially hydrogenated oils such as cottonseed, soybean, peanut or corn oil. The isomerization index is defined as the ratio of the rate of geometrical isomerization of an unsaturated group to the rate of hydrogenation. Isomerization indices from about 0.3 to 11 were found to occur for hydrogenations using commercial nickel catalysts. Calculation of both an isomerization index and a selectivity ratio will be useful methods of quantitatively characterizing the partial hydrogenation of triglyceride oils or the type of hydrogenation which can be obtained by various catalysts.     

Phase behavior in the solvent winterization of crude cottonseed oil in 85–15 acetone-hexane mixture as related to reduction in refining loss and color

Summary Fundamental physical chemical data have been obtained which indicate on a laboratory scale the feasibility and advantages of solvent winterization of crude cottonseed oil in 85–15 acetone-hexane mixture. The results show the effect of oil-solvent ratio, chilling temperature, duration of chilling, and the addition of adsorbents on the degree of winterization, the refining loss, and the color of the winterized oil. Crystallization is markedly inhibited by the presence of a phosphatide-rich material in the crude oil, but this can be overcome by the proper control of the oil-solvent ratio and temperature and by the addition of adsorbents. Winterization in this solvent with or without adsorbents results in the separation of a large proportion of the phosphatides, and a marked reduction in refining loss and color. The advantages of winterizing hexane-extracted cottonseed oils before refining are discussed. Resigned: July 9, 1954. One of the laboratories of the Southern Utilization Research Branch, Agricultural Research Service, U. S. Department of Agriculture.     

Ethanolamines and other amino- and hydroxyl-containing compounds in the refining of rice oil

Summary In the alkali-refining of rice oil by the usual procedure employed for cottonseed and similar oils excessive losses occur. A rice oil containing about 5% of free fatty acids may refine with a loss of over 40% by the cup method. A series of experiments has been performed which shows that the adding of certain organic compounds to the crude oil just before carrying out the regular refining procedure greatly reduces the refining losses. The technique was effective in both batch and continuous processes. Depending on the refining process used, reductions in the refining loss of 32 to 55% have been obtained. The organic compounds used as additives contained NH₂ and OH groups. Sucrose or blackstrap molasses appears to be the most practical material to use. However ethanolamines and various glycols and alcohols may also be employed. Presented at the 46th annual meeting of the American Oil Chemists’ Society, New Orleans, La., April 18–20, 1955. Agricultural Research Service, U. S. Department of Agriculture.     

Rice brain oil. I. Oil obtained by solvent extraction

1. Freshly milled rice bran has been extracted with commercial hexane and the recovered oil and extracted meal examined for their respective content of wax. The oils were refined and bleached by standards as well as several special methods. The crude, caustic soda refined, and several refined and bleached oils were examined spectrophotometrically.
2. When freshly milled rice bran of good quality is extracted with commercial hexane, an oil of relatively low free fatty acid content is obtained. This oil possesses good color and is as stable as other similar types of crude oils.
3. If the oils is extracted from the brain at a temperature below about 10°C. and the extraction is discontinued at the right time, the extracted oil represents 90–95% of the total lipids in the brain and contains very little wax. This wax, which is readily extracted with hot commercial hexane as well as other types of solvents, amounts to about 3–9% of the total extractable lipids.
4. When subjected to ordinary caustic soda refining methods, good rice brain oils behave much like cottonseed oils of comparable free fatty acid content. Both caustic soda refining in a hydrocarbon solvent and refining with sodium carbonate result in refining losses approximating the absolute or Wesson loss.
5. Some of the refined oils when bleached according to usual practice produce products acceptable for use in the edible trade. However, refined rice bran oil has a definitely greenish cast resulting from the presence of chlorophyll, but this color can be removed by bleaching with a small amount of activated acidic clay.