L. T. Black

Effect of temperature on soybean seed constituents: Oil, protein, moisture, fatty acids, amino acids and sugars

Soybean plants were grown at day/night temperatures of 24/19 C until the beginning of seed development, and then transferred to 5 different temperature regimes (18/13, 24/19, 27/22, 30/25 and 33/28 C) in the CSIRO phytotron. Mature seeds that developed under these conditions were analyzed for variances in composition. Fatty acid composition was strongly affected by temperature: linolenic and linoleic acids decreased markedly whereas oleic acid increased as the temperature increased; palmitic and stearic acids remained unchanged. Oil content was positively correlated with temperature, and protein content increased at the highest temperature. Of the sugars analyzed, sucrose concentration decreased by 56% with a 15 C increase in temperature, and stachyose showed a slight reduction; other sugars remained unchanged. Amino acid composition was generally stable; however, methionine increased with increased temperature during seed development. Moisture content was unaffected.

Quality of oil from damaged soybeans

Abstract and SummaryVarious processing steps were explored in an at-tempt to improve the quality of oil from field- and storage-damaged soybeans. A crude soybean oil (5.7% free fatty acid) commercially extracted from damaged soybeans was degummed in the laboratory with different reagents: water, phosphoric acid, and acetic anhydride. Two alkali strengths, each at 0.1 and 0.5% excess, were used to refine each degummed oil. After vacuum bleaching (0.5% activated earth) and deodorization (210 C, 3 hr), these oils were un-acceptable as salad oils. A flavor score of 6.0 or higher characterizes a satisfactory oil. Scores of water and phosphoric acid degummed oils ranged from 4.5 to 5.1, while acetic anhydride degummed oils aver-aged 5.6. Flavor evaluations of (phosphoric acid de-gummed) single- and double-refined oils (210 C deodorization) showed that the latter were signifi-cantly better. Flavor scores increased from 5.0 to about 6.0. To study the effects of deodorization tem-perature, the crude commercial oil was alkali-refined, water-washed and bleached with 0.5% activated earth, but the degumming step was omitted. Flavor evalua-tion of oil deodorized at 210, 230, and 260 C showed that each temperature increment raised flavor scores significantly. Further evaluations of specially proc-essed oils (water, phosphoric acid, and acetic anhy-dride degummed oils given single and double refinings and deodorized at 260 C) showed that deodorization temperature is the most important factor affecting the initial quality of oil from damaged beans. Flavor evaluations showed that hydrogenation and hydro-genation-winterization treatments produced oils of high initial quality, but with poorer keeping proper-ties than oils from normal beans. No evidence was found implicating nonhydratable phosphatides in the oil flavor problem. Iron had a deleterious effect in oils not treated with citric acid during deodorization.

Determination of oligosaccharides in soybeans by high pressure liquid chromatography using an internal standard

A method was developed for the quantitative analysis of oligosaccharides in soybeans by high pressure liquid chromatography (HPLC). The sugars were extracted from the soy flour using an ethanol-water solution. Separation of the oligosaccharides was effected by injecting a sample extract onto an HPLC equipped with a μBONDAPAK/carbohydrate® column. Three quantitative techniques were investigated for determining the separate sugars: (a) repetitive injection (i.e., alternately injecting equal volumes of standards and samples); (b) extract analyzed before and after spiking with raffinose (one of the unknowns); (c) the addition of a pure inexpensive internal standard, β-cyclodextrin, which was separated completely from the other oligosaccharides. These methods were successfully applied to the quantitative analyses of two varieties of soybeans and other soybean products such as soy milk and soy protein concentrate.

Iron and phosphorus contents of soybean oil from normal and damaged beans

Analyses of commercial crude soybean oils showed a highly significant correlation of 0.74 between free fatty acid and iron content. Poor flavor characteristics exhibited by finished oils extracted from damaged beans may be caused in part by a higher free fatty acid and related higher iron content in crude oils. Source of the increased iron appears to be both damaged beams and steel processing equipment. Crude oil from damaged beans is 2–10 times higher in iron than crude oil extracted from sound beans. Iron appears loosely bound in soybeans, since autoclaving, spontaneous heating in storage, or treating with alcohol increased the level of iron in laboratory extracted crude oil from 0.2 to more than 1 ppm. Present data do not indicate that iron and phosphorus contents are associated statistically in extracted oils.

Removal of phosphorus and iron by commercial degumming of soybean oil

Samples of crude and water-degummed soybean oils were obtained from five commercial processors. period of at least 2 weeks between samples. The crude and degummed oils were analyzed for iron and phosphorus content. Phosphorus removal within each processing plant was consistent, but between plants removal varied from a low of 79% to a high of 95%. Removal of iron compounds during commercial degumming varied from a low of 14% to a high of 57%. Significance of these results in steam-refining operations are discussed.

Partial hydrogenation and winterization of soybean oil

Soybean oil was hydrogenated under selective and nonselective conditions to give products with iodine values (I.V.) ranging from 85-115. The products were crystallized at 8C and examined for yield, stability, and fatty acid composition of the winterized oil. Changes in fatty acid composition, formation oftrans acids, and yield of winterized oil are approximately linear with the degree of hydrogenation. Stearine fractions, which are 15-20 I.V. units lower than winterized oil, were further crystallized in solvents to yield liquid oils and hard stearines.

Factor for converting elemental phosphorus to acetone insolubles in crude soybean oil

The official AOCS method CA 12-55 contains a factor of 30 in an equation for relating the phosphorus content of crude soybean oil to equivalent phosphatide. The historical derivation of this factor is discussed. The mean value was calculated to be 31.7 ±0.9 by correlation of phosphorus content with acetone insolubles in six lots of crude oil.

Removal of copper from hydrogenated soybean oil

Hydrogenation with a copper-chromite catalyst at 170 C, 30 psi, increased the copper content of a refined, bleached soybean oil from 0.02 to as much as 3.8 ppm. Removing residual copper from soybean oil is essential to the successful use of copper catalysts for selective hydrogenation. Various methods were examined to remove this copper, including alkali refining, bleaching, acid washing, citric acid treatment and cation-exchange resin treatment. Properly conducted, each of the methods except alkali refining gives 95% or higher removal of copper introduced during hydrogenation. Ion exchange appears to be the most economical, but addition of about 0.01% citric acid during deodorization may be needed to inactivate traces of unremoved copper. Soybean oil hydrogenated with a copper-chromite catalyst, bleached or treated with an ion-exchange resin and deodorized with 0.01% citric acid added had low AOM peroxide values and acceptable flavor scores after eight days at 60 C which indicate that removal of residual copper from the oil should be adequate for the production of stable oils low in linolenic acid content.

Char-ashing of glyceride oils preliminary to the atomic absorption determination of their copper and iron contents

Trace amounts of copper and iron were determined by char-ashing samples of molecularly distilled glyceride oil, copper hydrogenated edible oils and salad oils with added copper salts and copper-chromite catalysts. Char-ashing, coupled with the atomic absorption method of analysis, gave excellent reproducibility in a salad oil for copper at 0.025 ± 0.002 ppm and for iron at 0.082 ± 0.012 ppm. Agreement was excellent between the char-ashing method and the direct solvent method of analysis when levels of the two trace metals were high enough to be analyzed by direct atomic absorption. Copper in edible oils can be accurately analyzed at levels of less than 10 ppb by the char-ashing technique.

Reactions of Lipids in Corn with Ammonia

Ammonia has recently been employed in experimental tests for the treatment of corn to inactivate aflatoxin, to control molds, and as a preservative during ambient-air drying of freshly harvested high-moisture corn. When these various ammonia treatments are properly applied, no adverse effects have been found on any of the constituents of whole corn. However, in the work being reported when 0.1% or more ammonia was in contact with corn in the presence of air for more than a few days, irreversible changes occurred in the polyunsaturated lipids that were proportionate to the ammonia concentrations. The extent of the changes were dependent upon: (a) air-to-corn ratio, (b) ammonia concentration, (c) temperature, (d) corn moisture, and (e) time. The changes were characterized by a reduction in unsaturation of the lipid, by incorporation of nitrogen into the lipids, and by a consequent increase in lipid polarity. The change in polarity of these altered lipids rendered them unextractable with the usual fat solvents. Air (oxygen) and an initiating mechanism that occurs naturally in corn were required for the lipid-ammonia interaction to occur. This interaction involved only the polyunsaturated fatty acid moieties and formed a class of nitrogenous derivatives. Corn may be treated with ammonia for purposes of detoxification or preservation for long periods with no detectable adverse effects on the lipid composition, as long as headspace air is kept low during ammoniation. This may be accomplished in any of the following ways: (a) by ammonia ting the corn with a very limited headspace, (b) by ammoniating corn in a sealed bin and displacing the air in the headspace with ammonia gas, and (c) by replacing the headspace air with an inexpensive, inert gas such as nitrogen.