Water absorption of soybeans

The rate of water absorption of U.S. and Japanese soybeans has been measured at 10° and 25°C. and at initial moisture levels ranging from 7.5 to 14.0%. The principal controlling factor in absorption of water is the seed coat. However the rate of water absorption of sound whole beans is also influenced by the initial moisture level in the beans; the lower the moisture the slower the rate of water absortion. The presence of hard beans also reduces the rate of water absorption. U.S. soybeans usually have lower moisture and contain more hard ones than do Japanese beans. These factors are attributed to the climatic differences of the two countries. No fundamental differences were found in the rate of water absorption of U.S. and Japanese soybeans. This is a laboratory of the Northern Utilization Research and Development Division, Agricultural Research Service, U.S. Department of Agriculture.     

Sampling soybeans for analysis

Conclusion Under the conditions of this study, 30-gram samplings of mixtures of soybeans were found to differ significantly in oil and nitrogen content indicating the desirability of larger samples. The use of 120 to 240-gram aliquots from mixtures of soybeans which vary widely in chemical composition should tend to reduce differences due to sampling to a reasonable minimum. Differences among 30-gram samplings of highly uniform soybean seed of a single variety seem to be of slight significance. The limitations of present sampling methods should be recognized in any comparison or interpretation of chemical analyses of soybean seed. The U. S. Regional Soybean Laboratory is a cooperative organization participated in by the Bureau of Plant Industry, Soils, and Agricultural Engineering, Agricultural Research Administration, U. S. Department of Agriculture and the Agricultural Experiment Stations of Alabama, Arkansas, Florida, Georgia, Illinois, Indiana, Iowa, Kansas, Louisiana, Michigan, Minnesota, Mississippi, Missouri, Nebraska, North Carolina, North Dakota, Ohio, Oklahoma, South Carolina, South Dakota, Tennessee, Texas, Virginia, and Wisconsin. Assistant Chemists and Assistant Scientific Aide, respectively, U. S. Regional Soybean Laboratory, Urbana, Illinois.     

Phytic acid in soybeans

Phytic acid, the hexaphosphate of myo-inositol, is the most important phosphate reserve compound in many plant seeds, but many of its salts are poorly digested by animals. It can form complexes with seed proteins, some of which sequester metal ions, making them unavailable for the animal organism. Soya protein isolates may be higher in phytate content than the soya flour from which they are obtained. Zinc is the mineral of most concern because its bioavailability from some soya products is quite low and because of its marginal levels in some human diets. The availability of iron from soya flour and soya isolates is higher than that from some other plant foods with lower phytate contents. Processes for removing the larger part of the tightly bound phytates from soya protein isolates are described.     

Extraction of oil from soybeans

Modern processing plants extract soyabean oil by solvent liquid transfer. Soyabeans are cleaned, cracked, dehulled and conditioned into a thin flake before they enter the extractor. Extraction is by successive, countercurrent washes of hexane solvent. The extracted flakes are then carried by a sealed conveyor to be desolventized in enclosed vessels by application of jacket and sparge steam. Hexane is removed from the oil in rising film evaporators and with final vacuum distillation. Hexane is recovered from the meal and the oil in atmospheric condensers. The complete plant installation is explosion-proof and all equipment is sealed and vapor-proof. For a good operation, soyabeans must be clean, undamaged and at the correct moisture and temperature. Parameters of the process in the plant are: tonnage, hexane loss and energy usage. Oil quality is measured in terms of free fatty acids, absence of residual hexane and crude oil color. Meal quality is determined by residual oil, moisture, protein, urease activity protein solubility and mesh size in the finished product. Innovations at modern plants include degumming of the oil, lecithin drying and blending and production of soyabean meal with high protein solubility for human consumption.     

Quality of soybeans in export

Soybean quality is of concern to processors throughout the world, as deterioration during storage, handling and shipment can result in crude oil which is difficult to process and has high refining losses. Little information is available comparing the relative quality of soybeans in export shipment based on crop year and origin. Shipments of soybeans originating from the United States, Brazil, Paraguay, and Argentina were sampled in Europe and Asia during a four-year period. Soybean samples were graded, protein and oil contents determined, and oil quality characteristics assessed by laboratory procedures. Results of these analyses present, for the first time, direct comparisons of the quality of soybeans exported from the principal producing countries. The data suggests that United States (U.S.) farmers and exporters must continue their efforts to improve the physical characteristics of soybeans in export shipment; the emphasis of breeding and genetic engineering research should be to increase the protein content of soybeans grown in the U.S.; and that the high quality of crude oil recovered from U.S. soybeans should prove an advantage to the processor using soybeans imported from the United States.     

Quantification of sphingolipids in soybeans

Soybean is believed to be a rich source of sphingolipids, a class of polar lipids with desirable biological activities. Analytical methods for sphingolipids vary, and quantitative data for sphingolipids in foods, including soybeans, are scarce. the objectives of this study were to establish a method for quantification of sphingolipids in soybeans and to determine whether genotype, stage of maturity, and growing location affect sphingolipid content in soybeans. Separation of neutral lipids and interfering polar lipids from sphingolipids by saponification, transesterification, and solvent partition was studied. Solvent partition accompanied by TLC purification was determined to be the most accurate sample preparation method for HPLC quantification of cerebroside. There were significant differences in cerebroside concentration among genotypes, with a range of 142 to 492 nmol/g seed (dry wt basis). The differences in cerebroside concentration between immature and mature seeds of one genotype and between two seed production locations of one genotype were considerable but not statistically significant.     

Oil quality from hydraulic pressed soybeans

Summary HYDRAULIC pressed soybean oil quality is affected a great deal by the moisture of the beans at the time of milling. At moistures above 12 to 13% the oil quality deteriorates sharply. A great improvement in the oil from wet or even moisture damaged soybeans can be made by drying the beans in below 12% before milling. Even badly deteriorated (sample grade) beans have been vastly improved. Blending of wet and dry soybeans to an average moisture below 12% does not seem to yield as good quality oil as drying wet beans to a corresponding moisture. Normal variations in other soybean characteristics determining bean grade have lesser effects on soybean oil quality. Some data on the effect of bean damage, splits, off-color varieties, and foreign material are included in this paper. Hydraulic oil mills operating on soybeans will be able to make large improvements in oil quality by drying whole wet beans at the mill and by removing foreign material from the beans.     

The occurrence of phosphorus in soybeans

The phosphorous compounds present in soybeans have been tentatively divided into four groups. Methods for determining these groups have been studied and applied to the analysis of a sample of soybeans. A cooperative organization participated in by the Bureaus of Chemistry and Soils and Plant Industry of the U. S. Department of Agriculture, and the Experiment Stations of the North Central States of Illinois, Indiana, Iowa, Kansas, Michigan, Minnesota, Missouri, Nebraska, North Dakota, Ohio, South Dakota, and Wiscosin     

Volatiles from microwave-treated,stored soybeans

Soybeans were microwaved to inactivate enzymes and prevent oil deterioration during storage. Microwave time was varied from 4 to 10 min, in 2-min increments, and the treated and control soybeans were stored for 8 weeks at 40°C. Damage was monitored by analysis of peroxide value and free fatty acid content of the extracted oil and by volatile analysis of the full-fat meal and extracted oil. Volatiles were measured by multiple headspace extraction, and the formation of hexanal was monitored in both oil and meal. During storage of the control beans, peroxide value increased from 0.41 to 1.20 meq/kg, hexanal concentration changed from 29 to 94 ppb and free fatty acid content increased from 0.4 to 1.7%. Oils extracted from soybeans that were microwaved for 4 or 6 min had peroxide values of about 1 meq/kg and hexanal concentrations of 39–44 ppb after storage, indicating partial inactivation of lipoxygenase enzymes. However, soybeans that were microwaved for 8 min or more tended to oxidize during storage to a greater extent than the control soybeans, showing higher peroxide values and greater formation of hexanal in the samples. This suggests that soybeans microwave-treated in excess of 8 min are heat-damaged and susceptible to deterioration during storage. Free fatty acid content of the oils from all of the microwave-treated soybeans was about 0.4% initially, and did not increase with storage, indicating inactivation of hydrolytic enzymes. The mention of firm names or trade products does not imply that they are endorsed or recommended over other firms or similar products not mentioned.     

Limited extraction of soybeans with hexane

Soybean flakes were extracted with lower than optimal quantities of hexane in the laboratory and comparisons were made of oil yield, phospholipids yield and phospholipids composition as a function of the volume of hexane. Although the oil yield and the total amount of phosphorus were significantly decreased with limited volumes of hexane, the distribution of phospholipid components remained essentially the same. Because the oil obtained by this limited solvent extraction contained less phosphatides, it is expected to be more easily processed by conventional techniques.     

Head- and tail-end dehulling of soybeans

Head-end and tail-end dehulling systems are compared, including yield, investment costs, and energy consumption. A comparison of the European and US methods of using head-end and tail-end dehulling is provided. A combination of front-end and tail-end dehulling systems is shown, including the results in yield. Power consumption and investment costs are presented in comparison to front-end dehulling.     

Adiabatic reactor for simulating storage-damaged soybeans

An adiabatic reactor was constructed to simulate conditions that lead to storage-damaged soybeans. The heart of the system is an electronic temperature controller that causes the reactor temperature to closely follow intrinsic heating of the soybeans. Using moisture concentrations between 17% and 20%, we observed intrinsic heating ranging from 47 C to 52 C after 3–13 weeks. Quality of the extracted oil was determined by analyses for triglyceride (TG) composition, total phosphorus (P), peroxide value and free fatty acid (FFA). Higher FFA and lower P and linolenic acid concentrations in the damaged beans compared with undamaged beans agree with the literature and indicate reliability of the adiabatic reactor for further studies, e.g., the effect of enzymatic activity on the quality of resulting soybean oil. Presented at the Great Lakes Regional ACS Meeting, Normal, IL, June 1982.     

Estimating the processed value of soybeans

Interest in marketing soybeans on the basis of protein and oil content is increasing. Producers, breeders, handlers and buyers of soybeans need a method of evaluating soybean lots of different composition. A model is presented that predicts, given soybean composition and processing conditions, the yield of crude soybean oil and soybean meal from the processing of soybeans in a solvent extraction plant. From these yields, an estimated processed value (EPV) was calculated. For one set of price conditions, the EPV of typical soybeans had a range of $0.93 per bushel if premiums were paid for meal protein in excess of specifications and a range of $0.53 per bushel if meal protein premiums were not paid. Trading rules established by the National Oilseed Processors Association for domestic meal markets have a significant effect on the value and composition of soybean meal.     

Sphingolipids in immature and mature soybeans

Ceramides and cerebrosides were isolated from immature and mature soybeans, and structures of the constituents were investigated. As component fatty acids, normal, 2-hydroxy and 2,3-dihydroxy acids were found in ceramides, whereas only normal and 2-hydroxy acids were identified in cerebrosides. The principal fatty acid component was 2-hydroxylignoceric acid in ceramides, and 2-hydroxypalmitic acid in cerebrosides. Sphingoids in ceramides consisted mainly of trihydroxy bases, with 4-hydroxy-trans-8-sphingenine being predominant. In contrast, cerebrosides contained mainly dihydroxy bases, the principal constituent beingtrans-4,trans-8-sphingadienine. The only sugar in cerebrosides was glucose. The constituents of the two sphingolipids were similar to each other in immature and mature seeds. Possible metabolic relations of plant sphingolipids, based on composition, are discussed.