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Defatted soybean was subjected to isolation procedures as follows: NaOH extraction/acid precipitation (NaOH-IE); water extraction/acid precipitation (H2O-IE); NaOH extraction/cryoprecipitation (NaOH-CP) and citric acid extraction/cryoprecipitation (CA-CP). NaOH-CP and CA-CP each resulted in precipitation of one protein mainly consisting of glycinin and beta-conglycinin, respectively. The proteins were subjected to polyacrylamide gel electrophoresis (PAGE), SDS-PAGE, size exclusion-chromatography (SEC) and differential scanning calorimetry (DSC) for characterization. PAGE, SDS-PAGE, SEC and DSC confirmed the homogeneity of NaOH-CP. The gelation properties and structural characteristics of NaOH-CP were investigated; the minimum protein concentration required for formation of a thermally-induced gel from NaOH-CP was 8%. With cold-set gelation, in the presence of 30 mM CaCl2, the minimum protein concentration required for formation of a self-supporting gel was 4%. At 100 mM CaCl 2, cold-set gelation of 10% protein concentration gave gel of strength 7.4 N compared to the 7.8 N gel strength obtained with thermally-induced gel at 16% protein concentration. The effects of heating on the NaOH-CP structure, in the presence of varying concentrations of NaCl and reducing agents, were examined by Fourier transform infrared (FTIR) spectroscopy and DSC. FTIR spectroscopy revealed that at 25°C the NaOH-CP protein showed four bands at 1633, 1650, 1667, and 1689 cm-1. At 85°C, the temperature associated with gelation, the four bands decreased in intensity with the simultaneous increase in the intensity of a band at 1644 cm-1 as result of the protein unfolding, furthermore two new bands at 1616 and 1685 cm -1 appeared. The latter two bands are attributed to intermolecular mu-sheet formed during gelation. The NaOH-CP did not exhibit any aggregation band between 25--100°C in the presence of NaCl. The DSC studies revealed that the protein denatured at approximately 102°

The occurrence of starch and other soluble carbohydrates in the embryos and young developing fruits of 'Essex' soybeans were determined at anthesis and continuing 10 days after flowering (DAF). The embryo was shown to be filled with starch grains which disappeared with development. Digestion of embryo sections with a mixture of α- and β-amylases showed a rapid hydrolysis of the reserve starch, suggesting that enzymatic degradation in vivo may provide soluble sugars as substrates for embryo growth. Starch and soluble sugars in the young developing fruits were found to be high at anthesis and then decreased with fruit growth. However, 6-8 DAF, fruits 7-9 mm showed an influx of soluble sugars and an accumulation of starch. Glucose was the major component of the soluble sugars in the 80% ethanolic extracts analyzed by high performance thin-layer chromatography (HPTLC). Sucrose was present as a lesser component. Amylase activity was maximal at anthesis, but declined with increasing fruit size. Beta-amylase comprised a high percentage of the amylolytic activity in the developing fruits. Embryo development in fruits of greenhouse-grown plants collected 0, 2, 4, 6, 8, and 10 OAF closely paralleled that of greenhouse-grown plants sampled by morphological sizes. The stages of embryo development in fruits from field-grown plants sampled by morphological sizes were similar to anthesis, 2-5 mm, and 4-6 mm fruits of greenhouse-grown plants sampled by the same procedure. However, embryos of field-grown fruits 7-9 mm and 10-15 mm showed a more advanced growth than embryos of fruits of comparable size from greenhouse-grown plants. / M.S.