Study of soybean seed coat components and their relationship to water absorption

The occurrence of hard or "stone" seeds in shipments of food grade soybeans can cause I serious problems in processing, particularly in the preparatio n of fermented soy products. Climatic conditions during the growing season and as the seed matures may trigger the production of hard seeds. Total wat er absorption of soybeans is also a significant parameter in assessing qual ity for export markets. The seed coats of six varieties of soybeans, coveri ng a wide range of water absorption and stone seed content, were analyzed f or ash and cations, protein, lignin, and complex carbohydrates. The water a bsorption characteristics and macrochemical constituents of the whole seed were also determined. The results indicated that there was no correlation b etween the concentration of any of the cations and the occurrence of hard s eeds. The, results from analysis of the complex carbohydrates indicated the re were differences in hemicellulose content of seed coat fractions, partic ularly xylans, that correlated with the water uptake ratio and the occurren ce of hard seeds.