(291f) Value-Added Products from Protease-Assisted Aqueous Extraction of Soybean Oil

Because of the low bulk density of bio-based feedstocks, the transition from a petroleum-based to a bio-based economy will require the development of small-scale distributed production centers rather than large centralized facilities seen in industry today. To improve the economics of small scale vegetable oil production, it is necessary to find an alternative to hazardous organic solvent processes. Protease-assisted aqueous extraction is one such alternative. However, the economics of aqueous processes are presumed to be poor because oil extraction yields are lower than yields of hexane extraction processes. To improve aqueous extraction economics, other value added products, such as a high-nutrition protein hydrolyzate, must be identified and characterized. We have characterized the milk and residual fractions of aqueous soy extraction to serve as a basis for an economic analysis of a protease-assisted aqueous extraction process. Processing factors studied include type of starting material and degree of hydrolysis. Product characteristics include polypeptide molecular weight distribution and concentration, trypsin inhibition activity, oligosaccharide content, essential amino acid composition, and oil and fiber content. Enzymatic and ultrafiltration treatments to reduce antinutritional factors and to concentrate protein were also investigated. Results indicate that the polypeptides can be reduced to molecular weights of less than 10,000 kDa using the treatments studied, while the trypsin inhibition activity is effectively eliminated. Essential amino acid composition is unaffected. Stachyose, another antinutritional factor, can be eliminated using α-galactosidase or ultrafiltration, although ultrafiltration results in a loss of protein product, especially for peptides of a high degree of hydrolysis.