(31a) Protein Recovery from Enzyme-Assisted Aqueous Extraction of Soybean Oil

Because of the high transportation cost 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. In vegetable oil production, the use of hazardous petroleum solvents drives up capital costs, resulting in larger processing plants and, therefore, increased transportation costs. In contrast, enzyme-assisted aqueous extraction processing (EAEP) uses only water as a solvent and is potentially less capital intensive.

One EAEP process developed at the Center for Crops Utilization Research (CCUR) at Iowa State University uses extrusion to disrupt cells of soy flakes, from which oil and water soluble components are extracted with the assistance of proteases, resulting in three fractions: residual solids, skim (an aqueous fraction with emulsified oil stable toward creaming), and cream (emulsified oil). Protein values, which potentially account for 65% of total EAEP revenues, are in the solid and skim fractions. The skim fraction differs from the traditional protein-containing fractions and characterization and recovery of this protein is critical to implementation of this alternative process.

We have investigated methods to recover the hydrolyzed proteins of the skim fraction of the CCUR process with an additional benefit of reduction of antinutritional factors, such as oligosaccharides and trypsin inhibitors. Traditional protein concentration methods such as pH precipitation, ultrafiltration, and ion exchange chromatography are complicated not only by the increased solubility and small molecular weight of hydrolyzed polypeptides, but also by the presence of emulsified oil in the skim fraction. Results from alternative recovery methods will be presented.