Continuous Enzymatic Modification of Proteins in an Ultrafiltration Reactor

The feasibility of producing protein hydrolyzates using an ultrafiltration (UF) reactor system was evaluated. Soy protein isolate is reacted with a soluble protease in a reaction vessel coupled in a semi-closed loop configuration to a hollow fiber UF unit. Reaction products are pumped past the membrane where hydrolyzate of molecular size small enough to pass through the membrane is removed as permeate. Enzyme and unreacted protein are recycled back to the reaction vessel. The effect of operational parameters such as flow rate (flux), reaction volume, substrate, and enzyme concentration on reactor product output and conversion were studied. The product is typically 91% hydrolyzed protein (N × 6.25) and 9% ash, dry basis, and contains at least four fractions of molecular weight 2500 or less.