Functional properties of soy protein hydrolysate produced from a continuous membrane reactor system

Two types of soy protein hydrolysates were produced by hydrolysis of isolat ed soy protein (ISP) with a combination of Alcalase and Flavourzyme in a co ntinuous membrane system with 3000 and 30,000 daltons molecular-weight-cut- off (MWCO) membranes, respectively. Both hydrolysates were completely solub le over a pH range of 2-9. Their water-binding capacity increased 1.8-3.4 t imes at a water activity of 0.6-0.95 sts compared to intact ISP. The antiox idant activity of ISP was remarkably enhanced by enzyme hydrolysis. The hyd rolysate from the 30,000 daltons MWCO membrane had a much higher antioxidan t activity than that from the 3000 daltons MWCO membrane. The results sugge sted that both selected enzymes and MWCO membrane governed the functional p roperties of protein hydrolysates. Long-term operation study showed that th e membrane reactor system could maintain a steady production of ISP hydroly sate over 16 h. (C) 1999 Elsevier Science Ltd. All rights reserved.