STABILITY OF TRYPSIN AND CHYMOTRYPSIN PROTEOLYTIC ACTIVITY IN CLOSED ENZYMATIC PH-STAT SYSTEM FOR IN VITRO PROTEIN DIGESTIBILITY OF STANDARD FEEDSTUFFS

摘要

Protein digestibility is an important parameter for the classification of protein quality and can be assessed by in vitro and in vivo techniques. The pH-stat system is an in vitro method to measure protein degradation by digestive enzymes as the degree of hydrolysis. This parameter has been used to predict protein digestibility in both human food and animal feed (Alarcon et ah, 2002). Digestive proteases used in pH-stat system can attack each other, leading to undesirable loss of proteolytic activityand contamination of the in vitro assay. This study was designed to evaluate the hydrolysis and loss of activity of some alkaline digestive proteases used in pH-stat methodology.