Cereal Chem 66:415-422   |  VIEW ARTICLE

An Improved Colorimetric Method for Determining Antitryptic Activity in Soybean Products.

K. Liu and P. Markakis. Copyright 1989 by the American Association of Cereal Chemists, Inc. 

The current colorimetric method for determining the antitryptic activity of soybean products has been modified as follows: 1) water rather than dilute alkali is used for extracting the inhibitors; 2) the aqueous extract is destabilized with Tris buffer and filtered before, rather than after, the reaction; 3) porcine rather than bovine trypsin is used; 4) the enzyme and not the substrate is added last to the reaction mixture; and 5) the volume of the reaction mixture is reduced from 10 to 4 ml. The proposed modification has a theoretical basis and was more sensitive than the current method. The relative standard deviation in 55 independent measurements was +/- 3.5%.