Relative Tryptic Digestion Rates of Food Proteins

Abstract

ABSTRACT The kinetics of tryptic digestion of different food proteins were studied by measuring trichloroacetic acid soluble peptide release and peptide bond splitting either by proton titration at constant pH or by recording the pH drop in nonbuffered suspensions. The theoretical basis of the pH drop assay was described. Application of this method for comparative studies requires complementary determinations of buffering capacities of the samples and the time course of the reference protein digestion. It was shown that milk powder preparations differed in digestion rates by a factor of two and various lots of commercial soy meals differed as much as by a factor of three. Relative digestion rates of some food proteins from different sources could not be characterized by a single figure.