Heat-induced changes in the susceptibility of egg white proteins to enzymatic hydrolysis: A kinetic study

A kinetic study was conducted on the effect of heating in the temperature range of 50-92 degreesC, on the susceptibility of ovalbumin and albumen solutions to enzymatic hydrolysis by a mixture of trypsin and alpha-chymotrypsin at 37 degreesC and pH 8.0. Heat treatment resulted in an increase in degree of hydrolysis after 10 min of enzymatic reaction of both ovalbumin and albumen, as measured using the pH-stat method. The time-dependent change in the susceptibility to enzymatic hydrolysis after heat treatment was described by a fractional conversion model (based on an apparent first-order reaction kinetic model). Different end levels of degree of hydrolysis were obtained after heating for a long time at different temperatures, which suggests that the final degree of unfolding of the protein is temperature dependent.