DENATURATION IMPACT IN SUSCEPTIBILITY OF BETA-LACTOGLOBULIN TO ENZYMATIC HYDROLYSIS: A KINETIC STUDY

The aim of this study was to establish a kinetic model to describe the effect of heat processing on the susceptibility of beta-lactoglobulin to proteolysis. The kinetic study was performed in the temperature range of 62.5-78 degrees C on the susceptibility of beta-lactoglobulin to enzymatic hydrolysis by trypsin and chymotrypsin at 37 degrees C and pH 7 and 7.5. Heat treatment results in an increase in degree of hydrolysis after 10 min of hydrolysis, as monitored by pH-stat technique. For the hydrolysis experiments at pH 7, the values for activation energy were significantly higher for the susceptibility of beta-lactoglobulin to trypsin hydrolysis compared with chymotrypsin. In contrast, for the hydrolysis experiments at pH 7.5, beta-LG seems to be more heat-sensitive for chymotrypsin hydrolysis, confirming that the dimer dissociates when the pH is adjusted at 7.5, with the exposure of hydrophobic residues.