Influence of enzymes, pH and temperature on the kinetics of whey protein hydrolysis / Influencia de los enzimas, pH y temperatura en la cinética de la hidrólisis de las proteínas del lactosuero

Abstract

The influence of pH, temperature and the mixture of enzymes (MKC Protease 660 L and PEM 2500 S) on the enzymatic hydrolysis of whey proteins was studied. The experiments show that all results were reproducible via a kinetic model that supposes the rapid and irreversible binding of part of the proteases to an inhibitor in the substrate, followed by a zero-order hydrolysis with respect to the substrate which occurs simultaneously with a second order enzymatic denatural ization produced by an attack of the free proteases upon those bound to the substrate-enzyme complex. Use of the optimum operating temperature of 60 °C and pH 8-10 led to a greater degree of hydrolysis. However, increasing the pH to these levels means that the salt content, on neutral izing the hydrolysate, is somewhat high and this is often unsuitable for the preparation of special diets. In the experiments performed with mixtures of enzymes, two contrasting phenomena occurred; there appears to be synergism between the proteases, which is preceded by a loss in enzymatic activity greater than that which can be accounted for by the presence of the inhibitor in the whey proteins.