Milk-clotting activity of high pressure processed coagulants: Evaluation at different pH and temperatures and pH influence on the stability

Abstract

Abstract This study evaluated the milk-clotting activity (MCA) at different pH values and temperatures of milk and the influence of pH on the stability of commercial coagulants subjected to high pressure processing (HPP). The pressurized enzymes showed higher MCA for almost all conditions studied, as compared to the non-processed samples, and the differences were more pronounced at higher temperatures and lower pH values. For the conditions used in industrial cheese making (pH 6.6 at 35 °C), the HPP led to an increase in MCA of 27, 9, 8, and 5% for the recombinant camel chymosin, bovine rennet, calf rennet, and porcine pepsin, respectively. In addition, HPP increased the pH stability for most of the enzymes. Therefore, HPP emerges as an effective technology to improve the hydrolytic profile of these enzymes as a function of pH and temperature. Industrial relevance HPP was able to promote increased in milk-clotting activity and stability of coagulants at different temperatures and pH values. For some enzymes the pressurization increased the activity at a natural pH of the milk (pH 6.6), resulting in activity similar to that observed for native enzyme at lower pH and higher temperatures. Thus, such conditions lead the use of less enzyme concentration in coagulation process, reducing costs. Additionally, it was also shown that lyophilization preserved the changes induced by the HPP in enzymes solution. Therefore, HPP technology is a unit operation can be used to increase activity and stability of milk-clotting enzymes.