Determination and characterisation of milk-clotting activity of two Solanum tuberosum aspartic proteases (StAPs)

Abstract

To identify new coagulant enzymes as rennet substitutes, the aim of this study was to determine and to characterise the milk-clotting activity (MCA) of two potato aspartic proteases (StAPs). Both enzymes exhibited MCA in a dose-dependent manner. Optimum MCA values were determined at pH 5 and 30 °C. The ability of StAPs to degrade casein subunits was also evaluated. β-Casein was preferentially hydrolysed by both StAPs, followed by αS-casein and, to a lesser extent, κ-casein. These results confirmed the suitability of StAPs for producing curd and the possibility of using these proteases in artisanal cheese production.