Action of the chymosin on reconstituted casein systems

Abstract

The aim of this work was to study the chymosin-catalysed hydrolysis of reconstituted casein systems containing s1 -casein, s2 -casein, -casein and -casein or -casein modified via chemical glucosylation and/or enzymatic dephosphorylation. The systems containing modified -casein instead of -casein were destabilised after release of peptides in trace amounts. The coagulation of the systems reconstituted using -casein required release of much more peptides than coagulation of those containing modified -casein. Proteolysis range in both classes of reconstituted systems was much smaller than proteolysis range in milk. The specificity of chymosin against reconstituted systems was typical. The major proteolysis products were para--casein and caseinomacropeptide in the systems reconstituted using -casein as well as fragment 1-23 of s1 -casein and fragment 193-209 of -casein in all the systems used. Only the systems containing -casein formed gel with a structure similar to this obtained via casein coagulation in milk.