ASSOCIATION OF CHYMOSIN WITH ARTIFICIAL CASEIN MICELLES AS INFLUENCEDBY MICELLE COMPOSITION AND PH

The flavour of cheese develops partly due to retained milk-clotting en zymes in curd during cheese ripening. In this paper, the influence of the casein micelle composition, and the pH of the micelle solution on the amount of chymosin adsorbed onto casein micelles, are studied. Aft er incubation of chymosin with artificial casein micelles of four comp ositions and at four pH values, the amounts of chymosin remaining in t he supernatant were measured with an Enzyme Linked Immunosorbent Assay (ELISA) and a Milk Clotting Test (MCT). Results confirmed earlier fin dings, i.e. the lower the pH, the higher the adsorption of chymosin on to casein micelles. The beta/kappa-casein micelles adsorbed more chymo sin than alpha(s)/kappa-casein micelles of the same ratio of individua l caseins and pH value. Micelles of beta/kappa- or alpha(s)/kappa-case in of a ratio 12:1 were more influenced by pH than those of 3:2. Micel les of ratio 3:2, except at pH 5.2 for alpha(s)/kappa-casein, adsorbed more chymosin than those of ratio 12:1 at all pH values studied. (C) 1997 Elsevier Science Limited.