ENZYME-LINKED-IMMUNOSORBENT-ASSAY (ELISA) AND MILK-CLOTTING TEST (MCT) FOR DETERMINATION OF THE AFFINITY BETWEEN CHYMOSIN AND ARTIFICIAL CASEIN MICELLES

During cheese ripening, the flavour develops partly due to retained mi lk-clotting enzymes in the curd. The mechanism of incorporation of mil k-clotting enzymes into the curd is, however, not known. Two methods, Enzyme Linked Immunosorbent Assay (ELISA) and Milk-Clotting Test (MCT) , for determination of the affinity between chymosin and artificial ca sein micelles were compared. After incubation of chymosin with artific ial casein micelles of four different compositions and at four differe nt pH-values, the amount of chymosin in the 'whey' was measured using the two methods. The results showed that there were only small differe nces between measurements of immunological response (ELISA) and cataly tic activity (MCT) of the chymosin not absorbed onto the artificial ca sein micelles. This seems to conflict with earlier results, suggesting that rennet enzyme molecules, associated with casein breakdown produc ts, can affect rennet activity determinations. Essentially, the ELISA and MCT methods complement each other and should be used together to d etermine the affinity between chymosin and artificial casein micelles.