IDENTIFICATION OF PEPTIDES FROM OVINE MILK CHEESE MANUFACTURED WITH ANIMAL RENNET OR EXTRACTS OF CYNARA-CARDUNCULUS AS COAGULANT

Urea-PAGE of the water-insoluble extract (WISE) of ovine raw milk chee ses manufactured with proteinases of Cynara cardunculus or with commer cial animal rennet indicated that the animal rennet acts more intensiv ely, in quantitative terms, on ovine beta-, alpha(s1)-, and alpha(s2)- caseins than the plant rennet. The water-soluble extract (WSE) from ch eese produced by plant rennet was constituted by fragments of ovine be ta- and alpha(s2)-caseins; peptides beta-(f128-), beta-(f166-*), and beta-(f191-) were produced only by plant rennet, whereas peptides bet a-(f164-) and beta-(f191-*) were produced only by animal rennet. The peptide beta-(f1-190) was identified as the primary product of ovine b eta-casein degradation in the WISE for both rennets. The complementary peptides alpha(s1)-(f1-23) and alpha(s1)-(f24-191) were produced by b oth rennets from ovine alpha(s1)-casein; however, the bond Phe23-Val24 was cleaved by as early as 7 days in cheese manufactured with C. card unculus, whereas 28 days had to elapse before that could be detected i n the case of animal rennet. The peptide alpha(s1)-(f24-165) was produ ced only by plant rennet, whereas the peptide alpha(s1)-(f120-191) was produced only by animal rennet. The peptides produced from bovine alp ha(s2)-casein in cheese could not be traced as deriving from the actio n of proteinases from either rennet, so their existence is likely due to proteinases or peptidases released in cheese as a result of its ind igenous microflora.