Contribution of rennet and starter to proteolysis in Iranian UF white cheese

The relative contributions of rennet and starter to proteolysis during the storage of ultrafiltered (UF) Iranian white cheese were investigated. In the experimental design used, starter and rennet were, in separate treatments, omitted and gluconic acid-δ-lactone was used for acidification of starter-free samples. The experimental treatments used did not have significant effects on composition. Omission of rennet in manufacture significantly reduced proteolysis during ripening of UF white cheese, and caused differences in peptide profiles determined by both urea-polyacrylamide gel electrophoresis and reversed-phase HPLC; omission of starter had a considerably smaller effect on these parameters. In cheeses made without rennet, noticeable casein degradation was not observed suggesting little contribution of indigenous proteinases to proteolysis during the ripening of UF Iranian white cheese. Both rennet and starter contributed indirectly or directly to production of free amino acids in UF white cheese and omission of either of these agents strongly reduced production of FAA during ripening.