Casein breakdown during ripening of Idiazabal cheese: influence of starterand rennet type

The objective of this work was to determine the effect of starter and renne t type on casein breakdown during Idiazabal cheese ripening. Four batches o f cheeses were manufactured with two rennets, commercial calf rennet and ar tisanal lamb rennet, and the use of natural flora or a commercial starter. Electrophoretic analysis of cheese samples showed six bands identified as a lpha (s1)-, alpha (s2) + beta-, alpha (s1)-I-, gamma (1)-, beta -I- and par a-kappa -casein. As expected, the casein breakdown during cheese ripening w as considerably affected by rennet type and the use of a commercial starter . The artisanal lamb rennet produced a higher hydrolysis of casein fraction s than the commercial calf rennet, probably owing to its high percentage of chymosin (around 78%). The effect of addition of starter on proteolysis wa s dependent on the casein fractions generated by artisanal lamb rennet or c ommercial calf rennet. (C) 2000 Society of Chemical Industry.