Recombinant lamb chymosin as an alternative coagulating enzyme in cheese production

Recombinant lamb chymosin (RLC) was prepared and tested for its potential u se in cheese production. The milk clotting activity and proteolytic activit y of RLC were evaluated in comparison with commercial recombinant calf chym osin (RCC), cow rennet (CR), and microbial coagulant (MC). RLC, RCC, and MC showed similar responses to pH, with a sharp increase of the coagulation t ime at pH 6.6 to 6.8 and decrease of curd firmness at the pH 6.5 to 6.6. In the case of CR, we observed two clear increases in the coagulation time an d decreases in the curd firmness, at pH 6.4 to 6.5 and 6.6 to 6.8. Optimal clotting activity was obtained for RLC at 40 degreesC, for both CR and RCC at 45 degreesC, and for MC at 60 degreesC. The temperature instability of R LC at temperatures above 45 degreesC could constitute a benefit in making h ard cheese varieties. The additon of CaCl2 to milk resulted in enhanced clo tting activity of all coagulants, most prominently for CR. The proteolytic activity of RLC was significantly lower from that of CR but not significant ly different from the activity of RCC. The lower proteolytic activity in th e cheese made with RLC did not have negative effect on organoleptic propert ies. The overall quality of the cheese made with RLC was at least comparabl e to that of the cheese made with RCC, and both cheeses were better scored than the cheese made with CR.