A new effective milk-clotting enzyme (BY-1) was produced from Bacillus subtilis PNG27. The analysis of MALDI-TOF-MS/MS showed that it belongs to the peptidase M4 family and had 521 amino acids. It had a higher proteolytic activity on α-casein, β-casein, κ-casein, and β-lactoglobulin than Rennet. Besides, BY-1 could decrease the curd time of poor-curd, UHT, refrigerated, and reconstituted milk. Moreover, two kinds of cheese were, respectively, made by BY-1 and Rennet. The results showed that the protein hydrolysates (WSN, CTA-N, and PTA-N) of cheese made by BY-1 were higher than that of Rennet. Flavor compounds (28) were detected from the cheese made by BY-1, whereas 15 compounds were detected from Rennet. The sensory evaluation indicated that the cheese produced by BY-1 exhibited better flavor and overall acceptability. Therefore, BY-1 could be widely used in cheese production.
Keywords: cheese making; flavor; milk-clotting enzyme; quality of the cheeses.