Effects of animal rennet, fermentation-produced chymosin, and microbial coagulants on bovine milk coagulation properties

Abstract

Coagulants play a crucial role in cheese production by catalyzing milk curdling, with traditional animal rennet long serving as the primary choice. However, due to cost, availability, and ethical concerns, various substitutes such as microbial coagulants and fermentation-produced chymosin (FPC) have emerged. This study aimed to evaluate the effects of 8 commercial coagulants, including 1 bovine rennet, 2 bovine FPC, 1 camel FPC, 3 microbial (i.e., Rhizomucor miehei) coagulants, and 1 bovine FPC variant, on the coagulation properties of bovine milk. The coagulants were tested at 3 different doses (35, 50, and 65 international milk clotting units per liter) across 8 batches of unhomogenized, pasteurized, full-fat, bovine milk purchased from different commercial brands, in 2 replicates, for a total of 384 coagulation analyses (8 milk batches × 8 coagulants × 3 doses × 2 replicates). Specifically, traditional milk coagulation properties and curd firmness at given times were assessed using a lactodynamograph. Key findings indicated significant variations in coagulation patterns across the coagulants. Bovine rennet demonstrated an intermediate coagulation profile among all FPC and microbial coagulants. The bovine and camel FPC exhibited faster coagulation than the bovine animal rennet, with the camel FPC showing the quickest coagulation and curd-firming rates. The microbial coagulants, although exhibiting slower coagulation rates for a given dose, produced curd-firming dynamics different from those of all FPC. The bovine FPC variant exhibited high performance comparable to that of the camel FPC in the coagulation process. Overall, this study highlights the distinct coagulation characteristics of various coagulants, offering insights into their suitability for different cheese-making applications. The coagulant dose significantly affected the coagulation pattern, with a clear linear increase in dose influencing gelation and varying effects on other coagulation traits. These findings can guide producers in selecting the optimal coagulant and dose based on specific cheese production needs.