Production of a novel milk‐clotting enzyme from solid‐substrate Mucor spp. culture

Abstract

Calf rennet has been traditionally used for cheese making all over the world since ancient times. It is primarily a type of aspartic protease. Calf rennet, also known as chymosin, is considered the best milk coagulant in cheese manufacturing. Its usage and demand are increasing day by day in the food industry; however, some ethical issues are also related since it is naturally present in the calf's stomach and obtained by the slaughtering of young animals. Therefore, researchers are trying to introduce some new and better alternatives for chymosin in the food industry. Mucor racemosus f. racemosus CBS 381, Mucor racemosus DSM 62760, and Aspergillus oryzae were cultivated by solid substrate fermentation using the design of experiment (DoE) (MODDE; Umetrics, Sweden) to optimize and analyze the various combinations of different factors and responses (milk-clotting activity, proteolytic activity, specific activity). Based on the analysis of the screening and optimization results, Mucor racemosus CBS 381 was found to be the potential strain in terms of high production of aspartic protease, as well as had high milk-clotting activity under a solid-state fermentation system. However, molasses and casein were determined to be significant carbon and nitrogen sources, respectively, under conditions such as 70% moisture content and 25 • C temperature. The molecular weight of the enzyme (Mucor CBS 381) is ∼30 KDa and it exhibits maximum activity at pH 4.8 at 45 • C. The investigated enzyme was pronounced as thermal-sensitive and lost activity completely after 10 min incubation at 55 • C. The remarkable qualities of the studied enzyme, such as cost-effective production, milk-clotting and proteolytic activity make Mucor racemosus CBS 381 a promising alternate to calf chymosin in the cheese-making industry.

Occurrence, Risk Implications, Prevention and Control of CIT in Monascus Cheese: A Review

“…Subsequently, rennet plays a crucial role in the production of a cheese-like texture. After curing, whey is excreted, and the mixture is fed into a mold for shape . It is worth noting that salt treatment is an indispensable step in the commercial production of cheese, which can further discharge the internal whey and water before postripening to improve the hardness of cheese.…”

“…After curing, whey is excreted, and the mixture is fed into a mold for shape. 34 It is worth noting that salt treatment is an indispensable step in the commercial production of cheese, which can further discharge the internal whey and water before postripening to improve the hardness of cheese. Additionally, it can control the acidity, inhibit the growth of spoilage microorganisms that may occur during the process, and promote the maturation and flavor formation of cheese.…”