Microbial Rennets. Advances in Applied Microbiology Volume 20. Elsevier; 1976. pp. 135-57. [DOI: 10.1016/s0065-2164(08)70111-4]

Influence of culture conditions on the production of milk-clotting enzyme from Rhizomucor

The ratio of milk-clotting activity to proteolytic activity (MC/PA) was used as an index to determine the quality of milk-clotting enzyme. Solid-state fermentation on wheat bran for 5 days at room temperature gave optimal production for enzyme by Rhizomucor miehei and R. pusillus. A ratio of wheat bran to moisture of 1:0.6 (w/v) gave best results. Adding skim milk powder to the media of R. miehei did not improve the MC/PA ratio but 4% (w/w) of the powder did improve the ratio with R. pusillus. Co-cultivation of R. miehei with R. pusillus did not change the MC/PA ratio.

Effect of manufacturing factors, composition, and proteolysis on the functional characteristics of mozzarella cheese

Shredding and melting characteristics are vital to the function of low-moisture Mozzarella cheeses that are used as ingredients for pizza and related foods. Newly manufactured Mozzarella melts to a tough, extremely elastic, and somewhat granular consistency with limited stretch that is unacceptable for pizza. However, during the first few weeks of refrigerated storage, a dramatic transformation occurs as the unmelted cheese becomes softer and the melted cheese becomes more viscous, less elastic, and highly stretchable. Thus, the cheese attains optimal functionality for pizza. Over longer periods, Mozzarella becomes excessively soft and fluid when melted and is no longer acceptable for pizza. Low-moisture Mozzarella is correctly viewed as a cheese that requires aging. The functional characteristics of low-moisture Mozzarella are due initially to the chemical composition, including fat, moisture, NaCl, and mineral contents, and the structure of the paracasein curd matrix that is established during manufacture. Changes in functional characteristics during aging are directly related to proteolysis rate and possibly proteolytic specificity. Proteolysis during aging is influenced by manufacturing factors such as starter culture, coagulant, and stretching temperature, and possibly to indigenous proteases in the cheesemilk such as plasmin.