Proteolytic and Microbial Changes During Ripening of Cheddar Cheese Using Bacterial Enzyme as Milk Coagulating Agent

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Abstract
Twenty-nine lots of Cheddar cheese were prepared using coagulating enzyme prepa- rations from selected strains of Bacillus subtilis, B. megatherium, and B. cereus. The proteolytic degradation of cheese samples at different stages of ripening was studied for sodium citrate-HC1 soluble N, formol N, and concentrations of free tyrosine. The cheese samples were examined quantita- tively for presence of Lactobacilli, Strepto- cocci, spore-forming bacteria, acid-forming bacteria, proteolytic and lipolytic bacteria, in addition to yeasts and molds at different periods of ripening. Cheese whey from a few cheese preparations was examined for pH, acidity, soluble solids, total N, NPN soluble in 5% TCA, and formol N. Differ- ences in total N and formol N were found in 2% insoluble fraction obtained from bac- terial and calf rennet whey. Calf rennet and, more recently, microbial en- zymes have been employed for the manufacture of different varieties of cheese. While proteo- lytic degradation of Cheddar cheese using calf rennet has been reported extensively, reports on use of microbial enzymes have been rather re- stricted (3, 4, 6, 20). The degradative and flavor production in the cheese during ripening have largely been as- cribed to the presence of organisms such as Streptococci (10, 18), Pediococci (5), Lacto- bacilli (7, 13, 15, 17), Micrococci (1), Entero- cocci (8), and various proteolytic (23) and lipo- tytie (19) bacteria. In the present investigation the proteolytic degradation, as well as the micro- flora of Cheddar cheese prepared by using en- zyme preparation derived front selected strains of B. subtilis, B. cereus, and B. megatherium, has been reported.
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