Effect of fermentation time and acid casein concentration as nitrogen source on microbial rennet production

Abstract

We evaluated the effects of fermentation time and acid casein content on the microbial rennet obtained by solid-state fermentation using wheat bran as the carbon source. The experiments used two fermentation times (72 and 96 h), while acid casein content was 1.5, 2.0, 2.5, and 3.0 g. Rennet strength from eight enzymatic extracts was measured using pasteurized whole milk. Rennet strength of samples from 72 h of fermentation showed an increase when acid casein content increased. The rennet strength increased at 96 h of fermentation with increasing amount of casein (up to 2.5 g), and then decreased with the largest addition (3.0 g) of casein. Coagulation time for the sample with highest rennet strength was 420 s.

Optimization of protease production from Rhizomucor miehei Rm4 isolate under solid-state fermentation

“…The effect of casein concentration was not significant against both of spMCA and MCA/PA, probably because of the previous setup near the optimal values. The optimal ratio of casein addition was predicted to be 1.33% w/w, similar to the 1.5% w/w reported by Khademi et al [ 29 ], but in contrast to the 250% w/w reported by Fileto-Pérez et al [ 25 ]. Lower enzyme activity was obtained at lower and higher ratios.…”

“…Escobar and Barnett [ 22 ] have reported that Rhizomucor miehei cultures reached the stationary phase through 90−120 h. Enzyme yield and activity were decreased after 96 h of incubation, probably due to nutrient depletion, accumulation of organic acids, and lower pH. Similar findings were reported [ 25 , 26 , 47 ].…”

“…The values of response variables obtained under the optimized conditions are superior to those reported by Preetha and Boopathy [ 37 ], Silveira et al [ 41 ], De Lima et al [ 18 ], and Fileto-Pérez et al [ 25 ]. The reported values of response variables signify the high quality of the produced enzyme by the high milk clotting activity and the relatively low proteolytic activity, which is favorable in cheese making.…”

Novel Bacillus Milk-Clotting Enzyme Produces Diverse Functional Peptides in Semihard Cheese

“…Milk-clotting enzymes (MCEs), derived from animals, plants, fungi, and bacteria, are widely applied in cheese manufacturing . However, the low supply of calf rennet worldwide cannot fulfill the rapidly increasing demand for cheese.…”