Study On The Fermentation Of Chymosin By Mucor Indicus MJ229

The rennet initially found in the calf abomasums, is a key enzyme in the cheese manufacturing and has applications in other food, medicine, light industry and other fields. With the rise in world cheese production, rennet for cheese production is in increasingly short supply. People gradually turn their attention to the study of its substitutes. In the early 1980s, china has began to correlative research, but also lacked industry rennet production process. The production of cheese rennet depended on imports. Therefore rennet pilot the test has a high economic and social significance. In this paper, microbial fermentation rennet was studied. It includes:liquid fermentation, solid state fermentation rennet medium and the optimization of culture conditions, solid-state fermentation pilot test, the preparation of rennet enzyme preparation and curd enzymatic properties of the enzyme preparation and stability studies. The main results are as follows:According to the single factor experiment and response surface experiment, the liquid fermentation medium of MJ229 were optimized.The conclusions were as follows:rice add 6%,the bran extracts concentration 25.8%, the amount of amylase Add 79.3μL(about 1600U vitality), potassium sulfate concentration 0.037%, calcium chloride concentration0.04%,sodium chloride concentration 0.03%, inoculum’s size4%, initial pH, fermentation temperature 30℃. Optimized chymosin activity reached 91SU/mL (1516.7SU U/g rice)According to the single factor experiment and orthogonal experiment, the solid-state fermentation medium of MJ229 were optimized.The conclusions were as follows:rice:wheat bran:straw= 0.5:0.4:0.1, Tween-80 add 0.2%, materials song:tap water= 1:1, upload song 0.3Kg/disk, incubation temperature 30℃, inoculum’s size 10%. Optimized chymosin activity reached 3360SU/g rice. Pilot-scale production conditions of Mucor MJ229 by solid state fermentation for producing chymosin were formulated during Comparing.From the above, relatively high enzyme activity was obtained during the solid-state fermentation. Solid-state fermentation pilot experiments were researched.The natural state and control of moisture and temperature conditions for solid state fermentation were studied, after 48 h fermented the results showed that the activity in the regulating state fermentation was 25% higher than the state of nature. The temperature and moisture content of the materials song were controlled well.Pilot-scale production conditions of Mucor MJ229 was carried,200Kg per batch. The results showed that in the fermentation process, pH values varied between 6.4 and 6.6. After fermentation, the activity was up to 5333SU/g rice.Chymosin in the solid state fermentation material was extracted, concentratedand spray-dried; the activity was up to 4000SU/g.Enzymatic properties of rennet were studied. The chymosin was stored in 4℃ and 25℃ for stability studies, the results showed that:rennet enzyme preparation occurred small activity change within 6 months at 4℃ and the viability was maintained at 81.5%.At the same time the vitality of the six-month decline to 46% at 25℃.