Studies On Effects Of Culture Starters And Coagulants On The Quality Of Mozzarella Cheese For Pizza

This dissertation researched the effects of culture starter, coagulant type, amount of coagulant and coagulum time on the quality of mozzarella cheese for pizza. A "no-brine" Mozzarella cheese process was used to mike cheese for homogeneous chemical composition. The ultimate goal is to screen the optimum culture stater and coagulant. And get the optimum addition amount of coagulant and clotting time.This dissertation compares the effect of two kinds of cultures on Mozzarella cheese. One is single strain of Streptococcus salivarius ssp. Thermophilus; the other is a pair of Lactobacillus debrueckii ssp. Bulgaricus and Streptococcus salivarius ssp. Thermophilus. There is no effect of culture staters on cheese chemical composition. During ripening, the rate of proteolysis of the cheese made with pairs strain culture is higher than that of the cheese made by single strain culture. The meltability and free oil release of cheese made with pairs strain culture is better than that of the cheese made by single strain culture.The cheeses were made with three different coagulant types (rennet, mixture coagulant, microorganism coagulant): The results showed coagulant types have affected cheese protein and fat levels. During storing the rate of proteolysis is remarkably affected by coagulant types. The rate of proteolysis in the cheese made with microorganism coagulant is the fastest, and the pattern of proteolysis of microorganism is different from rennet and mixture coagulant. The coagulant types only remarkably affect the meltability and the free oil release. On the same condition, before melting the hardness and springness of cheese made with microorganism coagulant is lower than that of other two cheeses, but during melting it's meltability and free oil release is the best.In research of addition amount of rennet, I designed that the addition amount was 22mg/kg, 25mg/kg, and 28mg/kg separately. The results showed the addition amount of coagulant affect chemical composition especially moisture and protein content. If the addition amount of coagulant is higher, thecoagulation ability is better and the content of protein is higher .The defect of this cheese is mouthfeeling bitter. The more addition amount of coagulant is, the higher values of hardness meltability and free oil release of cheese are.Three firmness levels were tested, and these corresponded to average time of coagulum addition to cutting the curd of 30, 40,50min clotting. With the clotting time prolonging, the moisture content of cheese incresc, and the fat content of cheese decreased. The cheese made by clotting 50min has better in springness, meltability and free oil release. The texture of this cheese was softer and smoother.