Research On The Process Of Soymilk And Milk Mixed Cheese

Cheese is a nourishment dairy product. It has long history of cheese manufacture .In this thesis the process of milk and soymilk mixed cheese was established through simulating traditional process of hard cheese. There was no obvious different between soy-cheese and cheese in terms of nutrition and flavor. So soy-cheese was acceptable.Cheese starter has three important functions in cheese manufacture : acidification, formation texture of cheese and product flavor .It was reported that lactic acid bacteria of cheese is healthful. As cheese starter it must has the characters as follow: produce acid rapidly growth rapidly and can keep quantitative balance with another bacteria in one multiple-stain starter. In this thesis the multiple-stain starter compose of Streptococus Lactics(S.L.) Streptococeus Cremoris(S.C.) and Leuconostoc Cremoris(L.C.). S.L and S.C has higher acid-producing ability than L.C, and the L.C was indispensability to the flavor formation during cheese ripening .Investigation on the properties of the starter showed that starter has maximum cell number and acid-producing ability cultured at 32癈. The optimum culture condition of multiple-stain starter utilized in soy-cheese manufacture, was that cultured S.L , S.C and L.C at their optimum temperature respectively then mixed together .Rennet play a important role in cheese making industry . Calf rennet is the most widely used traditional coagulator. Traditional rennet extract from the fourth stomach of calf. It encloses two active enzymes: chymosin which is the major protease responsible for at least 85% of the total coagulating activity; the remainder is achieved by pepsin. This thesis investigate the influence of temperature ,pH value and the addition amount of Cad; on the activity of bacteria rennet .Investigate the influence of the bacteria rennet addition amount on the time of coagulation and the firmness of the soy-cheese gel. Then establish the process of soy-cheese manufacture .The optimum gel formation condition of soy-cheese was pH6.0, 32癈. 0.04%CaCl2 and 0.7% bacteria rennet. The activity of bacteria rennet was 500U/mL on the condition of pH6.4, 35 C, 0.04%CaCl2 .The investigation showed that the process of cheese and soy-cheese was similar, but the firmness of the soy-cheese gel was softer than pure milk cheese and the coagulation time of soy-cheese is longer than pure milk cheese . This because the glycinin block the casein net formation during gel forming. It limited the amount of soy-milk added in the mixed cheese.Cheese ripening was a complex biochemical process. Lactose fermentation, casein hydrolysis and degradation are the main transformation. This experimentation analysis the physical and chemical changes of soy-cheese at ripening period. Sense evaluation was employed to test the ripened cheese. The result show that there was similar in terms of flavor and nutrition between pure milk cheese and soy-cheese .There has a resemble trends between soy-cheese and pure milk cheese ,in terms of WSN/TN and 12%TCA-WSN/TN .Thebitterness of pure milk cheese appear faster than soy-cheese as well as disappear . The color of soy-cheese was darker than pure milk cheese ,and the texture of soy-cheese was softer than pure milk cheese .Employ soymilk to substitute partial milk to manufacture soy-cheese could decrease the cost of cheese productions . On the other hand , soy-cheese has more acceptable flavor than pure milk cheese. Because the different coagulation mechanism of glycinin and casein ,the amount of soymilk added in mixed milk were limited . The changes of giycinin during soy-cheese ripening and the influence of rennet on giycinin are unclear .It has a long way to go to make soy-cheese as popular as pure milk cheese.Candidate: Jang Feng Supervisor: Prof.Zhang Lanwei Major: Food Science...