The Study Of Key Processing Technology Of Double Protein Cheese

Cheese is a nutrient-rich dairy product, and cheese processing is a new growthpoint at the relatively slow developing stage of dairy industry. The cheese market hasgrown rapidly in China recent years, but the source of milk is relatively in shortsupply, the cost of producting cheese is high and the cheese flavor is unacceptable bythe majority of Chinese consumers. These factors limit the development of the cheeseindustry in China. As we all know, soy protein is a kind of nutrient-rich, low-cost,high-quality protein. Using soy protein as a substitute of milk protein in doubleprotein cheese helps alleviating the problem of insufficient milk source, and reducingmanufacturing cost, but also helps improving the flavor of cheese. In this study, twolactobacillus suitable for double protein cheese manufacturing were selected from sixlactic acid bacteria,using pure milk blending soy protein as the fermenting substrate ofhametz; The influence of eight different varieties of soy milk, different types of soyprotein, different the proportion of soy protein fractions7S (glycinin) and11S(soybean conglycinin) protein on cheese character and maturity physical and chemicalindicators changing during ripening were investigated; The effect of Physical factorsand enzyme modified soy protein, glucose-δ lactone and TG on double protein curdwere also studied. The main results obtained in this article are listed as follows:(1) XZ3303and HQ27-1strains were selected as the suitable fermenting lacto-bacillus for double protein processing from six bacterias by investigated the gelingcharacteristics and fermentation characteristics in raw milk and milk blending soypro-tein.The addation ration of XZ3303and the HQ27-1is defined as1:1by inspe-cting the breeding together research.(2) The physical and chemical targets of double protein cheeses during ripeningare different, but the trends of changing are similar. In the ripening period, the moi-sture contents of cheeses decreased; fat contents slightly increased; water-solublenitrogen and the alcohol-soluble nitrogen contents increased; in the textural aspects ofcheese, hardness, elasticity and cohesion of all gradually reduced.(3) All of the eight different varieties of soy milk improved yields of the double protein cheeses. The effect of soybean varieties on the yield, colour, and texture of thedouble protein cheeses are different, but the sensory evaluation results of them aresimiler. protein, fat and and cheese yield and textural properties There was no signi-ficant correlation among the the fat content, protein content, phytic acid content ofdifferent varieties of soybeans, cheese yields,texture targets. But the ratio of soyprotein ingredient (11S/7S) and the hardness and cohesiveness of thedoubleproteincheeses are significantly interrelated.(4) Addition of different types of soy protein has considerable influence on yieldsand texture of double protein cheeses. Addition of SPF reduced the hardness of thecheeses. And SPC andSPI increased the hardness of the cheeses, but with the increa-sing addition the hardness decreased. Addition of soy protein improved the elasticityand cohesiveness of the cheeses. The addition of soy protein has adverse influ-ence on sensory evaluation. Taking the results of the entire experiment, addition of theSPF depraved the cheese texture and flavor, and SPI had no obvious influence on thetexture and flavor. The double protein of addition of10%SPI had the best cheesetexture and flavor. With the increasing ration of11S in the soy protein,the hardnessand elasticity dropped.(5) NSI of soybean protein was improved after microwave and ultrasonic treat-ment and enzymolysis treatment, but the viscosities of the protein soluteion werereduced. Microwave and ultrasonic treatment did not change the first–level structureof protein molecule and lowered the molecular weight of the enzyme modified soyprotein. With the increasing processing power and time of the microwave, sonication,and increasing of DH, the double protein gel cost less time and curd of sensory scoresgradually increased. The largest curd strength obtained by addition of micro-wavemodified by microwave-modified160W for8min.Additon of soy protein treated byultrasonic400W for15min had the largest gel strength, increased by25.2%comparedwith the control group. The degree of hydrolysis of the soy protein added at12.9%to13.5%helped the gel forming the better texture.(6) With the amount of GDL and TG enzyme added increasing, the coagulatingof double protein curd taked less time.When added with GDL,the order of factors affectted the strength of double protein curd was the addition amount of soy protein,addition amount of glucose-δ lactone, the addition amount of rennet, the additionamount of CaCl2. When added with TG enzyme, the order of factors affectted thestrength of double protein curd was the addition of TG enzyme, the addition of rennet,the addition of CaCl2. With the curd strength as the envaluation index,the optimizedcoagulator combination was0.01%CaCl2,0.03%rennet enzyme and0.5%GDL addedto the milk blended with15%soy protein,and adding0.03%CaCl2,0.05%rennetenzyme and0.3%TG enzyme to the milk blended with10%soy protein.