Studies On The Preparation Of Soymilk Cheese By Wutungkiao Mucor Sce

To find new soymilk coagulase, Wutungkiao Mucor was used as species and wheat bran,soybean as raw materials in this article. The optimal culture conditions for enzyme productionby Wutungkiao Mucor was studied based on the extractive from fermentation of wutungkiaohas the ability to coagulate soymilk; The enzymatic properties of extractive were studied, andthen make the soymilk into soybean cheeses by extractive; The variety of physical andchemical during the ripeing of soybean cheeses were studied by TPA and SEM. The resultswere as follows:1. The extractive extracted from Wutungkiao Mucor has a soymilk-clotting enzymeactivity, can be used for preparing soymilk curd. It has a strong activity under neutralconditions, followed by the acidic conditions, the activity is low under basic conditions.2. The most influential factor to extractive activity extracted from Wutungkiao Mucor isthe culture temperature, followed by culture time, is less affected by the ratio of bran to water,and the impact of various factors on the soybean milk clotting activity and protease activityconsistent; Considering the impact of soymilk clotting and protease activity, and ultimatelythe optimized fermentation temperature from orthogonal tests was20℃, ratio of bran to water10:11, and culture time54h, resulting a SCA and protease of0.24U/mL and166.5U/g.3. The factors effect on soymilk-clotting enzyme activities of extractive weretemperature, pH, substrate concentration, and metal ions; The optimum temperature, and pHvalue for the SCA were50℃and5.9respectively. The SCA of the extractive was sensitive totemperature, and could be completely inactivated under70℃in10min, stability in the rangeof pH5.0-7.0. The higher substrate concentration, the faster enzymatic reaction to the positivedirection. Divalent metal ions such as Mg2+、Fe2+、Ca2+on the enzyme could promotecoagulation soymilk, a divalent metal ions K+、Na+is not obvious, beyond a certainconcentration range, Al3+inhibited the solidification process.4. With the increase of the amount of enzyme, the curd hardness and cohesiveness weregradually reduced; The hardness and consistency, cohesiveness and viscosity index of curdwere showed significant positive correlation（p＜0.01）;0.06%CaCl2can significantly improve the curd hardness and cohesiveness when adding1mL extractive to coagulatesoymilk; Under the same activity conditions, papain as contrast, the texture and proteindegradation of coagulum which coagulated by papain and extractive were studied respectively;The texture of crude coagulated by extractive is more dense compaction, hardness is relativelyhigh, during curd process, both of which make soybean protein rapidly degraded into smallpeptides and amino acids.5. Papain and extractive extracted from fermentation of wutungkiao as soymilk clottingenzyme, coagulating soymilk preparation soy cheese. We regarded the extractive amount,CaCl2amount, salt amount and fermentation agent amount as four main factors to affectsoybean cheese yield, adopted orthogonal test design; So we finally determined thetechnological parameters of papain soymilk cheese, namely,1mL0.5%papain,0.04%CaCl2,0.5%salt,0.01%fermentation agent, we can get the hightest soybean cheese yield,36.12%;The technological parameters of extractive soymilk cheese were1mL0.5%extractive,0.04%CaCl2,1.0%salt,0.01%fermentation agent, the hightest soybean cheese yield was33.12%.6. Total acid content and amino nitrogen content of the two kinds of soybean cheesesshowed an upward trend during ripening process; Total acid content and amino nitrogencontent of P cheese were1.44g/100g and0.30g/100g after ripening31d, respectively, totalacid content and amino nitrogen content of C cheese were1.15g/100g and0.30g/100g afterripening31d, respectively. By amino acid analysis, the main amino acid produced in the Pcheese ripening process were glutamic acid, leucine and phenylalanine, addition to the abovethree, but also produce a proline during the degradation of C cheese. The results ofelectrophoresis and SEM image shows that the protein is decomposed to small moleculespeptide and amino acids under the action of the protease, each subunit of the electrophoresisstrip was disappeared. Free water is difficult to discharge and higher viscosity owing tohomogeneous structure of the curd. The cheese texture gradually become closer and evenlyduring cheese ripening process after curd press molding. Throughout the ripening process, thehardness and fracturability changed significantly, chewiness and springiness changed notsignificant.