五通桥毛霉麸皮培养基的豆乳凝固酶活性研究

Soymilk-clotting Enzyme Activities in Bran Culture of Wutungkiao Mucor

研究了五通桥毛霉固态发酵条件以及温度、pH、金属离子等因素对其麸皮培养基粗酶液豆乳凝固酶活性的影响。结果表明：五通桥毛霉麸皮培养基粗酶液具有豆乳凝固酶活性，4mL粗酶液可使50g豆乳在20min内凝固。当培养基中麸皮与水的比例为10：11，在20℃培养54h时粗酶液酶活最高，达0．24U·mL^-1；粗酶液最适作用温度和pH分别为50℃和5．9；其对温度敏感，70℃保温10min豆乳凝固酶活性完全消失；在3．0—5．0mmol·L^-1浓度范围内。Mg^2＋、Fe^2＋和Ca^2＋可以提高酶的活性，K^＋和Na^＋作用不明显，而Zn^＋和Al^3＋则有抑制作用。

The effect of fermentation condition, temperature, pH and metal ions on the soymilk-clotting enzyme activities （SCA） in bran culture of Wutungkiao mucor was researched. The extractive of Wutungkiao mucor bran culture had soymilk-clotting enzyme activities, and 4 mL extractive could coagulate 50 g soymilk in 20 min. The optimized fermentation condition by orthogonal tests was as follows ： ratio of bran to water was 10 ： 11, and cultivated 54 h at 20℃, with the highest activities of 0.24 U· mL^-1. The optimum temperature, and pH for SCA was 50℃ and 5.9, respectively. The SCA of the extractive was sen-sitive to temperature, and could be completely inactivated under 70℃ for 10 min. Within 3 to 5 mmol· L^-1, Mg^2＋ , Fe^2＋ and Ca^2 ＋ could enhance the SCA of the coarse enzyme, no obvious effect was observed for K ^＋ and Na^＋ , while Zn^＋ and Al^3＋ showed inhibitive effect.