米曲霉PRB-1蛋白酶系和淀粉酶系与高盐稀态酱油理化特性关系的研究

本文采用一株自行分离的米曲霉PRB-1菌株(AP)进行制曲和高盐稀态酱油发酵。结果表明:AP成曲的酸性和中性蛋白酶活力达到398.53 U/g干基和1539.98 U/g干基,较米曲霉3.042(AO)分别提高71.79%和59.93%。AP成曲淀粉酶活力比AO略低。AP成曲含有5个中性蛋白酶组分,2个酸性蛋白酶组分和4个淀粉酶组分。其中,蛋白酶Rf6号和淀粉酶Rf3号活力最大。随着发酵时间的延长,AP和AO酱醪总酸含量呈现上升趋势。p H值由中性持续下降至偏酸性。氨基态氮含量持续增加,还原糖含量均呈现先显著上升后缓慢降低的趋势。发酵55d AP头油的氨基态氮含量为0.86 g/100 m L,原料利用率为81.97%,氨基酸生成率为61.37%,较AO均有较高的优势。AP头油的还原糖含量为4.82 g/100 m L,低于AO。成曲的中性蛋白酶活力和发酵酱油的氨基酸生成率呈正相关(p0.05),对其他指标无显著影响(p0.05)。

Relationship between the Protease and Amylase Systems of Aspergillus oryzae PRB-1 and the Physicochemical Properties of High-salt Diluted-state Soy Sauce

Isolated Aspergillus oryzae PRB-1(AP) strain was applied in the manufacture of koji and high-salt diluted-state soy sauces. The results showed that the acid protease and neutral protease activities of AP koji were 398.53 U/g and 1539.98 U/g, which were increased by 71.79% and 59.93% when compared with those of Aspergillus oryzae 3.042(AO), respectively. The amylase activity of AP koji was slightly lower than that of AO. AP koji contained five neutral protease components, two acid protease components, and four amylase components, among which protease Rf6 and amylase Rf3 showed the highest activity. The total acid content of AP and AO moromi samples increased as the fermentation time was prolonged and the pH value decreased from neutral to acidic. Amino acid nitrogen continuously increased in moromi and the reducing sugar content showed a slow downward trend after the initial sharp increase. The amino acid nitrogen content of AP first filtrate was 0.86 g/100 mL after 55 days of fermentation. Meanwhile, the utilization ratio of raw material (81.97%) and the amino acid production rate (61.37%) of AP were higher than those of AO. The reducing sugar content of AP first filtrate was 4.82 g/100 mL, lower than that of AO. The neutral protease activity of koji was positively correlated with the amino acid production rate (p < 0.05), but had no significant impact on other indices (p > 0.05).