黑曲霉固态发酵产羧肽酶条件优化及在酱油酿造中的应用

该研究以羧肽酶活力为考察指标，采用响应面法对1株高产羧肽酶的黑曲霉（Aspergillus niger）H1-6固态发酵产酶条件进行优化。首先采用单因素试验结合Plackett-Burman（PB）试验筛选出重要影响因子：麸皮添加量、水分含量和接种量，通过最陡爬坡试验获得重要影响因子的峰值范围，最后采用Box-Behnken试验、响应面分析对重要影响因子进行优化。结果表明，黑曲霉H1-6的最优产酶培养条件为：麸皮添加量36%、豆粕添加量50%、NaCl添加量10%、pH值为6.0、含水量56.6%，接种量1.3%。在此优化条件下，固态发酵羧肽酶的酶活力达到938.33 mU/g。将该羧肽酶粗酶液添加到酱油酿造中，能有效提高酱油中氨基态氮的含量（达到1.38 g/100 mL），进而提高其鲜味。

Optimization of solid-state fermentation conditions for carboxypeptidase production by Aspergillus niger and its application in soy sauce brewing

Using carboxypeptidase activity as indicator, the solid-state fermentation conditions of high-yield carboxypeptidases Aspergillus niger H1-6 were optimized by response surface methodology. Firstly, the significant influencing factors were screened out by single factor test combined with Plackett-Burman (PB) test, which were wheat bran addition, moisture and inoculum, and the peak range of the main influencing factors were obtained by the steep climb path test. Finally, the significant influencing factors were optimized by Box-Behnken test and response surface methodology. The results showed that the optimum culture conditions for carboxypeptidase production by A. niger H1-6 were obtained as follows: wheat bran 36%, soybean meal 50%, NaCl 10%, pH value 6.0, moisture 56.6%, and inoculum 1.3%. Under these optimal conditions, the activity of carboxypeptidase produced by solid-state fermentation reached 938.33 mU/g. Adding the crude carboxypeptidase solution to soy sauce brewing could effectively increase the content of amino nitrogen (1.38 g/100 ml) in soy sauce, thus improving its umami.