蛋白酶固定化条件优化及在酱醪发酵中的应用

本文以海藻酸钠浓度、氯化钙浓度、酶液与载体溶液体积比及固定时间为因素,优化中性蛋白酶固定化工艺,并将固定化中性蛋白酶凝胶颗粒应用于传统高盐稀态酱醪发酵,以缓解高渗透压环境对酶的胁迫作用,提高蛋白质利用率,缩短酿造周期。结果显示:当采用0.007 M海藻酸钠、0.27 M氯化钙,酶液与载体溶液体积比为12:30,固定2 h,固定化凝胶颗粒最稳定,相对酶活力最高;另外,酱醪发酵数据显示,酱醪总重17.5 kg,添加总酶量5.80 g(1000 U/g酶粉)时,外源游离蛋白酶和固定化蛋白酶试验组均能显著改善发酵过程各指标含量,平均缩短发酵时间20 d左右;与外源游离组相比,固定化试验组效果更加显著,蛋白质转化率较空白对照组与游离组分别提高达6.08%和1.88%。因此,在酱醪发酵过程添加固定化外源蛋白酶能有效提高高盐稀态酱油发酵蛋白质转化率,同时缩短发酵周期。

Optimization of Immobilization Conditions for Protease and Its Application in the Fermentation of Soy Sauce

The aim of this research was to increase the protein conversion ratio and short the fermentation period of traditional Chinese soy sauce by using immobilization technics. The concentration of sodium alginate, calcium chloride, volume ratio of enzyme to carrier solution and immobilization time were selected as the factors to optimize the immobilization process of neutral protease powder, and the immobilized neutral protease powder was applied in the fermentation of high-salt liquid state soy sauce. The results indicated that the optimal immobilization process condition of immobilized gel particles with good stability and the highest relative enzyme activity were 0.007 M sodium alginate, 0.27 M calcium chloride, and the volume ratio of enzyme to carrier solution 12:30 after immobilizing for 2 hours. Contrast to the control group, the index contents of the dissociative and immobilized group added with 5.80 g neutral protease in 17.5 kg sauce mash were improved significantly during the fermentation process, and the fermentation period was shorten by about 20 days; and the protein conversion rate of the immobilized protease powder group was improved by about 6.08% and 1.88% respectively, compared to the control and dissociative enzyme group. It is concluded that the immobilized neutral protease powder could improve the protein conversion rate and shorten the fermentation period of the fermentation of high-salt liquid state soy sauce.