发酵玉米粉酶解液制备天然鲜味料

本研究以玉米粉为主要原料，利用谷氨酸棒杆菌发酵生产新型天然鲜味料。首先通过单因素实验和正交试验优化玉米粉酶解工艺；然后在摇瓶水平对谷氨酸棒杆菌GL-6发酵产谷氨酸的条件进行优化，确定最佳氮源及含量和最佳玉米粉酶解液添加量，然后在20 L发酵罐水平进行验证，将5%的麦芽糊精加入发酵液上清中喷雾干燥得到鲜味料样品，最后对样品进行成分检测及评定。结果表明，玉米粉最佳酶解工艺为固液比1:4，酶添加量1%，温度90 ℃，时间3 h，在该条件下酶解度DE值达到60.84%；谷氨酸棒杆菌GL-6发酵产谷氨酸的最佳氮源为酵母抽提物FIG12LS 30 g/L，玉米粉酶解液最佳添加量为50%（v/v）；天然鲜味料样品MJ谷氨酸含量为43.9 g/100 g，氨基酸总含量为44.8 g/100 g，相较于不添加玉米粉酶解液发酵而得的鲜味料样品CK谷氨酸和氨基酸含量分别提高了24.0%和23.4%。此外，样品MJ富含坚果及咖啡风味的吡嗪类物质，相较于样品CK鲜味含量和营养价值均有提高，风味也更加丰富。本研究为用天然植物原料发酵生产鲜味料提供了新思路，提高了产品的市场竞争力。

Enzymolysis of Fermented Corn Meal to Prepare Natural Umami Flavoring

In this study, corn meal was fermented by Corynebacterium glutamicum to produce a new natural flavoring materia. Firstly, the enzymatic hydrolysis process of corn meal was optimized by single factor experiment and orthogonal experiment. Then, the fermentation conditions of C. glutamicum GL-6 were optimized at shaking flask level to determine the best nitrogen source and content and the best addition amount of corn meal enzymolysis solution. Then verification was carried out at the level of 20 L fermenter. 5% Maltodextrin was added into the supernatant of fermentation broth and spray dried to obtain the umami sample. Finally, the composition of the sample was detected and evaluated. The results showed that the optimal enzymatic hydrolysis conditions were solid-liquid ratio 1:4, enzyme dosage 1%, temperature 90 ℃, time 3 h, under which the enzymatic hydrolysis degree DE value reached 60.84%. The optimal nitrogen source for glutamate production by C. glutamicum GL-6 fermentation was yeast extract FIG12LS 30 g/L, and the optimal addition amount of corn meal hydrolysate was 50%（v/v）. The content of MJ glutamate was 43.9 g/100 g, and the total content of amino acid was 44.8 g/100 g, which increased by 24.0% and 23.4%, respectively, compared with that of CK without corn meal enzymolysis fermentation. In addition, sample MJ was rich in nutty and coffee-flavored pyrazines. Compared with sample CK, its umami content and nutritional value were improved, and its flavor was richer. This study provides a new idea for the production of umami flavoring by fermentation of natural plant materials and improves the market competitiveness of the product.