酶解玉米浆在谷氨酸发酵工艺中的应用

Application of enzymatic hydrolysate corn steep liquor in glutamate fermentation

玉米浆中虽然含有丰富的营养成分,是谷氨酸发酵所需的重要营养剂,但部分成分不能被微生物直接利用,影响了谷氨酸后提取收率。通过筛选复合酶对玉米浆进行酶解,可完全替代谷氨酸发酵培养基中的酸水解蛋白液。基于单因素实验基础进行正交实验,最后确定最佳因素组合应用于谷氨酸发酵工艺。结果表明:以水解度DH为指标,选用植酸酶和酸性蛋白酶复配酶解玉米浆,其中植酸酶添加量为0.15%,酸性蛋白酶添加量为0.3%,在50℃下酶解16 h,酶解pH为3.8时,玉米浆的水解度可达最高,酶解效果最佳。该工艺条件下获得的玉米浆酶解液应用于谷氨酸发酵后,产酸指标较原有工艺提高0.6%~0.8%,转化率提高0.5%~0.8%,各项指标提高的同时,谷氨酸发酵后提取收率也得到了提高。

Corn steep liquor is rich in nutrients and it is an important nutrient for glutamic acid fermentation.However,some components cannot be directly used by microorganisms,which affects the extraction yield of glutamic acid.Enzymatic hydrolysis of corn steep liquor by screening compound enzymes can completely replace by acid hydrolyzed protein liquor in glutamic acid fermentation medium.Based on single-factor experiment,orthogonal experiments were carried out to obtain the best combination of factors for glutamic acid fermentation.The results showed that the hydrolysis degree(DH)was taken as an indicator,and the enzyme hydrolysis of corn pulp was selected by the combination of phytase and acid protease.The amount of phytase was 0.15%,the amount of acid protease was 0.3%,and the hydrolysis degree of corn pulp was the highest when the pH of enzymatic hydrolysis was 3.8 and 16 h at 50℃.Compared with the original process,the acid production index of corn steep liquor hydrolysate was increased by 0.6%0.8%,the conversion was increased by 0.5%0.8%,and the yield of glutamic acid was also improved.