玉米清液发酵生产柠檬酸的工艺研究

Process Research on Fermentation of Citric Acid by using Corn Clarifying Solution

[目的]探讨用玉米清液发酵生产柠檬酸的工艺。[方法]以玉米清液为原料,以黑曲霉为菌种,用50L发酵罐进行柠檬酸发酵试验,研究接种量、起始pH值和不同玉米浆添加量对玉米清液发酵柠檬酸产酸的影响,以探讨生产柠檬酸的优化工艺条件以及优化条件下玉米清液发酵柠檬酸的产酸曲线和柠檬酸中黑曲霉的菌丝球形态。[结果]用玉米清液发酵生产柠檬酸的优化工艺条件是:接种量为12%,发酵起始pH值控制为5.6,玉米浆添加量为1.1%,在此条件下发酵72h,产酸可达15.5%,残总糖≤1.1%(W/V),糖酸转化率为97.1%。优化条件下用玉米清液发酵柠檬酸时,黑曲霉菌丝球伸展均匀,松紧适中,菌丝饱满且分枝多。[结论]该研究为充分利用玉米资源提高柠檬酸的发酵水平提供了参考依据。

[Objective] The study aimed to explore the process on the fermentation of citric acid by using the corn clarifying solution.[Method] With the corn clarifying solution as raw material and Aspergillus niger as the strain,the fermentation test of citric acid was conducted in the 50 L fermenter.The effects of the inoculation rate,initial pH value and addition amount of corn thick liquor on producing acid in the fermentation of citric acid by using the corn clarifying solution,so as to discuss the optimized process conditions for producing the citric acid,and the producing acid curve in the fermentation of citric acid by using the corn clarifying solution and the mycelium pellet shape of A.niger in citric acid under the optimized process conditions.[Result] The optimized process conditions for producing the citric acid by using the corn clarifying solution was that the inoculation rate was 12%,initial pH in fermentation was 5.6 and the addition amount of corn thick liquor was 1.1%,under which,when the fermentation was for 72 h,the final acidity could reach 15.5%,the residual total sugar content was no more than 1.1%（W/V）,and the version rate of glucose to citric acid was 97.1%.[Conclusion] This research provided the reference basis for making full use of corn resources and improving the fermenting level of citric acid.