以玉米为原料发酵生产L-乳酸工艺条件优化

Optimization of Fermentation Conditions for Producing L-lactic Acid from Corn

以玉米为主要原料采用微生物发酵制备L-乳酸,可提高玉米的利用价值,降低L-乳酸的生产成本。通过正交试验,考察不同温度、p H值、加酶量、反应时间等因素对玉米液化、糖化过程的影响,确定合适的液化、糖化工艺。基于单因素实验,利用二水平设计和响应面分析法,考察不同氮源、初始糖浓度及不同接种量、温度、p H值等因素对L-乳酸发酵过程的影响,确定了L-乳酸发酵的最佳工艺,即:初始糖浓度23%,玉米浆0. 8%,接种量10%,发酵工艺条件为温度50℃,p H值6. 2,L-乳酸产量达到218. 3 g/L。

L - lactic acid is prepared by microbial fermentation using corn as main raw material, it can im-prove the utilization value of corn, and reduce the production cost of L - lactic acid. By orthogonal experi- ment,the effects of different temperatures,pH value,enzyme dosage and reaction time on the liquefaction and saccharification of corn are investigated, and the appropriate liquefaction and saccharification process is determined. Based on single factor experiments, the effects of different nitrogen sources, initial sugar concentration, inoculation amount, temperature and pH value on L - lactic acid fermentation are investiga-ted by two - level design and response surface methodology. The optimum fermentation conditions are de- termined as follows： initial sugar concentration is 23% ,corn syrup is 0.8% ,inoculation amount is 10% , fermentation condition is that the temperature is 50 degrees, the pH value is 6.2, the L - lactic acid output is 218.3 g/L.