基于亚甲基蓝还原法确定酒精分批补料发酵的最佳补料时间

Optical feeding time determination of ethanol fed-batch fermentation based on Methylene Blue dye Reduction Test

采用亚甲基蓝还原法研究了酒精分批发酵过程中酵母活力,以确定最佳补料时间,旨在为木薯等淀粉质原料的补料发酵提供理论依据。通过不同初总糖浓度分批发酵试验确定最佳初总糖浓度,然后于分批发酵(初糖240 g/L)主发酵期不同时间点(6、8、10、12、14、16、18 h)取样进行亚甲基蓝还原试验,得出发酵液酵母活力最强的时间点,最后进行酒精分批补料发酵验证试验。结果表明:发酵液中酵母细胞还原亚甲基蓝的能力最大(亚甲基蓝脱色斜率最强)在10 h左右,此时补料发酵效果最好,乙醇浓度、乙醇产率和总糖发酵效率均达到最高值,分别为152.28±2.37 g/L,2.46±0.04 g/(L·h)和89.84%。说明通过亚甲基蓝还原试验评估酒精发酵过程酵母活力并作为补料时间指标是有效可行的。

To provide the theoretical basis for cassava and other starchy raw materials ethanol fed-batch fermenta- tion, the yeast ability in 1 mL broth was studied for the determination of optical feeding time during ethanol batch fer- mentation. Firstly, the optical initial total glucose concentration was determined by batch fermentation at various ini- tial glucose concentrations. Then the strongest yeast vitality was obtained based on the methylene blue reduction test （MBRT） by analyzing yeast vitality at different sampling time （6, 8, 10, 12, 14, 16, and 18 h） during batch fermentation of 240 g/L initial sugar concentration. Finally, ethanol fed-batch fermentation experiment was conducted to verify the conclusion. The results showed that the best fermentation effect was achieved at 10 h when Methylene Blue decoloration rate came to the highest. The ethanol concentration, ethanol yield and total sugar fermentation efficiency all reached the maximun of respectively 152.28 ± 2.37 g/L, 2.46± 0.04 g/（ L·h） and 89.84% , indicating that it was effective and feasible to evaluate the yeast vitality based on MBRT as an index of feeding time in lmL broth during ethanol fermentation process.