利用低温蒸煮工艺进行高浓度酒精发酵

本研究利用低温蒸煮工艺,探讨了玉米淀粉的高浓度酒精发酵。在80℃下对玉米粉进行蒸煮15min,同时加α—淀粉酶进行液化。经冷却后,在55℃下加糖化酶糖化30min。再度冷却到30℃,加酵母菌悬液发酵70h。并利用这一技术研究了产高浓度酒精酵母菌株的最佳发酵条件。在加糖化酶量200～300u/g原料。酵母接种量为3％(v/v),发酵温度为30℃,pH4～4.5,发酵周期为70h,原料水比为1:2条件下,所选用的菌株之一W_4可以产生17.5％(v/v)乙醇。发现该菌株在发酵速度和耐酒精能力方面明显地优于国内酒精厂常用的酵母菌株1300。在发酵结束时,成熟发酵醪的pH值为4.2。外观糖度为0(Bx),残还原糖为0.19％,残总糖为3.6％,淀粉利用率为90％。

High-Concentration Ethanol Production from the Corn Starch by Using Low-Temperature Cooking Process

In this study,the low-temperature cooking process was used for high-concentration ethanol production from corn starch. The corn starch was cooked at 80℃ for 15min,along with liquification of the starch by a-amylase. Then,the starch was cooled to 55℃ and saccharified for 30mm. by glucoamy-lase. The partly saccharified starch was cooled to 30℃ and fermented to ethanol by yeasts. The optimal conditions for alcoholic fermentation by the high-ethanol-producing yeast strain W4 were found that the amount of glucoamylase preparation was 200-300u per gram of the corn starch,the inoculation size of the yeast was 3%(V/V),the fermentation temperature was 30℃.the starting starch concentration was 33. 0% (W/V) ,the pH of the media was 4-4. 5 and the fermentation period was 70h. Under the conditions,the strain W4could produce 17. 5%(V/V) ethanol,with 0. 19% reducing sugar and 3. 6% total sugar remaining in the mash. Saccharomyces sp. 1300 only yielded 13.0%(V/V) ethanol under the same conditions.