麦秆碱预处理和同步糖化发酵工艺优化研究

摘要

Response surface methodology and orthogonal experiment were used to optimize alkali pretreatment conditions and simultaneous saccharification and fermentation conditions of wheat straw.Firstly,the effects of pretreatment temperature,NaOH mass fraction,pretreatment time and substrate mass concentration on the content of total reducing sugar were studied by Box-behnken design using wheat straw as substrate.Then simultaneous saccharification and fermentation conditions of wheat straw pretreated by alkali were optimized by orthogonal experiment.The results showed that the optimal alkali pretreatment conditions of wheat straw were obtained as follows:pretreatment temperature 137.64 ℃,NaOH mass fraction 6.72％,pretreatment time 41.93 min and substrate mass concentration 9.23 g/L.The maximum content of total reducing sugar was 496.00 mg/g under the optimal alkali pretreatment conditions,which was 5.12 times of that from raw materials,indicating that alkali pretreatment was necessary to improve the saccharification efficiency of wheat straw.The optimal simultaneous saccharification and fermentation conditions of wheat straw pretreated by alkali were obtained as follows:fermentation temperature 39 ℃,yeast inoculation 0.1％,enzyme mass concentration 0.2 g/L and fermentation time 2 d.The maximum of ethanol content was 22.84 g/L under the optimal simultaneous saccharification and fermentation conditions.%通过响应面法和正交实验分别优化了麦秆的碱预处理工艺条件和同步糖化发酵工艺条件.首先以麦秆为底物通过Box-behnken设计研究了预处理温度、NaOH质量分数、预处理时间和底物质量浓度对总还原糖含量的影响;然后通过正交实验对碱预处理麦秆的同步糖化发酵工艺进行优化.结果表明:最佳碱预处理工艺条件为预处理温度137.64℃、NaOH质量分数6.72％、预处理时间41.93 min和底物质量浓度9.23 g/L,此时总还原糖含量最高,为496.00 mg/g,为未预处理底物的5.12倍,说明碱预处理可以较好地提高麦秆的糖化率;最佳同步糖化发酵工艺条件为发酵温度39℃、酵母接种量0.1％、酶质量浓度0.2 g/L和发酵时间2d,此时乙醇含量最高,为22.84g/L.