己酸菌发酵液酯化合成己酸乙酯的研究

Esterification Synthesis of Ethyl Caproate in Fermentation Broth of Caproic Acid-Producing Bacteria

己酸乙酯是浓香白酒的特征香气成分,其含量的多少决定着浓香型白酒的品质。本研究对己酸菌发酵液酯化合成己酸乙酯的最佳条件进行探究,研究了不同条件下的酯化pH、不同酸调节pH以及乙醇、己酸浓度对己酸菌发酵液中己酸乙酯转化率的影响。结果表明,pH在3~4时己酸乙酯转化率较高,用乳酸调节p H效果最优,增加酯化体系中乙醇、己酸浓度均有利于提高己酸乙酯的转化率;使用己酸含量为18.86 g/L的浓缩己酸菌液,加入30%的无水乙醇,0.15%的酯化酶,用乳酸调节pH至4,34℃酯化24 h,己酸乙酯含量达到8962.99 mg/L,转化率为49.77%。

Ethyl caproate is the characteristic aroma component of Nongxiang Baijiu,and its content determines the quality of Nongxiang Baijiu.This study explores the optimal conditions for the esterification synthesis of ethyl caproate in the fermentation broth of caproic acid-producing bacteria,and investigates the effects of esterification pH,pH adjustment with different acids,ethanol content,and caproic acid content on the conversion rate of ethyl caproate in the fermentation broth of caproic acid-producing bacteria.The results show that the conversion rate of ethyl caproate is the highest at pH 3 to 4,and adjusting the pH value with lactic acid is the most effective.Increasing the content of ethanol and caproic acid in the esterification system is conducive to improving the conversion rate of ethyl caproate.The optimal conditions are as follows:using concentrated caproic acid-producing bacteria solution with the caproic acid content of 18.86 g/L,adding 30%anhydrous ethanol and 0.15%esterification enzyme,adjusting pH to 4 with lactic acid,and esterifying at 34°C for 24 hours.Under the above conditions,the ethyl caproate content reaches 8962.99 mg/L,with a conversion rate of 49.77%.