红曲霉Monascus sanguineus X1处理黄水的培养基优化及酯化液制备

黄水是白酒酿造的主要副产物之一,富含多种有机质,可用于制备酯化液促进白酒增香,提高其利用率。研究了一株高产酯化酶的红曲霉菌株Monascus sanguineus X1,以酯化酶活力为指标,从碳源、碳氮比、接种量和pH值4个方面对X1菌株的培养基进行单因素实验及正交试验优化;采用酯化酶液处理黄水,制备酯化液,研究了黄水、乙醇、己酸等酯化前体物质添加量对酯化液制备的影响。结果表明,该红曲霉优化发酵培养基组分(以100 mL计):大米粉7.0 g,大豆蛋白胨2.0 g,NaNO30.2 g,KH2PO40.15 g,MgSO4·7H2O 0.1 g,培养基初始pH值5.0,接种量10%(体积分数)。在此条件下,添加体积分数为10%的黄水和体积分数为4%的乙醇,酶活力可达745.80 U/mL。向酯化酶液中加入体积分数为0.8%的己酸和体积分数为20%的乙醇继续培养1 d后,酯化液中己酸乙酯的体积分数可达0.121%;而向酯化酶液中补加体积分数为10%的黄水后,己酸乙酯和乳酸乙酯的体积分数分别可达0.055%和0.032%。该结果旨在为将黄水资源用于白酒增香提供理论参考。

Optimization of Culture Medium for Treatment of Yellow Water by Monascus sanguineus X1 and Preparation of Esterification Liquid

Yellow water, the main by-product of Baijiu brewing, was rich in a variety of organic matter. It can be used to prepare esterification liquid, which can promote the aroma of Baijiu, and improve its utilization. Monascus sanguineus X1, a high esterifying enzyme-producing strain, was used to optimize the enzyme activity by single factor and orthogonal experiments from four aspects: carbon source, carbon-nitrogen ratio, inoculation amount and pH. Then, the esterifying solution was prepared by treating the yellow water with an esterifying enzyme solution, and the influence of the addition amount of the esterified precursors such as yellow water, ethanol and caproic acid on the preparation of the esterification liquid was studied. The results showed that the optimum fermentation medium for Monascus was(per 100 mL) rice flour 7.0 g, soybean peptone 2.0 g, NaNO3 0.2 g, KH2PO4 0.15 g, MgSO4·7 H2O 0.1 g, initial pH 5.0 and inoculation volume 10%(volume fraction). Under these conditions, adding 10% yellow water by volume and 4% ethanol by volume, the enzyme activity could reach 745.80 U/mL. After adding 0.8% caproic acid and 20% ethanol by volume to the esterifying enzyme solution for 1 day, the volume fraction of ethyl caproate in the esterifying solution could reach 0.121%, while after adding 10% by volume yellow water to the esterifying enzyme solution, the volume fraction of ethyl caproate and ethyl lactate could reach 0.055% and 0.032%, respectively. The results is intended to provided a reference for the study of yellow water resources for Baijiu flavor enhancement.