低产尿素黄酒酵母工程菌的酿造特性

Brewing characteristics of the engineered Saccharomyces cerevisiae with low production of urea in Huangjiu

为考察酵母工程菌在黄酒酿造过程中的发酵性能及其降低发酵液中尿素和氨基甲酸乙酯(ethyl carbamate,EC)的能力,以前期构建的降低黄酒中尿素和EC效果最好的酵母工程菌N85 DUR1,2-c为研究对象,利用单因素试验考察黄酒发酵工艺对其降低发酵液中尿素和EC能力的影响,并对其在生产试验过程中的发酵性能进行研究。结果表明,酵母接种量、发酵温度以及麦曲添加量等工艺参数对工程菌N85 DUR1,2-c低产尿素和EC的性能没有明显的影响,且含量低于亲本菌株。50 kL生产试验表明,工程菌N85 DUR1,2-c所酿黄酒中理化指标含量正常,符合黄酒国标的要求。而N85 DUR1,2-c发酵液中尿素和EC的含量分别为(2.4±0.2)mg/L和(14.9±0.6)μg/L,较亲本菌株分别降低了90.7%和54.6%,且贮存过程中EC含量增加缓慢。说明酵母工程菌N85 DUR1,2-c在不改变黄酒优良品质的前提下,能够显著地降低发酵液中尿素的含量,可以从根源上减少黄酒中EC的积累,提高饮用安全性。

The purpose of this study was to investigate the fermentation performance of the engineered Saccharomyces cerevisiae strain and its capacity to decrease urea and ethyl carbamate(EC)in Huangjiu brewing.Single factor experiments were conducted to evaluate the effect of fermentation parameters on the brewing performance of the constructed S.cerevisiae strain N85 DUR1,2-c,which performed best in reducing the concentrations of urea and EC.Meanwhile,an industrial production experiment was carried out in a Huangjiu brewery to study its fermentation characteristics.The results showed that the parameters including inoculation concentration,fermentation temperature and the amount of wheat Qu had no significant influences on urea and EC elimination property of N85 DUR1,2-c.At industrial fermentation in 50 kiloliters tank,the contents of ethanol,total sugar,amino acid nitrogen,total acid and main flavour compounds in the fermentation liquor of N85 DUR1,2-c were basically in accordance with the China national standard of Huangjiu.In addition,the concentrations of urea and EC were(2.4±0.2)mg/L and(14.9±0.6)μg/L in the liquor fermented by N85 DUR1,2-c,which were 90.7%and 54.6%respectively which was less than in parental strain.Moreover,EC content in the Huangjiu sample fermented with N85 DUR1,2-c increased at a much lower rate during storage compared with control.The concentration of urea can be significantly reduced in the Huangjiu sample fermented by constructed strain N85 DUR1,2-c.Therefore,the EC level in rice wine could be fundamentally reduced,which is beneficial to its safety.