己酸乙酯是浓香型白酒的重要风味物质,提高浓香型基酒中己酸乙酯含量有助于提高其优质酒率。通过传统筛选方法从不同酒曲中筛选出1株高产己酸乙酯酵母,采用形态观察、生理生化分析和分子生物学对其进行鉴定,并通过单因素试验优化发酵条件。从源于不同酒曲的79株酵母中确定了1株高产己酸乙酯酵母,命名为Y9,并鉴定为Hyphopichia burtonii。酵母Y9具有优良的NaCl、葡萄糖、乙醇和己酸乙酯耐受性以及宽广的pH适应性,能够较好地适应浓香型白酒酿造环境。在糖度为14°Brix、初始pH 5.0、诱导温度22 ℃且静置发酵、乙醇体积分数8%、己酸体积分数0.04%、发酵时间60 h时,酵母Y9所产己酸乙酯质量浓度达到15.0 mg/L。该研究为产香酵母Y9更好地应用于白酒发酵提供了理论基础。
Ethyl caproate is a crucial flavor compound in strong-flavor Baijiu.By increasing the content of ethyl caproate the productivity of high-quality raw Baijiu will be increased. In this study, a yeast isolate, strain Y9, with high yield of ethyl caproate was isolated from different Jiuqu (starter for Baijiu) samples. Strain Y9 was systemically identified to be Hypopichia burtonii. It exhibited excellent tolerance to NaCl, glucose, ethanol and ethyl caproate and a wide range of pH, indicating that it very adapted the condition of strong-flavor Baijiu brewing. A high yield of ethyl caproate (15.0 mg/L) was obtained following the fermentation conditions: sugar content 14 °Brix, initial pH 5.0, induction temperature 22 ℃ static fermentation, 8% (v/v) ethanol, 0.04% (v/v) caproic acid for 60 h. These results provide a theoretical basis for the better future exploitation of aroma-producing H. burtonii Y9 in Baijiu fermentation.
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