浓香型白酒糟醅中酵母Geotrichum sp.的固态发酵特性

Solid state fermentation characteristics of Geotrichum sp.in strong-flavor Baijiu

为了解Geotrichum sp.酵母在浓香型白酒糟醅中的生长特征及发酵功能,根据高通量测序结果,从浓香型白酒糟醅中分离到2株Geotrichum sp.酵母菌株,开展序列鉴定及生长代谢特征研究。研究发现,这2株酵母与地霉属4个种的26S r DNA序列相似性高于99%,对糖的利用情况类似Geotrichum sp.,但不能形成假菌丝,可耐受p H 4. 0及6%(体积分数)乙醇,在乳酸YPD液体培养基中的最适生长温度为28℃。在固态发酵糟醅中,2株酵母启动发酵较慢,但持续发酵能力较好,发酵24 d消耗淀粉的量分别是酿酒酵母的2. 2倍及1. 3倍,乙醇产量分别为7. 91和6. 71 m L/100 g,是其液态发酵产量的2. 5倍及4. 5倍,风味物质总产量分别为液态发酵的91倍及340倍,其中乙酸乙酯产量分别为1. 5和3. 0 g/kg,乙酸异戊酯产量分别为216和573 mg/kg,β-苯乙醇产量分别为658和477 mg/kg。结果表明,Geotrichum sp.酵母对浓香型白酒固态发酵糟醅适应良好,可长时间持续发酵,改善浓香型白酒花果香气,具有开发为新型白酒商业酵母的潜力。

In order to explore the roles of Geotrichum sp.in the strong-flavor Baijiu fermentation,two strains were isolated from the fermented grains of strong-flavor Baijiu.Their growth and metabolism characteristics were studied.It was found that the similarity of 26S rDNA sequence between the two isolated strains and four strains of Geotrichum was higher than 99%,and the utilization of sugars were also similar to Geotrichum sp.,while could not form pseudohyphae.The two strains could tolerate pH 4.0 and 6%vol ethanol,and the optimum growth temperature was 28℃in L-YPD medium.In the fermented grains,the two isolated strains started the slow but constantly fermentation ethanol production was 7.91 and 6.71 mL/100 g,respectively,which was 2.5 and 4.5 times of liquid fermentation,while the total yield of flavor substances was 91 and 340 times of liquid fermentation,respectively.They produced 1.5 and 3.0 g/kg ethyl acetate,216 and 573 mg/kg isoamyl acetate,658 and 477 mg/kgβ-phenylethanol in grains.The Geotrichum sp.grew well in the fermented grains of strong-flavor Baijiu,with constant fermentation and produced more ethanol than that of commercial yeast,and could improve the flower and fruit aroma of strong-flavor Baijiu,thus showed application prospect of new commercial yeast for Baijiu.