酒曲中产酶微生物的筛选及其对发酵米酒品质的影响

Selection of Enzyme-Producing Microorganisms from Jiuqu and Their Influence on the Quality of Fermented Rice Wine

为解决商业米酒品质稳定但风味寡淡,而传统米酒口感醇厚但品质难于控制的问题,本研究从不同地区的酒曲中筛选出产淀粉酶、蛋白酶、酯化酶的可培养真菌,将其与商业甜酒曲进行复配发酵米酒,测定米酒的各项指标以评估其对发酵米酒品质的影响。根据产酶特性及18S rDNA分子鉴定,筛选获得5株产酶真菌,分别为米根霉(Rhizopus oryzae)、卷枝毛霉(Mucor circinelloides)、兰瑟毛霉(M.lanceolatus)、两株扣囊复膜酵母(Saccharomycopsisfibuligera)。添加了S.fibuligeraHB单菌曲发酵的米酒提高了乙醇、氨基酸态氮的含量,丰富了有机酸的种类和含量,降低了苦味氨基酸的含量和占比,同时增加了挥发性物质含量,其中苯乙醇和乙酸乙酯的含量明显高于其他组。因此,S.fibuligeraHB能显著提升米酒品质,具有应用于强化曲进行发酵米酒的潜力。

Generally,commercial rice wine has stable quality with bland flavor,while traditional rice wine has a mellow taste but is unstable in quality.In order to solve this problem,the influence of mixed culture fermentation with monocultures of culturable fungi producing amylase,protease and esterase isolated from Jiuqu from different regions in China and commercial sweet wine koji on the quality of rice wine was assessed.According to the enzyme-producing characteristics and 18S rDNA gene sequence analysis,the five obtained strains were identified as Rhizopus oryzae,Mucor circinelloides,M.lanceolatus,and two strains of Saccharomycopsis fibuligera(XG and HB).The addition of S.fibuligera HB increased the contents of ethanol and amino nitrogen,enriched the types and contents of organic acids,reduced the contents and percentage of bitter amino acids,and increased the contents of volatile compounds when compared with the control group(commercial sweet wine koji alone).More importantly,the contents of phenethyl alcohol and ethyl acetate were significantly higher than those in the other groups.Therefore,S.fibuligera HB can significantly improve the quality of rice wine,suggesting its application potential in multi-strain Qu for rice wine.