宁夏贺兰山东麓葡萄酒酵母菌的筛选及应用

Screening and application of wine yeasts at the eastern foot of Helan Mountain in Ningxia Hui Autonomous Region

摘要:

【背景】宁夏贺兰山东麓是中国生态最佳、酿酒葡萄质量最优产区之一，也是中国“葡萄酒地理标志产品”保护区域之一。【目的】筛选宁夏本土优良酵母菌株，比较分析各个酿酒酵母菌株对赤霞珠葡萄酒香气质量的影响，并结合感官评价筛选对葡萄酒风味影响较大的酿酒酵母菌株。【方法】将筛选出的11株起酵速度快，而且对高浓度酒精、SO₂和葡萄糖及低酸环境有较强耐受力的酵母菌株进行26S rDNA鉴定，确定酵母种类。不同酿酒酵母发酵的赤霞珠葡萄酒通过顶空固相微萃取和气相色谱-质谱联用技术测定其香气化合物。【结果】筛选出11株可在15%酒精度、500 g/L葡萄糖、350 mg/L SO₂和pH 3.0环境下生长的酵母菌株，对其进行26S rDNA鉴定，确定10株酵母菌株H5、G9、G3、X8、G14、L10、H3、X11、Z17、Z24为酿酒酵母(Saccharomyces cerevisiae)，一株酵母菌L1为发酵毕赤酵母(Pichia fermentans)。测定的所有香气化合物中，酯类物质是赤霞珠葡萄酒香气物质的主要组分，其次是醇类。其中，乙酸乙酯、乙酸异戊酯、正己酸乙酯、辛酸乙酯、癸酸乙酯、1-辛烯-3-醇和β-大马士酮等的香气活性值较高，对赤霞珠葡萄酒的香气贡献最大，赋予葡萄酒苹果味、香蕉味、蘑菇味、茴香味、甜味等令人愉快的气味。对不同酿酒酵母赤霞珠葡萄酒样香气物质进行聚类分析发现，酒样G14和H3与商业酵母XR最为接近，在对赤霞珠葡萄酒特征香气影响方面较一致。【结论】酿酒酵母G14和H3具有良好的酿酒潜力，可以作为本土优良酵母用于葡萄酒发酵，为提高宁夏地区葡萄酒质量奠定基础。

Abstract:

[Background] The eastern foot of Helan Mountain in Ningxia was once regarded as the “golden zone” for wine grape growth and thus boasts high-quality wine. Wine produced in this area got the tile of geographical indication product and therefore this area was included in the protection catalogue for the product. [Objective] To screen excellent native yeast strains in Ningxia, compare and analyze the influence of each Saccharomyces cerevisiae strain on the aroma quality of Cabernet Sauvignon, and select strains with great influence on wine flavor according to sensory evaluation. [Methods] The 26S rDNA sequencing was performed on the 11 selected strains which featured rapid fermentation at the early stage and strong tolerance to high alcohol concentration, SO₂, glucose, and low acid environment for identification. The aroma compounds of Cabernet Sauvignon fermented by different strains were determined by head space-solid phase microextraction (HS-SPME) and gas chromatography-mass spectrometry (GC-MS). [Results] Eleven yeast strains which were tolerant to 15% alcohol, 500 g/L glucose, 350 mg/L SO₂, and pH 3.0 were screened out, among which 10 (H5, G9, G3, X8, G14, L10, H3, X11, Z17, and Z24) were identified as S. cerevisiae and one (L1) was Pichia fermentans. Esters were the main aroma compounds of Cabernet Sauvignon, followed by alcohols. Among them, ethyl acetate, isoamyl acetate, ethyl hexanoate, ethyl octanoate, ethyl decanoate, 1-octene-3-alcohol and β-damascone had high odor activity values and contributed the most to the aroma of Cabernet Sauvignon, endowing the wine with pleasant apple aroma, banana aroma, mushroom aroma, anise aroma, and sweetness. Cluster analysis of aroma components of Cabernet Sauvignon samples fermented with different S. cerevisiae stains revealed that the wine samples fermented with G14 and H3 were the closest to the wine fermented with the commercial yeast XR and the three showed consistent influence on the characteristic aromas of Cabernet Sauvignon. [Conclusion] S. cerevisiae G14 and H3 have huge potential for brewing, particularly for wine fermentation, which can help improve the quality of wine in Ningxia.