- 學位論文
酵母菌的篩選及混合發酵生產金香白葡萄酒
Selection of Yeasts and Mix-Fermenting Golden Muscat Wine
摘要
有許多研究報導，相較於單一菌種發酵，利用非釀酒酵母（non-Saccharomyces yeast）和釀酒酵母（Saccharomyces spp.）的混合發酵更能有效提升葡萄酒中香氣的含量與多樣性。本研究從水果果皮篩選可以適應釀酒環境之產香菌，並進行混合發酵之產香條件最適化研究。實驗利用添加氯黴素（Chloramphenicol）的YPDA培養基以及調整pH、葡萄糖濃度與酒精濃度的YPD培養基作為篩選平台，依外型挑選菌落進行分離純化。菌種鑑定以聚合酶連鎖反應擴增酵母菌之rDNA的ITS片段，經過定序後將定序結果與NCBI基因資料庫進行BLAST比對，以得知菌種。本實驗挑選Saccharomyces cerevisiae（A5）和 Pichia anomala（F8）進行反應曲面法實驗，實驗因子選擇菌株順序接種間隔時間、發酵溫度與初始葡萄糖濃度。根據RSM實驗結果，在發酵溫度21.36oC，初始糖度25.86%，接種間隔時間32.48小時具有最高乙酸乙酯產量85.77 ppm。儀器分析結果表明，經過乙酸乙酯最適化條件釀製的葡萄酒，在Ethyl acetate、1-propanol、Isobutanol、2-Methyl-1-Butanol、Ethyl octanoate、2,3-Butanediol、2-Phenylethanol以及Tyrosol等葡萄酒香氣成分的濃度上，均顯著高於未經過乙酸乙酯最適化條件釀製的葡萄酒。感官品評結果表明，在乙酸乙酯最適化條件下製作的葡萄酒在總體喜好、風味、口感和餘味的品評分數均顯著高於未最適化的葡萄酒和兩種商業葡萄酒。本研究證實最適化之混合發酵確實能提升葡萄酒的香氣含量，並擁有更好的風味，期待本研究成果能提供更多在釀酒工業上的應用。
並列摘要
Recently, many studies have reported that mixed fermentation of Saccharomyces yeast and non-Saccharomyces yeast has an effect on enhancing the content and complexity of wine aroma compared to single strain fermentation. In this study, yeasts were screened from fruit peels to adapt to the wine fermentation environment, and the optimum mix-fermentation conditions for ethyl acetate were studied. The experiment used YPDA medium which added chloramphenicol as a selecting platform, and YPD medium which adjusted pH, glucose concentration and alcohol concentration to mimic wine fermentation condition. Saccharomyces cerevisiae (A5) and Pichia anomala (F8) were selected for RSM (response surface methodology) experiments because of the high ethyl acetate production potential. Sequential inoculation interval time, temperature, and initial sugar concentration was chosen as the RSM factor to obtain the maximum ethyl acetate yield. After the RSM experiment, instrumental analysis and sensory evaluation using 9-Point hedonic scale method was carried out. According to the RSM experiment, the highest ethyl acetate yield of 85.77 ppm can be obtained at a temperature of 21.36oC, an initial sugar concentration of 25.86%, and an interval inoculation time of 32.48 h. Instrumental analysis shows an increase concentration of Ethyl acetate, 1-propanol, Isobutanol, 2-Methyl-1-Butanol, Ethyl octanoate, 2,3-Butanediol, 2-Phenylethanol and Tyrosol in optimized wine compare with un-optimized wine. In sensory evaluation experiment, five kinds of wine including three kinds of commercial wine and two kinds of self-made wine fermented under un-optimized condition and optimized condition was served to the judgers. The result indicates that the wine made under optimized condition was rated higher than the un-optimized wine and two commercial wine in overall liking, flavor, mouthfeel and aftertaste. This study confirms that the optimal mix-fermentation does enhance the aroma concentration of the wine and has a better flavor. It is expected that the research results will provide more applications in the wine industry.