红肉火龙果酒天然酵母发酵期间品质变化研究

Study on quality change of red pitaya wine during fermentation with autochthonous yeast

分析了红肉火龙果酒天然酵母发酵期间其糖组分、酒精度、p H、可滴定酸、总酚、抗氧化活性、甜菜苷含量、色泽、甲醇、高级醇和挥发性风味成分等的变化规律。结果表明,20℃发酵6 d后,可转化糖全部耗尽,酒精度达到10%(V/V)以上,该天然酵母菌株的起酵速度和转化糖利用率明显优于目前常用的商业葡萄酒酵母。发酵期间,火龙果酒中高级醇(异丁醇、3-甲基丁醇、2-甲基丁醇)和甲醇的含量均处于正常果酒含量范围内,并且也没有观察到明显的色泽变化。随着酵母发酵的进行,新鲜火龙果中正己醇(及其衍生物)和正十三烷两种主体风味成分的相对含量逐步下降。同时,生成了很多新的挥发性风味成分,主要是醇和酯类,其中乙醇、苯乙醇、乙酸苯乙酯、异戊醇、2-甲基-1-丁醇和异丁醇构成了火龙果酒的主体风味。

In this paper, changes in the sugar, alcohol, pH, titratable acid, total phenolies, antioxidant capacity, betanin, color, methanol, higher alcohol and volatile flavor were investigated during fermentation of red pitaya with autochthonous yeast. Results showed that the invert sugar was depleted, and more than 10% （ V/V ） of alcohol was produced after 6 d of fermentation at 20~C. And the autochthonous yeast showed a better ability in the fermentation rate and sugar conversion rate compared with other commercial grape wine yeast. Higher alcohol （ isobutanol, 3-methyl butanol and 2-methyl butanol ） and methanol contents were less than normal level of wine, and no significant color change was observed during fermentation. The relative content of hexanol （ and its derivatives ） and tridecane, as two main flavor of red pitaya, decreased with the increase of fermentation time, and also some new flavor （ alcohols and esters ） produced, including ethanol, benzene ethanol, benzene ethyl acetate, isoamyl alcohol, 2-methyl-1-butanol and isobutanol, that constituted the subject flavor of red pitaya wine.