添加不饱和脂肪酸对酿酒酵母胞内脂肪酸成分和葡萄酒香气的影响

【目的】研究葡萄汁中不饱和脂肪酸(Unsaturated fatty acids,UFAs,包括油酸、亚油酸和α-亚麻酸)含量同时变化对葡萄酒发酵过程中酿酒酵母胞内脂肪酸成分和酿酒香气的影响,为提高葡萄酒品质提供参考。【方法】选用‘美乐’葡萄(Vitis vinifera L.)汁为培养基,试验设置对照组(不添加UFAs,CK)、低浓度UFAs添加组(LFG)和高浓度UFAs添加组(HFG),比较葡萄酒酒精发酵过程中3个处理组间酵母(Saccharomyces cerevisiae EC1118)生长(OD_(600))、细胞内脂肪酸成分以及酿酒香气成分的差异。【结果】提高UFAs浓度能够促进酵母细胞生长以及对UFAs的吸收,使胞内UFAs含量迅速增加,但抑制饱和脂肪酸(C4:0—C24:0)的合成。分析UFAs对葡萄酒香气物质的影响发现,高浓度UFAs能够促进酵母高级醇和乙醇酯类(包括己酸乙酯、辛酸乙酯和癸酸乙酯)香气的产生,但抑制了中短链脂肪酸(medium-chain fatty acids,MCFAs,C4:0—C12:0)的产生,对来源于葡萄果实的醛类、单萜和降异戊二烯香气的影响较小。【结论】提高葡萄汁初始UFAs含量能够促进细胞生长,提高葡萄酒发酵速度,有利于乙醇酯类香气物质的合成,从而增强葡萄酒的果香、花香和甜香特征。因此,调控葡萄或葡萄汁中不饱和脂肪酸浓度可以作为调控葡萄酒香气品质的一种重要手段。

Influence of Addition of Unsaturated Fatty Acids on Fatty Acid Composition of Saccharomyces cerevisiae and Wine Aroma Compounds

【Objective】To provide a theoretical basis for improving the quality of wine, the effect of different concentrations of unsaturated fatty acids (UFAs, including oleic acid, linoleic acid, and α-linolenic acid) in grape juice on the intracellular fatty acid composition of yeast and volatile profile in wine were investigated in this study.【Method】 Different concentrations of mixed UFAs were initially added into ‘Merlot’ (Vitis vinifera L.) juice including the control without UFAs addition (CK),low concentration of UFAs addition (LFG) and high concentration of UFAs addition (HFG). The growth of yeast (Saccharomyces cerevisiae EC1118) growth (OD₆₀₀), intercellular fatty acid composition and wine volatile aroma compounds among the three treatments during alcoholic fermentation were compared.【Result】The increase of UFAs can accelerate yeast growth and promote UFAs absorption by yeast, while suppress yeast saturated fatty acids (C4:0-C24:0) synthesis. The influence of UFAs on wine aroma showed that the increase of UFAs can stimulate the production of higher alcohols and ethyl esters by yeast, such as ethyl hexanoate, ethyl octanoate and ethyl decanoate, but inhibit the generation of medium-chain fatty acids (MCFAs, C4:0-C12:0). The influence on grape-derived aldehydes, monoterpenes and norisoprenoids volatiles were little. 【Conclusion】 Increasing UFAs in grapes can considerably improve yeast growth and the wine fermentation rate, more importantly, it can promote yeast-derived ethyl esters volatiles production, which intensifies the fruity, flowery and sweet odors of wine. Therefore, manipulation of initial UFA contents in grapes or grape juice is a potential way to regulate wine aroma quality.