酿酒酵母对河西产区‘贵人香’干白葡萄酒单萜合成释放的促进机制研究

While monoterpene compounds are the characteristic aroma components of 'Italian Riesling' wine, The content in raw materials from Hexi wine-producing regions of Gansu province are limited in accumulation, causing defects in the typicalaroma of wine.Our recent study found thatyeast strain MQ-3, which were isolated and identified as Saccharomyces cerevisiae, was applied for 'Riesling' wine fermentation and it was foundthat both the type and content of monoterpenes were significantly increased, relating to glucosidase producing by the strain, and may also involve the biosynthesis of yeast itself.However,the mechanism of the anabolism of monoterpenes in the wine promoted by S. cerevisiae has not been reported. On the basis of the changes of glycoside activity and metabolismregulation of monoterpenes in the synthetic system of yeast strain MQ-3, the relationship between sterol biosynthetic pathway, leucine catabolism, mevalonic acid pathway and monoterpene synthesis by yeast were studied in this project. Moreover,themajor metabolic pathways, key steps and influence factors of monoterpenes metabolismby MQ-3 strain were revealed.By micro-fermentation, the mechanism of the synthesis and release of monoterpenes in the 'Italian Riesling' dry white wine promoted by S.cerevisiae was clarified, tolay the foundation of directional modification of the wine aroma quality.

单萜化合物是‘贵人香’葡萄酒的特征香气物质，甘肃河西产区原料中单萜积累不足，造成了酒体特征香气的缺乏。本课题组将筛选鉴定的酿酒酵母MQ-3用于‘贵人香’葡萄酒发酵，发现单萜物质的种类及含量均显著增加，这不仅与菌株产糖苷酶相关，可能还涉及酵母菌自身的生物合成，但酿酒酵母对葡萄酒单萜合成代谢的促进机制未见报道。本项目以酵母菌MQ-3在模拟体系中糖苷酶活性变化和单萜代谢规律为基础，研究甾醇合成途径、亮氨酸分解代谢及甲羟戊酸途径与酵母菌合成单萜的关系，揭示MQ-3菌株单萜代谢的主要途径、关键步骤及影响因素；通过微型发酵阐明酿酒酵母对河西产区“贵人香”干白葡萄酒单萜合成释放的促进机制，为葡萄酒香气品质的定向修饰奠定理论基础。

香气是构成葡萄酒品质的关键要素之一。其中单萜类化合物的感官阈值较低，具有浓郁的香味，对葡萄酒的呈香具有突出的贡献。本项目以甘肃河西地区酿酒葡萄‘贵人香’为试材，采用化学及生理生化分析方法，解析酿酒酵母菌株对单萜物质合成释放的作用机理及调控模式，分析探讨单萜代谢的主要途径及影响因素，并通过酿酒酵母优选与酿造工艺相结合，阐述单萜类化合物在‘贵人香’干白葡萄酒发酵过程中合成释放机制。研究结果如下：优化建立了单萜化合物的液-液萃取检测工艺和HS-SPME萃取条件；采用模拟汁体系，比较了5株酿酒酵母的产香性能，分析探讨了酿酒酵母菌株合成单萜化合物的代谢途径，确定了不同酿造条件对酵母菌株产香性能的影响；揭示了不同浸渍工艺和不同发酵因素对贵人香干白葡萄酒主要香气化合物的影响变化及响应规律；明确了在酒精发酵过程中，除α-萜品醇和法尼醇外，其余萜类化合物含量与β-葡萄糖苷酶活性无显著相关性。项目研究结果为开发干白葡萄酒增香酿造工艺提供了重要的理论依据和技术支持。