杨梅酒加工过程中花色苷的呈色和调控机制

Red bayberry wine is a high value-added product that increases farmers’ income and also solves the problem of losses and storage of fresh fruit. At present, the studies on yeast mainly focus on the efficient, the flavor and the mouthfeel of red bayberry wine, while no in-depth study on the loss of original color. Anthocyanins are the primary bioactive components in red bayberry wine and the major substances to response to the color. However, its structure can be transformed by reaction with enzymes, pyruvic acid and acetaldehyde produced by yeast metabolism. It is reported that supplementation of pyruvic acid in the course of fermentation can strengthen the stability of the grape wine color. In our previous simulated fermentation system of red bayberry wine, we found that pyruvic acid promoted the degradation of anthocyanins and loss of color, which may due to the increase of the expression or activity of enzymes. This meaningful phenomenon reveals the potential mechanism of yeast on anthocyanins during fermentation. In this study, we intend to further clarify the mechanism of yeast-derived enzymes on the degradation of anthocyanins in a model system and investigate the relationship of intermediate products from yeast metabolism and the formation of anthocyanin derivatives. In conclusion, our research work will reveal the metabolism of anthocyanins degradation during fermentation, which suggests the solution of strengthening the color quality in red bayberry wine. Our study will be a great significance for the development of the processing industry of red bayberry wine.

杨梅酒是解决杨梅采后减损、贮藏不耐及果农增收的重要深加工产品。目前国内外研究主要关注酵母对杨梅酒风味物质以及口感的影响，而对色泽的损失尚无深入研究。花色苷是决定杨梅酒色泽的重要物质也是其发挥功效的主要活性因子，而酵母发酵过程中的代谢产物酶、丙酮酸、乙醛等可以影响花色苷结构转变。文献表明，发酵时添加丙酮酸可增加葡萄酒色泽的稳定性，然而我们前期研究发现，在杨梅酒发酵模拟体系中加入丙酮酸可使降解花色苷的酶表达增高或活性增强，导致酒体色泽损失，揭示了酵母发酵过程中可能存在影响花色苷的新机制。因此本课题拟通过模拟体系进一步明确酵母在发酵过程中产生的可降解花色苷的酶的种类及其功能表征；明确酵母代谢中间产物在花色苷衍生物生成过程中的作用；最后进一步验证和探讨酵母在杨梅酒加工过程中对花色苷的影响机制。本研究对于提高杨梅酒花色苷稳定性，提升酒体色泽品质，推动杨梅酒加工产业的发展具有重要意义。

花色苷是一种水溶性的色素，是决定杨梅酒色泽的重要物质，而酵母发酵过程中的代谢产物丙酮酸等可以影响花色苷结构转变。本研究通过构建杨梅酒模拟发酵体系，添加杨梅中的主要花色苷矢车菊素3-O-葡萄糖苷，分析酵母发酵过程中丙酮酸胁迫条件下的溶液颜色变化情况。利用HPLC-MS对发酵过程中的花色苷、花色苷降解产物和花色苷衍生产物进行定性和定量分析，利用非靶向代谢组学分析发酵过程中的差异代谢物，解析了花色苷在酵母发酵过程中的主要降解途径和衍生化途径。通过分析花色苷及其产物和颜色的变化情况，表明酵母发酵过程中，丙酮酸会降低花色苷含量并促使花色苷发生结构转化，导致颜色损失。本研究对于提高杨梅酒花色苷稳定性，提升酒体色泽品质，推动杨梅酒加工产业的发展具有重要意义。