红葡萄酒中橡木多酚辅色化机制研究

Copigmentation between anthocyanins and copigments plays a key role in the stabilization and enhancement of red wine color. Previous researches have focused mainly on the copigmentation effects of grape-originated polyphenols, and little is concerned about oak wood-originated phenolic components and their copigmentation mechanism. Considerable production practices have demonstrated that aging in oak barrel as well as the addition of oak substitutes significantly increase the density and stabilization of red wine color. However, so far chemical mechanism of this phenomenon generation is still poorly understood. Exploring this mechanism helps to resolve key quality problems such as low color density and instability which are present in red wine production, from the perspective of brewing process. The present project is intended to analyze the correlations between the oak polyphenolic components and wine coloration in the red wines produced through different fermentation and aging processes, and to find the components with potential copigmentation. The copigmentation effects of these components are individually assessed, and the main oak-originated copigments will be screened out. Interaction mechanism between the main copigments and important anthocyanins are further studied by adopting a model wine system. The copigmentation and the coloration effect are verified through the application of these main oak copigments in different satges of wine-making. Consequently, copigmentation mechanism of oak polyphenols will be expounded. The findings not only enrich the theory of wine coloration, but also provide practical guidance for the production of red wines with high quality.

花色苷与辅色素分子之间的辅色化效应对红葡萄酒颜色稳定和增强起着极其重要的作用，然而已往研究主要关注葡萄来源多酚的辅色化效应，对橡木多酚的辅色化作用及其机制缺乏系统研究。大量生产实践表明：橡木桶陈酿和橡木桶替代物添加均可显著提高葡萄酒色度和稳定性，但目前对这一现象产生的化学背景仍知之甚少，探明橡木多酚的辅色化机制将有助于从酿造工艺角度解决红葡萄酒生产中面临的色泽较浅和颜色不稳定的关键品质问题。本项目拟分析不同发酵和陈酿方式生产的红葡萄酒中橡木多酚组成与呈色之间相关性，找出具有辅色化效应的组分；研究各个组分的辅色化效果，以筛选出关键的橡木辅色素；利用模拟葡萄酒体系探究关键辅色素与花色苷的互作机制，并通过葡萄酒酿造的不同阶段添加橡木辅色素，进一步验证其辅色化效果及对葡萄酒呈色的影响，从中阐明橡木多酚的辅色化作用机制；研究成果不仅可丰富葡萄酒呈色化学理论，而且对高档优质葡萄酒生产具有直接指导作用。

红葡萄酒颜色是其感官品质的重要组成，橡木多酚的辅色化机制对解决红葡萄酒生产中面临的色泽较浅和颜色不稳定的关键品质问题具有重要作用。本项目揭示了橡木多酚的辅色化机制及对葡萄酒的呈色效应：（1）通过高效液相色谱质谱联用技术建立了橡木板材中的12种酚类物质的色谱质谱谱库；（2）在葡萄酒模拟反应液中，所测试的12种橡木多酚中鞣花酸的辅色效果最好；羟基肉桂酸类化合物的辅色效果要优于羟基苯甲酸类物质，而酚醛类化合物的辅色效果不如其对应的酚酸类物质；辅色效应随苯环上羟基和甲氧基数目的增加而增强；（3）不同的因素（辅色素浓度、温度、pH值和乙醇含量）对模拟反应液的辅色效果的影响是不同的，辅色素浓度越高，辅色效果越好；而乙醇则会导致辅色效果弱化；当温度和pH值分别为20°C和3.0时，辅色效果最好；（4）结合热力学参数与量子化学数据分析表明，辅色过程为自发的放热过程，反应的焓值(ΔHº)和熵值(ΔSº)变化与反应分子的结构有很大的相关性，辅色素复合体之间的作用力主要为氢键和范德华相互作用力；（5）发酵前添加酚类物质，可增强发酵阶段花色苷的浸出和辅色化程度，有效降低红葡萄酒的颜色亮度(L*)，提升其红色色调(a*)以及色饱和度(C*ab)，增大其与对照酒样的颜色差异(ΔE*ab)。在随后陈酿过程中，添加酚类物质辅色的酒样红色色调(a*)下降和黄色色调（b*）上升明显减缓，表明葡萄酒颜色稳定性显著增强；（6）陈酿前添加酚类物质，可增加聚合花色苷的形成，使酒体颜色更为稳定。本项目研究成果不仅为有效解决国产红葡萄酒颜色快速老化的问题提供了重要的理论和技术支撑。依据项目成果所研发的红葡萄酒辅色化技术已经在我国新疆、宁夏、山东等主产区代表性葡萄酒企业推广应用，在提升了我国红葡萄酒整体质量中发挥了十分重要作用。包含本项目成果的“酿酒葡萄品质精准调控和葡萄酒定向酿造技术研发及应用”在2016年获得了中国食品工业协会科学技术奖特等奖。