红葡萄酒中酰基化花色苷辅色作用机制的研究

The copigmentation effects of the anthocyanins play a vital role in the color expression and the color stability of the red wines, which has a direct influence on their sensory qualities and commercial values. Although in recent years there were certain studies on the copigmentation mechanism in red wines, most of them were focused on the simulation of the intermolecular copigmentation between the non-acylated anthocyanins and different cofactors, as well as the related discussion. The widespread acylated anthocyanins in red wines were usually ignored, as well as their self-association, intramolecular and intermolecular copigmentation, thus, the chemical mechanism of them is still poorly understood until now. Acylated anthocyanins in red wines are varied, rich and more stable, which have great contributions to the red wine color. Therefore, it was impossible to fit the color expression of red wines by simply using the "non-acylated anthocyanins intermolecular copigmentation model". The present project aims to find, isolate and purify the most important acylated anthocyanin components in red wines; then explore their self-association, intramolecular and intermolecular copigmentation effects and corresponding influential factors in model wine solution systems; further investigate the copigmentation mechanism of the acylated anthocyanins by thermodynamics and quantum chemical simulation; and finally verify the findings by exogenous cofactor addition experiments during vinification. The findings of this project will not only enrich the theory of wine coloration, but also provide practical guidance for the production of premium red wines.

花色苷的辅色效应对红葡萄酒颜色至关重要，直接影响着其感官品质和商品价值。尽管近年来对红葡萄酒辅色效应机制有了一定的研究，但都集中于非酰基化花色苷与不同辅色素分子间辅色效应的模拟与探讨，却忽略了红葡萄酒中广泛存在的酰基化花色苷，及其参与的自缔合、分子内和分子间辅色效应，对这一系列机制的化学背景也知之甚少。红葡萄酒中的酰基化花色苷种类多，含量大，也更稳定，对红葡萄酒的颜色有着极为重要的贡献。因而，仅以“非酰基化花色苷—分子间辅色效应模型”常常无法正确拟合红葡萄酒的颜色表现。本项目拟寻找红葡萄酒中最为重要的酰基化花色苷组分并对其进行分离和纯化，利用模拟葡萄酒体系解析其自缔合、分子内和分子间辅色效应及其影响因素，结合热动力学分析和量子化学模拟系统探究酰基化花色苷辅色效应机制，通过葡萄酒酿造过程中的外源辅色素的添加实验进行验证，不仅可以丰富葡萄酒呈色化学理论，对优质红葡萄酒的生产也具有直接指导作用。

辅色效应指溶液中花色苷分子与其它分子通过非共价作用形成辅色复合体，从而促进红葡萄酒中花色苷类物质的呈色和稳定，其广泛存在于红葡萄酒中，是影响酒体颜色的重要因素。近年来，辅色效应对红葡萄酒呈色的影响机制得到了国内外相关学者越来越多的关注，然而已有研究仅仅局限于非酰基化花色苷参与的分子间辅色效应，而未涉及红葡萄酒中大量存在的酰基化花色苷参与的辅色效应机制及其对颜色的贡献和影响，因此现有理论无法阐明红葡萄酒中不同类型花色苷参与的辅色效应及其呈色机理。基于此，本项目旨在深度解析红葡萄酒中对颜色表现最为重要的酰基化花色苷参与的辅色效应的化学机制，并通过酿造过程中的外源辅色素添加实验进行验证，主要研究内容及成果如下：（1）借助高效液相色谱-质谱联用技术明晰了欧亚种葡萄和葡萄酒中关键的酰基化花色苷组分为二甲花翠素-3-O-(6-O-乙酰化)-葡萄糖苷和二甲花翠素-3-O-(6-O-反式-香豆酰化)-葡萄糖苷；（2）通过大孔吸附树脂和半制备高效液相色谱建立了一套从葡萄中分离纯化酰基化花色苷的方法，填补了缺少市售酰基化花色苷纯品的技术空白；（3）揭示了酰基化花色苷参与的不同类型的辅色效应机制，包括自缔合效应、分子内辅色效应以及分子间辅色效应；（4）在模拟溶液中探究了辅色效应对酰基化花色苷在长期储藏过程中的稳定性和颜色演变的影响，结果表明黄酮醇类辅色素对花色苷的保护效果最佳，而黄烷醇类辅色素会在储藏过程中由于氧化而导致黄化效应；（5）通过在红葡萄酒的酿造过程中外源辅色素的添加实验进一步验证了辅色素对花色苷呈色和稳定性的影响，证实在发酵前添加黄酮醇类辅色素能够通过增强红葡萄酒中的辅色效应，从而提升酒体的颜色表现和稳定性。本项目的研究成果首次系统揭示了酰基化花色苷的辅色效应机制及其对红葡萄酒呈色的影响，不仅可以丰富花色苷辅色效应和葡萄酒呈色的化学基础理论，对国产优质红葡萄酒生产工艺的改进与开发也具有直接指导作用。