绿原酸调控苹果酒香气释放的机理研究

Aroma is the core components of apple wine flavor. The regulation of aroma is always a focus in apple wine research. In the conventional aroma regulation research, much attention has been paid on changing the composition and concentration of volatile components in apple wine, while, controlling the release of volatile components based on the aroma-matrix interactions has been neglected. The polyphenols are important matrix components in apple wine, which affect the aroma release and perception of apple wine intensively. Chlorogenic acid is the representative polyphenols in apple wine. However, until now we know little about the mechanism of the regulation of aroma release by chlorogenic acid from apple wine. Therefore, in this project HS-SPME-GC-MS, dynamic headspace technique and descriptive sensory analysis are applied in real apple wines and model wine solutions to investigate the effect of chlorogenic acid on the headspace concentrations and sensory properties of volatile components in the wine. On this basis, a QSAR model of aroma release rate is established from molecular structural descriptors. The relationship between three-dimensional structure character of the volatile components and its release from chlorogenic acid is analyzed. Furthermore, combining the information from QSAR, the binding modes and sites between polyphenols and volatile components are investigated by one- and two-dimensional NMR. The mechanism of interaction between polyphenols and volatile components is illustrated. Results can provide scientific basis for the control of apple wine aroma.

香气是苹果酒典型风味的核心组成部分，其调控研究始终是苹果酒酿造学科关注的焦点。传统研究注重调控苹果酒中香气成分的组成与含量，却忽视了基于基质成分与香气成分的相互作用控制香气成分释放这个关键环节。多酚类物质是苹果酒中重要基质成分，强烈影响着果酒香气成分的挥发及感官品质，然而目前苹果酒中代表性多酚成分-绿原酸调控香气释放的机理尚不清楚。鉴于此，本项目以真实苹果酒和模拟酒液为对象，采用顶空固相微萃取-气质联用、动态顶空技术与感官香气量化品尝法，阐明绿原酸对香气成分挥发性和香气特征的影响及其规律。在此基础上，建立用香气分子结构描述符回归拟合相对释放率的3D-QSAR数学模型，理解香气微观结构同其在绿原酸基质中释放率间的关系。将3D-QSAR模型信息与一维及二维核磁共振分析结合，明确绿原酸与香气成分间结合方式与位点，阐明绿原酸调控香气释放的分子机理。研究结果将为苹果酒的风味调控提供有力理论依据。

香气是苹果酒典型风味的核心组成部分，其调控研究始终是苹果酒酿造学科关注的焦点。基质与香气成分的相互作用是控制果酒香气的关键环节，强烈影响着香气成分的挥发及感官特征。本研究以苹果酒中代表性多酚成分绿原酸为对象，全面解析绿原酸对苹果酒中香气成分释放和感官特征的影响规律，阐明绿原酸调控香气成分释放分子机理。主要研究内容及结果如下：1）以添加不同浓度绿原酸的苹果酒为研究对象，检测果酒中香气成分相对释放率的变化，同时利用感官描述定量法评估绿原酸对果酒香气特征及强度的影响。结果表明绿原酸对香气成分的释放均有显著影响，大多香气成分的挥发性显著下降。苹果酒的香气特征可以用5个类别的16个香气描述词表征，随着绿原酸浓度的升高，香气描述词柑橘、甜瓜、苹果、青草和南瓜的感官量化值显著下降。2）在模拟苹果酒中添加不同浓度绿原酸，采用静态和动态顶空技术考察绿原酸对香气物质顶空浓度的影响，此外通过感官品评考察香气成分感官强度的变化。结果表明酯类香气成分的疏水性越强，其挥发性下降越显著，含有芳香环结构的香气成分比直链香气挥发性下降更加强烈。与静态相平衡相比，动态相平衡时绿原酸对香气释放的影响力相对减弱。3）通过香气物质结构参数与其在绿原酸基质中释放数据的对应分析，建立用香气物质分子结构符回归拟合相对释放率的数学模型。由5个分子描述符（LogP，WA，CIC3，HATS1e和E2e）所拟合的QSAR模型可以解释93.7%的数据，能很好的预测香气成分在模拟苹果酒基质中的释放。4）采用1H NMR、2D NOESY NMR技术，考察了绿原酸与代表性香气成分间的结合方式与结合位点，结合QSAR模型，阐明了绿原酸调控香气物质释放的分子机理。研究结果将为苹果酒的风味调控提供有力理论依据。