Department of Viticulture and Enology, California State University, Fresno, California 93740-8003, United States.
J Agric Food Chem. 2013 May 8;61(18):4270-7. doi: 10.1021/jf400366z. Epub 2013 Apr 24.
The effect of grape and wine tannin structure on retention thermodynamics under reversed-phase high-performance liquid chromatography conditions on a polystyrene divinylbenzene column was investigated. On the basis of retention response to temperature, an alternative retention factor was developed to approximate the combined temperature response of the complex, unresolvable tannin mixture. This alternative retention factor was based upon relative tannin peak areas separated by an abrupt change in solvent gradient. Using this alternative retention factor, retention thermodynamics were calculated. Van't Hoff relationships of the natural log of the alternative retention factor against temperature followed Kirchoff's relationship. An inverse quadratic equation was fit to the data, and from this the thermodynamic parameters for tannin retention were calculated. All tannin fractions exhibited exothermic, spontaneous interaction, with enthalpy-entropy compensation observed. Normalizing for tannin size, distinct tannin compositional effects on thermodynamic parameters were observed. The results of this study indicate that HPLC can be valuable for measuring the thermodynamics of tannin interaction with a hydrophobic surface and provides a potentially valuable alternative to calorimetry. Furthermore, the information gathered may provide insight into understanding red wine astringency quality.
研究了在反相高效液相色谱条件下，葡萄和葡萄酒单宁结构对聚苯乙烯-二乙烯基苯柱保留热力学的影响。基于保留对温度的响应，开发了一种替代保留因子来近似复杂的、不可分辨的单宁混合物的综合温度响应。这种替代保留因子基于溶剂梯度突然变化时分离的相对单宁峰面积。使用这种替代保留因子，计算了保留热力学。替代保留因子的自然对数对温度的 Van't Hoff 关系遵循 Kirchoff 关系。对数据进行二次方拟合，从中计算出单宁保留的热力学参数。所有单宁分数均表现出放热、自发相互作用，观察到焓熵补偿。对单宁大小进行归一化后，观察到单宁组成对热力学参数有明显的影响。本研究结果表明，HPLC 可用于测量单宁与疏水面相互作用的热力学，这为量热法提供了一种有潜力的替代方法。此外，所收集的信息可能有助于深入了解红酒涩味质量。
