刺葡萄花色苷自聚合条件及水合动力学特性的研究

Self-association Conditions and Hydration Kinetics of Spine Grape Anthocyanins

摘要:

花色苷自聚合是实现其稳定化的重要途径。研究了花色苷浓度、pH、温度、时间、纯度、溶剂体系等对刺葡萄花色苷自聚合效应的影响。结果表明：刺葡萄花色苷粗提液适宜的自聚合条件为：pH 3，时间60 min，温度20 ℃，浓度超过0.24 mmo/L。在此条件下，聚合度达到50.5433以上。对于3种不同纯度的刺葡萄花色苷溶液，纯度越高，自聚合效应越强，且更易发生自聚合，提示刺葡萄花色苷分子间共色及辅色效应可能存在制约机制。模拟葡萄酒、葡萄汁的体系条件，发现刺葡萄花色苷在醇系中自聚合作用的强度大于在水系中，两者发生自聚合作用的初始浓度分别为0.03 mmol/L和0.06 mmol/L。通过对花色苷溶液水合动力学分析，发现花色苷浓度增大，其表观水合系数K减小，解离常数pK增大,说明花色苷的自聚合加强了其疏水性，使解离更加困难，稳定性提高。

Abstract:

Self-association of anthocyanins is important for stability. The effects of anthocyanin concentration, pH, temperature, time, purity, and solvent system on the self-association of spine grape anthocyanins (SGA) were studied. The results showed that the optimum conditions for self-association of SGA crude extracts were pH 3, 60 min, 20 ℃, and an anthocyanin concentration of greater than 0.240 mmol/L. Under these conditions, the degree of self-association reached 50.5433. For three SGAs that differed in purity, a higher purity resulted in molecules that could self-associate more easily and more strongly, indicating a common mechanism underlying self-association and copigmentation for anthocyanin. Solution systems were established by simulating grape wine and grape juice. The strength of self-association of crude extracts containing SGA in an alcohol solvent was greater than that in an aqueous solvent, and the initial anthocyanin concentrations that resulted in self-association in the two solvent systems were 0.03 mmol/L and 0.06 mmol/L, respectively. The anthocyanin hydration kinetics were also analyzed. As the anthocyanin concentration increased, the apparent hydration coefficient k decreased and the dissociation constant pK increased, indicating that self-association strengthened the hydrophobic properties and reduced the dissociation of anthocyanins, and therefore improved its stability.