Université de Bordeaux, Unité de Recherche Œnologie, EA 4577, USC 1366 INRA, ISVV, 33882 Villenave d'Ornon CEDEX, France.
INRA, ISVV, USC 1366 Œnologie, F-33140 Villenave d'Ornon, France.
Molecules. 2019 Apr 12;24(8):1448. doi: 10.3390/molecules24081448.
The effect of the botanical origin, pH level and ethanol content of different oenological tannins on the color of malvidin-3--monoglucoside solution, including their effectiveness as copigments, was studied. Briefly, a model wine solution (4 g/L of tartaric acid, pH 3.5 and 12% ethanol) containing 50 mg/L of malvidin-3--monoglucoside was prepared and supplemented with 0.1, 0.2 and 0.4 g/L of commercial tannins using (-)-epicatechin as reference control copigment. Six additional model wine solutions (12% ethanol at pH 3.1, 3.5 or 3.9, and 10%, 12% or 14% ethanol at pH 3.5) were prepared as previously described. Samples were stored under airtight conditions. After a week the full absorbance spectrum in the visible range (400-800 nm) was measured and CIELAB color space was determined. These measurements, including an increase in a* (redness), a decrease in b* (yellowness) and a decrease in L* (lightness), indicated that all oenological tannins had a clear positive effect on color copigmentation. Moreover, hydrolysable tannins appeared to be better copigments than condensed tannins as the copigmentation effectiveness (Cp) was found to be between two to four times higher. The effects of these tannins were dose-dependent because a higher addition resulted in a greater impact on copigmentation. In general, an increase in pH and ethanol content resulted in a decrease of the effect of tannins on color. Independent of intrinsic wine conditions, hydrolysable tannins, more specifically gallotannin, remain the most effective in increasing red wine color. These results prove that supplementation with oenological tannins, especially hydrolysable tannins, could be an interesting tool for the improvement of the red wine color.
研究了不同来源、pH 值和乙醇含量的植物单宁对矢车菊素-3-单葡萄糖苷溶液颜色的影响，包括其作为共色素的效果。简要地，制备了一种模型酒溶液（4 g/L 酒石酸、pH 3.5 和 12%乙醇），其中含有 50 mg/L 的矢车菊素-3-单葡萄糖苷，并使用（-）-表儿茶素作为参考共色素，分别用 0.1、0.2 和 0.4 g/L 的商业单宁进行补充。按照之前的描述，还制备了另外 6 种模型酒溶液（pH 3.1、3.5 或 3.9 时的 12%乙醇，以及 pH 3.5 时的 10%、12%或 14%乙醇）。将样品在密封条件下储存。一周后，测量可见光谱（400-800nm）的全吸收光谱，并确定 CIELAB 颜色空间。这些测量结果表明，所有的葡萄酒单宁对颜色共色素化都有明显的积极影响，包括 a*（红色）的增加、b*（黄色）的减少和 L*（亮度）的减少。此外，水解单宁似乎比缩合单宁更好的共色素，因为共色素化效果（Cp）被发现是两者的两到四倍。这些单宁的效果是剂量依赖性的，因为更高的添加量会对共色素化产生更大的影响。总的来说，随着 pH 值和乙醇含量的增加，单宁对颜色的影响会降低。独立于内在的葡萄酒条件，水解单宁，特别是没食子单宁，仍然是增加红葡萄酒颜色最有效的。这些结果证明，补充葡萄酒单宁，特别是水解单宁，可以成为改善红葡萄酒颜色的一种有趣工具。
