College of Science , Shantou University , Shantou 515063 , Guangdong , China.
The Australian Wine Research Institute , P.O. Box 197, Glen Osmond , South Australia 5064 , Australia.
J Agric Food Chem. 2019 Aug 14;67(32):8938-8949. doi: 10.1021/acs.jafc.9b01498. Epub 2019 Jul 30.
Polymeric pigments formed via ethyl linkages between grape tannins and anthocyanins are important to the development of stable red wine color. To determine the effect of tannin structure on the stability and color properties of ethyl-linked polymeric pigments, tannin fractions with average polymerization between 4 and 43 units were prepared from grape skins and seeds and combined with malvidin-3-glucoside (M3G) in model wine containing acetaldehyde. As tannin molecular mass increased, the reaction rate with M3G increased. Compared with skin tannins of comparable molecular mass, seed tannins reacted more rapidly with M3G but were prone to precipitation. This resulted in a loss of polymeric pigments formed from seed tannins, which was greater as tannin molecular mass increased. Aggregation occurred following the reaction of seed tannin with M3G, concomitant with precipitation. The aggregation-precipitation phenomenon was not observed for skin tannin-derived pigments, indicating a greater stability in solution than those formed from seed tannins.
通过葡萄单宁和花青素之间的乙基键形成的聚合颜料对于稳定红酒颜色的发展非常重要。为了确定单宁结构对乙基键合聚合颜料的稳定性和颜色特性的影响，从葡萄皮和种子中制备了聚合度在 4 到 43 个单元之间的单宁分数，并在含有乙醛的模型酒中与矢车菊素-3-葡萄糖苷（M3G）结合。随着单宁分子量的增加，与 M3G 的反应速率增加。与分子量相当的皮单宁相比，种单宁与 M3G 反应更快，但容易沉淀。这导致来自种单宁的聚合颜料形成损失，随着单宁分子量的增加损失更大。种单宁与 M3G 反应后发生聚集，伴随着沉淀。在来自种单宁的聚合颜料中没有观察到聚集-沉淀现象，表明其在溶液中的稳定性比来自种单宁的颜料更高。
