Anthocyanins and their variation in red wines. II. Anthocyanin derived pigments and their color evolution.

Originating in the grapes, anthocyanins and their derivatives are the crucial pigments responsible for the red wine color. During wine maturation and aging, the concentration of monomeric anthocyanins declines constantly, while numerous more complex and stable anthocyanin derived pigments are formed, mainly including pyranoanthocyanins, polymeric anthocyanins produced from condensation between anthocyanin and/or flavan-3-ols directly or mediated by aldehydes. Correspondingly, their structural modifications result in a characteristic variation of color, from purple-red color in young red wines to brick-red hue of the aged. Because of the extreme complexity of chemical compounds involved, many investigations have been made using model solutions of know composition rather than wine. Thus, there is a large amount of research still required to obtain an overall perspective of the anthocyanin composition and its change with time in red wines. Future findings may well greatly revise our current interpretation of the color in red wines. This paper summarizes the most recent advances in the studies of the anthocyanins derived pigments in red wines, as well as their color evolution.

Regional characteristics of anthocyanin and flavonol compounds from grapes of four Vitis vinifera varieties in five wine regions of China.

Anthocyanins and flavonols are important flavonoid metabolites in grapes, making a dominant contribution to the color, the mouth feel and even the flavor of grapes and wines. The accumulation of these flavonoids in grapes is greatly influenced by a many, diverse but interacting factors, of which variety and climate are among the most important ones. In the present study, the anthocyanin and flavonol profiles of four grape varieties (Vitis vinifera L.), Cabernet Sauvignon, Carmenere, Syrah and Merlot, from five major wine regions in China were examined for two consecutive years (2006 and 2007). The results showed that the total anthocyanin content of the berry skins in these cultivars tended to increase from east to west in China, yet the proportion of the acylated anthocyanins displayed the opposite trend. It seemed possible that the western grape regions, with their high altitude and low annual rainfall, had an advantage in producing high level of anthocyanins. In addition, a high proportion of trihydroxylated flavonols were always found in the western region grapes, whereas dihydroxylated flavonols were more prominent in the lower altitude eastern regions. This suggested that the relative amounts of these flavonoid compounds may depend on their corresponding cultivar characteristics, while the amounts are more affected by the environmental factors where they were growing.