Evolution of Polyphenols during Vinification and Wine Storage

Beginning with the ‘French Paradox’ observations in the 1990’s much interest has been devoted to the profile and contents of plant secondary metabolites, not only of grapes and wines, but also of numerous other plant foods, due to their assumed health-beneficial properties. Grapes belong to the most important fruit crops, and some 80% of this crop is processed into red and white wines. Anthocyanins are the most important phenolic compounds of grapes imparting color to red wines. Together with non-colored phenolic co-pigments they are further characterized by their diverse bioactive attributes, which still need unequivocal proof in most cases. For these reasons, comprehensive efforts have been undertaken to optimize vinification technology in order to maximize extraction rates of polyphenols from the grapes. The present review provides a survey of process strategies applied to achieve this aim, also taking into consideration innovative technologies for the production of both red and white wines. Furthermore, novel findings with regard to the evolution of phenolic compounds in the course of wine aging and storage and to the potential of winemaking by-products as a source for the recovery of phenolic compounds are considered. _____________________________________________________________________________________________________________