Structure and Formation of Pyranoanthocyanins During Winemaking

Abstract

The study of new pigments derived from anthocyanins has increased in recent years because these compounds appear in wines during the aging process, giving stability to their color. This review aims to provide an overview of the structure and formation process of these compounds. The main pyranoanthocyanidins are formed from the reaction between anthocyanins with some metabolites released during yeast fermentation, so the general structure includes an additional ring D formed between the group OH in C5 and the C4 of the anthocyanidin pyran ring. In this way, different structures can be found such as, for example, carboxypypyranoanthocyanins or type A vitisins, formed from the reaction between the enol form of pyruvic acid and anthocyanins; type B vitisins, when the cycloaddition occurs with an acetaldehyde molecule on an anthocyanin; methylpyranoanthocyanins, resulting from the reaction between acetone and anthocyanins; pinotins, resulting from the covalent reaction between hydroxycinnamic acids and anthocyanins and, finally, flavanyl-pyranoanthocyanins. In addition, the second generation of compounds, formed from the corresponding pyranoanthocyanins, has also been included in this work. These may include oxovitisins, vinyl-pyranoanthocyanins, pyranoanthocyanins linked through a butadienylidene bridge and pyranoanthocyanin dimers. In conclusion, this review provides an overview of anthocyanin derivatives, which may be of importance in the wine aging process, as they affect the color stability of wines.