Grape metabolites, aroma precursors and the complexities of wine flavour

Abstract

A critical aspect of wine quality from a consumer perspective is the overall impression of wine flavour, which is formed by the interplay of volatile aroma compounds, their precursors, and taste and matrix components. Grapes contribute some potent aroma compounds, together with a large pool of non-volatile precursors (e.g. glycoconjugates and amino acid conjugates). Aroma precursors can break down through chemical hydrolysis reactions, or through the action of yeast or enzymes, significantly changing the aroma profile of a wine during winemaking and storage. In addition, glycoconjugates of monoterpenes, norisoprenoids and volatile phenols, together with sulfur-conjugates in wine, provide a reservoir of additional flavour through the in-mouth release of volatiles which may be perceived retro-nasally. In this presentation a summary will be presented about recent research into the contribution to wine aroma and flavour from glycoside precursors of terpenes [1], norisoprenoids [1, 2] and phenols [3, 4], and also about aroma compound formation from sesquiterpene- [5] and sulfur-precursors [6, 7]. The diverse mechanisms involved in formation and degradation of wine aroma precursors will be discussed, as well as practical implications for grape growing and winemaking.

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