Reactions during winemaking

Fulcrand, IT., Duenas, M., Salas, E., and Cheynier, V. (2006). Phenolic reactions during winemaking and aging. Am. J. Enol. Vitic. 57, 289-297. 

Developments of successful tools for the control of enzymatic reactions during winemaking, regardless of the type of method employed to optimize enzyme activity (e.g. exogenous enzymes, selected yeast and bacteria, or genetically enhanced microorganisms), will benefit from further improvements in the understanding of wine flavor chemistry and sensory perception. 

Addition of exogenous enzymes is currently the most commonly adopted practice in the wine industry to optimize the rate of enzymatic reactions taking place during winemaking. The large amount of research carried out on this topic has led to the presence of a considerable number of commercial preparations on the market, although in some areas, particularly protein stabilization of white wines, exogenous enzyme-based approaches have been unsuccessful so far. 

A.2 Chemical Reactions of Anthocyanins During Winemaking Main Anthocyanin-... 

Fig. 9A.3 Main chemical reactions of anthocyanins during winemaking...

Hydroxycinnamic acids take part in numerous reactions that occur during winemaking and wine aging. They are important compounds in oxidation processes... 

The content and profile of monoterpene compounds in wine change during winemaking and aging due to acid-catalyzed reactions (Rapp et al, 1986 Di Stefano, 1989). At the pH of must and wine, some monoterpenes are transformed into a-terpineol and 1,8-terpines,... 

Adsorption phenomena are anofher aspecf of colloid activify. Adsorption is the reversible fixation on a solid surface of a body in solution (liquid or gas). This fixation does not involve any chemical reactions and is governed by the thermodynamic equilibrium. Adsorption phenomena occur during winemaking (Ribereau-Gayon et al, 1976) and have an effect on colloidal chemistry. These phenomena are more extensive when the adsorbent body is divided into smaller units, as the interface is proportionally larger. 

In the case of non-proliferating cells in a laboratory medium and during winemaking, lactic acid bacteria of wine transform L-malic acid exclusively into L-lactic acid. Seifert (1901) established the reaction of the malolactic transformation according to the following equation ... 

Changes in coloring matter the (mauve) complexes with ethyl cross-bonds develop into orange pyrano-vinyl procyanidins. The reaction kinetics are disturbed by the presence of polysaccharides and, are apparently temperature dependent. This explains the difference between great wines that remain truly red for many years and more modest wines that rapidly take on a more yellow hue, as well as those that are saturated with oxygen during the winemaking process. 

---