Processes and purposes of extraction of grape components during winemaking: current state and perspectives

The quality of red wine is dependent on the presence not only of volatile compounds that influence wine aroma but also on phenolic compounds due to their impact on mouthfeel, colour, flavour and ageing potential. Whereas wine aroma arises from the grapes, action of microorganisms and maturation phenomena, red wine phenolics are predominantly found in the grape berry skins and seeds and are extracted during maceration into the fermenting must (i.e. grape solids and juice). Thus, although every step in winemaking has a significant impact on the outcome of the finished product, it can be considered that fermentation and the ensuing extraction of grape components are the most critical value adding step in the process. This mini-review examines such aspects, and against this backdrop, considers the need for improvements to fermentation control during wine production, to optimise the outcome of extraction from grape solids. Specifically, there is interest in modulating and forecasting wine composition based on grape specifications, and with this, the ability to regulate winery production practices to achieve target quality specifications. Such predictions and measures are proposed to help winemakers adapt to emerging issues associated with climate change.