New approach to reduce energy consumption in alcoholic fermentation

Abstract

The wine industry is undergoing major changes in response to global climate change and societal concerns. In particular, it needs to reduce its energy footprint while preserving the organoleptic quality of wines. The aromatic profile of wines is closely linked to the grape varieties and the practices used during the winemaking process, particularly during alcoholic fermentation. The nutrients present in the must, the yeast strain used and the fermentation temperature all have a direct impact on the production of aroma compounds. Temperature has both a physiological and physical effect on the production and preservation of these volatile molecules in wine [1]. Firstly, fermentation temperature affects the regulation of metabolic pathways that enable the synthesis of different classes of aromas (higher alcohols, ethyl esters and acetate esters). Secondly, it has an impact on the loss of aroma compounds resulting from their evaporation during the process. These compounds have a low molecular mass, and their vapour pressure at atmospheric pressure and room temperature is sufficient to cause them to volatilise and thus be lost through evaporation. Furthermore, this phenomenon is amplified by the release of CO₂ during the fermentation process [2]. Thus, to minimise aroma loss through evaporation, the fermentation stage in white and rosé wine production is generally carried out at low temperatures (12-20 °C) [3]. However, the main reaction in alcoholic fermentation is exothermic. In fact, the heat production yield is 98.23 kJ/mol of sugars [4],[5]. Therefore, a lot of energy is required to maintain low temperatures. Increasing the fermentation temperature can certainly reduce the energy cost of the fermentation process, but it risks promoting the loss of volatile compounds of interest. However, these losses can be partially controlled by carefully selecting the yeast/nutrient combination used in the fermentation process. As wine quality is a highly multidimensional criterion, reducing the energy footprint of the winemaking process without compromising quality is a complex problem. It requires the development of disruptive strategies to find a suitable compromise between these two key factors.

References

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