Origin of acetic acid in wines made by carbonic maceration

The aim of this work was to determine the optimal conditions for the production of carbonic maceration (CM) wines on a small scale. For this purpose, wines were made in 300 L tanks at room temperature, generating anaerobiosis by means of exogenous CO2 for the first three days. However, and probably due to the fact that the optimal temperature of 32ºC was not reached spontaneously and an adequate anaerobiosis was not achieved, the wines were altered. This could have been caused by the shortage of yeasts and the high population of bacteria in the liquid phase of the tanks, but also by deviations of the anaerobic metabolism within the whole grapes, since at the time of pressing the must contained within the berries had very high concentrations of ethanal and acetic acid.

Until now it was known that MC wines tend to have a higher volatile acidity than those made by destemming and crushing (DC) due to the higher development of lactic bacteria during vatting and their moderate degradation of sugars. In this study, it was also observed that when the conditions in the tanks are not adequate, there is also a greater accumulation of acetic acid inside the whole grapes, which can contribute to increasing the volatile acidity of the wines.
This work showed that, unlike DC vinification, it is very difficult to make carbonic maceration wines in small volumes following the methods used in industrial wineries. In these vinifications there is a high risk of deviation of both alcoholic fermentation of the must and intracellular fermentation in whole grapes.

More information:
Pilar Santamaría, Lucía González-Arenzana, Rocío Escribano-Viana, Patrocinio Garijo, Rosa López, Susana Sanz, Ana Rosa Gutiérrez. Difficulties associated with small-scale production of carbonic maceration wines (Fermentation 2022, 8(1), 27;