Evolution of acetaldehyde concentration during wine alcoholic fermentation: online monitoring for production balances

Abstract

During alcoholic fermentation, acetaldehyde is the carbonyl compound quantitatively the most produced by yeasts after ethanol. The dynamics of acetaldehyde production can be divided into 3 phases. Early formation of this compound is observed during the lag phase at the beginning of fermentation before any detectable growth [1]. Acetaldehyde accumulation continues during the growth phase. Finally, the concentration decreases during the stationary phase until the end of alcoholic fermentation [2], [3], [4]. Accumulation of acetaldehyde differs according to yeast species and strains, ranging from 0.5 for the least productive to more than 700 mg/L for the most productive [5]. At low concentrations, acetaldehyde is a pleasant and fruity aroma while at high levels, its odor becomes irritating and pungent which depreciates the organoleptic qualities of wines for consumers. The primary objective of this study was to describe and understand the evolution of acetaldehyde concentration during wine alcoholic fermentation and to shed light on the impact of temperature, the main parameter that manages fermentation kinetics but also acetaldehyde dynamics synthesis. One recurrent question persisted on the kinetics of acetaldehyde production from biological and/or physical aspects: did the temperature impact on the metabolism of production of the molecule by the yeast or on the contrary, did it favor its evaporation, or did it impact of both mechanisms? Indeed, although contradictory, studies agree to consider the fermentation temperature as a key point of acetaldehyde production: for some authors, the fermentation temperature affects little the final acetaldehyde content, while others correlate the increase in acetaldehyde content with increasing fermentation temperature [6].

In the present work, thanks to new online monitoring approaches and associated mathematical methods for data treatment, complete acetaldehyde production balances during fermentation allow biological consumption to be dissociated from physical evaporation in order to answer many of the questions posed.

First of all, from a biological point of view, high fermentation temperatures lead to an important production of acetaldehyde at the end of the growth phase, but also favor a better consumption of the molecule by the yeast during stationary phase, leading to a low residual acetaldehyde content at the end of the fermentation. Additionally, physical evaporation is even more important at high temperatures due to the boiling point of the molecule, reinforcing the final decrease of the acetaldehyde concentration. On the other hand, thanks to the use of production balance, it was possible to determine that the decrease of acetaldehyde concentration during the stationary phase is mainly due to the yeast consumption than to the physical effect of evaporation. These different observations were further corroborated by the use of anisothermal temperature profiles. Finally, the consumption part being the most important in the decrease of the acetaldehyde concentration during the second part of the process, metabolic links were revealed between acetaldehyde and markers of metabolism such as organic acids.

References

[1] Cheraiti, N., Guezenec, S., Salmon, J.-M. (2010). Appl. Microbiol. Biotechnol. 86, 693–700.

[2] Aguera, E., Sire, Y., Mouret, J.-R., Sablayrolles, J.-M., Farines, V. (2018). J. Agric. Food Chem. 66, 6170–6178.

[3] Jackowetz, J.N., Dierschke, S., Mira de Orduña, R. (2011). Food Res. Int. 44, 310–316.

[4] Ochando, T., Mouret, J.-R., Humbert-Goffard, A., Aguera, E., Sablayrolles, J., Farines, V. (2020). Food Res. Int. 136, 109607.

[5] Liu, S.-Q., Pilone, G.J. (2000). Int. J. Food Sci. 35, 49–61.

[6] Li, E., Mira de Orduña, R. (2017). J. Ind. Microbiol. Biotechnol. 44, 229–236.