MOVING FROM SULFITES TO BIOPROTECTION: WHICH IMPACT ON CHARDONNAY WINE?

Abstract

Over the last few years, several tools have been developed to reduce the quantity of sulfites used during winemaking, including bioprotection. Although its effectiveness in preventing the development of spoilage microorganisms has been proven, few data are available on the impact of sulfite substitution by bioprotection on the final product. The objective of this study was therefore to characterize Chardonnay wines with the addition of sulfite or bioprotection in the pre-fermentation stage. The effects of both treatments on resulting matrices was evaluated at several scales: analysis of classical oenological parameters, antioxidant capacity, phenolic compounds, non-volatile metabolome and sensory profile. This integrative approach was used for the first time in the context of bioprotection on white wine. The analysis of classical oenological parameters did not reveal any differences between the two treatments. However, the use of sulfites in the pre-fermentation stage seemed to induce a higher antioxidant capacity than bioprotection in wine. This result was confirmed by the decrease in the concentration of some phenolic compounds in the bioprotected wines. UHPLC-q-ToF-MS analysis of finished wines revealed specific footprints reflecting the impact of each treatment. As a result, 618 biomarkers were associated to sulfite treatment, mainly represented by CHON compounds, which could correspond to peptides. Moreover, bioprotection treatment was characterized by 364 biomarkers, including predominantly lipids. These highlighted biomarkers could be associated with various metabolic pathways such as amino acid biosynthesis and cofactors biosynthesis. These important differences in metabolite composition observed between the wines could be explained by the presence or the absence of sulfites, known for their effects on yeast metabolism and wine compounds. In contrast to metabolomic analysis, a very small difference was perceived between the two treatment from a sensory point of view. Thus, this study revealed substantial changes in wines regarding their composition, without impacting their sensory profile. This integrated approach has provided new knowledge on the impact of sulfite substitution by bioprotection on Chardonnay wines.