Grapevine shoots extract as an alternative to SO2 in rosé wines. A double approach: Classical measurements and 1H NMR metabolomics

Abstract

The consumption of rosé wines has increased in the recent years, largely due to their attractive color and their simplicity, elegance, and freshness. However, rosé wines can easily oxidise, turning into an orange-brownish color, which leads its rejection by consumers. It is likely that alternatives to sulfur dioxide (SO2) in rosé wines have not yet been studied for this reason. The current work investigates the use of a natural stilbene extract, glutathione and combinations of both as possible alternatives to SO2 in rosé wines. The parameters selected for the evaluation of alternatives were fermentation kinetics, enological parameters related to quality, the main phenolic compounds, glutathione, grape reaction product, and amino acids and biogenic amines. Moreover, a 1H-NMR-based metabolomics study was carried out after 12 months of bottling. The results highlighted that stilbene extract inhibits malolactic fermentation, thereby preserving rosé wine quality. However, color-related parameters, phenolic compounds (malvidin 3-glucoside, caftaric and ferulic acids), glutathione, grape reaction product and amino acids were only slightly affected by the treatments. The 1H NMR targeted metabolomic study indicated that the stilbene treatment significantly affected the contents of threonine, myo-inositol, choline, arabinose and methanol in comparison to SO2 wines. The use of glutathione did not improve the quality of the rosé wines in any case (alone or in combination with the stilbene extract). We can conclude that stilbenes could be an alternative to SO2 to preserve the quality of rosé wines.