Sulfur dioxide‐free Verdejo wines through the use of a pure stilbene extract: exploring possible synergistic effect with glutathione

Abstract

BACKGROUND: The search for alternatives to sulfur dioxide (SO2) in white wine production is a tough challenge for the oenological industry. The current paper investigates the effectiveness of several preservatives in protecting Verdejo white wines. The following wines were elaborated: without preservative (CT wines), with SO2 (SO2 wines), with stilbene-enriched extract (ST99 wines), with glutathione (GSH wines) and finally with the combination stilbene extract plus glutathione (ST99-GSH wines). RESULTS: ST99 extract preserved the wines from malolactic fermentation (MLF), maintained the quality parameters of the wines but affected their colour from the beginning of the process. Synergistic effects between ST99 and GSH were found for oxygen consumption rates, related with oxidation processes. The content of amino acids and biogenic amines was slightly affected by the treatments, but the quality or safety of the wines was not compromised. However, after 12 months of ageing in bottle, the SO2 wines showed the highest score in the sensory analysis. The reasons for the evolution of treated wines and the implications of this study for maintaining the quality of free SO2 white wines are discussed. CONCLUSION: ST99 may be proposed as an alternative to SO2 in wines to be consumed in the short term. Its combination with GSH does not prolong its shelf-life.