Assessment of fumaric acid, ascorbic acid, and glutathione as alternatives to SO₂: Effects on red and white wine volatile composition

Despite the growing interest in reducing or eliminating the use of SO₂ in winemaking, the proposed alternatives have failed to completely replace it. This study evaluated fumaric acid, ascorbic acid, and glutathione as potential substitutes for SO₂ in preserving red and white wines and examined their impact on wine volatile compounds. Ascorbic acid affected red wine by enhancing the nitrogen fractions content and CIELab colour parameters. In white wines, it also raised nitrogen fractions and total phenols, particularly the a∗ value. The SO₂ alternatives promoted the activity of lactic and acetic acid bacteria in both red and white wines, resulting in higher lactic and acetic acids concentrations, suggesting that SO 2 is more efficient in microbiological control. Regarding the volatile composition, approximately 45 % of the volatile compounds identified in wines elaborated with SO₂ alternatives showed no significant differences compared to wines made with SO₂. However, an increase in the concentration of certain compounds, particularly acids, was observed in wines without SO₂. Although these alternatives can improve some parameters of the wine and the levels of certain volatile compounds were higher, they do not fully replace the efficacy of SO₂ and may not to provide sufficient microbiological control during alcoholic fermentation. • The alternatives had more lactic and acetic acid than SO₂, showing less control. • These additives may inhibit yeast metabolism, affecting the nitrogenous fraction. • Some volatile compounds showed no significant difference from the SO₂ control wine. • ASC produced a similar volatile profile to SO₂ in reds, but different in whites. • Combine SO₂ alternatives with low doses to ensure microbiological control.