Effects of Metal Ion Addition on Acetic Acid Removal by Saccharomyces cerevisiae during Lychee Wine Fermentation

Abstract

AbstractAcetic acid (AA) is the main component of the volatile acidity of lychee wine. It can be generated by yeast, contaminated lactic acid, and AA bacteria at any time during lychee wine fermentation. AA has a negative impact on yeast fermentative performance and affects the quality of lychee wine when present above a given concentration. Thus, excessive amounts of AA should be removed to control the quality of lychee wine. This study investigated the effects of supplementing lychee juice with different concentrations of metal (magnesium, potassium, and calcium) ions on AA removal during lychee wine fermentation at 20 °C. All treatments of metal ion addition negatively affected yeast growth. The addition of either magnesium or potassium ions decreased the AA content, and the lowest values were attained with the addition of 4 mM magnesium ions and 6 mM potassium ions. By contrast, the addition of calcium ions increased the AA content. The addition of metal ions significantly affected metabolites, because more succinic acid, more malic acid, more glycerol, and less acetaldehyde were produced with increasing activities of acetaldehyde dehydrogenase, acetyl-CoA synthetase, isocitrate lyase, and malate synthase. Moreover, the addition of metal ions significantly modified the aroma components of deacidified lychee wine. These findings offer insight into the mechanism of yeast utilization of AA and suggest that selectively adding metal ions may be used a tool to modulate the AA content of lychee wine.