Impact of Different Strains of Saccharomyces cerevisiae on Malolactic Fermentation by Oenococcus oeni

The ability of different strains of wine yeast ( Saccharomyces cerevisiae ) to inhibit malolactic bacteria ( Oenococcus oeni ) was studied using Chardonnay musts. Initial experiments indicated that the bacterial inhibition in a wine fermented by yeast V-1116 could be removed by addition of acetaldehyde or H 2 O 2 , compounds that can potentially neutralize the antibacterial properties of any SO 2 produced by yeast. Malolactic fermentation was induced in fermenting grape musts or wines inoculated with different commercial strains of S. cerevisiae . Although the yeasts released 2 during fermentation, little if any free SO 2 ( O. oeni was generally inhibited in wines that contained higher amounts of total SO 2 , the lack of free SO 2 suggests that bound SO 2 may be more inhibitory than previously thought. Furthermore, bacterial inhibition was strongest in wines where the majority of SO 2 was not bound to acetaldehyde but bound to other unidentified molecules. However, SO 2 production by yeast did not always account for the inhibition of O. oeni , and the presence of other inhibitory mechanisms is probable.