Abstract: Naturally selected yeast ICV-GRE and 71B, malolactic bacteria Lalvin 31, and genetically enhanced yeast
ML01 were compared for biodeacidification of malic acid in production of Vignoles wines. ICV-GRE yeast consumed
18% of malic acid with no lactic acid production. Lalvin 31 added to the wine fermented with ICV-GRE
converted the remainder of the malic acid to lactic acid and consumed some citric acid. The ICV-GRE + Lalvin 31
treatment produced less lactic acid compared with the ML01 treatment due to malic acid consumption by the ICVGRE
yeast and had the lowest titratable acidity. ML01 was effective at converting 5.7 g/L (100%) malic to lactic
acid during the first 60 hr of fermentation. The 71B yeast consumed 1.9 g/L (33%) of the malic acid with no lactic
acid production. Wine produced with ML01 had higher levels of total sulfur dioxide (SO2) than the other treatments.
A secondary experiment found that the ML01 yeast produced 34.6 mg/L SO2, which was three times as much as
ICV-GRE and six times as much as 71B. The amount of lactic acid and SO2 produced by ML01 yeast could be of
concern to enologists depending on style of wine desired.