Bacteria, lactic acid growth phase

Experience has shown that, even in sugar-containing media, lactic acid bacteria during their growth phase do not produce acetic acid and decompose only malic acid (Section 3.8.3). The complete depletion of malic acid, however, greatly increases the risk of serious alterations when the wine still contains sugar. For example, malolactic fermentation sometimes occurs before the wine has... 

Malolactic fermentation (MLF) in wine is by definition the enzymatic conversion of L-malic acid to L-lactic acid, a secondary process which usually follows primary (alcoholic) fermentation of wine but may also occur concurrently. This reduction of malic acid to lactic acid is not a true fermentation, but rather an enzymatic reaction performed by lactic acid bacteria (LAB) after their exponential growth phase. MLF is mainly performed by Oenococcus oeni, a species that can withstand the low pFi (<3.5), high ethanol (>10 vol.%) and high SO2 levels (50 mg/L) found in wine. More resistant strains of Lactobacillus, Leuconostoc and Pediococcus can also grow in wine and contribute to MLF especially if the wine pH exceeds 3.5 (Davis et al. 1986 Wibowo et al. 1985). The most important benefits of MLF are the deacidification of high acid wines mainly produced in cool climates, LAB contribute to wine flavour and aroma complexify and improve microbial sfabilify (Lonvaud-Funel 1999 Moreno-Arribas and Polo 2005). 

Lactic Acid Bacteria. In the last several years, California winemakers have reported increased instances of stuck red wine fermentations attributed to prefermentation or early fermentative-phase growth of native lac-tobacilli (generally believed to be L. brevis). In these cases, acetic acid levels were extraordinarily high generally ranging from 0.8 to 1.5 g/L and, on occassion, 2 to 3 g/L (van der Water, 1996 personal communication). 

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