Editing Malolactic fermentation (section)

===Volatile acidity===
While [[volatile acidity]] (VA) is usually measured in terms of acetic acid content, its sensory perception is a combination of acetic ([[vinegar]]y aromas) and [[ethyl acetate]] ([[nail polish remover]] and [[model airplane]] [[glue]] aromas). High levels of VA can inhibit wine yeast and may lead to a sluggish or stuck fermentation. Several microbes can be a source for VA, including ''Acetobacter'', ''[[Brettanomyces]]'', and [[Biofilm|film yeast]] such as ''[[Candida (fungus)|Candida]]'', as well as LAB. However, while LAB usually only produce acetic acid, these other microbes often produce ethyl acetate, as well as acetic acid.<ref name="Wine Faults"/>

Most wine-producing countries [[wine laws|have laws]] regulating the amount volatile acidity permitted for wine available for sale and consumption. In the [[United States (wine)|United States]], the legal limit is 0.9 g/L for foreign wine exported to the United States, 1.2 g/L for white table wine, 1.4 g/L for red wine, 1.5 g/L for white [[dessert wine]], and 1.7 g/L for red dessert wine. [[European Union wine regulations]] limit VA to 1.08 g/L for white table wines and 1.20 g/L for red table wines.<ref name="Wine Micro"/>

Heterofermenting species of ''Oenococcus'' and ''Lactobacillus'' have the potential to produce high levels of acetic acid through the metabolism of glucose, though with most strains of ''O. oeni'', the amount is usually only 0.1 to 0.2 g/L.<ref name="Zoecklein"/><ref>Krieger, S., Triolo, G., and Dulau, L. ''"[http://www.lallemandwine.us/pdf/article_state_of_art_ml.pdf Bacteria and Wine Quality]"'' Lallemand. (2000) Accessed: 14 May 2013</ref> Several species of ''Pediococcus'' can also produce acetic acid through other pathways. Wines starting out with a high pH levels (above 3.5) stand the greatest risk of excessive acetic acid production due to the more favorable conditions for ''Lactobacillus'' and ''Pediococcus'' species.<ref name="Wine Faults"/><ref>Wibowo, D., Eschenbruch, R., Davis, C.R., Fleet, G.H., and Lee, T.H. ''"[http://www.ajevonline.org/content/36/4/302.short Occurrence and Growth of Lactic Acid Bacteria in Wine]"'' American Journal for Enology and Viticulture. Vol. 36 No. 4 302-313 (1985)</ref> ''L. Kunkeei'', one of the so-called "ferocious ''Lactobacillus''" species, has been known to produce 3 to 5 g/L of acetic acid in wines—levels which can easily lead to stuck fermentations.<ref name="Wine Micro"/>