Post-MLF Bacterial Growth

When utilizable levels of L-malate and viable bacterial populations remain, the wine is at risk for continued microbial activity, resulting in spoilage of the bottled product. For instance, continued growth of Oenococcus or Pedio-coccus in wines supposedly MLF-complete based on detection of malic acid using paper chromatography has been reported (Wibowo et al., 1988  

To minimize the potential for secondary growth, winemakers should consider racking, SO2 addition, and acidulation where the pH has increased above 3.5. In this case, acid acljustment should be made with tartaric acid rather than malic or citric acids, compounds that provide a source of carbon for bacteria. Despite its relative low cost, citric acid should not be used for wines except immediately prior to sterile bottling due to the possibility of excessive diacetyl (Section 2.4.5). 

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