Microorganisms malolactic bacteria

Nonetheless, toxic compounds, including biogenic amines (BAs) and ethyl carbamate, which are a potential risk to human health, may be synthesized by microorganisms present in the food. Ethyl carbamate is a genotoxic and carcinogenic molecule that may be present mainly in fermented beverages but also in bread, fermented milk products, and soy sauce. Wine is mostly at risk, since during the malolactic fermentation (MLF) different ethyl carbamate precursors such as citrulline, and to a lesser extent carbamoyl phosphate, are produced by yeasts or bacteria from proteins (Weber Sharypov, 2009). 

The role of pH has diverse practical consequences in the control of the malolactic fermentation. First of all, the malolactic fennentation is initiated more easily and rapidly in press wines than in the corresponding free run wine. A partial chemical deacidification of wine may be advisable in the most difficult cases. It is especially recommended in the preparation of a malolactic fermentation starter—used for the inoculation of recalcitrant wine tanks. Finally, particular attention must be paid to musts and wines with elevated pHs. They sustain a more or less anarchic bacterial growth of a large variety of bacteria and are thus subject to spoilage. A sensible sulfiting is the only tool for controlling these microorganisms. 

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