April (No. 495)
Bacterial nutrition - the key to successful malolactic fermentation
Didier Theodore, Sibylle Krieger, Peter Costello, Ann Dumont , Lallemand
Malolactic fermentation (MLF), the conversion of L-malic acid to L-lactic acid and CO2, is a highly-important secondary fermentation carried out by lactic acid bacteria, typically Oenococcus oeni, during the vinification of most red wines and certain white wine styles. In addition to deacidification, other significant impacts of MLF include influencing the organoleptic characteristics of wine and conferring a degree of biological stability towards further degradation of L-malic acid. Of the different factors that influence the development of lactic acid bacteria in wine (Wibowo et al. 1985, Henick-Kling 1993, Fugelsang 1997), the physico-chemical properties of wine (pH, concentrations of alcohol and SO2, and temperature) are foremost in determining how well the malolactic bacteria will thrive and subsequently carry out MLF. Additionally, the ability of malolactic bacteria to grow and conduct MLF is highly dependent upon the nutritional status of the must/wine. In this regard, the availability of certain nutritional components required by malolactic bacteria can have a significant impact on the successful completion of MLF and also avoidance of stuck or sluggish MLF. In view of the importance of the nutritional requirements of malolactic bacteria in conducting MLF, this article provides a short review of:
- the wine environment and how it influences bacterial growth and metabolism
- latest research on bacteria nutrition.
NOTE: The complete article can be found in the April issue of The Australian & New Zealand Grapegrower & Winemaker.