Sibylle Krieger-Weber* and Magali Deleris-Bou
*Lallemand SAS, In den Seiten 53, Korntal-Münchingen/70825, Germany (skrieger@lallemand.com)

Four genera of lactic acid bacteria (LAB) were identified as the principal organisms involved in malolactic fermentation (MLF): Lactobacillus, Leuconostoc, Oenococcus, and Pediococcus. Wine pH is most selective, and at a pH <3.5, O. oeni is probably the best-adapted to overcome the harsh environmental conditions, so most commercial cultures consist of strains from this species. Under more favorable conditions above pH 3.5, species of Lactobacillus and Pediococcus may conduct the MLF. Among the LAB species, Lactiplantibacillus plantarum (formerly Lactobacillus plantarum) strains have shown interesting results under hot climate conditions, not only for their ca­pacity to induce MLF, but also for their homo-fermentative properties toward hexose sugars, which makes them suitable for induction of MLF in high-pH and high-alcohol wines, when inoculated at the beginning of alcoholic fermentation. Recently, a highly concentrated L. plantarum, produced with an optimized process, not only induced and finished a MLF before the end of alcoholic fermentation, when applied in co-inoc­ulation in high-pH red wines, but also worked for acidic white wines, characterized by a low pH (2.95) and high malic acid concentrations. Due to its good alcohol tolerance (≤15% vol) it can be applied in co-inoculation or in sequential inoculation. An inoc­ulation ratio could be used to control the amount of malic acid to be degraded to achieve either partial or a complete degradation of malic acid. Since this strain does not metabolize citric acid, no diacetyl is formed and so variety typicity is maintained. With the partial or complete removal of malic acid, labor-intensive chemical deacidifi­cation could be circumvented. For use in sequential inoculation, a simple MLF pretest can be applied to predict the success of the MLF in the winery.

Funding Support: Lallemand