Sibylle Krieger-Weber,* Magali Déléris, Iladar Nisamedtinov, Heili Anni, and Georg Arju
*Lallemand Inc., In den Seiten 53, Korntal-Münchingen / 71272, Germany
(skrieger@lallemand.com)

Chardonnay is the white wine variety most likely to undergo malolactic fermentation (MLF); however, Chardonnay is also most likely to experience stuck MLF. It is important to understand the reasons behind stuck MLF on a molecular level. Understanding the reasons behind sluggish or stuck MLF (nutrient limitation or inhibitory compounds) addresses these issues through development of MLF nutrients, detoxicants, or selection of specifically adapted bacteria strains. Over the past three years, we have tested >150 Chardonnay wines from across the world for malolactic fermentability and categorized them using both targeted and untargeted metabolome analysis on LC/MS, GC-MS, and MS/MS to identify causes of sluggish/stuck MLF in Chardonnay wines. To eliminate the impact of vinification protocol, including the effect of yeast and yeast nutrition used for alcoholic fermentation (AF), must samples of some Chardonnay wines were collected. These underwent a controlled AF in the lab under a standardized protocol. MLF feasibility was determined by a quick test using a high inoculum of commercial Oenococcus oeni or Lactiplantibacillus plantarum strains, then assessing malic acid degradation over 72 hrs. The success rate for inducing MLF was significantly greater for L. plantarum than for O. oeni. This highly-concentrated L. plantarum culture also performed well in wines from other grape varieties that are prone to stuck MLF, even those with high SO2 levels. Targeted and untargeted analyses supported by multivariate statistical analyses allowed identification of potential molecular causes of stuck/sluggish fermentations by O. oeni outside of pH, lactic acid, K, and Mg, which enhance MLF, or SO2 and EtOH, which hinder MLF.

Funding Support: Lallemand INC