Amandine Deroite,* Vincent Gerbaux, Céline Raynal, Magali Deleris-Bou, and Anne Ortiz-Julien
*Lallemand, 19 rue des briquetiers, Blagnac/31700, France (aderoite@lallemand.com)

Modern consumers are more frequently seeking natural products. Non-Saccharomy­ces yeasts are a good alternative to chemical inputs such as SO2. Among them, Met­schnikowia pulcherrima present interesting characteristics for bioprotection during pre-fermentative stages, allowing lower SO2 addition. Indeed, M. pulcherrima ensures biocontrol against spoilage microorganisms during pre-fermentation by (i) producing pulcherriminic acid, leading to iron depletion, and (ii) colonizing the niche without media alteration thanks to low fermentative metabolism. However, SO2 is not only an antimicrobial agent, but also an antioxidant. Therefore, to combine both antioxidant and antimicrobial properties, a study of M. pulcherrima biodiversity was conducted, and a specific M. pulcherrima was selected among 100 other yeasts for its ability to consume oxygen. This specific non-Saccharomyces yeast, isolated in Burgundy, France, has been deeply characterized since its selection. We confirmed its low fermentative capacity, good growth and survival under enological conditions (even at low temperature), low nitrogen requirement, pulcherriminic acid production, and high oxygen consumption rate. Moreover, we also demonstrated its huge ability to remove copper, an oxidation catalyzer, from the must. These antioxidant actions lead to visible color improvement when compared to no protection. Moreover, consequenc­es on wine organoleptic quality have been confirmed, with significantly more thiols produced with this specific M. pulcherrima in comparison to a classical bioprotection tool during winery-scale trials in Sauvignon blanc.

Funding Support: Institut Français de la Vigne et du Vin (IFV); Lallemand