Oenological compatibility of biocontrol yeasts applied to wine grapes
Antagonistic yeasts applied to wine grapes must be compatible with the thereafter winemaking process, avoiding competition with the fermentative Saccharomyces cerevisiae or affecting wine flavour. Therefore, fifteen epiphytic yeasts (6 Metschnikowia sp., 6 Hanseniaspora uvarum, 3 Starmerella bacillaris) previously selected for its biocontrol ability against Alternaria on wine grapes were evaluate for possible competition with S. cerevisiae by the Niche Overlap Index (NOI) employing YNB agar media with 10 mM of 17 different carbonate sources present in wine grapes (proline, asparagine, alanine, glutamic acid, tirosine, arginine, lisine, methionine, glicine, malic acid, tartaric acid, fructose, melibiose, raffinose, rhamnose, sucrose, glucose). Also, acetic acid production in YPD-calcium carbonate agar medium, H2S production in Biggy agar medium and the production of “Brett” character or other odour defects in pasteurized must with p-coumaric acid were evaluated. As result, all Metschnikowia sp. strains showed coexistence with S. cerevisiae because the NOI (number of common carbon sources used by the two microorganisms/number of carbon sources used only by the antagonist) was <0.9 (0.42). Meanwhile, all H. uvarum and S. bacillaris strains showed competition with S. cerevisiae (NOI=1) and between them (NOI=1). On the other hand, almost all H. uvarum(5 of 6) and all S. bacillaris strains produced acetic acid, whereas none of the Metschnikowia sp. showed acetic acid production. All the yeasts analysed produced H2S in Biggy agar medium. Nevertheless, the majority of them exhibited no defect or in certain cases a slight solvent or acetate odour (different from “Brett character”) in must. Therefore, among all the biocontrol yeasts evaluated, Metschinikowia sp. strains showed more compatibility features than the rest of the strains and its oenological behaviour should be further studied under vinification conditions.
Acknowledgements: Marie Sklodowska-Curie Research and Innovation Staff Exchange project (872394-vWISE-H2020-MSCA-RISE-2019) – European Comission.
Issue: ICGWS 2023
1ICAI (Instituto de Ciencias Aplicadas a la Industria, CONICET-Facultad de Ciencias Aplicadas, UNCuyo), Bernardo de Irigoyen 375, San Rafael (Mendoza), Argentina.
2Oniris (École nationale vétérinaire, agroalimentaire et de l’alimentation de Nantes-Atlantique), Rue de la Géraudière, CS 82225, 44322 Nantes, France.
3Facultad de Ciencias Aplicadas (UNCuyo), Bernardo de Irigoyen 375, San Rafael (Mendoza), Argentina.