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Influence of lactic acid bacteria strains on ester concentrations in red wines: Specific impact on branched
Marine Gammacurta1, Georgia Lytra2, Axel Marchal2
1Univ. Bordeaux, ISVV, EA 4577 œnologie, 210 chemin de Leysotte CS 50008, 33882 Villenave d'Ornon Cedex, France; INRA, ISVV, USC 1366 œnologie, 210 chemin de Leysotte CS 50008, 33882 Villenave d'Ornon, France; Biolaffort, 126 Quai de la Souys, 33100 Bordeaux, France.
Abstract:
This research investigated the influence of lactic acid bacteria (LAB) strains on ester levels in Bordeaux red wines. These wines were made in five Bordeaux areas in two vintages, using three yeast strains. Malolactic fermentation (MLF) was carried out using industrial starters or indigenous strains, each in triplicate. Ester concentrations were determined by liquid-liquid-extraction- or HS-SPME-GC/MS at various stages in the winemaking process. The levels of most compounds were slightly impacted by LAB, depending on grape variety. Nevertheless, branched hydroxylated esters, such as ethyl 2-hydroxy-3-methylbutanoate and ethyl 2-hydroxy-4-methylpentanoate were the only compounds to be strongly influenced by the bacteria strain, regardless of matrix composition or the yeasts used for alcoholic fermentation. Moreover, the effect observed after MLF persisted over time, for at least 12months. These esters are apparently important markers of LAB esterase activity. To our knowledge, this was the first time they had been identified in this role.