ROLE OF OXYGEN ON ACETIC-ACID PRODUCTION BY BRETTANOMYCES DEKKERA IN WINEMAKING/

Since the large occurrence of Brettanomyces yeasts in strict anaerobio sis environments (sparkling wines) has been found without an increase in acetic acid content, we evaluated the influence of the oxygen conce ntration on acetic acid production. Results showed that the oxygen con centration exerted a strong influence on both growth and acetic acid p roduction by Brettanomyces yeasts in winemaking. Full aerobiosis lead to a large production of acetic acid causing a block of metabolic acti vity. Semi-aerobiosis resulted in the best condition for alcoholic fer mentation (Custers effect) combined with acetic acid production. In an aerobic condition Brettanomyces yeasts did not result in high acetic a cid production and a pure, even if slow, alcoholic fermentation occurr ed. The absence of an increase in acetic acid in wines, does not exclu de the active presence of Brettanomyces yeast since the characteristic 'high acetic producer' in Brettanomyces yeast is linked to the presen ce of oxygen.