Expertise documents

The topic of acetaldehyde is very interesting as this compound has SO2 binding properties. The proper choice of wine yeast and bacteria are key factors in determining the final levels of acetaldehyde produced. If SO2 concern is an issue, then choosing a yeast with low final acetaldehyde production such as the Lalvin ICV OKAY® is very important. Wine bacteria can also be an ally as they will use acetaldehyde during malolactic fermentation. If color is an issue, and since acetaldehyde can help stabilize color, then a yeast with medium to high production can be used. When co-inoculation of wine yeast and bacteria is preferred, the acetaldehyde production by the yeast is used by the wine bacteria during malolactic fermentation. A proper fermentation management and nutrition has also been shown to influence the concentration of this compounds, as well as judicious oxygen management. With more and more conscious effort to properly manage the SO2 levels in wines, knowing how the wine yeast and bacteria were characterized for acetaldehyde production becomes a valuable tool for winemakers. This 'Wine Expert ' explores acetaldehyde management in winemaking WE#5 AUSTRALIA2  

 In addition to carrying out the bio-deacidification of wine, malolactic (ML) bacteria influence aroma and flavour through various mechanisms, including the production of volatile grape- and yeast derived metabolites. In wine, one of those volatile compounds – diacetyl – has important stylistic implications. This diketone, also known as 2,3-butanedione, is associated with the “buttery” character of wine and is formed as an intermediate metabolite in the reductive decarboxylation of pyruvic acid to 2,3-butanediol.The formation and degradation of diacetyl is closely linked to the growth of such ML bacteria as Oenococcus oeni and the metabolism of sugar, malic acid and citric acid. Yeasts are also able to synthesize diacetyl during alcoholic fermentation (AF). However, most of this diacetyl is further metabolized to acetoin and 2,3-butanediol. This issue of Winemaking Update will review winemaking practices and the latest findings to help modulate diacetyl content in wine through malolactic fermentation (MLF).

Lallemand Winemaking Update #15 2012 - Diacetyl Management