Oenococcus

Oenococcus is a genus of lactic acid bacteria that can cause spoilage in wine production. While these microorganisms are essential for controlled malolactic fermentation, their uncontrolled activity outside of strict winemaking protocols is considered a major biological disorder that negatively impacts the final product.

The primary pathogen within this group is Oenococcus oeni. These bacteria are characterized by their high tolerance to low pH levels and presence of ethanol. They metabolize malic acid into lactic acid, which, if occurring prematurely or in unwanted containers, alters the biochemical balance of the wine and causes irreversible spoilage.

These bacteria primarily target grape must and wines during the maturation process. They are often introduced into the production cycle through contaminated harvesting tools, wooden barrels that have not been properly sanitized, or damaged grape berries that host high bacterial populations before reaching the crush pad.

Common symptoms of an Oenococcus infection include the appearance of a buttery or vinegar-like aroma, excessive cloudiness, and a distinct lack of freshness in the wine's taste profile. In many instances, the wine loses its characteristic acidity and develops undesirable sediment, significantly compromising its stability and flavor profile.

The development of these bacteria is favored by warm storage temperatures and inadequate sulfite concentrations. The economic harm includes loss of product quality and potential disposal of contaminated batches. Protection and prevention strategies center on strict temperature management, thorough sanitation of cellar equipment, and maintaining appropriate levels of sulfur dioxide to suppress bacterial growth.