Wine yeast

Candida vini is a species of film-forming yeast that is widely recognized in the wine industry as the primary agent responsible for the condition commonly known as 'flowers of wine' (fleur du vin). This organism is not a plant pathogen in the traditional agricultural sense, but a significant spoilage yeast affecting bottled or stored wine products.

The primary substrates for this organism are finished wines and wine musts. It thrives in environments where wines are stored in tanks or barrels that are not kept full, allowing the yeast to form a surface film that is characteristic of the infection. It can occasionally be found in vineyards, but its economic impact is concentrated entirely within the winery environment.

The diagnostic symptoms of an infection include the appearance of a thin, white-to-grey pellicle on the surface of the wine. Over time, the film may become thicker, wrinkled, and folded. If the liquid is disturbed, the film tends to break apart and sink to the bottom of the container, causing significant turbidity and forming a distinct deposit that ruins the visual appearance of the wine.

The development and spread of Candida vini are strictly dependent on the presence of oxygen. Therefore, oxygen exposure is the primary driver of this spoilage. Other contributing factors include low acidity (high pH), warmer storage temperatures, and the presence of residual sugar, which provides an easy nutrient source for the yeast to proliferate rapidly.

The damage caused by this yeast is primarily biochemical; it consumes ethanol and organic acids, converting them into carbon dioxide and water. This metabolic process significantly reduces the alcohol content of the wine and introduces off-flavors, often described as musty or flat, which irrevocably lower the sensory quality and commercial value of the beverage.

To prevent and manage Candida vini, winemakers should employ several key strategies:

• Maintain full storage vessels to minimize headspace and oxygen contact.
• Use inert gases (like nitrogen or argon) to blanket the surface of the wine.
• Monitor and maintain adequate free sulfur dioxide levels to inhibit yeast growth.
• Practice rigorous sanitation of all winemaking equipment and barrels.
• Store wine in cool, temperature-controlled environments to slow down microbial activity.