Evaluating Commercial Active Dry Wine Yeasts by Fermentation Activity

Abstract

Active dry wine yeast (ADWY) in bulk form suitable for winery use has become available commercially. The performance of such yeasts under commercial conditions can be evaluated by determining yeast viability or fermentation activity. Determining viability from the staining of cells is unreliable; cell plating and counting of colonies or microscopic determination of budding cells is time-consuming. Such determinations may reflect the quality of the active dry wine yeast without indicating its performance in winery fermentation. CO₂ production rate, however, may reflect actual performance under various fermentation conditions, such as SO₂ concentration, yeast concentration, rehydration temperature, storage stability, etc. A recommended method for determining the fermentation activity of ADWY is described.