YEAST STARTERS PREPARATION AND PROPAGATION

In 1965, Red Star Yeast (Universal Foods Corporation) released the first commercial wine active dry yeast (WADY) in the United States. Today, the selection of routinely available, reasonably priced dehydrated yeasts has grown to include many strains marketed internationally by several companies. Although winemakers often have preferences for one strain versus another for particular applications, the issue continues to be one of debate. 

The winemaking community is widely divided with regard to the philosophy and practice of using yeast starters. At one extreme are those that use solely native yeasts and bacteria. Others prefer to begin with native yeasts and latter inoculate with Saccharomyces. Still others use Saccharomyces starters but at lower than recommended inoculum levels. Despite these 

One practice that should be avoided is the utilization of pomace, fermenting wine, or lees from an almost complete fermentation as inoculum. Although seemingly economical, this practice dramatically increases the potential for contamination as well as significantly decreasing yeast vigor and vitality. 

Actively growing yeasts, either recently rehydrated or from starter tanks, should not be transferred directly to chilled must. Cold shock may reduce the viable cell count by up to 60% (Cone, 1994 personal communication) and, in general, result in slowed growth and increased potential for stuck/ protracted fermentations. Yeasts should be acclimated to within 10°C of target temperature prior to inoculation. 

Rather than rehydrate yeasts on a tank-by-tank basis, economics may dictate preparation of starter tanks in which larger volumes of yeast are propagated and used, as necessary, over a short period. In these cases, it is necessary to prepare relatively large volumes of sterile juice and, during the propagation phase, maintain it without secondary contamination from other native yeast and bacteria. 

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