The use of selected starter cultures

A selected starter culture is the progeny of a single yeast cell having special properties like:

• Ensuring fermentation of grape and fruit must,
• Remedying stuck fermentations, as well as finishing fermentations of wine (up to 15 vol. %),
• Ability to ferment a must at low temperatures (low temperature yeasts  12 - 15 °C),
• Fermentation of sparkling wine (sparkling wine yeasts),
• Obtaining high alcohol concentrations (high fermenting yeasts: up to approx 16 vol. % with gradual addition of sugar).

The name of the yeast strain is free of choice and sometimes describes its origin. The quality of the must is decisive for the quality of the, with this yeast strain, to be fermented wine.

There is a variety of different commercial dried yeast strains. For an easier choice of the suitable yeast strain the Department of Microbiology and Biochemistry has created a yeast finder in cooperation with some yeast producers and the University of Applied Sciences Wiesbaden. This tool can be found under: The Geisenheim Yeast Finder.

The yeast strains delivered by the Department of Microbiology and Biochemistry are all adapted to a slight sulfuring of must. They are able to ferment musts containing up to 30 mg/l free SO₂. It is recommended to preserve the accustoming of the used starter culture to the sulfuric acid during propagation.

The delivered yeasts are grown in grape must. They are delivered immediately after successful propagation. Closed bottles can be stored up to 8 weeks in the refrigerator without impairment of the fermentation capability of the yeast starter culture.

The delivered yeast quantity is to be used in the following way: 2 - 3 % starter culture should be added to the grape or fruit must or the mash (for 100 liters must - 2 to 3 liters starter culture). For fermentation of wine and sparkling wine, for remedying stuck fermentations as well as for fermentation problems at least the double quantity of starter culture should be added.