Why Use Wine Yeast

There are many factors that contribute to the making of a great wine. From the regional origin of the grapes to the fermentation and ageing conditions of the finished wine, there are a lot of variables and few constants in the world of winemaking. If there is one consistency that a winemaker must have, it is in the quality of their yeast.

Fermentation, at the simplest level, is the first step in the recycling process which reduces a compound to its simplest elements. Fermentation used to produce foods is always a combination of the appropriate yeast and environment.

In fermentation there are two classifications of bacteria, favorable and unfavorable. Favorable refers to bacteria which either create the favorable conditions for other favorable bacteria and or create desirable aroma, flavor and texture compounds in the wine. Unfavorable agents are those which cause spoilage, degrade the environment required by favorable bacteria or taint the flavor and appearance of the finished product.

Favorable and unfavorable bacteria exist in all raw materials used in fermented food production. Grape juice, raw milk, and grains are examples of fermentation raw materials. Some of these common foods will contain harmful bacteria even under the best storage and handling conditions. For this reason the first step in fermentation is to stabilize the raw material. The method used depends on the material. Grape juice is stabilized by the addition of sulfite, milk is pasteurized by heat, meats are cured using salts and grains are cooked. In each case, the method used contributes to the quality of the finished product by contributing to a favorable environment for the proliferation of the desired fermentation bacteria.

Once the environment is stabilized; the yeast specifically suited to the type of wine being made is added. This assures that of all the bacteria (wild yeast) originally found on the grapes (the ones which produce the best wine) will dominate.