Yeast For Making Wine
There are many varieties of yeast strains that you can use to achieve the best results with the grapes you are working with. The type of yeast used contributes significantly to the flavor and aroma of the finished wine. This is particularly true for wines that are not barrel aged since the flavors from barrel aging will overpower the subtle flavors from the yeast.
In the initial stages of fermentation, yeasts cause aerobic respiration, meaning they use the oxygen present in the must to transform the sugar into water and carbon dioxide. After all the oxygen has been consumed, the real fermentation stage begins under anaerobic conditions. The yeast produces energy by oxidizing sugar and transforming it to ethyl alcohol and carbon dioxide.
There are hundreds of different yeasts available. Most suppliers will carry 20-30 strains of yeast so you need to due some research to determine which strain will achieve your desired results. The characteristics you should consider are speed of fermentation, color extraction, amount of alcohol produced, temperature requirements, hydrogen sulfide production, and, of course, the type of grape you are fermenting. Yeast may be purchased in both liquid and dry forms, but packets of dry yeast are easiest to use for the smaller producer.
Sometimes it pays to keep it simple, and for new winemakers and small operations, this is the route to go. Montrachet is the most popular for both red and white wine fermentation. Montrachet Red is used for reds and Montrachet White for the whites. Montrachet is noted for low volatile acidity, good complex flavors, and intense color. It will not work well for grapes with high sugar levels. Prise de Mousse has become popular as yeast for all fermentation by many smaller wineries and is excellent general purpose yeast. It has an advantage over Montrachet since it produces lower levels of hydrogen sulfide. If you concentrate on full bodied red wines, you might want to use Pasteur Red since it has good color extraction and is tolerant to heat and sulfur dioxide.
Malolactic fermentation or MLF may occur and is not caused by yeast. It is caused by certain types of bacteria capable of metabolizing malic acid leading to the production of lactic acid and carbon dioxide. It lasts usually from a couple of weeks to three or four months depending on the amount of malic acid present in the wine, the strength of the culture, and the conditions under which the fermentation is allowed to occur. This will result in a wine that is softer in taste and has greater complexity. Red wines usually undergo this process, while it is can be prevented in white wines by using a yeast such as Lalvin K1-V1116 (Montpellier) which is perfect for lighter fruitier wines such as Sauvignon Blanc and Chenin Blanc.
Author: Gino Marino
Article Source: EzineArticles.com
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