How to Re-Hydrate Yeast

How to Re-Hydrate Yeast

Yeast, a winemaker’s best friend, and star of the show when it comes to fermenting grapes into wine. They make it all possible. With a properly hydrated yeast your fermentation will start strong and be less likely to get stuck. Which is why it’s critical to understand how to re-hydrate yeast. What is dry yeast? Dry yeast is made up of small granules that consists of live, active yeast cells enclosed in a hard shell of dead yeast and a growth medium. In order for the live yeast cells to break free and ferment your must the shell must first be broken down. This is where hydration comes in. Whether you re-hydrate yeast yourself or allow nature to take it’s course in the must what you’re doing is breaking down that outer shell. If yeast is not properly re-hydrated the individual organisms can’t function properly. Their cell walls will not be fully permeable and they won’t be able to take in sugars and release carbon dioxide and alcohol. How does yeast re-hydrate if we don’t do it? In most wine kits re-hydrating the yeast is not only not necessary, the directions clearly state “do not re-hydrate the yeast”. You just add it straight to the grape juice concentrate and water mixture. By doing this we’re trusting that the dried yeast will hydrate well enough on its own. Kit makers choose the yeast strains based on many factors but one of the key factors is its ability to hydrate on its own in the must. If you read yeast hydration instructions, however, you’ll notice that the optimal water temperature for hydration is 104-109 degrees (F). Kits instructions call for innoculation temperatures of 72-75 degrees (F). These are less than optimal conditions for the hydration of yeast which is why kits only come with certain strains. How Re-Hydrating Yeast Affects Fermentation Hydrating your yeast at 104-109 degrees (F) helps break down that crusty outer layer and allows the live cells within to break free and begin multiplying. In just a few minutes your yeast population is already starting to explode. Contrast this with pitching dry yeast in a cool must. Without that heat it takes longer to break down the outer shell. This is why you only see evidence of fermentation two days or so into the wine making process. If you re-hydrate the yeast that comes with a wine kit you’ll likely see evidence of fermentation within a few hours. The rapid population growth speeds up fermentation because there are more of the little guys sooner. Another benefit of such a rapid population growth is that the yeast can dominate the environment much more easily. Keeping undesirable strains or other bacteria from getting established in your must. How to Re-Hydrate Yeast This process can vary slightly depending on the brand of yeast and the strain. However, here is the general process I’ve followed for quite a few re-hydrations. Heat 2 cups or so of water to 104-109 degrees (F). Pour 50 ml of the heated water into a dry sanitized container. Add the dry yeast to the water and stir for thirty seconds. This breaks up any clumps so...

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