I did not rehydrate my yeast before I pitched it. How do I do this and what happens if I don’t?

Dear Wine Wizard,

I did not rehydrate my yeast before I pitched it. How do I do this and what happens if I don’t?

John Eastwood
Cleveland

Wine Wizard replies: Rehydrating yeast before adding (pitching) it to juice or must is an important step in assuring a healthy fermentation. Adding dry yeast to a high-sugar solution such as grape juice is like giving a presentation to the boss without having first mapped it out — you’re just not prepared. Yeast cells in their dry form are in a “dormant” state and need to be “woken up” before they can be called on to perform their best for you. Rehydrating them is like lubing them up, getting their cellular mechanisms going, and giving the poor guys a chance to get their heads screwed on straight before they can start chewing away at the sugar. To rehydrate yeast, do what I do — follow the package directions. Companies that sell yeast know the best way to activate their product and will usually include directions on how to do so.

If there are no instructions, add about one tablespoon dry yeast to one-half cup water that is at about 100° to 110° F and do not stir. Let sit for 10 minutes and if the yeast looks like it’s gotten bubbly and has started to come to life, stir it directly into the juice or must to be fermented. If after 15 to 20 minutes the yeast have not started to look lively, it is likely that you have a bad batch of yeast and should open another envelope. A five-gram package is sufficient for six gallons (24 L). If you need to stretch a five-gram package to inoculate 12 gallons, dissolve a teaspoonful of sugar in the water, add yeast, cover with foil or plastic wrap, and let the yeast grow for two to three hours in a warm place before pitching.

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