Wine yeast is an essential ingredient of any wine recipe. It is the critical ingredient that does all the work. Wine yeast consumes the sugars in the wine must and converts them into alcohol and CO2 gas. Without the yeast you would have no wine. There are three different ways to add yeast to wine must. Each method has its own advantages and disadvantages. Here's a brief overview of each of them: Add The Yeast Directly To The Wine Must: This is the most common method. Simply open the packet of wine yeast and sprinkle it directly on top of the wine must. There is no reason to the stir the yeast into the liquid. It will dissolve into the wine must just fine on its own. Sprinkle the yeast and let it be. The obvious advantage to this method is that it takes no effort. The disadvantage is that you do lose some of the yeast's ability to ferment effectively at the very beginning of fermentation. The result is a delay in the startup of fermentation – usually a matter of 3 or 4 hours. Re-hydrate The Yeast. Then Add To The Wine Must: The wine yeast that you get in little packets has been dehydrated. All the moisture has been taken from the cells to make them inactive while in storage. Re-hydrate means to add water back to the yeast. When this process is done before adding the yeast to the wine must, you get a fermentation that takes off more quickly. It's no coincidence that this is the method you will find directed on the side of most packets of wine yeast. The producers of these yeast packets would prefer you use this method. The problem is that if you do not follow the directions "exactly" you can easily kill the wine yeast. Typical wine yeast re-hydration directions will read something like: "Put the yeast in two ounces of water that is between 104°F. and 109°F. for a period of 15 minutes." This method works well if you follow it without wavering in time or temperature. But if you don't use a thermometer to verify the water's temperature, or if you leave the wine yeast in the water for longer than directed, you can easily kill most or all of the wine yeast. Make A Yeast Starter. Then Add To The Wine Must: This method is often confused with re-hydration, but it's not the same thing. Re-hydration is getting the wine yeast back to its original state by adding water with it. But a yeast starter is actually letting the yeast ferment on a small amount of must before adding it to a batch of wine. A yeast starter usually take one or two days to get going before it is add to the entire batch. Making a yeast starter is fairly straight-foreword. If the wine must is already prepared you can use it as the starter. One pint of wine must in a quart Mason jar and a packet of wine yeast works perfectly for a five gallon batch of wine. If your batch is larger, multiply the starter's size proportionately. Add a 1/4 teaspoon of yeast nutrient along with the yeast packet and cover it with a plastic wrap secured with a rubber band. Prick a pinhole in the plastic wrap to allow the gasses to escape. Regardless of the starter size or how it was made, you want the wine yeast to maximize its level of activity before adding it to the wine must. You will see the yeast starter begin to foam up. I usually tell people to pitch the starter into the wine must once you see this foaming start to slow down. In other words, once the foaming has peaked. This is usually 12 to 18 hours after starting. When you make the yeast starter you can sprinkle the packet of yeast direction into it, but the purist will re-hydrate the wine yeast in water, first, before doing so. The advantage with the method of adding yeast to a wine must is that you will get the quickest and most thorough fermentation. Your yeast will also be under little stress, so the chance of the yeast producing any off-flavors is very minimal. The disadvantage is that it is more work, and you do need to plan ahead since the starter needs a day or two to get going. How you decide to add yeast to your wine must is entirely up to you. Any of these methods will work. Just consider the advantages and disadvantages of each one, and go with what works best for you. ----- Ed Kraus is a 3rd generation home brewer/winemaker and has been an owner of E. C. Kraus since 1999. He has been helping individuals make better wine and beer for over 25 years.