There are many factors that go into choosing a wine making yeast. This is the second most important decision you’ll have to make next to picking the grape varietal to make your wine from.
Choosing the right yeast is important for two reasons. First, different yeasts produce different flavor and aroma profiles to finished wines. This has to do with how the yeast processes the must when it’s digesting the sugars and nutrients.
The second reason your choice of yeast is so important is that not all strains have the same alcohol tolerance. Many wild yeasts have tolerances of only five to six percent alcohol. Other strains specifically cultivated for wine making may have alcohol tolerances upwards of 18% or more.
While this topic has been covered here before we’re going to dive into the specifics of how to do it right. So let’s get to it!
Choosing a Wine Making Yeast
Step One: Pick Your Flavor Profile
The first step in choosing a wine making yeast is to figure out what flavor profile you’d like to have. The stellar folks over at More Winemaking provide a great free resource called the Yeast and Grape Pairing Guide.
This guide breaks down what yeast strains give what flavor and aroma profiles for different grape varietals. Open up the guide and look for the varietal of wine you’re looking to make. For each varietal they list the most common yeasts used along with the different flavors and aromas that can be expected from using them.
You’ll notice that some yeasts are not meant to be used on their own. They’ll say something like “good for adding _____ to a blend”. This may be because that particular strain does not offer very much flavor but really packs in the aromas. These yeasts are best paired with another strain in either a mixed fermentation or a split fermentation.
Here’s a quick look at the difference between the two. A mixed fermentation is where you pitch more than one yeast strain at the same time in the same must. A split fermentation is where you ferment the same varietal grape must with different yeast strains in different fermenters keeping them separate until they’re finished. After fermentation you blend them back together.
Step Two: Verify the Yeast Alcohol Tolerance
Once you’ve got a handle on the flavor and aroma profiles it’s time to make sure that your yeast of choice is strong enough to completely ferment your wine. If the yeast you choose is not strong enough to finish fermenting your wine there’s a good chance it will be sweeter than you prefer.
To check the alcohol tolerance of your yeast strain head over to Lallemand and check out the Lallemand Yeast Charts. In addition to alcohol tolerances they provide other important information such as nitrogen demand, how competitive the yeast is, and a few others.
Be sure to book mark that table as you’ll want to refer to it at the start of any fermentation. I use it all the time to plan my wine making efforts.
Step Three: Estimate the Final Alcohol Content
To estimate your final alcohol content you’ll need to take a specific gravity reading of your must. Be sure to correct it for temperature using the specific gravity temperature correction calculator.
Assume that your wine finishes with a specific gravity of 0.990. While this is pretty low it’s entirely possible you could achieve this. Take your measured specific gravity and your estimated final gravity and plug it into the following equation:
Check this against your yeasts alcohol tolerance to see if it’ll ferment completely. If this estimate is less than what the yeast can handle you’re good to go.
What if The Yeast Isn’t Strong Enough?
If your yeast doesn’t have what it takes to finish fermentation you’ve got two choices. You could just pick another yeast that has the tolerance you need, however, if you’re standing there with a fermenter full of must waiting for you to pitch the yeast this isn’t an option.
Instead pitch the yeast you have and refer back to the Lallemand chart and the Yeast and Grape Pairing Guide to find a strain that is strong enough to ferment to your estimated alcohol content. Purchase that yeast and keep it on hand in the event your fermentation gets stuck.
Your preferred yeast that you used first will do the bulk of the fermenting and therefore provide more of the flavor and aroma. The second yeast will have some impact on flavor of course but it will be minimal. Mostly we just need something to complete the fermentation process.
Choosing a wine making yeast is important but it doesn’t have to be difficult. Follow this three step procedure and you should do just fine.
By the way More Winemaking is the best place I’ve found to purchase yeasts. They sell all the strains listed in their Yeast and Grape Pairing Guide which makes things easy. If you’re looking to purchase some please consider using this affiliate link: MoreWinemaking.com. There’s no difference in cost to you and you can help support the Academy.
Photograph by: Wollombi