Yeast is the most critical ingredient in the wine making process. When you pick a wine making yeast you are, in effect, choosing the destiny of your wine. The right yeast or yeasts can transform a good grapes into a great wine.

Yeast contributes so much to wine aside from just making its production possible. Discover how to pick a wine yeast for your next batch.

Wine yeast Saccharomyces Cerevisiae being grown in a lab.

Where do The Differences Come From?

These tiny organisms are truly amazing. Not only does it make the production of wine possible it is the only micro-organism capable of producing this elixir. However, the notion that different yeasts can alter the way a wine tastes in the end is a relatively new discovery.

For most of this worlds past 6,000 years of winemaking history winemakers didn’t even know what yeast was let alone understanding the different strains and what they can do. Only in recent history have we discovered that different strains will produce different characteristics in wine.

Fermentation, from the yeasts perspective, is merely the digestion of food. They consume and process sugars and produce alcohol and carbon dioxide as their byproduct. Some yeast strains may use more or less enzymes or esters and it’s these small differences in digestion that account for different flavor profiles.

To help you sift through all the different yeasts and how they affect different grape varietals our friends over at MoreWineMaking.com have put together an amazing guide! Click here to browse their entire collection of free manuals and pick up Yeast and Grape Pairing.

Picking A Winemaking Yeast

To give you an idea of how to pick a wine yeast I’ll walk you through my own decision making process. My next wine is going to be a Riesling kit and I’m going to do a little experiment. I’m going to pick my own yeast to replace whatever the kit comes with.

I’ll be using two different yeast strains in a split fermentation. Half of the grape juice will be fermented with one strain of yeast and the strain will ferment the other half. This way I can directly compare how the same wine tastes when made from two very different yeasts.

Here are the yeasts I’ve chosen and why.

The first yeast is W15. This yeast is known to produce citrus flavors, heavy mouthfeel, and can stand up to aging. Aging is an important characteristic for a kit wine for reasons we’ll explore here in a minute.

Th second yeast I’ve picked is R-HST (catchy name huh?). This yeast can produce rose and peach flavors, some mouthfeel, as well as minerality. Minerality is a quality that also lends itself to aging.

The Differences Take Time to Manifest

In an interesting article on the flavor contributions of yeast Cornell researchers found that most characteristics yeast impart on wine take six months to a year to show up. This is, in part, why it took so long for winemakers to figure out that different yeasts produced different flavor profiles. They were comparing wines too early.

Kits generally don’t produce wine that can be aged for very long. My concern is that the wine will start to decline before the yeast characteristics show up. This is why I chose two strains known to produce wines that can be aged.

Ferment Separately

Because it takes six months for any differences to become perceptible it’s important to keep the yeasts and the final products separate during that time. Otherwise you’ll never know the differences between the two end products.

There is another reason for fermenting separately though. Fermenting yeasts don’t get along well with other micro-organisms. They tend to expand in population so as to starve out any competitor for resources.

Usually one will dominate the other and force it into extinction. Even if they both strains coexist in your wine for the full duration of fermentation you’re still not guaranteed to have an equal contribution from each.

The only way to fully experience what these little dudes are doing for us is to ferment separately. Once they’ve matured you can begin tasting, comparing, and blending.

Blending Wine Made With Different Yeast Strains

Not all yeast strains can produce a well rounded, interesting wine. Some yeasts, in fact, aren’t recommended unless you blend the resulting wine with that of another strain. This is because it may offer one very strong characteristic but nearly nothing else. So you may get great aromas but weak flavor and no mouthfeel.

Thus you can blend wine from this yeast with another from a strain that produces better mouthfeel and a good flavor profile. The first yeast will intensify the aroma without sacrificing the mouthfeel and flavors produced by the second.

This is how you turn wine into a work of art! As the winemaker you get to pick and choose what you want your finished wine to taste, smell, and feel like. This is one of many brushes you can paint with.

For my Riesling experiment I’ll be fermenting W-15 and R-HST separately and aging them about six months. At that point I’ll likely bottle 3-5 bottles of each wine individually to see how they develop.

With the remaining wine I’ll be blending in varying proportions. So perhaps a few bottles of 50/50, 25/75, and 75/25 the other way. The main objective is to understand the impact yeast has on wine.

Where to Buy Wine Making Yeast

Most brewing and winemaking shops should be able to get you what you need if they don’t stock what you’re looking for. Some of the more unique strains may be difficult to locate.

If you’re an online shopper I’ve found that MoreWineMaking.com has the best selection by far. Not only do they provide a very comprehensive guide to pairing yeast and grapes they also offer just about all the yeasts they discuss in the guide.

Was this helpful to you? Please let me know in the comments!

Photograph by: Rising Damp