It’s the middle of August and decisions must be made. How many cases of each wine are we making? How many tons of grapes do we need to get to that quantity of cases? How many tons can we pick at one time in order to process the grapes in a timely manner? The final preparation is ordering all the winemaking chemicals that we will use, which includes the yeast that will be added to the crushed grapes or to the juice. I get asked all the time about the yeast we use – what is it and why we add and how we choose.

Yeast is a very basic organism, and it is naturally on many plant surfaces, but especially on items that contain sugar, particularly fruits. It is a single cell organism that multiplies by budding, and it multiplies in a relatively short amount of time. The yeast really has one function, and that is to convert sugar to carbon dioxide, with the other byproduct of alcohol, but that can be in very small quantities. Bread yeast produces only a small amount of alcohol, while wine yeast can produce up to 19% alcohol depending on the strain of yeast. Which leads me to the question of the type of yeast we use. Baking yeast is specific to baking as it produces mostly carbon dioxide = bubbles in the bread, and what little alcohol that is produced is evaporated. If we tried to use baking yeast in wine, that yeast would die at a low alcohol percentage of maybe 1% alcohol.

When looking for a wine yeast to use we have many possibilities to choose from, and there are routes we can take. Some wineries choose to use the yeast that is natural on the grapes, and they will call this a natural fermentation, or native fermentation. Some people think that you stay true to your vineyard, and it is a purity of vineyard expression by doing the native fermentation I have tried a few natural ferments and also have tasted many natural ferments and have found that the results can vary in flavors and aromas that result in the wines. Some results are really good, but I have seen some that are really not that good, which is why I like to add yeast to my juices - the results are relatively predictable in flavors and aromas, and so I buy commercially available wine yeast. All non-GMO, but rather selected out by characteristics unique to each, then isolated and regrown and freeze dried for easy use.

This is where I consult one of several companies who sell yeast, where I can peruse a list of up to 75 strains of yeast – yes there are that many developed for wine! Each strain they sell has a unique set of fermentation parameters and in some cases other byproducts that are produced during fermentation. Some yeast can live at high temperatures, which is good for red wine fermentations that occur at around 90F, but others only ferment well at 70F. Some need more nutrients during the fermentation, while others do not. Some tolerate alcohol levels up to 19%, but some only tolerate 13% alcohol. This is where important decisions are made so that you have the fermentation that you desire.

In the case of Chardonnay, I want the fermentation to be complete so I use a strong fermenter, one that tolerates alcohol well and can handle a lower temperature fermentation, as we barrel ferment at a fairly low temperature. The yeast supplier also claims that there are by-products of the fermentation that each yeast produces, such as fruit aromas or compounds that enhance mouthfeel, so that further helps choose a strain of yeast for Chardonnay. For Pinot Noir the yeast must tolerate higher temperatures up to 90F, as well as moderate alcohol, and I like it when the yeast produces some fruit compounds rather than earthy compounds. Merlot and Cabernet Sauvignon yeast is similar to Pinot yeast, but I have to make sure that they tolerate more alcohol, up to 16%, just in case the grapes are more ripe. Sometimes the more difficult fermentations are the cold ones, as in the case of Muscat Canelli or rose, because you want the fermentations to be cold and slow, between 55F and 60F. We must then choose cold tolerant yeast, and then if we want to stop fermentation while sweet, we need a yeast that is easy to stop by chilling to 40F.

Yeast choice is interesting, and each winemaker settles in on a certain yeast for a certain style of wine, and it becomes a fingerprint for their style. Rarely do we use the same yeast, just like we winemakers want to be different! gets into it and some of the inert gases that may be going into it from the process. I can’t say for sure why this happens, but it is a phenomenon that we know does happen. If you have any doubts about when to open a wine shortly after bottling - wait at least four months, but six would be better!

I prefer younger wines that capture the vibrancy of the fruit. Wine, whether white or red tend to lose the fruit characters the older they get, and eventually take on a sherry character. It takes a few years, but as this happens, they get darker to brown and eventually the fruit will be gone.

The other part of figuring out when to drink wine is the individual doing the drinking. As I said, I prefer a younger, fruit-driven wine, but I have met numerous people who prefer aged wines. There have been wines I swore are past their prime, but at tastings find those who have older vintages they claim are still wonderful. To each his own….
Since I mentioned our 2021 Cabernet Sauvignon, I should predict how long it will age, and I am guessing that in 10 years it will still be great, although I do think it is already really good now, so my bottles won’t last that long!