You can definitely use wine yeast for baking bread. Bread yeast and wine yeast are both Saccharomyces cerevisiae and both work the same way, by eating sugar and converting it into ethanol and carbon dioxide gas. In the case of wine, the sugar comes from the grapes. In bread, the sugar (simple carbohydrates) can come from the flour, which often contains somewhere between 1–2% simple sugars, or from a small addition of granulated sugar. When flour is mixed with water, the simple sugars can be eaten by the yeast, leaving the starch to create the bread. It is, after all, the carbon dioxide produced by yeast that allows a loaf of bread to rise.
That said, wine yeast is a little different than bread yeast strains. Bread yeast strains aren’t bred (ha-ha) to be able to withstand high levels of alcohol so it’s not wise to try to make wine with bread yeast. Wine yeast will be able to operate just fine in the bread environment, which is not a high alcohol situation. Wine yeast is also, depending on the strain, a little slower to start than “rapid rise” bread yeast or yeast made specifically for bread machines. Think of bread yeasts as speedy sports cars and wine yeasts are family sedans. They’ve got slightly different performance stats, but both are automobiles that have four wheels, consume gas, and can get you where you want to go.
If I were to use old wine yeast (or even a fresh packet) for breadmaking, I’d be sure to hydrate it properly, i.e. 1 tbsp. yeast with about 1⁄3 cup hotter-than-warm water, or about 100–105 °F (38–41 °C). A proper “proofing” of the yeast, i.e. letting it get nice and bubbly for a few minutes after hydration, is important to make sure it’s not expired and is ready to use. Be sure to deduct this water from the amount in your recipe. It’s not advised to “pitch” dried wine yeast directly into flour or a bread machine; you’ll want to make sure it’s active and healthy before using in a recipe.
Indeed, you can even try to isolate yeast from your winemaking if you’d like to have a “winemaker’s sourdough starter.” During the harvest of 2019, I cultured my own starter using Pinot Noir grapes from my company’s Stanly Ranch in the Carneros AVA here in California. I was grape sampling with my son, and we saved about four fist-sized clusters from our sampling buckets. I made a flour-water slurry with about ½ cup all-purpose flour and about ¾ cup filtered water in a large bowl. Then, I lightly squished the grape clusters over the bowl with my hands, allowing the juice to run into the bowl. I deposited all four of the squished grape clusters, stems and all, into the slurry and mixed it all around. We covered the bowl with a clean dishtowel and then set the bowl on the picnic table in the shade (about 78 °F/26 °C) for the day. That evening, I fished out the grape stems, being sure to leave the grape berries in the bowl, and stirred in another ¼ cup water and ¼ cup flour before covering the bowl, leaving it on the kitchen counter and going to bed.
Wine yeast is also, depending on the strain, a little slower to start than “rapid rise” bread yeast or yeast made specifically for bread machines.
The next morning, I noticed that my purple-and-white (no, it’s not an attractive process) slurry was a little bubbly and had started to smell slightly like wine. I fed in another ¼ cup flour and ¼ cup filtered water, stirred it, covered it, and left it in my oven on the “proof” heat setting all day. By that evening, I noticed it had started to get quite bubbly and between the natural yeast on the grapes and the sugar in the grape juice, I had a fermentation on my hands! It was then that I used a rough mesh strainer to get out all of the seeds and skins (passing though a colander would work too) out of my flour-grape slurry. I added another ¼ cup flour and ¼ cup water, stirred and went to bed. The next morning, I fed it again (by this time it was starting to grow quite a bit in the bowl), set it in the oven on “proof” again and checked to see how active it was in a few hours. By now there were definite bubbles of gas being created and it was quite active. I reserved 1 cup of this in a clean glass jar, covered it with a paper towel and stored him in the refrigerator . . . and that became “Stanly the Sourdough Starter,” whom I’ve since shared with friends and neighbors here in my hometown.
There are so many sources online to learn about how to use and maintain a sourdough starter, especially now that the entire country seems to be into baking bread. I don’t have the space in this column to go into bread baking master class, but my one piece of advice would be to “think like a winemaker.” You know yeast like food and the correct temperatures in which to grow, and that winemaking takes patience. So it is with sourdough baking. You’ve got a big leg up since you’ve already got “microbial smarts” when it comes to managing a yeast culture.
