We keep hearing about the shortage of yeast out there in the groceries, and we've had a few people reach out to ask if we have any yeast they can get. We tell them, uh, hey, we're natural winemakers! That means we use, um, native yeasts? And folks say, right, that's fine, we'd love to buy some native yeast, you got some?
This has been super helpful, because we're just realizing that unless you're a natural winemaker (or a winemaker or brewer at all) you might not realize that I have some really, really good news for you: you don't need to BUY native yeast. It's all around you, right now. It's free. And you can use it for making bread or whatever you're cooking.
Different yeast strains do act a bit differently. Some yeasts can live in high alcohol situations better than others. Some yeasts can survive with less oxygen or in cold temperatures. Some yeasts reproduce on the top of things, like an ale yeast; some sink to the bottle, like lager yeast. There are different strains of yeast out there, some of which are the common Saccharomyces cerevisiae (Latin for, basically, "sugar fungus"), which we use in baking and winemaking. But mostly the difference between yeasts unless you're a specialist is mostly that different strains of yeast produce different aromatics. We can get into esters and terpenes and all the science, but really all that matters is, if, as a winemaker, I wanted to make my Ortega smell like peaches, I could go to a commercial catalogue and order a yeast that resulted in peachy aromatics.
As a natural winemaker, I don't do that. Because Ortega does not naturally smell like peaches, certainly not in our climate, and it's hard for me to see anywhere naturally. So for a natural winemaker, what we're focused on is making wines that taste like this place--and that means not only don't we order up yeasts to alter the aromatics but we're focused on using only the yeasts that live in our vineyards and occur naturally. That means our wines have a whole variety of different yeast strains, reflecting the natural diversity and complexity of our farm land.
We could go on for days about the advantages of natural yeast, but let's cut to the chase: can't buy yeast at the grocery right now? This is not a problem. Here's how you can "capture" your own wild yeast for baking.
First, you basically want to think: yeast consumes sugar. It's their food. The byproducts of that consumption are carbon dioxide and alcohol (and other things). It can consume a couple of different kinds of sugars, but not all sugars, so let's keep this simple: stick with glucose or fructose, i.e. table sugars or fruit sugars.
Second, yeasts are temperature and oxygen sensitive.
Third, wild yeasts live everywhere, but they thrive outdoors. That's where you're going to have the easiest time "capturing" them.
First thing you want to find is an open-topped container. Plastic or glass is ideal. Metal is trickier. A glass or ceramic baking dish works fine. You want a nice wide top and a large surface area. If it's in your cupboard, it's fine. You don't want to douse it with bleach (not bleach especially) and don't need to obsess over sterilizing it, as long as it's clean. The next thing you have to decide is what's your sugar base. You can use white sugar, brown sugar, molasses, honey. If those were your only options, I'd stick with honey or sugar just because molasses has a strong flavour, but it certainly works. We use it all the time in making fermented compost teas. However, if you have access to any unwashed soft fruit from your garden, that's the very best thing of all. So if you have even just a few strawberries in your backyard that are coming on, that will do. If you froze blackberries you gathered wild on the roadside last August, that's perfect too.
If you have fruit, either thaw it or pick it fresh and smush it. As long as you're using COVID-19 good sense, smushing with your hands is actually the best, but you can use a potato masher as well. Just smush: you don't need a food processor here.
If you don't have fruit, then make a sugar and water solution. Raw honey is my preference, but sugar is the key thing. I do a 50-50% solution in warm water (warm enough that you can hold your finger in it but hot enough that you think, yeah, I'd soak in that). You can also take beer and add sugar to it as a solution base.
You want to plan this if you can for a spell of sunny days, and preferably you want warm days like we're finally starting to get on the island. Cold and rain aren't ideal conditions, though it's not impossible either.
Take your smushed or thawed fruit or your sugar - water solution. Put it in the open-topped container. Take it out to the garden, and place it on the ground amidst some plants. Leave there for a nice sunny afternoon. Leave it there for another day or two, until you see a fermentation starting.
That's it. If you have warm weather and leave sugar in solution outside, nature will find a way and you will get a fermentation. That fermentation is (among other things) the yeast you're looking for. You now have a "starter" that you can use in your baking recipes. If you "feed" your starter (adding sugar and letting it have oxygen) it will keep doing its thing. Some folks have starters that last for years.
And if you get stuck, let us know. We have starter from the vineyard always on the Aga here in our kitchen.