The idea with making a yeast starter is to create a solution where you increase dramatically the cell count of the yeast by feeding it with sugar before “pitching it” (pouring it) into your brew. The large quantity of yeast pretty much ensures a successful fermentation. The method I presently use is almost 100 percent effective.
- Make a sweet solution composed of 15 to 20 percent sugar and 80 percent water by volume. Don’t use tap water, which may contain chlorine. Honey can be used, too. If the liquid tastes quite sugary, you should be fine.
- Place the solution into a clean bottle or jar. Pasteurizing the container by placing it in boiling water for more than 10 minutes is even better and will increase your chances of success, but in my experience it’s not a must. Washing with soap and water also works well.
- Place your berries (or other foraged yeast sources) in the container with the sugar solution. I don’t have a precise quantity, but it’s usually around 20 to 30 percent of the solution or even more.
- You don’t want flies or unwanted bacteria to contaminate your starter, but you need to let fermentation gases escape, so tie a clean kitchen towel or paper towel — or even better, place an airlock — on top if you’re using a bottle. For jars, you can use a regular lid and band — just don’t screw it on too tightly. You want to let fermentation gases escape.
- Shake the container or use a clean spoon to stir the contents three or four times a day. If you’re using a jar, screw the lid tight before shaking, then unscrew it a bit again after-ward. Around 2 to 4 days later (less in hot weather), you will notice some bubbling in the solution. Congratulations: Your fermentation is active. Just in case, I like to smell it, too, as added insurance. If it smells really bad, don’t use it.
- Add some of the fermenting starter to the liquid you want to ferment. I use around 1/2 to 3/4 cup (120-180 ml) of starter for 1 gallon (3.78 L) of brew. If you have a recipe asking for 10 days of fermentation, start counting the days once you have achieved an active (nicely bubbling) fermentation. It may take 1 to 3 days to get a fermentation going with a starter.
Note: As you’ll learn later, mostly when making sodas, herbal meads, or even primitive beers, you don’t always have to use a starter. Sometimes I just let the wild yeast in the ingredients do its thing. A yeast starter is mostly useful when you’ve had to boil your ingredients to extract ﬂavors (and thus killed off any already existing yeast).
From The Wildcrafting Brewer by Pascal Baudar, © 2018 by Pascal Baudar. Reprinted by arrangement with Chelsea Green Publishing, White River Junction, VT.