How to use a Yeast Starter

When making your own beer, yeast may be one of the most important ingredients you use. The right yeast can bring out the mineral profile of an Irish stout or accentuate the clove and banana notes of a German hefeweizen. But what you may not know is that properly used, yeast can help keep your beer free of spoilage organisms when it comes time to ferment your brew. The reason for this is that yeast is an aggressive little organism. When the proper amount of yeast is added to your brew, it reproduces and spreads through the beer so quickly spoilage organisms don’t have much of a chance to get a foothold.

The key to this feature is pitching the right amount of yeast and this is where a yeast starter comes in. Basically, a yeast starter is a quantity of yeast in ready condition to be added to your beer to start fermentation. When adding yeast to your beer, you want to add enough so that there’s lots of yeast to start reproducing and spreading its way through your beer. a 2-2.5 cup yeast starter for a 5 gallon batch of beer is usually enough to do the trick. As with all things revolving around home made beer, there’s a procedure to follow in making and using a yeast starter.

To create your starter you’ll need a package of yeast, 1/3 cup dry malt extract, two cups of water and a saucepan. If you’re using dry yeast, take it out of the fridge and set it on the counter. In the saucepan put the malt extract and two cups water. Stir to combine and bring to a boil over high heat. Reduce heat and simmer for 20-30 minutes. Set the saucepan in an ice bath in the sink and let it cool to 70-75F. 

Now take a 22 fluid ounce beer bottle, wash it thoroughly inside out and sanitize it. Also wash and sanitize a #2 drilled rubber stopper, airlock, funnel and the outside of the yeast packet. Once the starter has cooled to 70-75F pour it into the sanitized bottle using the funnel. Open the yeast packet and pour it into the bottle as well. Insert the stopper into the bottle. Fill the airlock half full with water and insert it into the stopper. Being careful to keep the stopper in place, vigorously shake the bottle to aerate the yeast starter. Leave the starter in a dark place at room temperature for the next couple days.

If you’re using a package of liquid yeast (also called a smack pack) the procedure is almost the same as listed above. The only difference is you’re going to start earlier. Two days before you plan to make your starter take the liquid yeast pouch out of the fridge. Break the inner packet as per package directions. Shake vigorously to mix the pouch’s contents and leave at room temperature for two days until the package swells up. Then proceed according to the above directions.

There’s one final variation for me to confound you with before we go. Sometimes you’re going to want to cultivate yeast from a bottle of commercial beer. This is especially possible with European wheat beers, English “bottle conditioned” ales and Trappist ales from Belgium. Cultivating yeast fro these beers gives you the chance to mimic them in your home brewery. All you have to do is follow the original instructions and pour 1/4 of your beer into the starter. Easy.

No matter which yeast starter you decide to use remember the two cardinal rules: sanitize and aerate. Thorough sanitizing of everything your starter touches (including your hands) will help keep your starter from picking up spoilage organisms. Aerating the starter gives the yeast plenty of oxygen so it can reproduce quickly. Follow these directions and you’ll be a big step closer to making delicious, professional quality beer in the comfort of your own home.