While any beer will benefit from the use of a yeast starter, one should definitely be used if you're brewing a high gravity beer, such as a Barley Wine or an Imperial Stout. A yeast starter will result in a quicker start to fermentation, and a more complete fermentation.
How to prepare a yeast starter:
- If you have an Activator yeast pack, activate it 24-72 hours in advance. If you're using White Labs, remove it from the refrigerator 2-4 hours in advance.
- Mix 16 ounces of water and 1/3 to 1/2 cup of dry malt extract together and bring to a boil for 15 minutes. If you are using a flask it can be heated directly on an electric or gas burner.
- Cool this mix to below 80°F (an ice bath will work for this small amount) and then add the yeast. Another, more convenient option would be to use Fast Pitch canned wort. Simply add 1 can of Fast Pitch and 1 can of water for a 1 L starter, and double that for a 2 L Starter.
- Frequently aerate the mix to help aid in yeast production. This can be done by shaking the flask. A more precise method, that will result in a higher yeast count obtained from the starter would be to use a stir plate. A healthy froth on the yeast starter should develop after 1-3 days.
- At this point, the yeast is ready to be pitched (added to the wort).
- Add the yeast starter to your beer/wort after it has been cooled below 80° F. If you re making an ale, ferment at recommended ale temperatures. If you are making a lager, wait for fermentation to start and then reduce the fermenter's temperature to the recommended lager fermentation temperature.
- Signs of fermentation should be evident within 24 hours, depending on yeast strain, brewing procedures and fermentation temperatures.
You can use a larger beer bottle as well, but make sure that you have a stopper and airlock that will fit the bottle first. Also, you cannot heat a beer bottle directly on your stove. Only flasks can handle the higher temperatures.
If you are planning on doing a high gravity/alcohol beer, you can make a larger starter by keeping the 2:1 ratio in mind. You can mix 32 ounces of water with 1 cup of dry malt, for example. Larger starters will allow more yeast cells to form, which in turn will allow you to have more yeast to digest the fermentable sugars in the wort.How do I make a yeast starter? PDF