Yeast starter isn’t a requirement for brewing beer, but it is a good idea to ensure better fermentation of the beer. Making a yeast starter is the best idea if the yeast is past the ‘use by’ date, if the original gravity is over 1.060, or if pitching lager yeast at temperatures below 65F. In case of possible contamination, keep a back-up of dry yeast ready for brewing day.
Remove yeast from the refrigerator to come to room temperature before creating the starter mix. Many packets take one to three days to ‘puff up’ in the package and be ready to mix.
Sanitize everything needed that will touch the wort: 1000 mL beaker, #9 1/2 rubber stopper, fermentation lock, small piece of tin foil to cover the beaker. A candy thermometer may be useful, as well.
Required ingredients include water, brewer’s yeast, and fermentable sugar, like malt extract. The fermentation lock needs vodka or boiled and cooled water.
Mix the water and sugar together well. Boil on the stove for ten to twenty minutes. It is a good idea to keep track of the temperature of the wort during this pasteurization phase. A temperature of 195F is sufficient. Watch out to be certain the wort does not boil over. Place the tin foil over the beaker opening and remove from the heat.
Cool wort to room temperature or ‘pitching’ temperature, about 70F to 75F. Begin with tap water so the beaker does not crack from the extreme temperature difference. Swirl in cool water, and if needed as the beaker cools ice may be added in a pitcher to bring it to the proper temperature. Be careful not to chill it too much, as this is bad for the yeast.
Seal container with the rubber stopper and fermentation lock. Add the vodka or sterilized water to the lock. Wait one to three days as a yeast cake develops on the bottom of the beaker. The yeast cake will be the milky white layer. Store in a dark place within the temperature limits for the yeast used.
When ready to brew, decant the liquid from the starter vessel. Do not disturb the yeast cake. When the wort and the yeast are at the same temperature, which is usually room temperature, the yeast must be roused into suspension and then pitched into the fermenter.
A few general rules for starter volumes of five gallons follow. Use one pint of water with one half cup dry malt extract to activate yeast. Use two pints of water with one cup of dry malt extract to revitalize yeast beyond the Best Before Date or for high gravity beers. For low temperature 50F to 55F starting fermentation lager beers, use four pints of water and two cups dry malt extract. Liquid malt extract may also be used.
Don’t forget to smell the yeast before pitching it into the wort. It is possible to get some contamination and ruin the batch of beer.
A medium sized pot with a lid may be used instead of a beaker, and a funnel to direct it all into the glass jug with a rubber stopper to hold it, but this requires another set of items that must be cleansed and sanitized. The second step may add contamination, too.
Repeating the starter process can provide stronger fermentation, since there will be more yeast to handle the process before the alcohol overcomes them.
Creating a starter for the yeast helps the beer ferment faster and allows the brewer to work with different types of beer with a higher original gravity or a lower fermentation temperature. This short process helps the brewer have more control over the finished product and create many different beers.