There are several aspects to yeast; it is the other major factor in determining the flavor of the beer. Different yeast strains will produce different beers when pitched to identical worts. Yeast is available both wet and dry, for Ale and Lager, et cetera. For the first-time brewer, a dry Ale yeast is highly recommended. There are several brands available, including Coopers, Edme, Nottingham, and Red Star. All of these listed will produce good results.
Ale yeast are referred to as top-fermenting because much of the fermentation action takes place at the top of the fermenter, while Lager yeasts would seem to prefer the bottom. While many of today’s strains like to confound this generalization, there is one important difference, and that is temperature. Ale yeasts like warmer temperatures, going dormant below 55F (12C), while Lager yeasts will happily work at 40F. Using Lager yeast at Ale temperatures 65-70F (18-20C) produces Steam Beer, or what is now termed California Common Beer. Anchor Steam Beer ™ was the founder of this unique style.
For more information, see the Recommended Reading section.
Liquid yeast must be and all yeast should be, pitched to a Starter before pitching to the beer in the fermenter. Using a starter gives yeast a head start and prevents weak fermentations from under-pitching. Dry Yeast should be re-hydrated before pitching. Re-hydrating dry yeast is simple.
1. Put 1 cup of warm (90F, 35C) boiled water into a sterile jar and stir in the yeast. Cover with Saran Wrap and wait 10 minutes.
2. Stir in one teaspoon of sugar.
3. Cover and place in a warm area out of direct sunlight.
4. After 30 minutes or so, the yeast should be actively churning and foaming. This is now ready to pitch.
Liquid yeast is regarded as superior to Dry yeast because of the refinement of yeast strains present and little risk of bacterial contamination during manufacture. Liquid yeast allows for greater tailoring of the beer to a particular style. However, the amount of yeast in a liquid packet is much less than the amount in the dry. For best results, it needs a starter. The packet must be squeezed and warmed to 80F at least two days before brewing. One day before, it should be pitched to a wort starter made from 1/4 cup of DME and a pint of water that has been boiled and cooled to 75F (25C). Adding a quarter teaspoon of yeast nutrient is also advisable. Let this sit in the same warm place until brewing time the next day. Some foaming or an increase in the white yeast layer on the bottom should be evident. The Starter process may be repeated to provide even more yeast to the wort to insure a strong fermentation.