TWO DAYS BEFORE BREWING: POP POUCH TO ACTIVATE YEAST (WYEAST)
Hold pouch in one hand, firmly "clapping" with the other. Feel pouch to make sure that inner bubble has burst. Shake pouch vigorously for a few minutes. Keep pouch at room temperature (65º-80º F) to allow culture to grow. Pouch should swell as fermentation occurs. If pouch swells too fast, move to a cooler environment. Avoid temperatures over 85º F.
ONE DAY BEFORE BREWING: MAKE A STARTER (WYEAST & WHITE LABS
Simmer 2 tablespoons of malt extract & a half dozen hop pellets in two cups of water. Cool briefly and pour into a sanitized 750 ml wine or 22 oz. beer bottle, adding yeast nutrient if desired. Top bottle with an airlock and #2 stopper, allowing starter to cool to room temperature. Shake vigorously to aerate the starter. Use a flame to sterilize the mouth of the bottle and dip the corner of the pouch (Wyeast) or the vial (White Labs) in sanitizing solution. Snip corner of swollen Wyeast pouch or simply unscrew White Labs cap. Pour contents of pouch into bottle and replace the airlock. Store at room temperature. Fermentation should begin within 24 hours.
BREW DAY: PITCH THE YEAST
Once wort has been boiled and cooled, aerate it by shaking / rocking the primary fermenter vigorously for a few minutes to add more dissolved oxygen. Allow about 15 minutes for trub to resettle. Agitate your starter to rouse any sediment and add entire mixture to the wort... The yeast will acclimate to their new environment and use any dissolved oxygen to reproduce. Once the oxygen is exhausted, fermentation begins. This la g time (the time between adding the yeast and the onset of fermentation) should be between 3 and 24 hours.
HELPFUL HINTS REGARDING YEAST STARTERS
Yeast starters are highly recommeded for all Wyeast "smack-packs!" Fermentation will begin and finish much more rapidly bydramatically increasing the pitching rate of your yeast.
If you are brewing strong beers (i.e. with gravities beginning over 1.070), starters are even more highly recommended. These worts require higher pitching rates of yeast and more aeration after cooling.
It is generally not necessary to make a yeast starter for the White Labs Pitchable Brewers Yeast. Still, if you are brewing a lager, high gravity wort or if your yeast is over 6 - 8 weeks old, it is recommended to prepare a yeast starter.
Please note that lager yeasts work noticeably faster if a yeast starter is utilized.
The limiting factors in minimizing lag time are the amounts of nutrients, dissolved oxygen and yeast. Yeast nutrient is recommended for extract based batches, though usually not necessary for all grain batches. Agitating your primary fermenter to oxygenate your wort usually works well for home-sized fermentations. If you have problems with stuck fermentations (beers that do not fully attenuate), you may wish to seek ways of adding more oxygen to your cooled wort (i.e.: aquarium pumps). One pint of actively fermenting yeast starter is sufficient for 5 gallons. Using the Wyeast package without a starter will result in lag times of 2 - 4 days - more than enough time for wild yeast and bacteria to establish themselves. It only takes a few cells of these organisms to make their presence known through filminess, cloudiness, off-flavors or outright spoilage. A healthy yeast starter will begin fermentation faster, retarding many of these organisms through the lowering of pH and production of alcohol and carbon dioxide.