Yeast Starter

After all the boiling, adding hops, and cooling to fermentation temperatures comes the yeast.  Yeast is a living organism that eats up all the available sugar....bi-product being alcohol and CO2.  A good yeast starter supplies plenty of healthy yeast ready to go to work on your brew. Starters usually results in less lag time from time of pitching yeast to start of fermentation.

Here's the link  Homebrewing wiki on making a starter.  

http://www.homebrewtalk.com/wiki/index.php/Yeast_Starters

 

Yeast Starters

With most liquid yeasts, the use of a starter is necessary in order to create a viable amount of pitchable yeast. Even yeasts marketed as directly pitchable can benefit from the creation of a starter. A starter reduces lag time, before fermentation commences, and can help prevent a stuck fermentation. A typical starter involves fermenting a vial or package of liquid yeast in a small amount of wort a few days before brewing. Dry yeasts typically do not require a starter. Making a starter with dry yeast can be detrimental to their performance because they may deplete their nutrient reserves before pitching.

Contents [hide] 1 Theory 2 Yeast Starter Procedure 3 Yeast Starter Equipment 4 Navigation

[edit] Theory

The recommended pitching rate for most ales is 0.75M-1M cells/(mL*P) and 1.5M-2M cells/(mL*P) for most lagers, where P is the degrees Plato of the wort. Given unlimited oxygen and nutrient supplies (think DAP and Stir Plate), a starter produces 10M-15M cells/(mL*P). Most brewers restrict the Plato of the starter to be 10P or less, citing yeast stress and off-flavors for more concentrated starters.
For example, suppose I want to make a starter for 19L of ale at 12P. This requires 1M cells/(mL*P) * 19,000mL * 12P = 228G cells (228 billion). Since the typical White Labs vial and Wyeast Activator packet only provide 100G cells, it is in my best interest to make a starter. If the starter wort is 10P, then the volume of the starter should be 228G cells / (10M cells/(mL*P) * 10P ) = 2,228 mL.

[edit] Yeast Starter Procedure

Making a starter is relatively straightforward, far easier than brewing an entire batch of beer.

• Allow yeast to come to room temperature. If it is a smack pack, smack it first.
• Bring one pint of water to a boil in a two quart saucepan on the stove top.
• Reduce the heat, add one half cup of Dry Malt Extract (DME) to the water, and mix it thoroughly.
• Gently boil the wort for ten minutes.
• Remove the saucepan from the stove top, and cool it to room temperature, ~75ºF (~24ºC).
• Put the cool wort into an approximately half gallon (~2L) container.
• Cover and aerate thoroughly.
• Pour the contents of the yeast vial or smack pack into the container.
• Shake to mix the yeast into the wort.
• Cover the container with a piece of foil or a loose-fitting cap. Place on stir plate at this time if you have one.
• There will be very little sign of activity, but the starter should be ready in one to three days.
• You may step up the starter by adding additional wort over a period of days.
• After you have brewed your full batch, you may either:
  • Shake the entire mixture again and pitch it into the wort

OR

• Chill the mixture a few hours to a day before pitching to drop the yeast out of suspension
• Decant off the top layer of liquid before pitching just the yeast into the wort

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