Pints for Prostates

Monday, November 28, 2011

How to Make a Yeast Starter

The night before brewing our third beer, a Chinook IPA, I got a chance to make a yeast starter for the first time. I wanted to make sure that the liquid Wyeast I purchased nearly a month earlier was still viable. The yeast pack was puffed-up already and was in the refrigerator. Making a yeast starter gave me a chance to learn about and practice the process.

For many brewers, making a yeast starter before brew day is a typical part of the process. A yeast starter can 1) increase the yeast count and 2) ensure viability of the yeast. I have read forum posts by homebrewers that are concerned that the fermentation does not appear active, which necessitates a drive to the local homebrew shop to buy more yeast. Making a yeast starter will reduce the lag time between when the yeast is pitched and vigorous fermentation.
Yeast Starter
A yeast starter is a basic beer without flavor. You use water, dry malt extract (DME), and yeast. The steps are as follows:
  1. Mix 2 cups of water and a 1/2 cup of DME in a sauce pan. (This measurement will differ depending on the size of beer batch and the beer style. For a typical 5 gallon batch of beer, this amount is fine--about 192 billion cells. Strong beers require more of everything.)
  2. Boil the wort for 10 minutes.
  3. Cool the wort in a cold water/ice bath to 70 degrees.
  4. Pour wort into sanitized glass container, using a sanitized funnel.
  5. Add yeast.
  6. Cover container with sanitized tin foil (which allows some oxygen in for the yeast).
  7. Swirl mixture to aerate.
  8. Place in warm, dark/dim area for 24 hours or so.
Carbonation on top, Yeast cake on bottom
I thought there would be a thick slurry of yeast. Instead, what I had the next morning is carbonation on top and a small yeast cake on the bottom. This is normal. It smelled like bread yeast and had a slight vinegar or wine smell (though I used a wine bottle so that may be the cause).

I pitched the whole yeast starter, as opposed to decanting the liquid and adding just the yeast cake. I pitched when the Chinook IPA was cooled to 100 degrees (maybe less with the refrigerated spring water I added). It is important to "pitch up," which means that the wort should be warmer than the yeast. My yeast was at room temperature (65 degrees) and the wort was between 70 and 100 degrees.

The stopper on the fermenter was starting to bubble when I woke up the following day, which suggests that the yeast is healthy and doing its work.

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