15 June 2010

American Hefeweizen Yeast Starter

Get excited -- a new batch of beer is imminent.  I took the first step this evening by making a yeast starter for the first time.  I'll boil the wort and pitch this starter on Wednesday.

There's two main reasons for doing a starter -- basically a small amount of sanitized unfermented malt to which the yeast is added a day or so prior to brewing.  First, it confirms the viability of the yeast, which can be an issue with shipped liquid yeasts like White Labs' product.  Second, it provides a larger quantity of yeast cells (approximately 200 billion compared to 30-60 billion, according to Northern Brewer) to be pitched into the wort, which should decrease the lag time before fermentation begins and aid the beer in achieving full attenuation.

The starter consisted of the following ingredients:
  • 1/2 cup Briess Dry Malt Extract Golden Light
  • 500 mL water 
  • White Labs Liquid Yeast "American Hefeweizen WLP320"

I picked the Briess Golden Light because it was light and mild -- I intend to use this extract as starter material for a variety of beers, and I don't want it to impart any off flavors to the beer to which it's added.  I mixed the extract and water in an Erlenmeyer flask (a generic borosilicate Pyrex knockoff) and boiled it for about 15 minutes directly on my gas range.  The advantage of this was the wort and flask were sanitized during the boil, but I had to watch it very carefully and regularly adjust the burner to prevent the starter from boiling over.

Next, I cooled the starter in a scaled-down version of the wort cooling method from my Brown Magic ale: a salted ice water bath.  As an aside, I couldn't resist checking the temperature of this bath right before adding the starter.  Indeed, the salt depressed the freezing point of the mixture enough to have it reach equilibrium at about 30 °F Have I mentioned how much I love my Polder instant-read thermometer?  I think it's incredible for brewing, cooking, whatever...hell, if I had a child, it'd be my first choice to check his temperature when he had a fever, but that's neither here nor there...

Finally, I added a sanitized rubber stopper and airlock to the starter.  My brew date is set for Wednesday, so stay tuned to see how the yeast starter improves the process!

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