Thursday, November 10, 2011

How (and why) to Make a Yeast Starter

Making a yeast starter for your homebrew is a fast and easy way to gain more control over your final product and ensure the results you are after.

Let's start with the "Why" of making a yeast starter for your homebrew.  First, it should be acknowledged that making a yeast starter is by no means required.  Most beginners, including myself, have pitched the dry yeast packets that come with a basic kit and achieved acceptable results.  Some opt for the liquid yeast varieties from either White Labs or Wyeast and the results are sometimes even better.  So why ever bother with the extra steps of creating a starter?  Below are a few reasons that I think make the exercise worthwhile:
  1. Build up the cell count.  The more active yeast cells you have the more they can get to work and do their job of converting sugar to alcohol.
  2. Full fermentation.  With more active yeast cells you have a better chance of achieving your desired finishing gravity.  Let's say you start off with an original gravity (OG) of 1.051 and want to end up at 1.012.  If you under pitch the yeast and the rising alcohol content overwhelms the active yeast you could stall it out before reaching your final gravity and not reach the desired alcohol content.
  3. Reduce risk of contamination.  The faster your yeast is able to do it's job the less time your beer has to be exposed to contaminants.  The less lag time you have the less chance of contamination.
  4. Better tasting beer!  Yeast does more than just convert sugar to alcohol.  It contributes to the overall taste of your beer and when it is pitched in the proper ratios it can help reduce off flavors.
Let's move on to the the "How" of making a yeast starter beginning with the equipment and supplies you will need to get started:
  1. 1 gallon glass growler or a 2 liter glass pyrex flask
  2. Rubber stopper and airlock
  3. Approximately 1/2 cup light dry malt extract (DME)
  4. 1 quart of water
  5. Aluminum foil
  6. Medium-sized sauce pan
  7. Yeast appropriate for your homebrew recipe
Making a yeast starter is actually very simple.  In fact, if you've made even one batch or beer you have already done most of the basic steps.  While there are variations galore on how to do this task, I find the steps below are easy to follow and yield consistently good results.  Begin your yeast starter at least 2 days before you intend to brew.
  1. Start by removing your liquid yeast pack or vial from the refrigerator.  If it is a "smack-pack" go ahead and activate as per instructions.  Your yeast should have several hours to warm to room temperature before moving to step 2.
  2. Bring 1 quart of water to a boil.
  3. Add 1/2 cup of light dry malt extract (DME) and stir until dissolved.
  4. Boil for approximately 15 minutes.
  5. Cool the DME and water mixture (wort) by placing the saucepan in sink and surround with ice water and stir gently until liquid is room temperature or below 80 degrees.
  6. Transfer cooled wort to carboy or flask.
  7. Add (pitch) yeast to wort.
  8. Cover with aluminum foil and shake vigorously to aerate.  You can also choose to oxygenate the mixture.  Instructions can be found HERE.  Note: reduce time to 10-15 seconds.
  9. Add rubber stopper with airlock and allow to begin fermentation at room temperature.
  10. You should see fermentation activity within 24 hours if not much sooner.
  11. You now have your yeast starter!
  12. When it comes time to pitch your yeast in you homebrew recipe you can simply pour the entire mixture into the fermentation vessel or use this optional method:
  • Optional - 24 hours prior to brew day you can transfer your wort to the refrigerator.  This will cause the yeast to separate or sink to the bottom of the container.  Remove from refrigeration and pour off most of the top liquid.  Let the remaining yeast warm to room temperature and pitch the resulting yeast slurry into your wort at the appropriate time.  Removing the extraneous liquid may reduce off flavors.  
Well, that's it.  I hope you find this a useful process in your homebrewing adventures.  Happy brewing!

See these links for more information on creating a yeast starter:

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1 comment:

  1. Just did this the other day. Fermentation in the car boy now is going wild!