Homebrewing Yeast Starters


By Chris Butt

Deluxe Yeast Starter Kit - 2000 mL

Many homebrewers have experienced brewing an exciting recipe, adding the yeast, and then waiting more than 2 days for signs of fermentation.  These circumstances, and the associated anxiety, are most likely due to “underpitching.”  That is, not enough active yeast cells were present to drive vigorous fermentation within the first 24 hours.
Underpitching should be avoided because it provides an opportunity for unknown microbes (“wild yeast”) to get established and ruin the taste of your beer.  Initiating a small yeast culture the night before brew day is the best way to avoid underpitching, otherwise known as creating a “starter” or “jump” culture.
The combination of several approaches can allow you to optimize the number of yeast.  For example, the types of grain, the original gravity of the wort, the efficiencies of the yeast and brewhouse, the original gravity of the starter, and oxygenation all influence how many yeast result from the starter.  These more technical aspects may be explored in future articles, but the following is a basic starter culture setup for a typical 5-gallon batch:

Items needed for making a Yeast Starter


  1. Yeast
  2. 2-liter Erlenmeyer flask made of Pyrex glass
  3. Funnel
  4. Aluminum foil
  5. StarSan sanitizing agent in a spray bottle
  6. 2 liters of water
  7. 1 cup of dried, pale malt extract
  8. 1-gallon, pourable pot
  9. Stove, but a laboratory hot plate with a stirring function is preferable
  10. Oven mitt or similar form of heat protection
  11. Kitchen sink
  12. At least 5, medium-sized ice packs

Steps to making a Yeast Starter

Method (night before brew day; presuming no stir plate)

  1. Set out yeast to warm slowly to room temperature
  2. Cut 2 pieces of foil.  One for the funnel, one for the flask.
  3. Sanitize the flask, funnel, and foil pieces
  4. Assemble the funnel on the flask and cover the funnel with the foil
  5. Heat 2 liters of water to a boil
  6. Once water is warm, add the extract, and stir as needed
  7. Look out for over boils, but once a stable boil is achieved, continue for at least 7 minutes
  8. Sanitize foil for flask and outer packaging of yeast while waiting
  9. After 7 minutes, pour hot wort into the flask and cover the flask with foil
  10. Plug sink
  11. Place flask in sink, add ice packs, and fill sink to wort level
  12. Swirl flask periodically until temperature is close to ambient
  13. Swirl flask vigorously to oxygenate directly before pitching yeast
  14. Pitch yeast and re-cover the flask with foil
  15. Maintain flask at ambient temperature and swirl occasionally
  16. Signs of fermentation are typically seen by morning and certainly by the end of brew day
  17. Swirl occasionally during brew day
  18. Sanitize and swirl vigorously directly before starting primary fermentation
  19. Pitch starter culture into the real batch of beer

These basics can be improved with different equipment, calculations, and consistency.  For example, do not be surprised if blow-off of the primary fermentation occurs by the next morning.  Be prepared by having secondary containment available. Overall, remember the immortal words of Charlie Papazian: “Relax, don’t worry, have a homebrew!“

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