Making a wine yeast starter

The following instructions are for making a 700 mL starter in a 1000 mL flask using a Wyeast Activator pack. If you are propagating a vial of White Labs pitchable liquid yeast or a pack of dry yeast, you can skip the incubation phase in step #1.

Refer to the note below for making a larger starter in a 2000 mL flask.

  1. Break the inner pouch to activate the yeast; ideally, the yeast would be allowed to incubate for 6 to 8 hours, but it can be pitched immediately.
  2. While the yeast incubates, measure 600 mL of water, boil briefly in a covered pan to sterilize, and allow to cool to room temperature, still covered.
  3. While the water cools, sanitize the flask, stopper, airlock, yeast pack, and a pair of scissors.
  4. Pour 600 mL of sterile water into the sanitized flask. Add grape concentrate to bring the volume to 700 mL.
  5. Measure ˝ teaspoon of yeast nutrient and add to the must in the flask. Gently swirl the flask to dissolve the nutrient and aerate the must.
  6. Using the sanitized scissors, cut off a corner of the yeast pack and pour the yeast into the flask.
  7. Seal the flask with the sanitized stopper and airlock; add approximately 1 teaspoon of water or vodka to the airlock.
  8. Allow the yeast starter to ferment for 1 to 2 days at room temperature. During yeast starter fermentation the airlock may bubble, but often the amount of foam on the surface will be small or nonexistent. The best indication of yeast activity is a layer of white sediment on the bottom of the flask.
  9. To pitch the starter into the main batch, swirl the flask to pick up the sediment at the bottom, and pour it into the fermenter – this is the best method to use if the starter is still actively fermenting. Alternately, you may wish to decant the spent wort from the flask and add only the thick yeast slurry at the bottom. To decant the spent must – chill the flask for several hours to cause the yeast cells to settle out of suspension. Remove the stopper and airlock and carefully pour out and discard the liquid portion, leaving as much thick slurry as possible in the flask. Before pitching, add 100-200 ml of boiled and cooled water to the flask and swirl vigorously to dislodge the slurry.

2000 mL starters

Follow the above procedure, but use the following quantities:

1200 mL of boiled, cooled water

200 mL grape concentrate

“Building up” twice

To increase pitching rates even more for larger batches, allow the starter to ferment completely. Chill the flask to cause the yeast to settle, then decant the spent wort and add a greater quantity of boiled and cooled water and grape concentrate at a 6:1 ratio. Remember to follow strict sanitation procedures!