Best Practices

Best Practices: Yeast Harvesting

Best Practices: Yeast Harvesting

Based on our work with operating breweries, below are our best practices for harvesting our yeast.

1. Ferment

  • We recommend harvesting yeast from beers that have a starting Plato of 18 °P or lower. At higher gravities, yeast are put under significant stress that will decline overall yeast health.
  • Cool wort and aerate using standard brewery procedures.
  • Pitch yeast at a rate of 750K – 1.5M cells/mL/°P (depending on strain).
  • Monitor attenuation.
  • Dry hopping is detrimental to yeast health. We recommend harvesting yeast before dry hopping.

2. Settle (Two Options)

Option 1: Pressure Method

  • Cap the fermentor 1–2 °P before terminal gravity.
  • Let pressure increase naturally as the yeast consume the remaining sugar.
  • Once the gravity has stabilized, increase the pressure to 8 psi by adding CO₂ through the racking arm (positioned upward).
  • Allow the yeast to settle into the cone for 12–24 hours.

Option 2: Soft-Crash Method

  • Once fermentation has subsided (3–5 days), set the fermentor temperature to 57–60 °F.
  • When the target temperature is reached, add CO₂ through the racking arm to increase the pressure to 8 psi.
  • Immediately release the pressure with a quick burst by opening the valve connected to the blow-off. This will help break apart any top-cropping yeast.
  • Wait 24 hours for the yeast to settle to the bottom of the cone.

3. Harvest

  • To prevent channeling, harvest yeast through a narrow diameter (0.75–1ʺ) sight glass and butterfly valve.
  • Verify yeast viability is above 90% before repitching.
  • Pitch yeast directly into another tank or store it in a brink for later use. Keep the yeast cold (32–40 °F) if not pitched immediately.
  • If using a brink, a sterile filter can be used to allow off-gassing. Yeast will be healthiest if stored below 2 psi.
  • When ready to repitch, check viability and calculate the correct amount to match the specs of your next brew.

Cell Counting Tip: London-based strains tend to clump together, making counting difficult. To disperse cells for accurate counts, conduct dilutions in a 0.25 M EDTA solution.