Among the four main ingredients in brewing, yeast is the only one that can be reused from one batch to the next — making effective yeast management a key skill in every brewery.

Brewers are constantly looking to reuse the yeast to save money and produce a consistent beer, batch after batch. With each generation, a particular yeast strain tends to mutate over time, resulting in beers with more depth and complex flavors. But to achieve that, a brewer needs to know when and how to harvest yeast, how to crop it correctly, and how to store yeast for reuse in the next batch. If done correctly, yeasts can easily last up to ten generations, thus offsetting the cost from the initial purchase.

Yeast cost per hectolitre change with repitching

Choosing Quality Yeast for Reuse in Brewing

It all begins with choosing the right yeast product if you’re looking to re-pitch. Always look for a premium product and choose one that is clean and has low levels of wild yeast and lactic acid bacteria (LAB).

Unless intentional, it is recommended to go with yeast that has a low cell count of bacteria and/or wild yeast, so that it can be used for multiple generations without the risk of infection from growing unwanted colonies. Read the technical data that comes along with the product and look for properties such as LAB, wild yeast, etc. These values are often denoted in cell counts, so shoot for the one that has less.

Yeast Cropping: Best Practices for Small Breweries

It’s essential for a brewer to know which sections of the fermenter cone to harvest. Proper yeast cropping not only improves fermentation outcomes but also supports consistent yeast viability and vitality over generations.

To summarize, when a fermenter is ready for a harvest, it is categorized into three sections: top, middle, and bottom. The bottom of the cone mostly consists of trub and dead yeast. The middle is where the ideal and healthy yeast sits, and this is what needs to be harvested. The top portion consists of poorly flocculated yeast with a thin consistency, and therefore can be ignored.

When cropping, always dump the initial bit of trub and dead yeast. Once that is done, collect all the slurry from the middle portion that has a thick consistency similar to dough or pancake batter. This slurry is ideal and packed with healthy yeast cells. Once the slurry starts to thin out, shut off the valve — at this point, you may be drawing out beer and don’t want to shave off your final beer yield.

Avoid the Tunneling Effect when drawing yeast from your fermenter during harvesting

Make sure to draw the yeast out slow and easy. Rushing the process might draw the yeast too fast from the cone, creating a “tunneling effect” – a channel that forms through the yeast in the fermenter cone during harvesting, mixing beer with the yeast slurry. This will cause you to end up drawing beer and a thin layer of yeast.

Check out our article on Yeast Harvesting Best Practices HERE

Step-by-Step Guide: Harvesting and Cropping Yeast

• Step 0: Make sure all of your fittings and equipment are sanitized/sterilized as necessary
• Step 1: Pressurize the tank to about 5 PSI to prevent vacuum
• Step 2: Transfer the slurry from the bottom of the cone into a yeast brink. If needed, use a sight glass to monitor the consistency of the slurry
• Step 3: With a bleed-off valve, dump the initial bit of trub and dead yeast
• Step 4: If tunneling happens, wait for the yeast to settle and try again
• Step 5: Once done collecting, record the weight and store appropriately

How to Store Harvested Yeast for Reuse

There are many tools and vessels to store the harvested yeast (a ‘brink’). It can be as simple as a plastic bucket to a fancy yeast brink that has mounted valves and pressure gauges. Whatever the vessel, always make sure that anything that comes in contact with yeast is either sanitized or sterilized.

• Store it cold: Ideally between 0°C and 4°C, which helps prolong yeast viability and minimize mutation or contamination risk.

• Monitor Head Pressure: Pressurize the brink (if possible) to about 2–5 PSI. Do not exceed this limit as yeast should never be stored under excessive pressure, which can create a stressful environment for the cells.

• Avoid Harvesting from High Gravity Beers: It is always recommended to harvest yeast from beers that are about 4–6% ABV. Anything beyond that results in stressed yeast cells that may either stall fermentation or create undesirable off-flavors.

• Re-pitch: Most brewpubs aim to reuse harvested yeast within a week to maintain optimal viability and fermentation performance. While some breweries may stretch storage up to 10–14 days under ideal conditions, it’s generally not recommended without regular lab checks on yeast health, viability, and vitality.

Yeast brinks come in many shapes and sizes

Good yeast storage practices are critical to extending reuse and reducing the cost per hectoliter in any small-batch brewery.

With practice and rigorous sanitation, yeast harvesting becomes a straightforward process for any brewery. This technique not only drives significant cost savings but also allows brewers to maintain unique house yeast strains, creating distinctive flavor profiles that set their beers apart.