What do home brewers and industrial brewers have in common?
They all create wort and pitch yeast to make beer. The processes used may be different, but the one constant thing is “yeast.” Without it, beer production wouldn’t be possible.
Yeast is the most important part of fermentation. This little microbe is the cornerstone of how beer tastes, smells and gets one inebriated. Hence, harvesting and repitching yeast is a common practice in many breweries.
Professional brewers reuse yeast all the time, mainly because the cost of yeasts can be prohibitive in large batches. Brewers can reuse yeast for up to 10 generations if good yeast harvesting and storage practices are followed.
This article will discuss the best and worst yeast harvesting practices for breweries. But first, a quick primer on yeast harvesting.
Yeast harvesting is the process of culturing yeast from a previous batch, yeast pack, or bottle to build up the cell count and pitch it again.
By harvesting and reusing yeast, brewers can save money and even become familiar with a particular strain—what flavor it produces, its standard flocculation rates, what temperature it likes, and its normal fermentation time frame, among other things.
Harvesting can be done by either top cropping (open vessels) or bottom cropping. With the advent of cylindro conical fermenters, bottom cropping has become the norm and is considered the best harvesting method for breweries.
As mentioned earlier, the best yeast harvesting methods can generate up to ten generations from one initial purchase. Here are the best yeast harvesting practices to follow.
The timing of cropping impacts the quality and density of the slurry. So, it’s critical to maintain consistent timing to help keep the desired characteristics of the culture. Using brewery management software helps brewers track these crucial timing windows.
In bottom cropping (Dish Bottom Vessels and Cylindroconical tanks), harvest yeast:
In an open vessel (top cropping), harvest yeast:
Yeast is usually cropped from the bottom of the conical fermenter cone after fermentation and cooling to ensure fermentation has completed and cells have flocculated out of the beer and sedimented at the bottom.
This process produces “3 layers” within the yeast cone, which must be managed.
The best yeast cells to harvest settle in the middle layer. This is the section of the cone you’ll harvest. The middle layer is composed of healthy yeast and dense culture, which is fit for fermentation.
Under perfect conditions, brewers’ yeast can be reused indefinitely.
But in the real world, conditions change each time you harvest yeast for the next brewing cycle. Even minor changes can stack up to the point where the beer loses its flavor or won’t be the same as the first batch.
As such, experts recommend you reuse the yeast for 5 – 6 batches and not more than ten.
The more you reuse the yeast, the bigger the variance you’ll see from the original batch. Plus, there’s always the risk that some wild yeasts or bacteria will creep in with each new generation. This may not be a problem for home brewers doing it as a hobby, but a lack of consistency can be a major problem for breweries. Brewery software can track yeast generations, helping brewers monitor yeast health and fermentation performance.
Yeast should be used as soon as possible and not stored for long periods before reuse. There are many options for yeast storage vessels (also known as brinks). A brink can be as simple as a bucket or a keg modified for pitching.
Whatever yeast vessel you choose, make sure it’s easy to clean and has a way to relieve pressure when yeast is stored.
When it comes to yeast storage, the following practices should be observed:
Before using a yeast storage vessel, disassemble and soak the fittings to wipe out any bacteria and purge the vessel with CO2 to minimize the slurry’s contact with oxygen. Breweries can use brewery management software to schedule yeast usage and monitor storage conditions to ensure yeast remains fresh for the next batch.
To maintain the quality of your beer, avoid these common yeast harvesting mistakes.
Storing yeast in the fermenter leads to uneven temperature regulation. Yeast contains insulating properties, which can cause the middle layer of the yeast cake to overheat. High temperatures reduce yeast viability, shortening its lifespan. It’s better to transfer yeast to a storage brink once harvesting is complete.
When storing harvested yeast, avoid filling the brink to the top. Yeast slurry is rich in CO2, causing it to expand and foam. Always leave some space at the top of the brink to account for expansion, preventing overflow and waste.
There you have it—the best and worst yeast harvesting practices.
By following the best yeast harvesting practices, breweries can improve efficiency, reduce costs, and maintain consistent beer quality. Utilizing brewery software like Beer30 enables breweries to track yeast generations, manage fermentation schedules, and optimize storage processes, ensuring better operational control and product consistency.
