Can Beer Yeast Be Reused? How to Repitch Yeast

A common question among brewers large and small pertains to the use, and reuse, of yeast.  Yeast may have the single biggest impact on beer. In terms of flavor and aroma profile, of course, but also in terms of length of fermentation, CO2 production, and of course alcohol content, yeast is the king of beers.

Given the weight and gravity of the role yeast plays in beer, it can be tricky to determine which type of yeast to use, how to pitch it, and if you should repitch it (as well as how to do that).

With so many concerns, it can be helpful to have a one stop complete guide to the issue of the use and reuse of yeast in beer.

Click here to Get access For Free to a detailed manual (25 pages) describing all the steps of the yeast repitching process!

Dry Yeast vs Liquid Yeast

The first concern of brewers is often whether to use dry yeast or wet yeast. It was once believed that dry yeast was only for novice brewers experimenting with first batches. Liquid yeast was the only way to go for serious brewers, and dry yeast was for amateurs. Those days, fortunately, are past.

Still, there are advantages and disadvantages to both.

Dry yeast has become quite the darling of some brewers, and for good reason. It is cheaper, easier to use, and it comes packaged already sterile, strain-pure, and ready to pitch.

It is also durable and has a long shelf-life. Dry yeast can be stored in a cool, dry place for up to 3 years.

The downside to dry yeast is that only certain strains of yeast can be dried, so dry yeast will always be limited to fewer strains, which means fewer experimentation and variety for brewers. Indeed, all commercial brewers use a liquid yeast, and most smaller brewers are fashioning their beers after at least some rough version of those commercial brewers.

Wet (or liquid) yeast then has the obvious advantage of having far more options in terms of strain, which allows brewers to experiment and explore, cross strains, and find that perfect batch to match every time. Consistency, after all, is key.

Test Your Yeast

 

The downside to liquid yeast is that it does take more knowledge and experience to work with, which takes time, patience, and a dedication to your craft. It also has a much shorter shelf life, only lasting 3 months from the time it is cultured, and losing viability the whole time.

It is critical with liquid yeast that you keep a consistent cell count throughout its time on your shelf and not in use.

Finally, liquid yeast is more expensive than dry yeast, making it one of the pricier ingredients on the brewer’s list.

Alas, there is a solution to that expense: repitch your yeast.

Repitching Yeast

The truth is you can repitch dry yeast or liquid yeast, so if you do find a dry yeast that you absolutely love, you can save even more money by going with your dry yeast and then repitching it a few times.

What is repitching?

Repitching yeast is essentially using your yeast again once you have already pitched it into a batch of wort and the yeast has done its job.

Some naysayers will talk about the disadvantages of repitching yeast and advise against it, but the disadvantages, while present, are all avoidable and manageable when understood and prepared for.

Disadvantages to Repitching Yeast: Myths and Truths

Contamination

The number one concern of naysayers to repitching yeast is the potential for contamination. But here it is important to note that contamination only occurs in the beer due to outside factors such as unsanitary equipment, exposure to oxygen, or other contaminants in ingredients. Then, the beer contaminates the yeast.

The easiest way to avoid contamination of your yeast for repitching is to ensure proper sanitation and procedures during the brewing process.

And the truth is if you have a contaminated batch of beer, you will have much more to worry about than contaminated yeast. You will have to toss a whole batch of beer!

So let’s avoid contamination at all costs.

Yeast Vitality and Viability

The argument here is that yeast becomes less vital and viable each time it is repitched.

This worry is far from true.

The trick to handling the yeast vitality and viability issue is to ensure you have proper equipment to track your yeast cell count and assess your yeast’s viability.

Repitching Complications

The only pitching complications you will hear of, and they will be the same with a first pitch or a repitch, with liquid yeast, will be with yeast vitality and viability.

The primary concerns is that if you have second or third (or beyond) generation yeast, the yeast cell count, and therefore the viability, of your yeast, could be affected. This would mean that while you think you are pitching one amount, you are actually underpitching. The danger of trying to compensate for that error is in overpitching.

There is an easy solution to either of these concerns, though, and that is to have the proper lab equipment on hand to measure your yeast cell counts, vitality, and viability.

That way, with any generation, you can ensure a consistent pitch.

Advantages to Repitching Yeast

The advantages are myriad for a brewer.

The primary advantage to repitching yeast is in cost. Yeast can typically last up to five generations of repitching, and oftentimes even more, saving you a ton of money on pitching fresh every single time, either dry or liquid.

The next advantage, and this is a big one, is in consistency. If you have a batch of brew you love, odds are great that it is largely because of the yeast. Reusing that yeast then over and over again, checking your cell counts and viability along the way, is more likely to get you a spot on match to that original batch.

Another advantage of reusing yeast is that repitched yeast often performs even better in the second or third pitch in terms of fermentation and flavor compounds. If you liked that first batch, you’re gonna love the second batch!

The key then, to repitching yeast is to ensure sanitary equipment and procedures throughout and to take regular and accurate measurements of your yeast cell count and viability. Once you’ve done that, you’ve essentially eliminated the downside and can only benefit from the upside.

Yeast Management

So, how do you repitch yeast?

The first step to repitching yeast is called yeast cropping. This is where you harvest your yeast from a previous fermentation.

There are two ways to crop (or collect) yeast from your beer once it’s done its job fermenting.

For ales, you will crop from the top of the tank.

For lagers, you will crop from the bottom of the tank.

Cropping from the bottom can be much easier because the yeast can settle in the conical fermentor cone after fermentation and cooling.

Once all the cells have collected at the bottom of that cone and the beer has cooled, you know the yeast is ready to be cropped.

Typically, yeast will settle into three layers:

1.     Trub – Bottom Layer

That first, bottom layer will be dark brown and beige in color. You want to dump this layer entirely as it is mostly dead yeast cells and leftover proteins.

2.     Ideal, Healthy Yeast – Middle Layer

Layer 2 is the layer you want. It will be light beige to tan in color, and it is full of the healthy, fit for fermentation yeast. This is the yeast you want to crop and reserve for future pitching.

3.     Poor Flocculating, Thin Yeast – Top Layer

That top layer is very light, and it is the thin, poor flocculating yeast that is not good for repitching. You can toss that.

When yeast cropping, ensure you don’t have tunneling, which is when the yeast allows for a tunnel to bore into the cake and allow beer to pass through. Begin your cropping very slowly, which will force tunnel collapse and proper collection of the healthy yeast and removal of the rest.

Storage of Cropped Yeast

Remember that you are dealing with live and active yeast, so it will only last for 3 months from the time you crop it. Plan to repitch within that time, and then you can crop and store for another 3 months.

Store cropped yeast in a container called a brink. A yeast brink is a sanitized, and sanitizable, container used to contain cropped yeast under CO2 but not under extreme pressure.

You can use an unscratched plastic bucket or a stainless steel bucket, as long as you have an airtight lid.

Ensure you don’t fill your brink to the rim as the CO2 still present in your cropped yeast (now in slurry form) will tend to expand.

Keep your yeast in a cool, dark place with no access to light, alcohol, or oxygen. Any exposure to any of these elements will encourage premature fermentation of your yeast cells, causing them to die sooner.

When you pull your yeast for repitching, take an accurate measure with lab equipment. If your culture is 70% viable or higher, you’re good to pitch.

How to Repitch Yeast

Two methods exist for repitching yeast. You can either pour it directly into your wort or you can inject the yeast into the brew during transfer.

To pour directly in does not require much. It is pretty much like it sounds, and is efficient and effective for small breweries.

Simply ensure your wort has cooled all the way down or your yeast will get overheated and die. Then, add your wort to your fermentation tank and pour the yeast in over the top manway.

This method is much more challenging for larger and more complicated fermentation tanks, at which point you will need to inject the yeast.

To inject the yeast, you must pressurize the yeast brink. Attach a valve to the brink and connect it to the chilled wort as it enters the fermentation tank.

Sometimes, brewers want to use a pump to inject, which is typically not advised as it can overpressurize the yeast or yeast could leave the device as it is pumping.

If you must use a pump, ensure the PSI on your pump matches the PSI on your brink, usually between 10 and 15PSI.

How Much Yeast to Pitch

The most important question here relates, again, to your cell count (concentration) and viability. You want to ensure you have more than 70% viability, and ideally higher, up to 90%. Remember, higher viability means better fermentation and flocculation. You want a nice thick slurry.

Measure your cell count concentration, aiming for .5 – 1.25 million cells/mL/P.

From there, the rule of thumb is 1L of slurry per hL of beer.

Check out our Yeast Target Pitch Rate Calculator!

Yeast Starter

It is also a good idea to get your yeast going in a yeast starter. Essentially, you’ll be pitching actively fermenting beer into your wort, which will supercharge your wort to get started fermenting, rather than pitching just the yeast and waiting for the action to begin.

You can make a starter easily with canned condensed wort.

Combine the can, add 16 ounces of cool water, add your yeast, and cover the container with sanitized aluminum foil for 24 hours.

Then pitch into your wort.

Easy!

Equip Yourself

As you can see, the biggest asset you can invest in to save you time and money when it comes to repitching yeast is the proper equipment to measure your yeast concentration and viability, such as an automated yeast cell counter.

An innovative lab equipment for these purposes will measure accurately, quickly, and conveniently, making your job in brewing easier, not more of a headache. Having the proper equipment will help you on your journey to repitching yeast, saving time, money, and energy in the long run.

Cheers!

Are you still pitching fresh yeast every time? By reusing your yeast, you can save up to hundreds of thousands of dollars per year on just yeast alone!

Join the hundreds of brewers from all around the world using the Smartest Automated Yeast Cell Counter! Request a Free Demo Account today and experience firsthand how Oculyze can take your brewery to the next level! 

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