The question of how to save and reuse yeast gets
brought up on a lot of online homebrew forums, so I thought that I'd
write up a little how-to to show people what's worked for me.
*SAFETY TIP* I only use plastic containers to save
yeast because they can withstand the pressure that sometimes
builds up with saving yeast. That way, I can have a
completely sealed container and not worry about any funk getting
in. If you choose to go with glass, make sure you don't
completely seal the vessel. Use a stopper with an airlock
or some other method that will allow pressure to escape.
Make a 6 gallon batch of beer when you know you're going to save
the yeast cake. When you transfer your beer into the
fermenter, leave the last gallon of break material and hops
behind so it doesn't end up in the saved yeast slurry.
Always pitch up in gravity
Only save yeast for 2 to 3 generations to avoid mutations
What's Needed to Save Yeast? All you
need to save yeast is a few 16 oz plastic beer bottles (as seen
above), a funnel, some type of label, and an empty 6-pack holder.
The reason I use plastic bottles instead of glass is simple.
Even though the yeast will be stored in the refrigerator, they are
still working and putting off CO2 at the lower temperature.
The plastic bottles can handle quite a bit of pressure without
bursting. When I pull the yeast out of the fridge on brew day,
often times the bottle is under quite a lot of pressure and is very
hard to press in on.
How Long Can the Yeast be Saved Before Use?
I typically try to reuse my yeast within a month or two, but I've
heard of people using it several months later without any problems.
If you have saved yeast for longer than 2 or 3 months, it would
probably be best to make a starter to check if the yeast is still
viable (which it almost definitely should be). I've had good
luck pitching straight from the bottle at least 2 months after
saving the yeast.
When Should the Yeast be Saved? I
like to keep mostly all of my beers in the primary fermenter for at
least 2 weeks. This gives the yeast plenty of time to eat
through the sugars and clean up any of their byproducts. It
also allows the yeast to drop out of suspension so you can be sure
you're getting most of the yeast at the bottom of the fermenter.
What Type of Beers Can Yeast be Saved From?
I typically save yeast from lower gravity beers like English
Bitters, Scottish 60 /-, American Wheat, Cream Ales, Blond Ales,
etc. By saving yeast from lower gravity beers, you are putting
less stress on the yeast and ensuring that what you end up with will
be fresh and won't produce any off-flavors. NOTE: Always try
to pitch up when saving yeast. For example, don't pitch a
yeast slurry from a 1.060 beer onto one that's 1.040. You may
experience some off-flavors when doing this. Also, I usually
don't save any yeast from beers over 1.060 as a general rule.
By that point, the yeast may start producing undesirable flavor
characteristics. I also only usually save 2 or 3 generations
of yeast before starting over. When saving yeast at home you
can only be so clean and will likely cause some yeast mutation down
the road. I remember having a slurry of WLP002 that was a few
generations old and the beer I made with it tasted more like a
Belgian. It wasn't infected, but the flavor profile of the
yeast had definitely mutated.
Now that I've given you a little background on
what you need to get started, here's my procedure for saving yeast:
Sanitize three 16 oz plastic beer bottles along with the other
equipment you use to transfer your beer.
Siphon your beer off the yeast cake, but be sure to leave about 1/2
inch of beer behind to help get the yeast back into suspension.
Once the beer has been siphoned off the yeast cake, arrange the
sanitized beer bottles in the empty 6-pack holder. You can see
how I distribute them above. With the lid on your fermenter,
swirl the bucket to get the yeast back into suspension with the
little bit of beer you have left. If you still have chunks of
yeast sticking to the bottom, use a sanitized spoon to stir them
into your slurry. If you're using a bucket for a fermenter, be
careful not the scratch it with the spoon. A plastic spoon
would be your best bet here.
When you have gotten your beer and yeast mixed up into a slurry,
place your sanitized funnel into the plastic beer bottles and begin
filling them up. I find that I can fill three 16 oz beer
bottles from a standard yeast cake. You may want to sanitize
an extra bottle if it's your first time saving yeast. I
typically will fill each bottle about 3/4 of the way and then go
back if I have any yeast slurry left over. Once the bottles
are filled, screw down the sanitized cap fairly tight to ensure a
proper seal. Dry off the top of the cap and apply a label that
gives the strain of yeast and the date it was saved. I like to
use the little round garage sale stickers that come in a variety of
colors. This helps me keep track of the different strains
The above pictures show what the yeast slurry looks like after it's
settled and been in the fridge for awhile. You can distinctly
see the yeast on the bottom of the bottles. The pictures on
the right show the different strains of yeast that are stored in my