Reusing Yeast

[TylerPrime]

So I know from a financial standpoint, it's probably worth while to reuse yeast.

That being said, what about from a quality stand point? After a few generations, I'd assume the yeast takes it's own characteristics. What about after 5-10 generations? Is it advisable to re-use your own yeast to that extent?

I've heard that after a few generations, the yeast can/will become infected with wild yeast/bacteria and will eventually start to produce bad batches. Is this true as well?

Thanks

 

[jimmykx250]

I re pitch all the time. I think the yeast companies put that info out there. IF your sanitation is good i dont see where infection would come from? I let it ferment out normally around 10 days rack to secondary before any dry hopping and depending on the yeast its pretty easy pickings from there. Layer on the bottom is calling your name!

 

[ProblemChild]

Takes practice and strict attention to sanitation/sterilization, but once you get the hang of it, is worth it.

Dedicated storage is helpful though....... Don't want it to get pushed around in the fridge and maybe sit too close to the door.....

 

[jimmykx250]

Another point to bring up is don't store if you are not using it frequently. Saving a slurry to sit in the fridge for 2 + months doesn't make much sense. Also for storage i use small glass mason jars leave the lid loose then place in a large thin bag and tie a loose knot in the top. Ive had one slurry pop the top in the garage fridge.

 

[RPh_Guy]

IF your sanitation is good i dont see where infection would come from?

Air.

But most people seem to have success re-pitching so apparently it's not much of an issue.

 

[balrog]

I build starters. I overbuild using a calculator (like this) to get 100b more than I need on brew day. I make in advance, let it sit in a cool place a day before use, decant off some clear-ish liquid, swirl up the rest, save off the proportional amount to save 100b and pitch the rest. I store the 100b saved in a 16oz mason jar and have successfully reused up to 6 times, and up to 4 mo old. Only once have I had an issue and it was clear when I went to make a starter that the save 100b mason jar was mangy-orangutan-flatulent-yak-decaying-octopus bad.

 

[TylerPrime]

Thanks for the details. Looks like I'll be harvesting my own yeast when I bottle in a day or two.

 

[homebrewer_99]

Whenever I make a starter with new yeast I will decant some of it into the old WLP vials and use them to make new starters.

I also harvest after racking if I plan on brewing another batch. Sometimes (depending on my mood) I will brew the same beer (with harvested yeast)...3 batches in 3 weeks...and blend them after the last one is ready to keg.

 

[stieg000]

If your making a similar beer you can dump the new wort on the yeast cake. I've done this a few times.

 

[TGFV]

I've been re-pitching some of my yeasts for 6 generations (my saison yeast), usually aplitting the cake in half.

One half goes to a saison I can save the yeast from, the other half a wierd one I wouldn't want to re-use.

Other than that I have only had some yeasts hit 3-4 generations. (Notty, MJ witbier, 2 coopers for country punch, Scottish ale)

 

[jalc6927]

For $3 per pack of dry yeast almost not worth it in my humblest of opinions

 

[waldoar15]

For $3 per pack of dry yeast almost not worth it in my humblest of opinions

For something like US05, I agree.

It's different when you're getting to lager yeasts or liquids though. Even with 34/70 you're pitching a couple of packs and I tend to reuse it a few times.

 

[mirthfuldragon]

I think I am on my 4th batch with Omega Belgian W (trappist high gravity) - a tripel, a quad (including adding yeast back when bottling), and now a big witbeer (6.5%), which would have been something like 8 or 9 packs of liquid yeast total.

At least for the vigorous Belgians, if there is cross-contamination, I can't tell. Once you get to the point of making starters and harvesting/re-using yeast, the ability to over-build and pitch fresh, aggressive, active yeast (plus good sanitation practices) is going to compensate for the risks of contamination.

For starter wort, I upped the mash size on a pale ale and then pressure-canned a dozen quarts of 1.035 second/third runnings. Note: you parents or grandparents may have a pressure canner sitting unused in the basement, if you ask nicely. Mine is still in the original box, along with the original receipt dated four years before I was born.

 

[Northern_Brewer]

That being said, what about from a quality stand point? After a few generations, I'd assume the yeast takes it's own characteristics. What about after 5-10 generations? Is it advisable to re-use your own yeast to that extent?

I've heard that after a few generations, the yeast can/will become infected with wild yeast/bacteria and will eventually start to produce bad batches. Is this true as well?

There's various considerations. One is just the accumulation of mutations that affect both brewing performance and general health - some strains are more prone to mutations than others, but most pro brewers repitch their yeast about 8-10 generations before starting from scratch again.You can go out to maybe 20generations with some strains, but it is very strain dependent, and aiming for 8-10 is more normal

Talking of which, another problem is trying to repitch a blended yeast, the different strains grow at different rates and so the mix of the blend drifts with each generation until one yeast dominates that probably isn't very representative of the original blend. Most liquid yeast are single strains (some aren't though), but a lot of dry yeasts are blends, most notably Nottingham. Having said that, some British family brewers have been repitching their yeast for decades now - but they are complex multistrains that have reached an equilibrium between the different parts. So with blends you might be only able to repitch for 2-3 generations before it goes "off".

Then you also have the possibility of accidentally selecting for certain characteristics - for instance if you harvest from the top of the trub, you'll tend to select for the slow-flocculating variants, whereas if you harvest from the bottom you'll select for fast flocculation mutants that will probably not attenuate quite as well.

And then yes, there is always the possibility of getting infection, but in general that's the least of your worries as long as you're reasonably clean.

 

[Jtk78]

I'm also in the over making starters and saving some for another day camp.

 

[CA_Mouse]

I always over-build my starters and store the excess in a 50% sterilized water/50% Glycerol solution in an auto-claved test tube. Rule for this is a freezer with no defrost cycle and/or a storage container with ice packs around it (to keep the temperature of the test tubes constant). I've used some strains as long as three years after storing them.