Collecting yeast

[Labratbrew]

Had a buddy tell me today that he collects the trub and keeps it in the fridge and when he's ready to reuse it he adds yeast "food" to get it started again.... Does this work?! Seems too easy!

 

[FarmBoy530]

Yes it does, but its a bit more tricky then that. Go to the Brewing Network and listen to the brewstrong show on how to rinse yeast.

 

[NordeastBrewer77]

or read the sticky here on 'yeast washing'.

 

[Dr. Francois]

I think it really is that easy.

Yeast washing seems to be a great process to encourage pure sampling and guarantee prolonged storage, but gloopy slurry has been used for hundreds of years. If you'll be using the gloop quickly, I don't think you have much to worry about. The main concerns I can see are encouraging further growth of a small infection (not noticeable in the first batch) and spoilage of the fats and proteins in the trub.

I use dry yeast, so it's almost never worth it to re-use yeast. I would consider the process if I had a low gravity and high gravity beer planned...I would use the low gravity beer to build an army to eat the high gravity.

If I paid 8 or 9 bucks for a yeast sample, I'd take re-use much more seriously.

 

[FarmBoy530]

I know its talked about a lot so I don't want to extend this to far. But why would you want to repitch on a slurry of dead yeast and stuff that you didn't want in your last batch? It fell out of your last beer because you didn't want to bottle it Don't put clean wost on top of it. Just rinse that crud away and use the same, good, clean yeast. This is just the way I think about it.

 

[Xier]

Just think of it like this:
When you fermented, the yeast dominated your brew. You started with a pack of 100% pure yeast. But, here is the thing, other stuff was in your fermenter as-well. As you brew, it all grew and multiplied. In one batch's time it wasn't enough to be a problem, the increasing alcohol content kept much of it down also.

Now, you drain out your beer and what is in there? Maybe 95% yeast (a guesstimate) and 5% of other living stuff. When you pitch this into fresh wort, those other organisms will not be held back like they were before by the alcoholic soup of beer.

Then, they get up to let's say 10% in that batch. If you keep re-using the post-fermentation gunk, their numbers will keep increasing till they hit a natural equilibrium with the yeast.

So, what can you do about it? Well, you could streak it on agar and collect a pure colony of yeast. Then, pitch it into larger and larger starters till you hit a size suitable for fermenter pitching.

 

[NordeastBrewer77]

Just think of it like this:
When you fermented, the yeast dominated your brew. You started with a pack of 100% pure yeast. But, here is the thing, other stuff was in your fermenter as-well. As you brew, it all grew and multiplied. In one batch's time it wasn't enough to be a problem, the increasing alcohol content kept much of it down also.
Now, you drain out your beer and what is in there? Maybe 95% yeast (a guesstimate) and 5% of other living stuff. When you pitch this into fresh wort, those other organisms will not be held back like they were before by the alcoholic soup of beer.
Then, they get up to let's say 10% in that batch. If you keep re-using the post-fermentation gunk, their numbers will keep increasing till they hit a natural equilibrium with the yeast.

if you're sanitary during your brewing and fermenting process, your yeast in the cake should be the same as that you pitched, just one generation down..... people reuse yeast all the time without your scenario happening. the idea of slanting is great, but definitely not necessary to reuse yeast.

 

[icanbenchurcat]

if you're sanitary during your brewing and fermenting process, your yeast in the cake should be the same as that you pitched, just one generation down..... people reuse yeast all the time without your scenario happening.

People reuse yeast a FEW times. There is the inevitable wild yeast and wild bacteria that will creep into your culture, which is fine if the style permits. For an ale or lager, this wouldn't b acceptable after a few generations.

 

[NordeastBrewer77]

People reuse yeast a FEW times. There is the inevitable wild yeast and wild bacteria that will creep into your culture, which is fine if the style permits. For an ale or lager, this wouldn't b acceptable after a few generations.

oh, for sure, you don't wanna take washed yeast beyond a few generations because the yeast will begin to mutate into something they weren't as they go from generation to generation, but you can still wash and reuse yeast without risking contamination. saying that reusing yeast is a risk is just silly.

 

[Xier]

oh, for sure, you don't wanna take washed yeast beyond a few generations because the yeast will begin to mutate into something they weren't as they go from generation to generation, but you can still wash and reuse yeast without risking contamination. saying that reusing yeast is a risk is just silly.

Well, there is of-course some mutation happening, but that would likely not be of too much concern. Even big companies like Wyeast and such would be in big trouble if yeast mutation was happening that quickly. What causes the yeast to become unusable after a few batches is the ever increasing contaminant population. Of-course, this could be desirable in certain styles, like lambics.

What is used during normal beer brewing is an artificial niche. In nature, yeast can not sustain such a strong dominance over other other micro-organisms. Inevitably, unless you are sterile to the point of laboratory grade equipment and procedures, these other things will be in your brew and will continue to increase in number with each re-use. That will happen till they level out into a more natural niche like you would find in a lambic fermentation or some other equilibrium which would likely be terrible.

 

[FarmBoy530]

Well, there is of-course some mutation happening, but that would likely not be of too much concern. Even big companies like Wyeast and such would be in big trouble if yeast mutation was happening that quickly.

You can change flocculation in 2 generations depending on when you harvest. The important thing to remember is, if you are very sanitary, you can reuse yeast 3 or 4 times without a major worry.

 

[shadows69]

I can tell you for a fact you can use yeast at least 7 time per gen. I used the same washed yeast 1056 for a year now just re-washing it between batches. Washed yeast starts faster and no off flavors to speak of. Bottom line it saved me a lot of money with gas going up and all. Food for thought.

 

[NordeastBrewer77]

You can change flocculation in 2 generations depending on when you harvest. The important thing to remember is, if you are very sanitary, you can reuse yeast 3 or 4 times without a major worry.

exactly my point. washing and reusing yeast isn't a concern (infection-wise) if you're doing it in a appropriate manner. i'm not saying that there's not a chance of other organisms being present, but you're more likely to have your reused yeast mutating before anything else takes hold. i've seen flocculation and flavor characteristics change within a couple generations, i've yet to see an infection in a beer, and i reuse yeast quite regularly.

 

[FarmBoy530]

Not to mention its fun. If people are getting bad beer from it they should stop doing it. Its definitely a better brewing practice then pitching on trub. Some say its better then using a starter. Some like a starter with the right amount of yeast more. my only problem with it is it doesn't allow you to know your yeast count.