Growing Yeast

[monsteroyd]

Hi,

I am thinking of washing some yeast from the next batch of beer after my stir plate gets here. And then I was thinking, why not just start with nice clean yeast, water, and DME? I mean just grow the yeast right from the dry packet. Couldn't I then just feed it and split it, then feed those and split them, and just keep doing that when ever I needed yeast for a batch of beer? Wouldn't that solve the generational problem, the fact that you can't really keep washing the yeast more than say 5 times before you need to start fresh again? Just curious, and I don't know what I am talking about at all, just thinking that all I ever hear about is washing yeast from used trub, but never hear about just growing your own yeast. So there is probably a good reason that it is not done. My Mom used to do something like this with her sour dough 'starter'. She would split it into 2 equal parts, feed the original water, flour and sugar to get it back to original volume, and then either use the other part to make bread, or feed it to make more yeast, or toss it, if she didn't need it. Can you do this sort of thing with brewers yeast?

Thanks
Monty

[Bluejaye]

I don't know, but I am definitely interested in the answer.

[John Sand]

The answer is that you can, and some do. Check the yeast forum on HomeBrewTalk.

[mashani]

I've done this to turn 1 smack pack of 3787 into 8 batches of beer.

But there is a limit to how many times you can keep splitting those split batches before your yeast will start to mutate into "something different". Eventually the resulting beers made from them will start to change unless you can re-isolate the "pure" not muated cells. The same goes for starters from a yeast cake too however, it isn't anything special about doing it this way.

[monsteroyd]

Interesting, so you can stretch the yeast, but there are limits. I did not realize that yeast would mutate that fast, I was thinking it was more a generational thing, ferment beer, wash that, then ferment again, then wash that, etc. Or that you'd eventually get contaminated with something.

Monty

[RickBeer]

It does mutate fast. Back in the 50s a young brewer let it get out of control and it was not pretty.

[Kealia]

Interesting, so you can stretch the yeast, but there are limits. I did not realize that yeast would mutate that fast, I was thinking it was more a generational thing, ferment beer, wash that, then ferment again, then wash that, etc. Or that you'd eventually get contaminated with something.

Monty

Keep in mind that with a starter you are fermenting wort. So the yeast are multiplying, fermenting, then sleeping. Then you split it, grow it again, etc. so you're getting the same "generation" effect regardless of the way that you do it.

But, as you've noted, starting with a fresh vial/pack and doing a starter is a good way to start off with good, clean yeast.

[mashani]

FWIW, you can attempt to recover a strain that gets weird, but it takes some testing (as in you need to make beer) assuming you don't have the scientific equipment to actually find and isolate the good cells from the mutants.

The way to do it is to brew up a bunch of severely under pitched starters with impeccable sanitation. Under pitching is important. If you are lucky some of them will get a bunch of the "good" cells and a bunch of mutants that don't grow so well. The goal is to extend the growth phase a lot - produce a lot of healthy daughter cells with the vast majority of them coming from the better yeast. If you pitch a lot of yeast, you don't grow as many cells, and if the mutants can "ferment" but don't grow well, you in effect are not weeding them out by having them be out competed for growth. So again underpitching is really important if you want to try this. It's best to do it on a stir plate with added nutrients in the wort, so you promote as much growth before fermentation begins as is possible.

If your lucky the "good" cells will outcompete the mutants, and provide you with a starter of a lot more good cells. Any starter that seems healthy, use to make a little batch of small pale lightly hopped beer (think a 1.03ish beer). Taste them when done. If they taste like you would imagine a beer of that type should with your yeast strain, you've gotten yourself a revived batch of yeast.

Or if your even luckier and you have no real viable old yeast strain but a particularly lucky mutant, you will have promoted the growth of a mutant strain that is viable, a good fermenter, and actually makes good beer. Then you can give it a name and sell it to Wyeast LOL.

Is it worth that effort? That's the question...

[Insanitized]

I'm thinking about harvesting my yeast from the get go, since I have the time and space right now. Do I label it as I bought it? Just wondering how you guys catalog yeast strains you harvest I guess.

From my basic understanding of yeast you can keep a particular strain alive forever, right?

[Inkleg]

I label mine with the
Yeast type
1st, 2nd, 3rd or 4th washing
And the date
I don't go more than 4, but that's me.
I'll do the same thing if I'm farming yeast. Making a 2 liter starter when I only need 1.5 and pouring 500mL into a pint jar.

[mashani]

From my basic understanding of yeast you can keep a particular strain alive forever, right?

It will eventually mutate or "evolve" which could be good or bad. For example a whole bunch of breweries in Belgium use a strain that came from Westmalle, but none of them are exactly alike anymore because they each "evolved" to the brewing conditions where they are used. As in the yeast mutants that like the temp or ph or wort composition of those breweries beers that out compete the others and over time become the predominant strain.

You can try to fix a strain that goes weird on you, IE it stops fermenting well or starts to make weird beer. See my post a few up from here. That's the only way to recover a strain without lab equipment and the ability to actually isolate individual cells and having a baseline to compare against. But the way I described above is a time honored way of doing it though - even some modern breweries do it to try to salvage their strains before they go out and buy new yeast which can be "spendy".

[Insanitized]

Thanks guys, doing my first starter today to brew some lager tomorrow.

[Insanitized]

Do you guys spin your yeast at 33 1/3 or 45?


Seriously, think it's fast enough to have an effect?
https://www.youtube.com/watch?v=bT3d_P0gxmE&

[mashani]

Well, that is interesting but not really the idea.

It's not about "spinning" directly - the stir bar creates a vortex - like a little tornado - that continuously brings more oxygen into the starter wort. The continuous influx of oxygen extends the yeast growth phase until the yeast run out of other nutrients. Without the extra oxygen they will start to ferment before they run out of the other nutrients once they run out of oxygen which is needed for the growth phase. Once they start to ferment they are not making lots of hungry new cells. Your trying to make as many hungry new cells as you can when you make a starter.

You have no stir bar, no magnets, so you have no vortex. Your just making the yeast dizzy more or less. I suppose there could be a slight effect, but it's probably just as effective to shake it every time you walk past.