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5gBrewer

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There have been a lot of threads on reusing yeasts, and yeast cakes. I recently had the opportunity to go to one of our very successful local micro breweries. Talking with one of the brewmasters, the subject of yeast came up. He told me that on average they reuse yeast strains up 19 times.

I thought that sounded a little excessive, but their beers are excellent, and quite consistant in flavor, so something must be alright with doing that.

Personally, I've only reused yeast up to a 2nd generation. I'm into reusing yeast, but just haven't had the opportunity to go beyond a 2nd gen. I'm going to push it to 3rd to 4th gen. with my next few IPA/IIPAs.

So... what do you guys think about reusing yeast up to 19 times?

5gB
 
Seems excessive to me too. I have gone 3 generations with no problems.

It seems to me like the safe way to get more uses out of a single vial (or smack pack) would be to initially break it up into three or so parts, grow them in three starters, and save two for later. Use the first one three times, then the second three times then the last one three times.

You get nine batches out of a $6.50 package of yeast ~$0.72 per batch not including the cost of starters.

- magno
 
A brewer (pub) I know probably is in the range of 20 times as well. Key thing for them though is they're moving it out of those conicals directly into storage without ever touching o2. He nabs about 3g worth of yeast and it goes right into a corny keg and then off the the fridge.
 
homebrewer_99 said:
I remember reading somewhere that one brewery in Belgium has been using the same yeast for over 150 years...:confused: ...over and over again...

See, that's crazy. We must be missing something here. Well I'm taking the plunge. I'm going to make IPA after IPA on the same yeast as many times as i can (ie. until things start tasting strange i suppose).
 
5gBrewer said:
See, that's crazy. We must be missing something here. Well I'm taking the plunge. I'm going to make IPA after IPA on the same yeast as many times as i can (ie. until things start tasting strange i suppose).

Thank you 5gBrewer! I just sent this idea to BasicBrewing Radio in the hopes they'd do this experiment. I feel too inexperienced to be able to do a really consistent recipe 5+ times clean/exact that would have the ability to show yeast flaws from too many generations. I think you'll get 10+ at least w/o problems and will probably get more, if you keep going.
 
If you are adding a relatively small amount (say 3 gallons as mentioned earlier) to a brewpub size batch of beer, I would think it would be fine. If you took a cup of your sludge out of every primary (which would be way overpitching anyway) you wouldn't really be transferring that much nasty crap into your new wort and it will work fine.

Yeast is a budding organism, a new yeast cell buds off an old one and leaves a scar, yes, once an 'old' cell buds off hundreds of new cells, it is basically not viable any more, but it has created 100 new cells with no scars which can each create 100 more cells, etc.

I doubt very much that the genetic mutation rate in beer yeast growing in a 'healthy' environment (water, sugar, alcohol) is high at all, and most likely, any mutations picked up in a cell would not be evolutionarily advantageous, and that cell would not replicate as fast as normal ones.

Think about bread, there are bakeries that mix in a little dough from previous batches with new ones, and have been doing this for decades.
 
ColoradoXJ13 said:
snip...

Think about bread, there are bakeries that mix in a little dough from previous batches with new ones, and have been doing this for decades.


Isn't that what makes San Francisco sour dough bread special? They've been using the same sour dough yeast since it was first discovered.
 
I think the biggest concern we have is the chance of introducing other strains and bacteria and has very little to do with the original yeast mutating. For this reason I agree it's far better to split a known pure culture and propagate rather than doing it in a linear fashion like pitching on yeast cakes indefinitely. When I collect slurry out of primaries, I label really well so that I can discard it if I sense any off flavors in the batch of beer it came from.
 
How do the yeast labs keep a strain alive? They have to keep resuing it over and over, right?

Another q: how long can it stay in the fridge? Is it possible for me to dry it for long term storage?
 
Cheesefood said:
How do the yeast labs keep a strain alive? They have to keep resuing it over and over, right?

Another q: how long can it stay in the fridge? Is it possible for me to dry it for long term storage?

There are a number of threads and links on this forum for methodology for freezing yeast, which stores it indefinitely.
 
I've heard of breweries, Boddington's and Hacker-Pschorr, which have yeast strains that are several centuries old. My understanding that is they have a lab where they separate out and encourage the healthier yeasties.
 
Bobby_M said:
I think the biggest concern we have is the chance of introducing other strains and bacteria and has very little to do with the original yeast mutating.

I agree with this. The primary issue with reusing yeast is not genetic mutation, but contamination. As hard as we might try, we are not going to be able to maintain the same level of sanitation in our homebrew environment as a professional brewery. The number of times that a brewpub can reuse yeast has no bearing on how many times we can do the same, and in fact there's probably a huge amount of variance in the number of generations individual brewers here can get since our own individual procedures and sanitazton will vary.

As a side note, I've heard Charlie Papazian mention in interviews that he's been using the same yeast culture since like 1982 (and that he uses it for pretty much everything - ale OR lager). So, it IS possible for a homebrewer - but he's also doing more than just collecting slurry in a sanitized mason jar.
 
I went ahead this weekend and reused the yeast cake from my wheat and from an ale... and had almost explosive fermentation at lightning speed. A number of forum members said that it could be done and considering my newness to the hobby I figured I'd try and experiment. Also saved me a nominal amount of $ in the process...
:)
 
So far I've collected slurry from Nottingham, Saflager23, and WPL001 and I'm scared as hell to pitch any of them because I'm always second guessing my sanitation. You might wonder why the hell I'd risk it on $1 packets of dry yeast strains but I'm thinking of it more from a viable cell count perspective vs. cost. A cup of slurry is what, like 10x the cells of an 11g packet? For the 001, I collected about 14 oz in a PET coors light bottle. I used PET so I could squeeze it and get the headspace out. Hopefully it's clean. I'd swab the mouth with some vodka prior to pouring out.
 
eh, I guess I have it easy working in a laboratory with access to yeast media, *sterile* techniques, and autoclaves...I have every strain I have every used/bought/isolated frozen down at -80*C. Any time I brew with one, I just start up a new culture from my freezedown and grow it up over a few days, spin it to remove most of the growth media, and pitch.

I would bet most larger (i.e. Sam Adams size and larger) have bio labs on site to do this, in fact, I have seen the one at New Belgium (would love to get a job there!)
 
One of the big reasons that a microbrewer can reuse yeast 20 times without off-flavors is because they are using their yeast immediately (usually within 24 hrs). The storage process kills many cells and somehow facilitates off-flavor development.
 

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