Reminder to watch your generations of repitched yeast

[shoreman]

I had been repitching a Belgian "House" yeast for a good year or so (not sure how many batches but a good amount) that was Ardennes w/ Safale Abbey mixed in at some point and looks like on this last batch it must have mutated. Crazy sulfur during fermentation (which never happened before) and the beer was a total dumper as the yeast never cleaned up the sulfur in the nose or the taste.

Good reminder that unless you are plating out yeast or saving multiple jars, keep your eye on your generations of repitching. I hate to dump beer, but it has to happen sometimes for the learning process.

 

[madscientist451]

I've got a house saison strain going for a few years now, it just keeps plugging away, but I realize at some point its going to get dumped. Its a calculated risk I'm willing to take at this point.
I usually make a saison "garbage beer" with second runnings when I make a barley wine or other high ABV beer and use up old hops that always seem to accumulate. I always get something drinkable or blend-able but if it has to get dumped its no big deal to me.
If I'm making a specific style I usually use fresh yeast and don't use the strain more than 7-8 times.

 

[shoreman]

If I'm making a specific style I usually use fresh yeast and don't use the strain more than 7-8 times.

Good idea, I don't think I'll be going this route for too much longer. Most of my beers are sub 1.050SG so I thought maybe it wasn't an issue b/c of stress, but I guess I was wrong.

Generally like with Conan I'll take that maybe 4 generations and the fall/winter brewing season is over. I'll start fresh the following year. I think I'll do the same moving forward with my Belgian strains.

 

[JimRausch]

Thanks for the warning shoreman. I usually reuse a yeast 3x in a related series (for example Vienna->Marzen->Bock or Dopplebock) so I haven't run across a problem yet, but it is good to know.

 

[Rob2010SS]

I know it's been asked before, but instead of repitching yeast, why not just overbuild starters and save it from there? What's the advantage of repitching yeast vs overbuilding starters?

 

[RPh_Guy]

Is there any evidence out there that changes like this are due to mutation rather than contamination? The latter seems much more likely to me.

 

[JimRausch]

What's the advantage of repitching yeast vs overbuilding starters?

Well, in my case it's time and effort. I might overbuild a starter for 2 brews that will happen within a week or two, but the exampled series above will happen over a month-6 weeks, and is lager yeast. So I build up a good active starter for the Vienna. Then when I rack that over for lagering, I save out 2 qts. of yeast slurry for the Marzen. When the Marzen is ready for lagering, I'll save out 2-3 qts. for the Bock. If I had to build up the initial starter to account for the other brews, I would have a chit load of yeast to store.

 

[HiImBrian]

How long are you guys storing the yeast between pitches on average?

 

[shoreman]

Is there are evidence out there that changes like this are due to mutation rather than contamination? The latter seems much more likely to me.

I obviously didn't do a side by side test with this yeast and another but I'm pretty certain my sanitation standards are pretty spot on (been brewing for close to 20 years). It is a possibility though, but the yeast seems to be the cause. I brewed with the same gear about 2 weeks later with another yeast and no issues.

I read about he mutation from John Palmer somewhere and there is some info on Wyeast http://www.wyeastlab.com/yeast-harvesting-re-pitching about pitching over 7 times.

 

[shoreman]

I know it's been asked before, but instead of repitching yeast, why not just overbuild starters and save it from there? What's the advantage of repitching yeast vs overbuilding starters?

I don't make starters, too lazy. Although I'm interested in Omega's Propper Starter cans, I would use those.

I generally just brew a clean beer, say blonde and save out 3 mason jars for repitching in the following beers. This works for me b/c I brew in bunches, so I'll brew maybe three batches in 3-4 weeks.

 

[shoreman]

How long are you guys storing the yeast between pitches on average?

That might have aided in this issue with this beer as that pitch was fairly old, maybe 1-2 months.

 

[RPh_Guy]

This thing about yeast "mutations" gets parroted around the forum but simple yeast stress or contamination seem like much more likely causes of yeast-derived off flavors in my opinion.
Yeast can be stressed after multiple generations from the alcohol level, osmotic stress, lack of nutrition, etc., leading to increased byproducts.
Also, the fact is that beer is not produced in a sterile environment. No matter how good your sanitation is, the threat of contamination is always there since wild microbes are everywhere.

The page you referenced mentioned potential drift in flocculation tendencies with repeated pitching based on harvesting factors. This may slightly affect fermentation speed and attenuation.
But new flavors? I haven't seen anything to suggest that's a reasonable possibility.

Unfortunately it's very rare that homebrewers have the yeast/beer tested for contaminants when there's something off, so data are lacking. I'm just not sure why people are so stuck on this idea of mutations.

 

[Rob2010SS]

This thing about yeast "mutations" gets parroted around the forum but simple yeast stress or contamination seem like much more likely causes of yeast-derived off flavors in my opinion.
Yeast can be stressed after multiple generations from the alcohol level, osmotic stress, lack of nutrition, etc., leading to increased byproducts.
Also, the fact is that beer is not produced in a sterile environment. No matter how good your sanitation is, the threat of contamination is always there since wild microbes are everywhere.

The page you referenced mentioned potential drift in flocculation tendencies with repeated pitching based on harvesting factors. This may slightly affect fermentation speed and attenuation.
But new flavors? I haven't seen anything to suggest that's a reasonable possibility.

Unfortunately it's very rare that homebrewers have the yeast/beer tested for contaminants when there's something off, so data are lacking. I'm just not sure why people are so stuck on this idea of mutations.

I'm not saying this as a negative thing, but perhaps people jump to the idea of mutations because it's easier to accept that hypothesis as we have less control over it, whereas yeast stress or contamination is likely due to "user error". In other words, it's the yeasts' fault, not mine.

I could be wrong, and again, not being negative. Just my 2 cents

 

[shoreman]

This thing about yeast "mutations" gets parroted around the forum but simple yeast stress or contamination seem like much more likely causes of yeast-derived off flavors in my opinion.
Yeast can be stressed after multiple generations from the alcohol level, osmotic stress, lack of nutrition, etc., leading to increased byproducts.
Also, the fact is that beer is not produced in a sterile environment. No matter how good your sanitation is, the threat of contamination is always there since wild microbes are everywhere.

The page you referenced mentioned potential drift in flocculation tendencies with repeated pitching based on harvesting factors. This may slightly affect fermentation speed and attenuation.
But new flavors? I haven't seen anything to suggest that's a reasonable possibility.

Unfortunately it's very rare that homebrewers have the yeast/beer tested for contaminants when there's something off, so data are lacking. I'm just not sure why people are so stuck on this idea of mutations.

I’m not even close to be claiming to be an expert on yeast and will never know what happened to this beer without some sort of lab results.

What I do know is the profile of this yeast as I’ve been brewing
With it for a bunch of years (Ardennes). Could it have been mixing the Abbey in there, who knows?

I’m drinking the beer I brewed before this one right now, super clean, never has a touch of sulfur.

Could there have been contamination? Sure but I’m not sticking around to find out, it got dumped with that yeast.

The reason I mention mutation is just on what I read from experts that know more on the subject than I do. In the article on the Wyeast website that I linked there is an entire paragraph on Selective Mutation, check it out. That, and other articles out there are reasons people probably refer to mutations when you are very used to using a yeast and all the sudden it acts way out of character.

I’ve tasted plenty of infected beer as a bjcp judge, but this was just plain wierd acting yeast during fermentation and after.

 

[Northern_Brewer]

It's complicated, but mutation is definitely part of the story, and it increases in stressful environments like beer. There's quite a lot of work going on at the moment about this kind of thing, as genome sequencing has got cheaper so people can monitor mutation directly.

Also a dry yeast isn't helping - they seem to go weird quicker than liquid yeasts.

 

[RPh_Guy]

For anyone interested, some digging revealed this article:
https://onlinelibrary.wiley.com/doi/pdf/10.1002/j.2050-0416.1968.tb03167.x (Thorne, 1968)

They ran a continuous fermentation for 9 months and said there were no contaminants. A significant portion of isolates had mutated, some producing detectable off-flavor (e.g. sulfide).

Still, I'm not ready to immediately jump to a conclusion when there's a yeast off-flavor. I guess the culture is useless no matter what the cause so it doesn't really matter.
Cheers

 

[HTH1975]

Poor yeast handling makes more sense. Think about breweries where they repitched the same yeast for 100 years, the likes of Burton Union.

I know from viability tests we do at work that this decreases significantly if the same ‘skim’ is used/kept for a few brews, and also subsequent generations of skins lose viability. This obviously increases the opportunity for other yeasts to gain some foothold. Yeast will naturally mutate to match their surroundings too - I know of one local brewery where their original yeast mutated and they liked the mutated yeast better, so this is now kept on slants and new yeast introduced on a cyclic basis.

I think tha once you start storing yeast for any length of time, then you are chancing off flavours and poor fermentation. The smallest amount of zinc will help fermentation - like literally 3g in a 20BBL batch in the boil kettle.

 

[Tobor_8thMan]

I had been repitching a Belgian "House" yeast for a good year or so (not sure how many batches but a good amount) that was Ardennes w/ Safale Abbey mixed in at some point and looks like on this last batch it must have mutated. Crazy sulfur during fermentation (which never happened before) and the beer was a total dumper as the yeast never cleaned up the sulfur in the nose or the taste.

Good reminder that unless you are plating out yeast or saving multiple jars, keep your eye on your generations of repitching. I hate to dump beer, but it has to happen sometimes for the learning process.

Read thru the posts, but forgive me if I missed an answer to my following question.

When repitched was the saved everything just dumped in? Or, was the creamy, white layer only repitched?

 

[shoreman]

When repitched was the saved everything just dumped in? Or, was the creamy, white layer only repitched?

It's washed once - saved yeast in a mason jar. Liquid poured off before pitching.

 

[Moose_MI]

 

[Tobor_8thMan]

Hmm... something caused the mutation...

 

[Tobor_8thMan]

View attachment 604442

Sounds like a Steely Dan song...