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Advise please with possible yeast issue

noodle

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Hi,

We are brewing 20 gallons at a time and have had a couple of batches go bad. The taste is fine after first fermentation and the same when we keg. After a few weeks, we taste and have a spoiled product. It taste a bit funky, not right. We are thinking that it is a yeast issue.

Here is our process and some results.

First, we are extremely carefull to sanitize everything.

We have been starting with fresh yeast and then re-pitching it for the next four to five batches.
This has worked ok but what is your take on that? We also re-pitch to different styles for example, we may start with a brown ale then the next week make a porter and then a red ale. Is it a good idea to use the same yeast in different batches/styles?

We made a great oktoberfest last year with fresh yeast and then about two months later we made another batch pitching yeast that has been reused for 4 or 5 batched. This batch of oktoberfest is not good.

Should we only re-pitch yeast to make the same style? How many times can you do this?

I'll stop here and wait for advise. Please let me know if you need more info.

Thanks,

Noodle
 
You'll get various opinions on this in general, but with each re-use, you'd face two risks.  Tired, worn-out yeast, possibly mutated by too-warm ferms, or who knows?  Second, each time you also risk some type infection, however slight. 

And since your initial batches turn out OK, it would seem that your general sanitation is fine, and it is in the yeast re-use process that something is going awry. 
 
We're using a reverse coil to controll temperature going into fermentation.

What is the proper way to reuse yeast?

Thanks,
 
noodle said:
We're using a reverse coil to controll temperature going into fermentation.

What is the proper way to reuse yeast?

Thanks,

I have a few questions for you.  Why do you believe that it is the yeast?  Secondly, what is it about your brew that you consider bad or spoiled?  Answering those two questions would help in figuring out your issue.

My initial thoughts would point to your bottling/kegging process.  If the beer is spoiled then it could be an oxidation issue, but that is hard to call without specifics of what is wrong with the beer.

As far as repitching yeast, I have had several pro brewers in my area tell me that yeast are very hardy organisms and most of them repitch yeast over several generations.  I know a guy who brews lagers that will leave his yeast slurry in the bucket after he transfers to a secondary, then pour in some fresh wort right on top of it.  And he does this like 3 or 4 times with different style lagers.....and they all taste great. 

But then again, it's hard to know your situation so take my words with a grain of salt.  My advice is to do some experimentation to narrow down the possible causes of this issue.  Pitch fresh yeast, make a smaller batch, change bottling/kegging techniques.

Good luck,

James
 
I'm also in the camp that says it is your bottling/kegging process or equipment. Especially if there are no detectable problems in primary or secondary. If it were yeast You would know by the third batch for sure! Disassemble everything including all your equipment, hoses, pumps, valves, conical's, etc. and wash thoroughly, Rinse in HOT water, and use a good sanatizing solution. boil what you can for a min  of 20 min.

As for the styles and yeast, as long as your recipe/ingredients are in the style of the yeast, or you are using a neutral yeast it should not mater. However, if you are mixing styles, I would say you need to change yeast. For instance, you cant use S05 on a scotch/old ale or Belgian's, It just doesn't work! The yeast characteristics make the style, not the ingredients.

+1 ML & Berkyjay

Cheers
Preston
 
I'm comparing two batches of oktoberfest.

First batch was great with new yeast. Second batch was repitched 3 or 4 times from a brown ale I believe (I have to check my records) We've been using a german yeast for all of our ales with great luck.

The beer has an off smell and taste. It's drinkable but not right. Not sour but just not right.
It tastes the same until after kegging.

We sanitize the kegs and then syphon from the secondary fermentation tanks. We carbonate with CO2 and leave unit ready to drink. We check all fittings and relube seals as required.

It seems that the first few batches come out good and then something goes wrong. This is why I'm thinking it's the yeast. We syphon from first to second and then pour new wort into the primarys with the yeast that remains.

Thanks,

 
noodle said:
I'm comparing two batches of oktoberfest.

First batch was great with new yeast. Second batch was repitched 3 or 4 times from a brown ale I believe (I have to check my records) We've been using a german yeast for all of our ales with great luck.

The beer has an off smell and taste. It's drinkable but not right. Not sour but just not right.
It tastes the same until after kegging.

We sanitize the kegs and then syphon from the secondary fermentation tanks. We carbonate with CO2 and leave unit ready to drink. We check all fittings and relube seals as required.

It seems that the first few batches come out good and then something goes wrong. This is why I'm thinking it's the yeast. We syphon from first to second and then pour new wort into the primarys with the yeast that remains.

Thanks,

Hmmm, Are you detecting any off flavors before kegging?  And how are you storing the yeast between brews? 

I had some similar problems with my Belgian ale having some bad aftertastes after it was bottled.  But I used fresh yeast every time.  As a result I started lagering once I reached my target gravity to clear out the old yeast.  Then I transfer the clear beer to another carboy then repitch with a neutral yeast like Safale US-05, then I bottle.  This has worked out really well for me but it kind of fits the style.  I'm not sure how it would play with the German ales.  It might be something you could try once just to as an experiment.
 
The taste is fine from wort thru primary and secondary.

We've done about 12 batches and have had three that have this off taste/smell. Some of the batches were with fresh yeast but most were repitched. I'll have to check my records to see if iit s always the last batch that goes bad. This is why I suspect the yeast.

We were brewing every week so the yeast doesn't sit.
 
noodle said:
The taste is fine from wort thru primary and secondary.

We've done about 12 batches and have had three that have this off taste/smell. Some of the batches were with fresh yeast but most were repitched. I'll have to check my records to see if iit s always the last batch that goes bad. This is why I suspect the yeast.

We were brewing every week so the yeast doesn't sit.


Oh, so it's not every batch that you brew with repitched yeast?  How many generations do you usually repitch the yeast?
 
4 to 5. We had a problem last spring now a problem with two of the batches from fall 2009.
 
noodle said:
4 to 5. We had a problem last spring now a problem with two of the batches from fall 2009.

Well 4-5 shouldn't be a problem,  but from what I have learned about repitching yeast, you want to watch how many generations you go into.  Because each generation will cause mutations in the yeast, which build upon each other, eventually decreasing the performance of the yeast.

http://www.wyeastlab.com/com-yeast-harvest.cfm

This link is a good source of yeast info.

But as far as your problem, the only advice I have left is testing and the process of elimination.  Start by doing a once over of sanitation on your brewing equipment.  I agree with Preston that sanitation is uber important.
 
Thanks for the link.

We are very carefull about sanitizing and our beers are coming out well but this is a problem we need to solve. I hate pouring out beer. :(
 
Yeah, I had to pour a batch of failed chocolate stout out earlier this month.  But I know what I did wrong so my next batch will be successful.  Hopefully you can nail down what is going wrong so your loss of beer will be worth something.

Good luck!

noodle said:
Thanks for the link.

We are very carefull about sanitizing and our beers are coming out well but this is a problem we need to solve. I hate pouring out beer. :(
 
I just read the wyeast link and they speak of harvesting yeast "Yeast to be harvested should be selected from the middle portion of the yeast bed when harvesting from the bottom of a tank, or from the middle skim when harvesting from the top of a tank."

We are just syphoning from the primary into the secondary and then using the primary fermators and pouring new wort into them. We are not removing anything.

"Always evaluate the yeast slurry as it is harvested. The slurry should appear thick and creamy with very little trub and no “off” flavors and aromas."

What is trub?

Could this be our issue? We may be getting away with this method for two to three batches but then mutation may start and cause problems.

Thanks,

Noodle
 
noodle said:
I just read the wyeast link and they speak of harvesting yeast "Yeast to be harvested should be selected from the middle portion of the yeast bed when harvesting from the bottom of a tank, or from the middle skim when harvesting from the top of a tank."

We are just syphoning from the secondary into the kegs and then using the secondary as our primary fermators and pouring new wort into them. We are not removing anything.

"Always evaluate the yeast slurry as it is harvested. The slurry should appear thick and creamy with very little trub and no “off” flavors and aromas."

What is trub?

Could this be our issue? We may be getting away with this method for two to three batches but then mutation may start and cause problems.

Thanks,

Noodle

The trub is pretty much everything that ends up at the bottom of your fermenting vessel.  It contains mostly proteins, dead yeast cells, and live yeast that has flocculated.

http://en.wikipedia.org/wiki/Trub_%28brewing%29

In some cases this could cause off flavors, but not usually.  But, if you are using the trub over and over I can see you building up  more and more not so good stuff in your trub with less and less healthy yeast.  One of the reasons why I use fresh yeast every time that I brew is because I am not able to properly collect and store yeast for repitching.....it's hard collecting from a glass carboy.
 
noodle said:
We are just syphoning from the primary into the secondary and then using the primary fermators and pouring new wort into them. We are not removing anything.

If you are doing this repeatedly, then I suspect that is largely the issue.  Brewers often brew a lower alcohol brew first, say a bitter, and then put a new barley wine on the large yeast cake.  But then the yeast is cooked and should not be used again. 

Even with "average" OG worts, the hot break/cold break, trub, and gunk is accumulating from batch to batch in the primary.  If this is the current practice, I would not go beyond the second batch.  If you want to re-use yeast beyond that, I think you'd have to get into taking large, clean samples from the first primary and doing fresh starters from them, so the proportion of fresh, healthy yeast remains high. 

And if you're doing ales with lager yeasts, then you might also consider some dry yeasts.  They're cheaper, work well, and Nottingham (for example) is very clean and ferments from 57F to 70F.  Rehydrated properly, it could easily handle most typical OG's of 5 gallons.
 
One of the great benefits of a conical fermenter is the ease of removal of trub before and during the fermentation process. It also facillitates a clean way to "harvest" clean healthy yeast.

I usually will drain off trub after sitting in the fermenter within an hour of transfer (amazing the amount there), unless transfer protocol for that batch insured a clean wort. Because you are able to do this, a "secondary" ....perse..... is not necessary.

Then before kegging you are able to either:
1) drain off and save healthy yeast (after the discard of the first little bits) ....or
2) Pour in the next batch on top of the healthy yeast.

The only down side is that just pouring your new beer on top of the old yeast doesn't allow for a "cleaning" period where you can take the valves apart and such. And those krausen rings always scare me.... but its a very effective method for keeping trub off the beer, and saving the healthy yeast for as long as two weeks.

I know there has been some discussion about these units, but I love them! And support is A1 despite others' experience.

http://conical-fermenter.com/products/conical-fermenters/14-5-conical/
(this one is only $400)
 

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Thanks,

We would need a 20 gal unit.

What range room temp should you ferment at?
 
We would need a 20 gal unit.

0r two 14.5's giving you the option of different dry hopping and/or yeasts (for experimentation).

I built a well insulated 12X12 "Brewhouse" that I typically keep at 60*-62* even in these frigid months,  depending on what stage of fermentation and style.
 
I suggest that you hang on to it and  see if it sorts itself  out.
Often as not a brew that seems to have "issues" manages to sort it all out and be fine.
So don't flush it.   Give it a few weeks.

Meanwhile go over your ancillary equipment and  fermenter with the sure knowledge that  you have a fair chance of an infection.

It's possible your yeast may have mutated.  It's possible but not the most probable.  Granted they go through a lot of iterations  and the chances of a mutation are pretty much even money at 30 million iterations,  which is why no one in the molecular Biology field takes Polymerase Chain Reaction past that number.  
But still yeasts are tough little buggers.  they can survive enormous environmental stresses and come out smiling.

I think you have other bugs.

And as to the other bugs if their demise will allow the brew to revert and correct then you might as well let the isomerized alpha acids, the CO2 tension,  the alcohol, the hostile enzymatic  environment the yeast manufacture , the pH,  and other factors in beer that provide a very unaccommodating environment for pathogens and nasty bugs well let them do their magic.  That environment tends to kill most everything. 

All in all  there's fewer than  200 organisms  that can tolerate that milieu well while also making it taste strange.
And not one of them can survive very long.

So, give it some time.








 
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