Author Topic: Advise please with possible yeast issue  (Read 11386 times)

Offline noodle

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Advise please with possible yeast issue
« on: January 26, 2010, 12:18:51 PM »
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

Offline MaltLicker

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Re: Advise please with possible yeast issue
« Reply #1 on: January 26, 2010, 01:59:40 PM »
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. 

Offline noodle

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Re: Advise please with possible yeast issue
« Reply #2 on: January 26, 2010, 02:11:07 PM »
We're using a reverse coil to controll temperature going into fermentation.

What is the proper way to reuse yeast?

Thanks,

Offline Berkyjay

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Re: Advise please with possible yeast issue
« Reply #3 on: January 26, 2010, 02:46:30 PM »
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

Offline UselessBrewing

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Re: Advise please with possible yeast issue
« Reply #4 on: January 26, 2010, 03:04:55 PM »
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
« Last Edit: January 26, 2010, 03:13:21 PM by UselessBrewing »
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Offline noodle

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Re: Advise please with possible yeast issue
« Reply #5 on: January 26, 2010, 03:18:42 PM »
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,


Offline Berkyjay

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Re: Advise please with possible yeast issue
« Reply #6 on: January 26, 2010, 03:35:58 PM »
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.

Offline noodle

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Re: Advise please with possible yeast issue
« Reply #7 on: January 26, 2010, 03:41:46 PM »
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.

Offline Berkyjay

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Re: Advise please with possible yeast issue
« Reply #8 on: January 26, 2010, 03:47:47 PM »
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?

Offline noodle

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Re: Advise please with possible yeast issue
« Reply #9 on: January 26, 2010, 03:49:44 PM »
4 to 5. We had a problem last spring now a problem with two of the batches from fall 2009.

Offline Berkyjay

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Re: Advise please with possible yeast issue
« Reply #10 on: January 26, 2010, 04:03:21 PM »
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.

Offline noodle

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Re: Advise please with possible yeast issue
« Reply #11 on: January 26, 2010, 04:23:40 PM »
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. :(

Offline Berkyjay

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Re: Advise please with possible yeast issue
« Reply #12 on: January 26, 2010, 04:59:13 PM »
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!

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. :(

Offline noodle

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Re: Advise please with possible yeast issue
« Reply #13 on: January 26, 2010, 05:18:29 PM »
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
« Last Edit: January 26, 2010, 05:57:00 PM by noodle »

Offline Berkyjay

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Re: Advise please with possible yeast issue
« Reply #14 on: January 26, 2010, 05:36:42 PM »
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.

 

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