Author Topic: My yeast is stressed. Why?  (Read 1404 times)

Offline Derek Toering

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My yeast is stressed. Why?
« on: March 17, 2018, 03:31:20 AM »
Hi.  I have had some issues with my brews of late.  After analysis we have determined that the off flavour is from a stressed yeast.  After doing some research it fits the bill.  To prove this, I will pitch multiple smack packs next time I brew as opposed to building a starter.  Then I will hopefully pin point the issue or at least rule out one process.

Assuming however that it is my yeast process giving issues, the steps below are what I use.  Hopefully someone can point out any obvious issues.

  • Create a starter of DME and water in my flask to approximately 1040.  Quantity as advised in beersmith with the use of a stir plate
  • Cool flask in cold water until cool
  • Run oxygen through a beer stone.  Usually a couple of minutes.
  • Pitch yeast and place on stir plate in a mild temperature space.  Typically the kitchen bench, so around 22 degrees ambient
  • Run this for 24 hours minimum.
  • Come brew day, the yeast is paced into fermenter and wort is transferred directly on top.  Wort goes through plate chiller, and inline oxygenator from the boiler to the fermenter
  • At this point everything goes fine.  The beer attenuates well enough, the ferment behaves correctly as you would expect.
  • Beer comes out with solvent like characteristics.  Ferment temp is controlled so is not an issue.  It does improve...but not all the way.

To me the process seems ok...but I am doing something wrong.  Any suggestions would be welcomed.  I appreciate that the above is all quite general from a diagnostic perspective.  Happy to give additional details if required.  Thanks in advance...

Derek

Offline brewfun

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Re: My yeast is stressed. Why?
« Reply #1 on: March 17, 2018, 05:54:17 AM »
Two things I would add to your process:
1) Add some yeast nutrient, like superfood or servomyces.
2) Ensure that little to no hot break is in the starter.

You didn't say if the issue was across multiple strains or if this is your house yeast. I'm taking the "after analysis" point to mean that you've determined that you're at the proper pitching rate. Still, you might consider one more pitch up step for more volume.

The aeration stone is redundant to the stir plate. It doesn't hurt, but just running the stir plate will oxygenate the wort.
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Offline Oginme

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Re: My yeast is stressed. Why?
« Reply #2 on: March 17, 2018, 06:01:55 AM »
You process looks OK. I don't see any alarms there versus what others do.

Some things to look at:

If you are using a stir plate, you don't need to oxygenate your starter wort much if at all.  I use a loose cap of aluminum foil over the flask and pretty good yeast growth without using Oxygen. 

How long before brew day do you make your starter?  How is it stored between finishing and your pitching it? 

Is it the same strain of yeast each time or do you get the same solvent flavor with different strains? 

Just for comparison of techniques, I make an ample starter as I am usually splitting it based upon cell count to build up the extra for the next batch.  I also add yeast nutrient to the starter to provide missing minerals (usually Zinc) that will not be plentiful enough in the DME.

Once the starter has finished with the growth stage (usually 24 hrs to 36 hrs depending upon strain), I place the flask in cool storage (~12?C to 14?C) and then transfer it to a refrigerator until brew day.  On brew day, I decant the excess starter wort (try tasting it, it is usually pretty bad, or at least not what I want in my recipe), do my cell count, and measure out the starter slurry I want to pitch.  The rest will be used in the next starter.

I typically fill my fermenter and put it into my fermentation chamber to allow it to reach the temperature I want to pitch at.  Meanwhile, I take the wort I have used for measuring gravity and wort pH and add that to the yeast I will be pitching.  I shake this well and allow it to start activity.  By that time, usually around 4 hrs to 8 hrs after the fermenter has gone into the fermentation chamber, the flask has a good layer of krausen on top and I pitch it into my fermenter.

Bottom line, my suspicion is that the amount of Oxygen in your starter is most of the issue, but I've never done that to confirm the result.  When I bubble Oxygen through my fermenter before pitching my yeast, I only flow it for about 45 seconds.  I ask the rest in case I am missing something else which is critical.
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Offline Derek Toering

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Re: My yeast is stressed. Why?
« Reply #3 on: May 28, 2018, 02:23:10 AM »
Have just brewed again.  This time I pitched 2 packets of yeast into my 2L dme starter. Was on stir plate for 36 hours. I didn't chill starter to drop out yeast, but at room temp it dropped enough to decant half the liquid.  I just pitched the whole lot.

Have not gotten into yeast cell counts etc so will learn that.

I abandoned my inline oxygenator and bubbled diffusion stone for 3 minutes (34L batch)

Yeast activity seems fine after 1 day...but the proof will be in a week or so.  1056 yeast sitting on 19.4 degrees C now seems happy.

Will advise...   

Offline jomebrew

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Re: My yeast is stressed. Why?
« Reply #4 on: May 28, 2018, 11:51:39 AM »
I know you said you have temp control but I would look closely at fermentation temperature. In my experience, fermentation temperature is often the cause for solvent like flavors. 

However, solvent off flavor is a phenol and can come from sources such as chlorophenols.  Treating filtered water with campden or pre-boil and cool water before using.  Chloramines can't be removed by boiling though. 

Iodine or bleach sanitizer can also contribute to the flavor.  Good sanitation and rinse processes will eliminate this.  It is also critical to use sanitizers as directed.  I see so many people do this wrong.

Anecdotally, one homebrewer always used a regular green garden hose to for brew water.  He was adamant it had nothing to to with the plastic or chemically off flavor.  To prove me wrong he used a white potable water hose and the flavor went away.  He actually didn't realize it until he tasted two of his beers side by side. Very often we are immune to our own processes or "house" flavors.

Good luck and hope this brew is  to your taste!

Offline kimmysawi

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Re: My yeast is stressed. Why?
« Reply #5 on: July 04, 2018, 03:40:37 AM »
You process looks OK. I don't see any alarms there versus what others do.

Some things to look at:

If you are using a stir plate, you don't need to oxygenate your starter wort much if at all.  I use a loose cap of aluminum foil over the flask and pretty good yeast growth without using Oxygen. 

How long before brew day do you make your starter?  How is it stored between finishing and your pitching it? 

Is it the same strain of yeast each time or do you get the same solvent flavor with different strains? 

Just for comparison of techniques, I make an ample starter as I am usually splitting it based upon cell count to build up the extra for the next batch.  I also add yeast nutrient to the starter to provide missing minerals (usually Zinc) that will not be plentiful enough in the DME.

Once the starter has finished with the growth stage (usually 24 hrs to 36 hrs depending upon strain), I place the flask in cool storage (~12?C to 14?C) and then transfer it to a refrigerator until brew day.  On brew day, I decant the excess starter wort (try tasting it, it is usually pretty bad, or at least not what I want in my recipe), do my cell count, and measure out the starter slurry I want to pitch.  The rest will be used in the next starter.

I typically fill my fermenter and put it into my fermentation chamber to allow it to reach the temperature I want to pitch at.  Meanwhile, I take the wort I have used for measuring gravity and wort pH and add that to the yeast I will be pitching. visit phenq review hereand you can shake this well and allow it to start activity.  By that time, usually around 4 hrs to 8 hrs after the fermenter has gone into the fermentation chamber, the flask has a good layer of krausen on top and I pitch it into my fermenter. 

Bottom line, my suspicion is that the amount of Oxygen in your starter is most of the issue, but I've never done that to confirm the result.  When I bubble Oxygen through my fermenter before pitching my yeast, I only flow it for about 45 seconds.  I ask the rest in case I am missing something else which is critical.

It was just a fluke that hits those ground seriously
« Last Edit: July 04, 2018, 03:58:09 AM by kimmysawi »

Offline Kevin58

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Re: My yeast is stressed. Why?
« Reply #6 on: July 04, 2018, 10:32:15 AM »
Try making your starter a little sooner than 36 hours before using it. I make mine no more than 24 hours before brew day. The best steps I ever took to improve my beer was paying attention to yeast health. Make a starter. Use nutrient. Oxygenate. Temperature control during fermentation.
PS. if you use Beersmith it will suggest how many cells you need and predict how many your starter will produce. Good luck.
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Offline flars

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Re: My yeast is stressed. Why?
« Reply #7 on: July 05, 2018, 03:29:15 PM »
Does the Beersmith calculator estimate fairly close to his calculator?
http://www.brewunited.com/yeast_calculator.php

What is the temperature of the wort when you rack on top of the yeast?

Which yeast are you using and what is the temperature of the beer in the primary during the first three days of the fermentation?  Fermentation temperature will always be higher than the ambient temperature.  The yeast produces heat as the sugars are consumed.

Your fermentation temperature may be too high for the yeast and fusel alcohols are being produced.