Author Topic: Banana ester in my lager after diacetyl rest  (Read 4443 times)

S. cerevisiae

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Re: Banana ester in my lager after diacetyl rest
« Reply #15 on: November 10, 2015, 06:44:43 PM »
For my vienna, I used 2 fresh vials of 830 in 2L 1.040 in a 5L flask.

I have stated many times that the vessel has to be at least four times the volume of the medium, which means that a 2L starter requires an 8L or larger vessel. 

https://www.homebrewersassociation.org/forum/index.php?topic=24447.15

https://www.homebrewersassociation.org/forum/index.php?topic=24447.msg311561#msg311561


Now, add in the fact than an Erlenmeyer flask is a less than optimal choice for a shaken, not stirred starter due to its geometry, and one is pretty much ensured to be underwhelmed with the results. The best geometry for a shaken, not stirred starter is a cylinder where the height-to-diameter ratio is no more than 2:1. Additionally, while it does not hurt to pitch 2 vials of yeast into 2L of wort, only one is needed.  Pitching two vials instead of one does not buy one much in the grand scheme of things.


Offline majorvices

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Re: Banana ester in my lager after diacetyl rest
« Reply #16 on: November 11, 2015, 02:15:36 AM »
A 2L starter in five gallons is not underpitching by any stretch of the imagination.  That's a roughly a 10-to-1 step.  My bet is on wort composition.  Banana is the ester known as isoamyl acetate, which is formed via a condensation reaction between isoamyl alcohol (a.k.a. isopentanol) and acetic acid.

C5H12OH + CH3COOH  → C7H14O2 + H2O

The reaction shown above reads isoamyl alcohol plus acetic acid produces isoamyl acetate plus water.   What this reaction means in layman's terms is that your fermentation generated isoamyl alcohol, and there was acetic acid available with which to form isoamyl alcohol.  Acidic acid comes from acetyl-CoA.  We know that higher alcohol (isoamyl alcohol is a higher alcohol) production increases with biomass growth; however, so does acetyl-CoA utilization.  On the other hand, overpitching results in elevated acetyl-CoA lower and lower higher alcohol production.  This batch was neither overpitched nor underpitched, which means that something else went wrong.   What was the original gravity?  What was the wort composition?  How much trub did you carry over from the kettle?
 

The original gravity was 1.051, it was a extract brew, 100% pilsner liquid malt extract from morebeer. I racked off the trub after letting it settle for 3 hours. I did pitch at 60 degrees which I now know is not good. The other thing I now know I did wrong is I added all of wort from the starter rather than pouring of most off the liquid.

That right there is you problem.

Offline chumley

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Re: Banana ester in my lager after diacetyl rest
« Reply #17 on: November 11, 2015, 04:10:02 AM »
majorvices hits it!

I unfortunately started my last lager at 65°F.  I discovered that one cannot rely on dial thermometers stuck into kettles when a wet horizontal snow is falling at a rapid clip.  It is still fermenting, but I will be curious to see if I get a banana ester from fermenting too warm.  It is at 48°F now, but the damage may have been already done.

I once tried using 34/70 at 62°F and wound up with fruitcake pilsner.

Offline wmsouthworth

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Re: Banana ester in my lager after diacetyl rest
« Reply #18 on: November 11, 2015, 04:11:33 AM »
If I had to guess, the beer is either too young and you're perceiving something other than isoamyl acetate, or you picked up a wild yeast at some point.

The problem could be due to a wild yeast or bacteria infection, but it could also be due to a mislabeled vial of yeast.  It does happen from time to time.  The only thing that could rule out receiving a mislabeled vial of yeast is fermentation temperature.  However, then again, fermentation temperature would also rule out wild microflora, which leads us back to wort composition, complete lack of trub, and/or dissolved O2 concentration.

There was a complete lack of Trub, the wort was completely clear.  The beer had sulfur notes during primary and started to smell of banana when I raised the temp at the end. Maybe lack of trub was the problem? There was plenty of oxygen in the wort prior to pitching.  I am serious about sanitation, but we all make mistakes. If the yeast was possibly mislabeled what would it be? what produces banana ester at 50F ?

Offline majorvices

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Re: Banana ester in my lager after diacetyl rest
« Reply #19 on: November 11, 2015, 01:09:28 PM »
If I had to guess, the beer is either too young and you're perceiving something other than isoamyl acetate, or you picked up a wild yeast at some point.

The problem could be due to a wild yeast or bacteria infection, but it could also be due to a mislabeled vial of yeast.  It does happen from time to time.  The only thing that could rule out receiving a mislabeled vial of yeast is fermentation temperature.  However, then again, fermentation temperature would also rule out wild microflora, which leads us back to wort composition, complete lack of trub, and/or dissolved O2 concentration.

There was a complete lack of Trub, the wort was completely clear.  The beer had sulfur notes during primary and started to smell of banana when I raised the temp at the end. Maybe lack of trub was the problem? There was plenty of oxygen in the wort prior to pitching.  I am serious about sanitation, but we all make mistakes. If the yeast was possibly mislabeled what would it be? what produces banana ester at 50F ?

A little trub is actually good for a beer. Too much may cause problems but I highly doubt this is your problem. Look, all due respect to our resident yeast expert, there is a very tried and true method to making great homebrew lagers. And it doesn't involve overcomplicating things.

If you are not using a stir plate, then you should start with a 4 liter starter. 2 vials per 4 L per 5 gallons of 1.050ish wort is not going to be too big. Aeration at the start will benifit greatly. Ferment you starter at room temp. When finished cold crash. Decant starter wort. Cool your wort all the way down to 46-48 degrees for pale lagers, 50-52 for dark lagers. Aerate 2Xs as much as you would for ales. Pitch yeast. Once fermentation is active hold temp at 48-50 for pale lagers and 50-52 for dark lagers for 48-72 hours. After this you may want to ramp the temp up a couple degrees or hold for as long as 5-7 days before ramping up to about 58 degrees (I go about 2 degrees a a day when I am ramping and I wait till the end of fermentation.)

Hold at 58 (or even as high as 62) for the remainder of fermentation. You will have a very clean, diacetyl and isoamyl-acetate free lager. I promise.
« Last Edit: November 11, 2015, 01:12:14 PM by majorvices »

Offline Wort-H.O.G.

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Re: Banana ester in my lager after diacetyl rest
« Reply #20 on: November 11, 2015, 04:18:02 PM »
^^^^^ +1 to this. other than than non-stir plate part for me where im usually about 3L one vial stirred, everything else the same in my process.

great clean lagers will be the result.
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Offline blatz

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Re: Banana ester in my lager after diacetyl rest
« Reply #21 on: November 11, 2015, 05:36:11 PM »
To clarify.  The OP I don't think used 2 vials - that was me commented on the shaken not stirred that I clearly did not follow directions on, shame on me.  10 gal batch thought I would double things :(

I follow Majorvices process almost exactly, having built up from 2-3 vials.

while I didn't realize he pitched at such a high temp, and I agree that is the culprit I also think had he pitched more yeast he may have had a better result.

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Re: Banana ester in my lager after diacetyl rest
« Reply #22 on: November 11, 2015, 05:41:50 PM »

To clarify.  The OP I don't think used 2 vials - that was me commented on the shaken not stirred that I clearly did not follow directions on, shame on me.  10 gal batch thought I would double things :(

I follow Majorvices process almost exactly, having built up from 2-3 vials.

while I didn't realize he pitched at such a high temp, and I agree that is the culprit I also think had he pitched more yeast he may have had a better result.

The same two things that killed me with lagers in my early/ first lagers Paul.


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Ken- Chagrin Falls, OH
CPT, U.S.Army
https://www.facebook.com/pages/Harveys-Brewhaus/405092862905115

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Serving:        In Process:
Vienna IPA          O'Fest
Dort
Mead                 
Cider                         
Ger'merican Blonde
Amber Ale
Next:
Ger Pils
O'Fest

S. cerevisiae

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Re: Banana ester in my lager after diacetyl rest
« Reply #23 on: November 11, 2015, 07:45:25 PM »
That right there is you problem.

That's not it.  I start every lager that I make at 16C/61F before dropping the temperature slowly to 13C/55F, and I never get isoamyl acetate.  There's zero need to ferment a lager below 13C. The use of Saccharomyces pastorianus in brewing is the result of selective pressure placed on mixed Saccharomyces pastorianus and Saccharomyces cerevisiae cultures at 13C/55F, which is the year-round temperature below the frost line. 
« Last Edit: November 11, 2015, 08:33:27 PM by S. cerevisiae »

Offline majorvices

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Re: Banana ester in my lager after diacetyl rest
« Reply #24 on: November 11, 2015, 08:00:00 PM »
The original gravity was 1.051, it was a extract brew, 100% pilsner liquid malt extract from morebeer. I racked off the trub after letting it settle for 3 hours. I did pitch at 60 degrees which I now know is not good. The other thing I now know I did wrong is I added all of wort from the starter rather than pouring of most off the liquid.

That right there is you problem.

That's not it.  I start every lager that I make at 16C/61F before dropping the temperature slowly to 13C/55F, and I never get isoamyl acetate.  There's zero need to ferment a lager below 13C. The use of Saccharomyces pastorianus in brewing is the result of selective pressure placed on mixed Saccharomyces pastorianus and Saccharomyces cerevisiae cultures at 13C/55F, which is the year-round temperature below the frost line.
[/quote]

I know that there are many folks who do use that method successfully, I am trying to give him a simple method that works for a great majority of us lagering brewing folks here on the forum. I have been brewing lagers for 15 years and have never gotten isoamyl acetate by pitching cold. I also brew commercial lagers that are distributed across two states using this method (though, at a much larger scale) and it is a tried an true method that works.

Mark, I'd love to have your deep understanding of microbiology and chemistry and I hope to hire a guy someday who has that knowledge but for homebrewers the method I have described works.

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Re: Banana ester in my lager after diacetyl rest
« Reply #25 on: November 11, 2015, 08:04:41 PM »
If you are not using a stir plate, then you should start with a 4 liter starter. 2 vials per 4 L per 5 gallons of 1.050ish wort is not going to be too big. Aeration at the start will benifit greatly. Ferment you starter at room temp. When finished cold crash. Decant starter wort. Cool your wort all the way down to 46-48 degrees for pale lagers, 50-52 for dark lagers. Aerate 2Xs as much as you would for ales. Pitch yeast. Once fermentation is active hold temp at 48-50 for pale lagers and 50-52 for dark lagers for 48-72 hours. After this you may want to ramp the temp up a couple degrees or hold for as long as 5-7 days before ramping up to about 58 degrees (I go about 2 degrees a a day when I am ramping and I wait till the end of fermentation.)

Hold at 58 (or even as high as 62) for the remainder of fermentation. You will have a very clean, diacetyl and isoamyl-acetate free lager. I promise.


That's pretty much exactly what I'm doing now for lagers and it's the best, most consistent method I've used, by far.  No diacetyl or other off flavors/aromas.
Jon H.

Offline ynotbrusum

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Re: Banana ester in my lager after diacetyl rest
« Reply #26 on: November 11, 2015, 08:47:15 PM »
My observances on a couple issues raised in this thread:

My last Helles was a 10 gallon batch - the starter was the first gallon run off from the kettle into a 3 gallon better bottle with solid stopper (silicone o-ring tight), shaken like I needed bail from a brother-in-law who owed me money, pitched two packs of 2038 at room temperature, held to high krausen and pitched into the chilled and aerated wort about 7-8 hours later (after return from a neighborhood gathering).  It was off and running/roaring like an ale when I checked in the following morning.

As to starting warm and dropping after fermentation becomes active - I know a solid award winning lager home Brewer who does it this way and we just agree to enjoy each other's beers without challenging process.  (BTW his day job allows me to purchase his pro wares at the local beer store - he is Siebel taught and knowledgable).
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S. cerevisiae

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Re: Banana ester in my lager after diacetyl rest
« Reply #27 on: November 11, 2015, 08:52:03 PM »
I know that there are many folks who do use that method successfully, I am trying to give him a simple method that works for a great majority of us lagering brewing folks here on the forum. I have been brewing lagers for 15 years and have never gotten isoamyl acetate by pitching cold. I also brew commercial lagers that are distributed across two states using this method (though, at a much larger scale) and it is a tried an true method that works.

Mark, I'd love to have your deep understanding of microbiology and chemistry and I hope to hire a guy someday who has that knowledge but for homebrewers the method I have described works.

It's just that telling a home brewer that he/she needs to pitch 2 vials of yeast into 4 liters of wort for a 5-gallon batch is extreme overkill.  That is a 5-to-1 step, which is higher than I use in an aseptic setting when growing yeast from a slant.  There is a lot more that can go wrong when working with a culture that small than working with one or two cultures that started out as 100B cells.  The difference between pitching one vial and pitching two vials is 90 minutes of propagation time at room temperature, that is, as long as there is enough carbon, volume, and dissolved O2 to support the growth.


The number one mistake that home brewers make when propagating Saccharomyces pastorianus (a.k.a. lager yeast) is propagating at lager fermentation temperature.  Low temperatures suppress metabolism, and anything that suppresses metabolism suppresses biomass growth.  All starters should be propagated at room temperature.

For those who want to understand more about yeast growth, please take a minute to read the following entry from my blog: www.experimentalbrew.com/blogs/saccharomyces/yeast-cultures-are-nuclear-weapons

« Last Edit: November 11, 2015, 08:53:53 PM by S. cerevisiae »

Offline majorvices

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Re: Banana ester in my lager after diacetyl rest
« Reply #28 on: November 11, 2015, 08:52:34 PM »
My observances on a couple issues raised in this thread:

My last Helles was a 10 gallon batch - the starter was the first gallon run off from the kettle into a 3 gallon better bottle with solid stopper (silicone o-ring tight), shaken like I needed bail from a brother-in-law who owed me money, pitched two packs of 2038 at room temperature, held to high krausen and pitched into the chilled and aerated wort about 7-8 hours later (after return from a neighborhood gathering).  It was off and running/roaring like an ale when I checked in the following morning.

As to starting warm and dropping after fermentation becomes active - I know a solid award winning lager home Brewer who does it this way and we just agree to enjoy each other's beers without challenging process.  (BTW his day job allows me to purchase his pro wares at the local beer store - he is Siebel taught and knowledgable).

It's like I tell the brewers who work under me. There isn't necessarily a right way to do things, but there are certainly wrong ways. Whatever way works is the best way. That said, when you are doing something that isn't working, and someone suggests a way that does work for lots of people, you might want to try it!

S. cerevisiae

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Re: Banana ester in my lager after diacetyl rest
« Reply #29 on: November 11, 2015, 08:55:29 PM »
shaken like I needed bail from a brother-in-law who owed me money

ROTFL!  May I use that one?