Banana esters @ 66 Degrees

[280220]

Hi guys,

I am not exactly a beginner, but this is a beginner question. The sweet stout I just brewed has a relatively strong banana ester smell coming from the airlock on day 3 and 4 of fermenting. I have two 5 gallon batches in glass carboys (on brewed saturday and one brewed Sunday). The fermometer on Saturdays brew says the wort is 66 degrees (actually 64 kinda between 64 and 66). The femometer on Sundays says 63. I am using Nottingham Yeast in both.

I have never had this happen before (with the exception of my first brew that hit almost 80 degrees). Why would I be getting this at 66 degrees? I have never noticed my fermometers to be off, but this is the first time I have used these two carboys and these two stick on fermometers. Has anyone ran into this before? I am kinda frustrated with it, because I feel like I may have 10 gallons of Banana Stout sitting in a dark, not as cold as I apparently thought closet.

 

[cheezydemon3]

Stick on will be 3-4 degrees off of the center of the wort.

From your post, it sounds like it was 64-66 today, what was it saturday?

If the yeast are awake and you pitch at 70, you will be lucky to ferment any lower than 70 without outside temp control, and more likely 72-74F.

For some reason, stouts seem to be more susceptible to this problem.

 

[BigFloyd]

I'd not worry much based on fermentation smells.

I'd also not want to let Notty get above 66*F.

 

[BeerGrylls]

I also would not base any opinions on the aroma of the fermentation. However, temperature is not the only way to introduce esters into beer. You must also watch pitch rate and oxygenation. Also, there are factors such as unsaturated fatty acids (from the malt) and carbon to nitrogen (C/N) ratio.

All that said, wait until it's finished and conditioned before you jump to any conclusions.

 

[280220]

I have used nottingham for a lot of beers and have hit 69 without issues. I am just surprised by the smell. I pitched at 60 (the built in thermometer on my brew pot said 60 but the fermometer actually said 57...). There was plenty of oxygen, and I am under the impression that there is no such thing as to much unless I am pumping it in.

64 - 66 is the highest the temp has been. I am pretty anal about that stuff and I work within walking distance of my apartment, so I am positive it hasn't gone above that at any point. I check it an unreasonable number of times per day haha!

What would cause the unsaturated fatty acids?

 

[BeerGrylls]

What would cause the unsaturated fatty acids?

Actually, the presence of UFAs are critical to the process but is a secondary element that can only be controlled through other factors. I really wouldn't worry about this as all healthy, modern, well-behaved yeasts will produce their own UFAs and sterols in the presence of properly oxygenated wort, through their own metabolic processes. The oxygen is critical here, because excess ester production will only be averted if the yeast can convert the UFA precursor (Acetyl CoA) in an aerobic process. Anecdotally, I think this can be avoided with, at the very least, the 120 seconds of shaking to introduce ~2+ ppm o2.

This article is fantastic if you want to read up. This guy is much smarter than myself. http://sciencebrewer.com/2013/04/08/hombrewers-lecture-series-esters/

 

[280220]

Thanks! I will be sure to give it a good read today.

This entire thing sure is frustrating. I only brew in the winter, because the summer is filled with other things, but last winter all my batches were delicious. This winter I have done 2 batches before these two from the weekend, and there has been some issue with all of them.

I have gone crazy about perfect sanitation, I am doing full boils, I am getting it down to pitching temp in under 15 minutes, I am being sure to get oxygen in by running it over a mesh filter in my funnel and then shaking the crap out of it, and I am keeping temperatures well within the temp range of the yeast (the highest the dark blue on my fermometer has seen is 64.... it was a faint green on 66...). I am hoping that the banana isn't present in the finished project.... or is at least something that I can pass as intentional! Haha. I am certainly losing some of the brewers confidence. Last year I won local competitions. This year I can't even compete.... womp womp.

 

[CUrchin]

I've noticed that the yeast cake I got from Notty has smelled banana, but it hasn't transferred over to flavor in my beer (thank goodness because I can't stand banana beer). Keep temps under control I think you will be fine (IMO).

 

[fearwig]

I'd not worry much based on fermentation smells.

I'd also not want to let Notty get above 66*F.

Second on both of those. When I started out I read that notty has a flexible temperature range and was like "that's for me!" And I quickly learned they meant downward . Not a tasty yeast when it's stressed.

For OP I may also suggest you up your pitch rate with a starter next time, if you didn't, and if temp control isn't enough. Underpitching will produce esters as sure as overheating.

 

[280220]

I've noticed that the yeast cake I got from Notty has smelled banana, but it hasn't transferred over to flavor in my beer (thank goodness because I can't stand banana beer). Keep temps under control I think you will be fine (IMO).

This is reassuring! Did you have it coming out of the airlock in early fermentation as well?

 

[280220]

Second on both of those. When I started out I read that notty has a flexible temperature range and was like "that's for me!" And I quickly learned they meant downward . Not a tasty yeast when it's stressed.

For OP I may also suggest you up your pitch rate with a starter next time, if you didn't, and if temp control isn't enough. Underpitching will produce esters as sure as overheating.

See the thing is, is I used the crap out of notty last year. I never had a bad experience with it. I have a black ale (basically the best beer I make) and I used notty in it last year with a fermentation temp of 69 degrees with no banana esters. The starting gravity for that was 1.080. I didn't use a starter, just pitched the packet. The starting gravity for this beer is 1.068 (with 1/2 lb of lactose) and I was at a lower temp. That is part of the reason I am so surprised. Maybe I was just lucky last year?!

 

[CUrchin]

This is reassuring! Did you have it coming out of the airlock in early fermentation as well?

That I can't say (and yes I do sniff airlocks from time to time). Again, try to keep the temp down (I shoot for 62) and you should be fine.

I am curious why people are suggesting starters-It was my understanding that as long as you hydrate per the instructions you really shouldn't need a starter with dry yeast when brewing an ale with the exception of a large batch or high OG.

 

[BigFloyd]

I am curious why people are suggesting starters-It was my understanding that as long as you hydrate per the instructions you really shouldn't need a starter with dry yeast when brewing an ale with the exception of a large batch or high OG.

Your understanding is correct. Rehydration is the best course of action with dry yeast to get a sufficient cell count with a reasonable amount of effort.

 

[fearwig]

That I can't say (and yes I do sniff airlocks from time to time). Again, try to keep the temp down (I shoot for 62) and you should be fine.

I am curious why people are suggesting starters-It was my understanding that as long as you hydrate per the instructions you really shouldn't need a starter with dry yeast when brewing an ale with the exception of a large batch or high OG.

My mistake, I always repitch, somehow didn't think about notty being dry. I've seen some high sweet stout OGs but I guess OP would have mentioned if this was a big beer. I do use a small starter even with my dry yeasts to get the yeast riled up. Not mandatory.

But I do stick by the advice, if your temperature is reasonable and you taste fruit where you shouldn't, and you control for everything else, pitch a little bigger. Think temp is the culprit here, though.

 

[280220]

My mistake, I always repitch, somehow didn't think about notty being dry. I've seen some high sweet stout OGs but I guess OP would have mentioned if this was a big beer. I do use a small starter even with my dry yeasts to get the yeast riled up. Not mandatory.

But I do stick by the advice, if your temperature is reasonable and you taste fruit where you shouldn't, and you control for everything else, pitch a little bigger. Think temp is the culprit here, though.

I just have no clue how temp can be the culprit. I have pitched nottingham in bigger beers at higher temps with no issue at all. I know that when you go through your chart of off flavors/smells and you see banana you get "Was your temp to high?", "Enough Oxygen when you pitched?", "Not enough yeast?." I just can't believe any of them would be the issue. Unless of course I have just been super lucky every other time I have used Nottingham.

The beer never left the mid 60's. Had a faint green on 66 for a very short while, but that was it. Right now the fermentation has slowed down and it is at 57 (dark blue with the light green at 60) which is right were I pitched it. So we are talking 6 degrees up and 6 degrees back down to the starting point tops according to the fermometer. It is pretty low gravity (1.068 with lactose) and I have used it in my black ale at 1.080 several times with no issue (and at 69 degrees). My practices for introducing oxygen were the same as always - siphon over a mesh filter and shake the carboy like crazy. I just can't wrap my head around it haha. I am hoping it is just some goofy smell coming off and it won't be in the finished product.... but I guess we shall see at this point.

 

[BigFloyd]

I am hoping it is just some goofy smell coming off and it won't be in the finished product.... but I guess we shall see at this point.

There are a whole bunch of fermentation smells that aren't detectable in the finished product at all.

Here's to hoping it will be just fine.