Stumped where I picked up banana flavors...need some help

[HossTheGreat]

Ok, so normally I'm an AG brewer but I had just enough left-over DME to get a batch in last week. I was just going to make a light, low gravity beer that I had planned to rack to secondary and add some frozen blackberries.

First, here's my recipe:

Batch Size: 5.5 gal
5lb 14.4 oz of Light DME
12oz Crystal 40L
2oz of Special B

Hops:
46g Crystal 3.3AA for 60min
15g Crystal 3.3AA for 10min
5g Crystal 3.3AA for 0min

Yeast:
1pkg Rehydrated Safale US05

Measured OG: 1.043
Measured FG: 1.011


After the 60min boil, I promptly chilled to 65% and racked to my primary. I then pitched my rehydrated dry yeast. I fermented at 65 degrees, as I do all of my ales. My temp probe is insulated in bubble wrapped and taped to the side of the carboy, so I know I'm getting a fairly accurate reading of the fermentation temp.

Fermentation began within 24 hours (can't remember exactly what the lag was). During active fermentation, I caught a noticeable smell of banana coming out of the carboy. Tonight (1 week later) I took a sample. If I hadn't known anything about this beer, and someone handed it to me, I would swear it's a Hefe (a style I do not particularly care for, unfortunately). The banana flavor and aroma is very dominant in this beer.

I'm very confused as to where I picked this flavor off. Like I said, I used US05 which always has fermented very clean for me in the past. I also very carefully control my fermentation temps. In fact, this was the second beer of a double brewday. The first was an AG American Amber in which I brewed a couple of hours before. It fermented right beside this beer in the chest freezer and it has no noticable off flavors. Any thoughts, I'm kinda stumped?

 

[passedpawn]

wild yeast perhaps. US05 is very clean. I made a beer with wild yeast from the neighborhood and it had some clovey flavors.

 

[HossTheGreat]

I suppose it's a possibility. Though I'm very thorough in sanitation and try to limit the exposure my chilled wort has to the open air, I do brew outside so it's always possible that I picked something up.

 

[passedpawn]

It was just a wild guess.

That's how they (used to) brew in Belgium. Unlike bacteria, wild yeast won't sour your beer, but might give it some knuckleball character. Enjoy it.

 

[HossTheGreat]

Unfortunately, Hefe is probably my least favorite style. Just not a big fan of banana (or clove). Don't like to dump, but this might be a candidate.

 

[HossTheGreat]

A follow up...

Just over a week ago I did an English Summer Ale that was in the Nov/Dec edition of Zymurgy:

7.5lbs US 2 Row
1.5lbs Vienna
5oz White Wheat
16G Magnum for 60 min

This time I used S04 for the yeast. I pitched the yeast at around 65 degrees and it fermented at 63-64 degrees in about 3 days. I just sampled it after 10 days in the primary and it had the exact same Hefe banana/clove flavor to it. This is the second batch in a row with this problem, but here's the confusing part....I used a different fermenter than last time and I used different tubing to transfer the wort to the primary. The only thing that would have been the same that would have touched the wort post-chilling would have been my oxygenation stone/tubing.

Today I went ahead and did a "scorched earth" on my brewery. I broke down my electric kettle and boiled every stainless steel fitting, o-ring, and silicone tubing. I then bleached my fermenters and all plastic. Hopefully this will solve the problem.

I have also been carbon filtering my water and treating it with campden tablets prior to brewing, but I also think that I'll switch from my tap to RO water for my next brew just to eliminate any issues with that. Hopefully this takes care of the problem. A frustrating problem, to say the least.

 

[brewtus_]

Underpitching the yeast, low oxygen concentration and/or too high of fermentation temps can all cause banana flavors. It looks like you're not underpitching and you've said that you're oxygenating and your temps look good. How are you controlling your temperature over the primary fermentation period? Edit: Nevermind, I see you're using a chest freezer and had another beer fermenting side by side. I'm stumped.

 

[NordeastBrewer77]

do any of your enemies know you dislike hefe's and have access to your yeast stores? no, really, that's pretty weird. i'd be interested in knowing what you find to be the culprit.

 

[HossTheGreat]

Underpitching the yeast, low oxygen concentration and/or too high of fermentation temps can all cause banana flavors. It looks like you're not underpitching and you've said that you're oxygenating and your temps look good. How are you controlling your temperature over the primary fermentation period? Edit: Nevermind, I see you're using a chest freezer and had another beer fermenting side by side. I'm stumped.

I've completed the complete nuking of my brewery. All stainless/silicone hose has been boiled and all plastic has been bleached. Hopefully if there was a wild yeast in there somewhere, this took care of that that booger.

The oxygenation system that I've been using is similar to this one. The black tubing that is connected to the stone is very rigid and I never was able to remove it to clean/sanitize properly. After each brew, I'd rinse with hot water and sanitize. After my first bad batch, I actually boiled up some water and dunked it for several minutes to sanitize, hoping that would take care of it. Since my latest bad batch, I've removed the black tubing and replaced it all together with a more flexible tubing that I can easily remove after brew day. I've also boiled the stone along with all of my other stainless fittings. This is the only logical thing that I can think of being the culprit. Hopefully this will eliminate it.

 

[MrManifesto]

the first batch you tasted after a week and the 2nd after 10 days?

it's going to taste of esters because you haven't given the yeast time to clean them up.

 

[HossTheGreat]

the first batch you tasted after a week and the 2nd after 10 days?

it's going to taste of esters because you haven't given the yeast time to clean them up.

I've brewed over 50 batches previously and have never had these off-flavors...ever, which is why I've posted this thread. I'd understand them being there if I fermented warm, underpitched, etc. However, these should have both fermented clean given the conditions.

 

[Beerbeque]

This frustrating Belgian- like off flavor has happened to me several times as well. I hate it and I really hate dumping my beer. It seems to me that this common problem is the single biggest misunderstood problem in homebrewing. I've read many threads over the last 3 years of brewers complaining of the problem with lots of guesses as to the cause but as far as I can tell nobody has been able to really nail it. I know that I and most of you others are sanitizing, pitching and fermenting properly yet the problrm still occurs occasionally. I wonder if the same problem also occurs occasionally with commercial brewers?

 

[badhabit]

I too have had the same experiance a couple times. I have never been able to discover the problem and I have never had it back to back....always seperated by years and many batches in fact. Cleaned everything double checked fermentation temps, double checked pitching rate, everything I could think of. The strangest part was that the off flavor was not notibly evident until after conditioning. Lucky me, my mom likes Belgium style beers, so she gets these batches from me

 

[periwinkle1239]

I too have had the banana flavor in one of my Belgian dubbels. The yeast was 1214 which is supposed to be bananas especially at high ferment temps. So I fermented at 60 degrees to try and avoid it, but the banana was still so strong it was hard to drink.

I retraced my steps and believe that it was caused due to underpitching since I didn't make a starter (doh!).

On the plus side, the bananas started to go away over time and after 3 months and it turned into a delicious beer. (I just kicked the keg last night)

So I wonder if your 05 and 04 lost some its viability which would be like underpitching?

 

[HossTheGreat]

So I wonder if your 05 and 04 lost some its viability which would be like underpitching?

Hard to say. I guess I could see if it were both the same types of yeast from the same lot, but I wouldn't think it would happen to 04 and 05 batches back to back. I'm going to brew up a dry stout tomorrow and pitch a starter of Wyeast 1056. I hope after my thorough cleaning and sanitizing that the off-flavor won't be back.

 

[WingShooter]

I too have had the banana flavor in one of my Belgian dubbels. The yeast was 1214 which is supposed to be bananas especially at high ferment temps. So I fermented at 60 degrees to try and avoid it, but the banana was still so strong it was hard to drink.

I retraced my steps and believe that it was caused due to underpitching since I didn't make a starter (doh!).

On the plus side, the bananas started to go away over time and after 3 months and it turned into a delicious beer. (I just kicked the keg last night)

So I wonder if your 05 and 04 lost some its viability which would be like underpitching?

Same thing happened to a Friend of mine, after a month or so it turned out very good, so I wouldn't dump it yet.

 

[foltster]

I've completed the complete nuking of my brewery. All stainless/silicone hose has been boiled and all plastic has been bleached. Hopefully if there was a wild yeast in there somewhere, this took care of that that booger.

The oxygenation system that I've been using is similar to this one. The black tubing that is connected to the stone is very rigid and I never was able to remove it to clean/sanitize properly. After each brew, I'd rinse with hot water and sanitize. After my first bad batch, I actually boiled up some water and dunked it for several minutes to sanitize, hoping that would take care of it. Since my latest bad batch, I've removed the black tubing and replaced it all together with a more flexible tubing that I can easily remove after brew day. I've also boiled the stone along with all of my other stainless fittings. This is the only logical thing that I can think of being the culprit. Hopefully this will eliminate it.

Make sure you dont use any yeast form your old beers at this point as those jars of yeast will contain any microbes that were in your previous batches!

 

[HossTheGreat]

Make sure you dont use any yeast form your old beers at this point as those jars of yeast will contain any microbes that were in your previous batches!

Excellent point. Actually I haven't been reusing any yeast. I have a fresh pitch ready to go. Changed things up just a bit. Gonna do a pale ale today instead of the stout. That way I'll be able to pick out any potential off-flavors a little easier.

 

[robtotten]

How are you controlling the temperature of fermentation? It could be quite a nit hotter than you think in the middle of your carboy / bucket.

 

[HossTheGreat]

How are you controlling the temperature of fermentation? It could be quite a nit hotter than you think in the middle of your carboy / bucket.

I have a chest freezer with a digital Johnson temp controller. I place the probe directly on the wall of the carboy, then on top of that I use a folded piece of bubble wrap to insulate it. I then tape everything to the side of the carboy. This way I'm getting a fairly accurate reading of the temp inside the carboy.

 

[HossTheGreat]

Just an update....I brewed a Pale Ale on 1/31 (pitching a starter of Wyeast 1056), so it's been in the primary for a little over a week. I've sampled the beer a few times and there is absolutely no indication of clove/banana flavors. I still believe that some wild yeast was the culprit and it looks as though the bleach bomb has taken care of it. Thanks for all the input everyone.