Banana Flavor

I've brewed 8 batches to date, and 7 of them have adopted a hint of a banana aroma. Assuming it was just the esters from the yeast, I've made it a point to use different yeast strains to see if I could avoid the banana, but to no avail. I thought it might be a result of fermenting at too high temperatures, so I always keep it a steady 68-72 degrees. But still, banana.

Where does this banana aroma (and flavor!) come from? How do I avoid it?

I guess it's better than cardboard or mediciney off flavors, but still...

What types of beers and what types of yeasts? It seems odd that all beers would have that same flavor, so if you have any data on recipes, etc... we might be able to find a common link.

In my experience, this is almost always caused by high fermentation temps. Ferment the coolest you can with the yeast strains you're using. There's a good chance you wort is somehow getting significantly warmer than the ambient temps.

Banana tends to be a Weizen yeast thing.

These weren't wheat beers, were they?

I think 72 degrees can be too warm. If that's ambient room temperature, the fermentation can cause temperatures to go even higher. What I mean is that fermentation is exothermic- and some have seen they see a 6,7,8, even 10 degree temperature difference in fermenting wort and the air temperature. What that can mean that the room might be 72 degrees, but the wort can be fermenting at more like 80 degrees. I have those cheap stick on thermometers on each fermenter, and while they are not perfectly accurate, they are great for keeping an eye on the actual temperature of the beer/wort as it ferments.

Right now, I have a wine and a beer fermenting at 64 degrees (actual wort temperature).

Thanks Yooper. I missed that. You definately have to take into account that the wort will ferment warmer than ambient temperature. I've got some off flavors in my IPA, most likely as a result of warmer temps.

I think the warmer temp thing may be it... The last batch I did was the first one that didn't have the banana flavor or aroma, and it was the first time I employed the wet T-shirt method to keep the carboy cool.

Thanks! If I ever make a Banana Ale, I'll be sure to purposefully ferment it at a higher temperature. =)

I consistently had the same problem when fermenting at any temp over 70. Personally i like the fruity/banana flavor in my wheat beers and my friends request it so i ferment at the higher temps with those types on purpose.