Banana-like aroma

2 days in the primary and my English Brown Ale is wafting some wonderful banana-like tones out of the airlock. I'm worried about the potential fruitiness from what is supposed to be a bitter mild. Anyone know what's going on, and if this is a problem, how can I mitigate it?

What is your fermentation temperature? Sounds like you may be fermenting too warm.

Yup - sounds a lot like you're getting esters (fruity-smelling byproducts of fermentation) from a warm ferment. The easiest thing you can do to reduce them to a level at which they actually make your beer taste good (and not like bananas) is to always cool your wort to 68 F or lower before pitching. Then place the fermenter somewhere where the ambient temperature is in the mid-60s, as fermentation will raise the temperature of your beer by a few degrees. Pitching into warm wort, even if it cools afterwards, will cause substantial ester formation. I drank a lot of terrible beer before I had this explained to me!

With winter coming many people in the northern half of the country will have a decent heat sink--the concrete floor in the basement. Even if ambient in your basement is running 65 the concrete slab should be a few degrees lower. Get those buckets off the shelf and on the floor.

Any suggestions for what to do if you're brewing in, say, a dorm room and don't have a handy heat sink such as a basement floor?

Put them in the bathroom, close the door and open the window?

Heh dunno, last time I was in a dorm room was Berklee College of Music in Boston and it was three to a room. Guess you could get an appropriately-sized trash can or bin and judiciously add frozen water bottles or just go swamp cooler ghetto style with the wet shirts and the fan.

Or make a box of insulated material with foam insulation and duct tape for your fermentors, and then periodically switch out frozen water bottles.

There are a lot of options, some are more of a pain in the ass and less accurate than others.

The good news is, even if you don't do any of the above you'll end up with enjoyable, drinkable beer!

Wrap a wet towel around the fermenter. Check the temp after a day, if you are still too warm, add the fans. Remember to keep wetting the towel when it gets dry. Th evaporation of the water from the towel will pull the heat out of the fermenter.

Just a side note for all you outdoorsy people. I learned this trick a few years back. If you are backpacking and there is not the option to pack ice in with you and you want to bring some beverages. Grab a cheap box of wine and take out the bladder. When you get to your campsite, get a towel wet and wrap the wine bladder in the towel and hang it so the wind can hit it. You will have cold wine in no time, and there is no need for ice. I supposed you could do the same with a growler or nalgene with beer in it as well (creatively named a nalgebeer) in my college days.

You're in Vermont, no? Well, I'd suggest leaving buying an accurate thermometer for your room, leaving your window open a crack and monitoring to ensure the temperature stays around 65, and investing in some nice warm clothes. You might be chilly every now and then, but your beer will be awesome.

I have had California Lager and Nottingham yeast both emit pleasant banana aromas, even when they were fermenting in the low 60s.

The beer did not taste like bananas, so I would not despair over your beer; it might not even be "too hot".

The wet towel method will get you a several degrees below ambient depending on humidity, but sitting the carboy in a shallow water bath (bucket or cooler), to which you occasionally add ice as required, allows a lot more control for a similar amount of attention IMHO.

What yeast are you using ? S-04 for me gives off all kind of nice fruity smells, including banana, and I ferment in the mid to low 60's.