Oktoberfest and Bananas?

I brewed my first Oktoberfest the second week of July, it was an all grain batch, a recipe that Yooper posted several years back. Brew day went great all temps/quantities went well. I nailed the OG and felt really good about the process. I pitched the yeast and put the bad boy in a cool dark corner and covered it with a towel to reduce the chance of off flavors from light exposure.

I bottled this batch last weekend and tasted it for the first time.
I can definitely taste the malt on the front end. The hops were a little more mild than I thought they would be but so far so good. It had a decent mouth-feel and finished with a slight alcohol heat.
The problem: I'm getting a kind of fruity banana flavor on the back end. This was unexpected and frankly it puts me off a little.

Observations:
1.) I didn't lager this at a lower temp (partially due to the fact that I was moving and my keezer was down and also because I've heard that some lager yeasts can ferment at slightly higher temps and still make a great beer).
2.) I let this batch sit on the cake a lot longer than I have any other batches I've made. (Probably 6 weeks post primary fermentation)
3.) I only racked it once before bottling, though it was pretty clear.

I realize that bottling and carbonation may change the flavor profile a bit, but is this baby ruined? I'm thinking my higher fermentation temps caused the fruity back end flavors??? I imagine i made several mistakes here, but the fruity stuff I don't want to replicate in a beer like this. Any thoughts?

Like you suggested, this is most likely due to fermenting temperature not being low enough. Most lager yeast are meant to ferment at low temperatures. What strain did you use? I don't know how strong the banana phenol production is, but I wouldn't call it ruined unless it's undrinkable. The beer probably doesn't fit the style guideline but hey, if you can drink it....

I used a Wyeast Oktoberfest strain - as I'm at the office I don't have my notes with me so the exact strain i'm not sure of. I'm wondering if the taste will subside with time or if it's something that will get worse/stay the same?

I would hazard a guess that maybe just maybe some time will help the funk to subside. I have a massive (10%) pale ale that I left on the yeast cake too long that came out tasting very much of soap and cloves. The only batch I've ever considered tossing. 4 months in a closet made it drinkable. It's not perfect, but I can drink it and almost enjoy it. If yours isn't as bad of a starting taste as mine (I can almost assure it is not), then you're already ahead of the game Let it age out, forget about it a bit, and continue on down the pipeline. If it gets better, awesome. If it doesn't, then hey...at least your pipeline is full again.

Wyeast Octoberfest Lager Blend
Temperature Range: 48-58° F (9-14° C)

Sorry I meant esters (fruit, banana) and not phenols (spice, clove). From what I know, in addition to the warmer temperature, underpitching yeast might result similar result.

I read somewhere that hops aroma decrease rapidly while malt taste slowly increases for months before dropping out. This increase might result in hiding other tastes?

BigPoppa502 said:

I

Observations:
1.) I didn't lager this at a lower temp (partially due to the fact that I was moving and my keezer was down and also because I've heard that some lager yeasts can ferment at slightly higher temps and still make a great beer).
2.) I let this batch sit on the cake a lot longer than I have any other batches I've made. (Probably 6 weeks post primary fermentation)
3.) I only racked it once before bottling, though it was pretty clear.

Click to expand...

I'm only guessing, but it sounds like there are a couple of things going on. First, it sounds like fermentation temperature was way too high. 50 degrees, more or less, works best for most lager strains. That's not "lagering temperature", though. That's fermentation temperature. Lagering seems to give the smoothest crispest flavor at 32-34 degrees to me.

Letting it sit on the cake for 6 weeks is also an issue. I know some brewers will tell you they have done it, but for a lager that is supposed to be without yeast character or flavor to sit on a cake that long is something I wouldn't do. Yeast character is often present even in ales that sit on a yeast cake for an extended time. Some people don't find it unpleasant, but it in a lager it's considered a flaw.

There are a couple of keys for lagers. They aren't hard things, but they are important. One, is to pitch a big starter at the proper temperature. HUGE starter, like a three gallon starter, would not be too much yeast. The "proper temperature" is a hard one, because I've found that the best lagers I've made have been pitched below optimum fermentation temperature, and then allowed to rise to 50 degrees. I'd pitch a 40 degree yeast starter (decanted of the spent wort) into a 45 degree wort and let it rise to 50 degrees and keep it there 7-10 days before doing a diacetyl rest and racking. I'd then lager at 32-34 degrees for 6-8 weeks.

I have a strong feeling that your "banana beer" won't improve much at this point, but aging it might help.

Banana flavour is a common indicator of high fermentation temperatures.

Thanks to everyone for all the good responses. I think everyone has confirmed my suspicions and also given some really good info for next time. While I've only done two "lager type" brews I am intrigued by the processes and challenge. I'll let this one sit and see what comes of it in a few months. It's drinkable now so nothing lost however, I've gained that experience...

thanks again!