What exactly makes banana flavors?

My wife and I recently went to a beer festival where we got to try 24 kinds of craft brews. About 4 or 5 of them had mild to strong banana flavors, and we both agreed that we hated that flavor.

From the searching I've done, the banana flavors come from certain esters produced by the yeast. Are there hops that produce this as well? It sounds like this is normally a characteristic of some German strains of yeast, and is perpetuated by higher than normal fermentation temperatures. Is that something to worry about only in fermentation or also in bulk ageing? Are these strains of yeast guaranteed to get that banana flavor even under well regulated conditions? Also, is it possible that it is more a symptom of over-fluctuating temperature instead of or in addition to higher temp?

Just trying to find out what steps to take to avoid this flavor in my beers. I understand some people find it desirable, but I do not.

It's hefeweisen yeast. The banana flavors typically come out of that yeast at higher fermentation temperatures (70+). If you want to make a hefe (or use a hefe yeast) and avoid those flavors just make sure you ferment cooler (65ish).

And no. There are no hops that taste like bananas.

Yeast produce different esters at certain fermentation temps. These esters usually have a fruity characteristic. Hefeweizen yeast often produce esters of banana and clove. You were most likely drinking hefes or beer made with hefe yeast.

There's only one hefe I've found that has way too much banana for my liking and that's Sierra Nevada's Kellerweis. It tastes like banana extract.

Thanks for the info. Unfortunately, many of the beers had very little info on them, though it usually included style, ABV, and about 1/2 the time the IBU. Oddly enough, the one "hefe" I did like was Widmer's Hefeweizen, which BA calls an American Pale Wheat Ale. The one that was strongest in banana flavor we tried was Starr Hill's The Love (a hefe).

Erroneous said:

Thanks for the info. Unfortunately, many of the beers had very little info on them, though it usually included style, ABV, and about 1/2 the time the IBU. Oddly enough, the one "hefe" I did like was Widmer's Hefeweizen, which BA calls an American Pale Wheat Ale. The one that was strongest in banana flavor we tried was Starr Hill's The Love (a hefe).

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American wheats are fermented with neutral American ale yeasts. And I totally agree, banana is disgusting in beer and The Love is wretched.

I got banana flavor in a few brews that fermented at too high temperature. Keep it on the low side to avoid that.

Erroneous said:

Thanks for the info. Unfortunately, many of the beers had very little info on them, though it usually included style, ABV, and about 1/2 the time the IBU. Oddly enough, the one "hefe" I did like was Widmer's Hefeweizen, which BA calls an American Pale Wheat Ale. The one that was strongest in banana flavor we tried was Starr Hill's The Love (a hefe).

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I hate to say it as a local but Starr Hill's beers are very uni-dimensional. They mostly seem to be crafted to appeal to the largest population (aka lowest common denominator when it comes to craft brew).

I do like me some banana though, when appropriately mixed with clove. Try Schneider Weisse for a classic version.

isoamyl acetate

orangehero said:

isoamyl acetate

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This. Hefeweizen yeasts aren't the only ones to produce this ester, but they do produce more of it than most yeasts. I find Achouffe's strain to put off a lot of banana as well, in particular.

That banana and clove taste is way polarizing for beer drinkers. It is a product of the yeast. I happen to be in the camp that is a big fan. It is not just a product of too warm a fermentation either, although that can exaggerate the taste in many yeast strains.

I just finished fermenting a Bavarian Hefe 2 days ago using Weihenstephan yeast, which is an Uber traditional German Hefe yeast. I fermented the entire thing between 64 and 65 degrees and it has a lovely balanced clove banana taste in the sample I took when I kegged it. It's win/win cuz the girlfriend loves it too. Too me the American Hefes are just too bland with the clean ale yeasts they use. It loses all the character of the German versions.

Now I get it, if you don't like it you don't like it. But it is inherent to the German Wheat style, not a fermentation error. Just sayin.

I understand it is an important characteristic of some styles of beer, which can be popular. I'm not saying beer+banana=crap, only that I prefer a very limited banana flavor. Since it is a characteristic I am not a fan of, I'm trying to identify what factors to limit should I ever try to do a beer that might produce that if handled a certain way. On that note, if I happen to work with German strains of yeast especially, I should monitor temperature control carefully since right now I just leave my fermenters at room temperature (about ~70-74) and don't currently control or stabilize the temperature. I plan on amending that on my next brew with an arduino controlled freezer. Important to note, if I ever want to make a hefe, I should probably go more for a clove flavor than banana by keeping the temp closer to 65.

Erroneous said:

I understand it is an important characteristic of some styles of beer, which can be popular. I'm not saying beer+banana=crap, only that I prefer a very limited banana flavor. Since it is a characteristic I am not a fan of, I'm trying to identify what factors to limit should I ever try to do a beer that might produce that if handled a certain way. On that note, if I happen to work with German strains of yeast especially, I should monitor temperature control carefully since right now I just leave my fermenters at room temperature (about ~70-74) and don't currently control or stabilize the temperature. I plan on amending that on my next brew with an arduino controlled freezer. Important to note, if I ever want to make a hefe, I should probably go more for a clove flavor than banana by keeping the temp closer to 65.

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Sounds good! Temperature control is a major part of keeping esters tame.

Just to add another data-point to the mix, though: my experience is that the cool=clove and warm=banana distinction is way too simplistic to be useful. I ferment my hefes at 62 degrees and I get a nice balanced ester profile that I think is quite consistent with the big german examples. The cool keeps the beer from turning into bubblegum, but it doesn't eliminate the banana or disproportionately favor the clove. I've also had warm fermented hefes that were excessively clove. The metabolics involved here are complicated and I don't pretend to understand them, but the yeast certainly can and do make the banana esters at cool temperatures. If you don't like the flavor, you might just want to consider skipping hefeweizen.

+1 to MalFet

As stated the banana/clove is just a characteristic of the German Hef yeast. If you don't care for it, as quite a few don't, the answer is not to try to manipulate the ferment to avoid it. It will be there anyway. It's just what those yeast do.

If you want a crisp, clean wheat style without the German esters, the answer is too ferment it with a neutral yeast that doesn't throw those flavor esters to begin with. If you do try a cool ferment on a German Hef yeast, and find you just can't stomach the flavor, I'd be happy to take that off your hands for you.
Viva la difference.

Cheers

I brewed a hefe using WLP300 and thought it had a bit of a strong banana flavor but that was cause the beer was young 1 week later it was perfect!!

I love banana in wheat beers. Just opened a Weihanstephan hefe yesterday and found it a bit TOO tame.

Commercial beers are quite limited in selection where I live, but I picked up some Weihanstephan (accidentally bought 3 instead of 2, which is why i opened it yesterday), Schneider Weisse, Erdinger, and Hacker-Pschorr, and I plan to try them side by side to compare and see if I can zero in on a profile I'd really like.

I'm an absolutely huge fan of Schneider Aventinus though... I really love the ester profile in that one, although it's a weizenbock, not a weissbier.