Banana Flavours in homebrew

Mau5

Tried one of my batches today and it had an overpowering banana taste to it. Almost like a wheat beer like Paulaner or somthing like that.
It was a lager I brewed with hopped spraymalt, any ideas what would have caused this?

thelynchfella

Could be the the yeast fermenting at a high temperature.

Mau5

Fermented it at 20C-22C is that not normal temperature?

thelynchfella

depends on whether it was an ale or lager yeast used....it too high for a lager yeast, ale yeast ferments usually between 16 and 24, but i tend to notice a banana taste in my beers i've brewed around 22. You might want to ask on the Irish craft Brewers forum, the folks there would be more educated than i would be and they're a friendly and helpful bunch too

http://www.irishcraftbrewer.com/community/



edit.....just reread that you said it was lager....that typically needs to ferment between 7 -15 degrees....i'd say the high temp is your problem

Mantel

It's esters - http://www.homebrewzone.com/esters.htm

Like the thelynchfella said it's caused by fermenting at a highier temperature OR it's the way it's supposed to be since some yeasts are selected to produce that flavour. Both really depend on what yeast you used for fermenting, is this a new yeast you've tried or have you used it before without getting the banana flavours?

Most yeasts like a temperature in and around 20c as long as it's stable, lager yeasts are the exception as they like lower temperatures and go through fermentation a bit differently.

oblivious

Mau5 wrote: »

Fermented it at 20C-22C is that not normal temperature?

Yea fermentation temp not the then of the room as the fermentation then can be a bit higher than the room

noby

thelynchfella wrote: »

edit.....just reread that you said it was lager....that typically needs to ferment between 7 -15 degrees....i'd say the high temp is your problem

Most lager kits use an ale yeast anyway.


EDIT: Sorry, just saw the other thread, seems it was a lager yeast.

thelynchfella

noby wrote: »

Most lager kits use an ale yeast anyway.


EDIT: Sorry, just saw the other thread, seems it was a lager yeast.

So they lie when they say lager!!!! Feckers!!!!:)

oblivious

thelynchfella wrote: »

So they lie when they say lager!!!! Feckers!!!!:)

Yea, but unless you can control fermentation temp at around 9-10c and then at 0-1c any lager yeast will can ester just like an ale yeast.

thelynchfella

oblivious wrote: »

Yea, but unless you can control fermentation temp at around 9-10c and then at 0-1c any lager yeast will can ester just like an ale yeast.

whats the 0-1c for??? Conditioning??

oblivious

thelynchfella wrote: »

whats the 0-1c for??? Conditioning??

Lagering

rubadub

It is ethyl acetate. I made a rum wash (I think it was treacle and proper brown sugar) and it absolutely stank of bananas when heated, my house mate came running down saying "WTF is with all the bananas", with none to be seen. I would not have fermented it past 25C, I had heard rum washes can get smells of bananas before, was there no added sugars? had you used the malt before?

oblivious

Its believe its iso-amyl acetate

rubadub

Correct, I was mixed up, the ethyl acetate is the real nasty stuff.

Esters are flavour compounds responsible for many of the characteristic tastes we know very well:


Propyl acetate (Pears)
Octyl acetate (Oranges)
Isoamyl acetate (Banana)
Ethyl butyrate (Pineapple)
Butyl acetate (Apple)
Methyl trans-cinnamate (Strawberry)
Ethyl cinnamate(Cinnamon)

(See http://www.leffingwell.com/esters.htm. There are many others and a web search will turn up many more if you're interested.)

Esters are the product of a reaction between an organic acid and an alcohol. Read the back of a wine bottle you'll see wine described as tasting of all sorts of different fruit (except grapes, of course because any fool can do that). Yeast, by its very nature, produces a range of organic acids and a range of alcohols during the fermentation process. These combine to form a range of esters responsible (along with other chemicals) for the flavours in wine that aren't in the original grape juice. This is where the interests of a winemaker differ from someone trying to make clean neutral spirits - winemakers see ester formation as desirable. Yeast makers even advertise their yeasts on how good they are at producing damn esters.

The problem with esters is that a little goes such a long way. Most have detection thresholds measured in parts per billion (ppb). Ethyl butyrate – the fruity pineapple ester listed above - has an odour detection threshold in water of 1ppb. As a comparison, ethanol in air has an odour detection threshold of about 50 parts per million (ppm). In other words, it's odour is 50,000 times more powerful than ethanol. For those of you obsessed by percentages, your distillate could be 99.9999999% ethyl butyrate free and you'd still be able to smell the damn stuff. Great if that's what you want, bad if you don't.