# Isoamyl Acetate aroma from Brett L. Pellicle



## Dove (28/10/14)

Hey AHB,

I have a brew that has been in the fermenter for about six weeks now. The Wyeast Brett L. seems to be forming a pellicle but has a strong aroma of isoamyl acetate. Still tastes like a sour ale though. Other bugs in this beer include: Wyeast lactobacillus brevis, dregs from Oude Beersel Geuze and dregs from Boatrocker Mitte Berliner Weisse.

I kept the beer at 24 degrees for about 4 weeks and now it is sitting at ambient temperature in a closet. The isoamyl acetate aroma is a recent thing as well as the pellicle. 

Is it possible that the saccharomyces present in the dregs of the other beers is producing these esthers as a result of the warm fermentation? 

OR

Do brett l. pellicles just smell like that sometimes???

Any info would be great, I'm thinking if this aroma is going to worsen and effect the flavour of the beer then I will drink it soon but if it's part of the pellicle being formed then it would be cool to leave it for a while longer and let the brett do it's work.

Also the gravity doesn't seem to be moving from around 1.009 but I realise brett is a super slow worker.

I'm a total noob to sour brewing and wasn't intending to brew a proper flanders-ish sour beer but sort of fell in to it.

Thanks!


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## manticle (28/10/14)

My experience of brett is that time is a good thing. Mine are generally conditioning for 12+months. I also manage primary ferment with a sacch yeast and keep temps low for that. Any reason for 26?


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## Not For Horses (28/10/14)

This PDF is a pretty good read. Two things of particular interest to you: The first being that esterases associated with brett species will actually decrease the levels of isoamyl acetate. Secondly, the article makes mention of ester production and also notes that isoamyl acetate is not detectable from brett ferments.


http://www.mbaa.com/districts/michigan/events/Documents/2011_01_14BrettanomycesBrewing.pdf


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## Dove (30/10/14)

manticle said:


> My experience of brett is that time is a good thing. Mine are generally conditioning for 12+months. I also manage primary ferment with a sacch yeast and keep temps low for that. Any reason for 26?


I did realise that brett generally needs about a year, I don't really have the fermenter space etc so was wondering what a slightly younger brett beer would be like. I was fermenting a bit warm because the lactobacillus brevis likes the warm temperatures, I didn't find that the brett produced any off flavours during the temp controlled part of fermentation.



Not For Horses said:


> This PDF is a pretty good read. Two things of particular interest to you: The first being that esterases associated with brett species will actually decrease the levels of isoamyl acetate. Secondly, the article makes mention of ester production and also notes that isoamyl acetate is not detectable from brett ferments.
> 
> 
> http://www.mbaa.com/districts/michigan/events/Documents/2011_01_14BrettanomycesBrewing.pdf


Thanks for the link! I didn't think brett produced many similar esters to sachh but the pellicle smells hugely of banana which is very weird. Could be a banana smell that's not isoamyl acetate!


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