Ester problems (banana, nail polish) after a month of bottling.

[javert]

Here I was brewing a standard belgian witbier with coriander / orange zest. Didn't notice problems at bottling time since it tasted fine and after 2 weeks of bottling it had great clear light color and a good balanced taste of wheat, coriander and orange which got me excited to present it to my family and friends. Yesterday I decided to taste a bottle of the batch which is like a month and a half old and... oh god :

• The clear light color turned into a yellowish, golden one. Not bad per se but this was supposed to be a white beer.
• Some of the sediment which I assume it's the yeast has a black color so it looks like floating dirt on the glass.
• The coriander / orange notes disappeared... and all it remains is a crazy banana flavor and also nail polish on the tongue.

I used Lallemand Abbaye yeast on this batch which got fermented at 19 °C (66,2 °F). After bottling, the bottles were stored on the same room which has its temperature regulated with a mini split air conditioner. Used cane sugar to carbonate: beer already felt carbonated the first time I tasted it.

Apparently this is a case of excess estery flavor and the cited causes are stressed yeast, high fermentation temperature and low pitching rate. However, I'm a little perplexed at finding this off flavors only after a month and a half of storage in the bottle. How much is flavor supposed to change and degrade after carbonation? Can it still be called "fermentation" at this point? I'm afraid of realizing that maybe I need to store all the beer cold (4 °C) to make sure it doesn't devolve past its prime moment although getting another fridge is going to be expensive.

 

[Jayjay1976]

The black sediment and color change sound like something other than beer yeast got in there. IIRC, botulism is black

You prolly shouldn't taste any more or let anyone else taste it till you get a response from someone rmore knowledgeable than I.

EDIT: It's not botulism, I just did some reading and that particular infection is not a concern for homebrewers since it can't reproduce in the acidic conditions. Sorry for misleading you.

 

[Metalhead_brewer]

have you tried another bottle? may be that one was infected, it happened to me a couple of times, one bottle tastes like hell but the rest are just delicious.

 

[javert]

@Jayjay1976 Dood don't scare me like that! Imagine if beer were something that could kill you if done slightly wrong...

Have been browsing the issue. Here are the most possible explanations:

Yeast in suspension does impart a clearer color and when it falls down and beer clarifies it darkens.
Oxidation also darkens a beer.
As yeast dies down it leaves a black residue.

But the clear winner is... Brettanomyces. Taken from a document:
"Produce large quantities of acids and are a major contributor of other off-flavors (ethyl acetate and ethyl lactate), especially in draft beers. Aerobic. Very slow growing (detect problem after 1- 2 months!)"

Since ethyl acetate is the primary responsible of nail polish flavor, all evidence points to this nasty yeast. Even worse, ethyl acetate is reported to be a "biochemical deadend" in the sense it doesn't get degraded any further, so no hopes of beer getting better with time.

Apparently this yeast is happy to use oxygen for its nefarious workings, so any oxigen leakage into the beer contributes. Since beers are properly carbonated, I don't think there's a physical leak / entry of gas, so it is probably diffusion through the cap liner. Might the caps be cheap?

Either way, I instantly hate this yeast for life!! To think some people actually look forward to putting this on their beers!

 

[helibrewer]

You MIGHT have a Brett infection but oxidation is more likely. Beer doubles the rate at which it ages for every 10 degrees F it is stored. Store your bottles as cold as possible after carbonating. Was your orange zest fresh or packaged (dried)?

 

[ba-brewer]

Yeast falling out of suspension is normal, I think I read it is common practice to swirl the dregs and dump into the glass to enhance the cloudiness for some hefewiezen beers.

Your time frame is pretty quick for yeast turning dark but that will happen to standard yeasts as well. I captured some bret and used it for a while and the yeast cake was light tan and creamy even the stuff in the bottle was not really dark even after a year or more.

Bret as a sole fermenter is suppose to stop within a reasonable amount time pretty like any other yeast, but added as a secondary yeast it will attenuate more and make use of residual sugars left behind by the primary yeast. If you had a bret infection(or any kind of infection) I would expect your bottle to be gushers or at least seem to have more carbonation than normal.

Banana is a stated flavor of the yeast you used. Wheat will also cause the increased production of phenolic flavors and esters. What did you use for water? If you have chlorine or chloramine those will enhance the phenolic flavors.
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