Tainted Love: an off-flavour tasting

Is it just a certain cross-section of modern beer drinker that likes to torment themselves? A thought along those lines crossed my mind the other day; seconds before the sensation of vomit-tainted Fosters arrived, spiraling upwards from my protesting tastebuds. What would my Dad say, for instance, if I told him I was willingly mixing one of the worst beers known to humanity with a capsule of powdered puke? I imagine he’d shake his head, incredulous, before muttering and turning back to his Thwaites Bitter. He may actually have a point, when you think what us ‘craft’ beer drinkers heap onto ourselves: expense. The agony of missing a rare beer. Heightened tooth sensitivity from keg pours. Bruised ribs when the imperial walnut saison (lambrini barrel-aged version) causes a bar scramble. RSI in the untappd finger. Didn’t beer used to be fun?

It still is, though; mostly. And yet, there we were, deliberately making Fosters taste worse. Or taste of something, maybe. Times have moved on from way back in the day, when everything was easier. Then, you walked to your nearest alehouse and drank whatever they were serving until your pancreas burst. Now, many people take a keen interest in their beer – to the extent that they are willing to subject themselves to how it can taste very, very wrong indeed, in order to appreciate the work of our brewers that little bit more. It’s a kind of ‘I like watching boxing – so let’s see if I can take a punch’ mentality. Set the feet, close the eyes, and hope it’s over quickly.

FlavorActiV are one of the world’s leading authorities on controlled flavour standards, and specialise in the wonderful-sounding ‘sensory taster management and taster validation’. In short, they create pharmaceutical-grade copies of flavours you really hope never end up in your beer (and other beverages). Kind of like those sachets you used to get in ‘Flavour Shake’ crisps, before they vanished from the shelves without a murmur (Salt and Shake still exist, though). What FlavorActiV do is big business – training drinks industry staff in sensory perception, giving them the ability to learn to detect nasties before they ever get near the public.

Very nicely, FlavorActiV sent through their Beginner Kit, which contains five off-flavours commonly encountered in the brewing industry, and I managed to get together a few people to put these colourful little capsules to the test. The first question was what to use as a base beer. The official suggestion is a ‘standard American light lager’ – presumably to offer as little background hum as possible. In my local Scotmid, Budweiser (the obvious choice) was right at the back of the fridge, and therefore probably too cold – so I went with Fosters, and bought a crate (for £9!), before hoisting it on the shoulders and heading off to the tasting, and the first of the pills…



1. Diacetyl
One of the more commonly-encountered off-flavours (at least to my nose), diacetyl was the most immediately noticeable – when added to the Fosters, it yielded a big buttery whiff, like liquidised Butterkist popcorn. The crib sheet suggested only smelling this one, so unsure of what to do, we all tasted it as well. It certainly removes the blandness of Fosters, that’s for sure, replacing it with a cream soda finish. There’s always the debate about whether some diacetyl is acceptable – but it was fairly universal in our panel that it is not (although, we were drinking what were, to most of us, high concentrations of these flavours). Having said that, it wasn’t hugely offensive, even if it did make the beer pretty much undrinkable.

Comments –
“That smells like my home-brew”
“It’s like drinking a pint of butter”
“Werther’s Originals”

2. Isoamyl Acetate
Another sniffer-only, that we all ended up tasting, Isoamyl Acetate is produced by yeast during fermentation, and is therefore present in all beers. Some more than others, though – it’s the characteristic banana-y sweetness prevalent in wheat beers. Mind you, I’ve never had it as prevalent as in this small half-cup of Fosters. It was like drinking foam banana sweeties. Thankfully, I LOVE them, and could quite happily have drunk this all day. It turned Fosters into an artificial-banana-flavour alcopop.

Comments –
“Yep, that’s the wheat beer aroma I don’t like”
“That’s basically Yazoo”
“I don’t think we should be discussing how it’s made the beer taste better”

3. Metallic
And then, the fun stopped. ‘Metallic’ is a great flavour to include, as it’s something everyone can imagine. And if you doubled what you’re thinking of, and then tripled it, you might be right. Contact with metallic ions adversely affects the flavour of beer – and they really don’t help with the taste of Fosters. A proper screw-up-the-face, ferrous mouth-filler. Fascinatingly, it didn’t have much of an aroma – but when a finger was dipped in and rubbed on the arm (as was suggested), it really, really smelled like the iron-y tang of blood.

Comments –
“Like licking a battery”
“It’s like that taste you get when you bite your tongue”

4. Papery
Another self-evident flavour; despite not making a habit of munching through a Daily Telegraph, we all pretty much know what paper might taste like. Despite a faint aroma, this one really delivered on the flavour. And then it just kept on going. Dry, stale and shriveling, it turns up the corners of the tongue and is impossible to shake, making the Fosters so much worse. It was like finding a half-drunk can from last week’s party and finishing it off. Oxygen: you can’t live without it, yet it really is the enemy of beer.

Comments –
“Oh, that’s rank”
“Like eating an envelope”
“It’s the gift that keeps on giving!”

5. Butyric
“If anyone wants to smell intense baby sick, then come and get it!” Amazingly, chairs were scraped back at this point. Yes, butyric – one of the more infamous off-flavours – and represented by a picture of a screaming baby. Formed by bacterial spoilage, the suggested terms on the crib-sheet were ‘rancid’, ‘putrid’, ‘baby sick’ and ‘fatty acid’.* One panellist with two kids under 5 took one sniff and leaned back “Yes, that’s baby vomit. No doubt about it.” Some people are hugely perceptive to this off-flavour, ruining many a beer with even the faintest of concentrations. I can understand why.

*’I’ll take Fatty Acid for ten please, Bob’

The instructions were even more complicated than the Metallic capsule, with orders to hold the nose whilst taking some in the mouth, then swallowing as you exhale through the nose (which is harder to do than it sounds). It smelled a lot worse than it tasted, but the flavour was definitely putrid, and really built on the linger. And as for the aroma – yes, it smelled like puke. No escaping that. How very strange, to be sitting in the kitchen of an Edinburgh tenement flat and willingly drinking lager flavoured with vomit. The things we do.

Comments –
“If you didn’t hold your nose, you’d never want to drink it”
“I want to swirl it around, but I don’t want to get it on my hand”
“Thank you for making me drink vomit”

So, that was that. A fascinating exercise – as expected, the sick and metallic flavours were really bad, putting the buttery and banana ones into an odd kind of perspective. The stand out though (if you can call it that), was the Metallic – which, hands-down, won the final vote:-

‘Worst flavour’ votes
0 Diacetyl
0 Isoamyl Acetate
0 Metallic
7 Papery
1 Butyric

The overall consensus was that it was a fascinating exercise, albeit one in which we hope (as customers and beer servers) that we would never actually have to experience in those concentrations on a day to day basis. That’s why it is so valuable, though – as by tasting ‘extreme’ versions, it attunes the nose and tastebuds instantly to what can go wrong, increasing our chances of detecting these off-flavours in smaller quantities. FlavorActiV produce a range of sensory kits – including those with twenty different off-flavours, which would be some outing. It might be light years away from Thwaites Bitter, but sometimes you can survive being outside a comfort zone (even if, you can’t necessarily say it’s a wonderful trip).



Disclosure – many thanks to FlavorActiV for sending through the sensory kit – which you can buy here. Yvan over at Ale is Good also conducted a night of off-flavour goodness, andyou can read his blog post here.

4 thoughts on “Tainted Love: an off-flavour tasting”

  1. Good post Richard! We did a similar experiment with the FlavorActiv capsules and it was interesting indeed. Think we used Heineken for our base beer. The off-flavour I love to hate is Acetaldehyde – grassy or green apple skins, which is unfortunately all too common in a lot of cask beer these days, making some of it undrinkable (even worse than the FlavorActiv spiked beer!), and sometimes in good reliable beers from well respected breweries too. It’s a sign of the beer being too young and not given enough time in contact with the yeast. Not sure whether it’s down to increasing pressure to fulfill customer orders or whether some brewer’s just aren’t picking it up as an off flavour. But it begs the question – what to do in a bar if you taste one of these off-flavours in your beer?

  2. The problem is that some consumers have become accustomed to (or even enjoy) off flavors. Many Americans associate imported beers with oxidized flavors (not that they consciously identify them that way), and when they taste the beer fresh think it’s “weird”. It must drive brewers crazy to spend so much time on quality when the consumer’s definition of quality is unclear.

    However, I think we can all agree “baby sick” will never be a fan favorite. Another good one is octanoic acid, commonly described as “goaty”, which always begs the question: who’s job was it to lick the goat?

  3. Acetaldehyde can be present in young beer, yes, but in my experience when you encounter it in cask beer it’s more often for a different reason – which is why it also appears in flat, tired beer that’s been hanging around too long.

    Once oxygen and acetobacter get to work on the beer they produce acetaldehyde as a precursor, which is then turned into acetic acid and the beer goes sour. It’s (thankfully) become quite rare to get a vinegary pint in a pub, but you do still encounter oxidised or appley beer a fair bit.

  4. Great article. It’s amazing how these flavours can put people off their beer when they’re presented like this, yet so many wouldn’t notice them in the amounts they normally appear in badly handled/stored beer.

    Another one, not on your selection, which stunned me the first time I tried it as a spike, is lightstruck – it tastes of every beer I’ve ever drank in a student union, a Scream bar, or from an Innis and Gunn bottle. To have it presented to you is quite bizarre, because it’s one of the flavours often present in beer that people aren’t able to place, but is actually a taint.

    @Danno, believe it or not, butyric acid (baby sick flavour) is not unpleasant in small doses, and can come across as a creamy, almost yoghurty flavour.

    @Ian, if you know what you’re tasting, and depending on the type of establishment you’re in (how many eyes/guns does the barman have?) you should be able to send back your beer. Papery means they are storing it badly, and buttery most often means their lines need cleaning (unless it’s a Czech pilsner, where it’s ok in low amounts.)

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