Friday 24 June 2011

When beer goes bad: Phenolic

Plasters, Islay whisky, TCP, smoke, clove; very few beers should taste like this.

A phenolic aroma and flavour should be present in some beers, including wheat beers and some Belgian ales, where it gives a faintly smoky or clove-like aroma, but if you find it in a pale ale, lager or bitter then things aren’t quite right. And this is another off-flavour which some people are more susceptible to tasting than others.

The phenolic flavour most often comes from a reaction between chlorine and the phenolic acid naturally found in malt; this could be from the chlorine content in the water (especially if it’s untreated) or from a cleaning solution used in the brewery which contains chlorine.

This aroma and flavour can also come from the yeast (wheat beer yeast, for example, will produce it, and I’ve had a few wild beers which have smelt like smoky swimming pools). Peated malt will also have this flavour but it will often add a different character more along the lines of charred toast than TCP. 

If a phenolic flavour is appropriate to the style then it’s fine. I’m sensitive to the flavour in beer and I don’t like it at all – I like wheat beers but not ones which are heavy on the clove. I also sometimes taste it as flinty or like concrete. Interestingly, however, I love massive smoky whiskies (and I really like stouts aged in smoky whisky barrels - if the flavour is from a barrel like this then it isn't an off-flavour). When it shouldn’t be there it dives out the glass at me and I find it undrinkable.

Is this a flavour which you can easily detect in beer? If so, do you like it or hate it?

I only realised recently that it was the clove-like flavour which I didn’t enjoy in wheat beers and some Belgian ales. I typically described it as ‘spicy’, which does no justice to what it is; it was just the word which meant to me that it tasted a bit funny.

For this post I used this and this for references.


  1. Good post. but, what the hell do plasters taste like!? I've never thought about licking a plaster before.....

  2. I don't like phenols at all but cloves in moderation I can stand as I find the two different. It is that TCP taste I dislike.

  3. Are you studying for the BJCP Mark??!

  4. Don't plasters taste like Germolene?

    Can't say I've ever really noticed this one at all in beer.

  5. I don't understand how anyone knows what plasters taste like!?

  6. This is an easy one to detect, albeit in my experience less common than some other faults. TCP is a disgusting taste (in beer, at least) but I'm amnazed that some brewers refuse to believe there is anything wrong with it.

    Btw, I think you should keep an eye on "Claudia Becks" and her not-so-subtle marketing agaenda.

  7. Neil - Think of it like the way plasters and hospitals smell. That over-clean aroma. Or, take a plaster and give it a chew!

    Tandleman - I'm with you and as long as you know which is meant to be there and which isn't then it's fine. I'm still not a huge fan of strong cloves though, even if it should be there, but that's just personal preference.

    Barm - Nope, just trying to learn more!

    Tyson - It's not a common one, thankfully. I did have a few beers from one brewery recently which were all affected by it, which was a shame.

  8. Some people really hate phenols. I generally love them in stouts. In pale beers they can be a little more difficult to cope with even when they are supposed to be there.

    I remember once drinking a beer at GBBF that I loved. Another drinker tried the same beer and declared it tasted like a factory full of marker pens.

  9. I've picked this one up before, but not realised what it was. It always makes me think of the old Beechams Powders sachets.

  10. Surely, you've omitted the biggest contributor of phenolic tastes in beer? Never mind "chlorine + phenolic acid" - bacterial infection wins the prize!
    Having said that, it's a moveable feast: I had a beer that was horribly infected, nasty TCP phenolic taste (albeit a flavour I am strongly sensitive to), which I thought 'well I'll just leave that alone'. 12 months later some magic has occurred and now my "vintage pale ale" has no trace of TCP and in fact tastes better than the original - the same, but smoother...
    Welcome to the weird world of beer!

  11. This link
    describes the following chemical culprits (from a wine perspective, but applies to beer as well):

    4-ethylphenol: Band-aids, barnyard, horse stable, antiseptic
    4-ethylguaiacol: Bacon, spice, cloves, smoky

  12. Just got a phenolic beer and I'm fairly sure its unintended. I quite like it though. Reviews to be posted soon

  13. Just opened a Green Jack Baltic Trader. Vikki's first tasting note? Plasters! Quite suits a big stout though, nicely balanced with a dry finish. I've had it in some pale beers where it can be really offputting, but like you say is a common characteristic in wheat beers and one of the flavour profiles I quite enjoy in the style.