BJCP Training – Month 4

Off flavours training

This month we took a break from our usual set of grouped beers to taste and decided to start getting our palates used to picking up different chemicals that should not (or rarely) find their way into beers. We acquired a 12-flavour tasting kit and bought some budget-supermarket brand ‘premium’ lager to spoil.

The flavour kit comes with twelve individual phials of chemicals, each one treating 1 litre of beer. With 250ml bottles we figured this would be fairly easy to do, but it turned out to be more difficult than imagined. A single drop was all we were after, but some of the liquids were quite oily and didn’t want to leave the tiny bottle. Good job we had a large pack of 1ml syringes!

Picking up 0.1ml of each chemical, we dosed a single bottle between 5 of us. We figured 50ml of rank tasting beer was enough. Add the off flavours and that really would be enough! JK. We had a non-doctored bottle of the same beer as a control. So what did they each smell and taste of?

Character Notes

Acetaldehyde: Very fresh green apple aroma, quite pleasant. More subtle flavour, did not come across as cidery.

Butyric Acid: I could not stand this one, probably the worst aroma of all of them. Very off cheese or baby (milk) vomit. Once I was able to get it to my lips, it actually had no taste.

DMS: Aroma of canned sweetcorn. Subtle vegetal flavour and change in mouthfeel (slicker?)

Diacetyl: This is one I couldn’t detect, at least not at this threshold. I know I have smelled/tasted diacetyl in beer before (dirty beer lines) but I couldn’t detect it on this test. Others could 🙁

Earthy: This for me was quite difficult to detect, I had to really look for it. Swirling the glass around to release some bubbles helped but it was pretty non-descript for me.

Ethyl Acetate: On aroma I couldn’t detect this. There was a very slight solventy taste right in the finish.

Ethyl Heaxanoate: Again not much on the aroma but had a liquorice flavour. Similar to DMS, the mouthfeel also changed to a little thicker.

Geraniol: Completely understand where Geraniums get their name. So floral in both aroma and flavour. Could get this from hops but at this level was too much.

Indole: Fecal, manure aroma. Like fart spray the kids had at school. Really unpleasant. Didn’t particularly taste the same but the smell added its own taste perception.

Isovaleric Acid: Another one I couldn’t taste, but the aroma was so bad you wouldn’t want to. Sweaty gymness and old cheese. If you can get this from aged hops I’m throwing out any stock that is past its use by date, do not want this.

Papery: Very woody aroma, cedar like. Taste was exactly like eating paper or licking cardboard. Not pleasant, but not the worst on this list by far.

Spicy: Smelled and tasted just like all spice mix. This was actually really nice, and made the beer much better. When I did the dry hop test recently, this is exactly what high levels of Mittlefruh smell and taste like.

Off flavour tasting


The most interesting aspect of this for me was to understand that we all have different thresholds in being able to detect different chemical compounds. I couldn’t detect diacetyl at this level, but everyone else in the group could. It was odd because I know that I can detect it though, as I’ve had it in beer before. I think actually everyone had at least one on the list they didn’t get much from. It was as much of an understanding of what our limits were when it comes to picking up on these off flavours as it was understanding what they smelled and tasted like.

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