Flavour Compound of the Week - Trichlorophenol

Mmmmm TCP! I really love the sweet, clean smell of TCP. I have fond memories of using it as a mouthwash as a child. Before you ask (assume) it wasn’t as a punishment for another bout of Tourette’s, it was for mouth ulcers. So why you ask is TCP a flavour compound in beer? The truth is that it isn’t, unless the beer has been touched by what is known in the brewing trade as a tosser. TCP is only present in beer if the beer has been in contact with hypochlorite. Hypochlorite is a sterilent used in breweries and pubs (where it is used to clean beer lines). If hypochlorite solutions are not rinsed properly, free chlorine (Cl-) attacks phenolic compounds in the beer to produce TPC or similar compounds.


Once at Sharp’s we had one such tosser, who decided to rinse a tank out with hypochlorite before filling it with beer. Don’t ask why. When I sampled the tank two days later I was not best pleased. The tosser in question reconsidered his career in brewing after he collided with a full 9 gallon barrel in a mysterious accident about 5 minutes later (only joking HSE).