Trichlorophenol

So I’m being plagued by phenolic flavours lately.

That’s a problem.

Step 1 in fixing the problem is to identify where the phenol flavours are coming from.  At the last local brewclub meeting the local gurus indicated 2 major potential sources:

1. Too much chlorine in the water
2. Wild yeast

A bit of a search around also seems to point to the fact that it could be caused by a Bacterial Infection.  The BJCP Beer Fault List shows the phenol flavours can come from:

• Water with chlorine or chloramines
• Bleach sanitizers
• Astringency
• Infection
• Too high a fermentation temperature

There are time-based indicators which could help identify the potential cause of the off flavours:

Flavour Effect	Implication
Increase with time	This would imply that the off flavours are being caused by something still in the beer.  Possibly a bacterial infection.
Stays the same	This should mean that whatever caused the flavour isn’t volatile and isn’t active.  Could implicate chlorine or chloramine in the water or perhaps a bleach sanitizer.
Decreases with time	This would indicate that the yeast is capable of cleaning this flavour up.  Which according to my logic means that it’s a byproduct of a high fermentation temperature.

I haven’t had the opportunity of keeping a sample for an extended period of time so I have made an effort of keeping 8 bottles from my previous batch.  I’ll try a couple of them each month and see if there is any change in the off flavours.

In the meantime though I’ll be keeping an eye on my water source and sanitation practices.

New brewday now includes an extra step to boil all water I use before-hand as well as to add metabisulphite to the water.  This should in theory get rid of all chlorine and chloramine in the water.  Note: I did this for the last batch but rinsed my no-chill cubes with hot water straight from the tap.  Hopefully that won’t have a negative flavour impact.

Also, cleaning and sanitation is going to get some serious attention.  I currently clean with a solution of Caustic Soda and sanitize with Chlorine Dioxide.  It’s already a pretty complete cleaning and sanitation procedure, so I’m just going to spend a little more care on the actual rinsing process of all equipment (such as the cubes in the previous paragraph)

Let’s hope the last batch doesn’t have any of the phenol flavours coming through.