Cork taint in wine
by Roar Lie
I enjoyed your post with a lot of useful information on corked taint. However, I would like to add a comment concerning chlorophenols and chlorine.
Chlorophenols and chlorine (or chlorinated water) do not generate nasty aroma compounds, such as TCA. as stated in your equation: «chlorophenols + chlorine = nasty aroma compounds, such as TCA (2,4,6-trichloroanisole)».
The correct version is «TCA can originate from 2,4,6‐trichlorophenol (TCP) produced from naturally‐occurring phenol and chlorine (from sanitizers and cleaning products, and town water)».
It should be pointed out that TCA is a microbial metabolite and not the result of a simple chemical reaction i.e. chlorophenols + chlorine.
Chlorophenols, e.g., 2,4,6-TCP, is a precursor of 2,4,6-TCA, a fungal metabolite, and can be transformed into nasty smelling TCA by a process called biomethylation. Chlorophenol O-methyltransferase, or CPOMT, is the enzyme that methylates chlorophenols into chloroanisoles.
Let me quote from «Causes and Origins of Wine Contamination by Haloanisoles», Institute of Biotechnology of León (INBIOTEC):
«From a biological point of view haloanisoles originate from a biochemical defensive reaction known as biomethylation, that occurs in certain microorganisms (mainly filamentous fungi). This reaction takes place when the filamentous fungi get into contact with halophenols (mainly chlorophenols -see figure 1.2- and bromophenols), which are massively used as highly toxic pesticides and fungicides. As a result of this biomethylation reaction the highly toxic halophenols are converted into non-toxic haloanisoles (see figures 1.6 and 1.7). Therefore, the formation of haloanisoles is a survival mechanism for many microorganisms when exposed to environments polluted by halophenols».
TCA is not the only nasty compound in cork taint. TBA (2,4,6-Tribromoanisole) is important since it is used in paint and wood preservatives and fire retardant clothing and thus may easily contaminate wine cellar environments.
If a winery and its production facilities are TBA contaminated, little can be done to save it. As the story goes, an Australian winery was heavily TBA tainted. They got the advice: Torch the place, and so they did being the only option.