Hi Clark,
I have been meaning to ask you this question for a while:
Why we never see anyone saying that an old bottle of wine (let's say older than 20 years) has Brett (or high levels of 4-EP if you prefer)?
I don't know if you agree with this proposition, but I don't recall ever in my life having opened an old bottle and going "ouch! barnyard!!". Assuming that it had Brett in its youth, what happened?
Very best,
Luiz Alberto, #winelover
Founder & CEO
Member of the Circle of Wine Writers
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Luis,
This is an area of some controversy. To begin with, I have seen plenty of old bottles that are quite Bretty. But I also observe that the apparent Brett has everything to do with the integrative power of the wine’s structure, which will vary over time.
4-ethyl phenol (4-EP) is not synonymous with Brett, merely a good indicator. It smells like shoe polish and is not particularly offensive on its own. Linda Bisson at U.C. Davis has shown that the Brett genome varies wildly from country to country, and doesn’t even have a stable number of chromosomes. As a result, the mix of 4-EP, 4-ethyl guaiacol (a smoky/meaty aroma), isovaleric acid (the vomit small), VA and the mousy compounds varies greatly among strains and vigor within a strain. The constituents of the wine are also important. White wines have no coumaric and ferulic acids, the precursors to 4-EP and 4-EG, and thus smell entirely different.
It is also possible that some of these constituents, such as the volatile phenols and iso-valeric acid (the vomit smell) react with other wine constituents to render themselves non-volatile or even pleasant. T my knowledge, we haven’t studied this enough to know. Finally, the masking effects of the wine’s overall aromatic development may incorporate an originally pronounced Animalia into something less apparent and even profound.
I certainly experience in sulfite free reds a “dump” of phenolics about three years into barrel ageing in which the wine appears to shed its skin and emerge as a well-integrated whole. I would liken this to the transformation from ruby to tawny port, except that there is an active microbial component to the transformed aromas.
Clark