In a previous blog post on the subject I quoted Tim Hanni as saying “fat actually increase[s] the intensity of […] the astringent feeling of tannin”. But as far as I could establish, Hanni has no evidence for this other than experiences from his own workshops. In direct contradiction of Hanni, recently published correspondence in Current Biology from Catherine Peyrot de Gachones et al seems to show that fatty and astringent substances moderate the effect of each other.
I say “seems too”, because the source of fat in the experiment is salami, which also contains protein and salt. It is unfortunate that they did not use a purer fat, so it is still a possibility that it is the protein or salt that reduced the astringency, as suggested by others.
On the other hand, as 3 different astringent liquids were tested, it is a lot more certain that the astgringency itself reduced the fatty sensation, rather than anything else common to each of the liquids.
Regardless, to me it intuitively seems a lot more convincing that it is fat, rather than the protein or salt, that reduces astringency in wine. The idea that astringent wines “cut through” fatty meats is well-known and accepted. And from a wine and food matching point of view, I can appreciate that it is good to have alternate opposing sensations in the mouth from sipping red wine while eating meat – the astringency from the wine, and the slippery richness of the fat.
The final lesson we can take from this research concerns the assessment of the astringency of wine. The research clearly shows that as you take multiple sips of a tannic liquid, the perceived degree of astringency increases over time. So to fairly compare the astringency of different wines, we really need to make sure we start with a clean palate for each wine, and assess each one after the same number of sips.