Comment by Arch-TK

The video explains how the gas based mass spectrometers he had (indirect) access to don't normally pick up nonvolatile compounds like tannins. It was a big breakthrough that since he didn't have cocoa leaf extract, and he basically nailed everything else, he couldn't really understand what he was missing until he realised the extract would likely contain tannins.

So there may be other nonvolatile compounds which nevertheless impact the flavour profile. While a lot of flavour is in your nose, not all of it is...