AVA140: Keys might actually have their own flavor

This question was sent by Irineo, and he writes: Hello there once again, maestro Pinkevicius. Now THAT IS an interesting subject you chose for your podcast. Actually, I suspect different keys have different "taste" or meaning depending on each individual. For instance, Bach's splendid Toccata in G-minor BWV 915 has a fantastic Fugue which is not only splendid, but jocular. It's extremely witty as far as I'm concerned. It sure DOESN'T sound "sad" or "dark" a bit. But there's supposedly this "treaty" about different keys and the way they "taste" or are perceived by people. I couldn't locate a good friend of mine who told me about it many years ago, nor could I learn its name. But I recall having read about a luthier who developed a very special instrument (harpsichord) and stated that keys might actually have their own "flavor". Like C having a tart/sour taste, D being tasteless, E having a sweet one, F a bitter one and so on and so forth. Can you perhaps guide me here, maestro? By the way, I'm still working on the translation of my short chorale (which has a feature I've yet to see in music history, I daresay) but as soon as I finish it, I'll upload it as you kindly suggested. Keep up the good work, you both! Greetings as usual. Very truly yours, Irineo.