answer:All the ones we know of are. :-) When I was a kid, they were teaching that we have only four kinds of taste buds; sweet, sour, bitter and salty. Now it’s five. They added umami, which is the taste of meat broth. So who’s to say definitively that a sixth taste bud can’t possibly be found? All the enormous subtleties of taste we actually experience come from (as far as we know today) feedback from the five basic taste buds plus our sense of smell, which is fantastically more nuanced than the taste bud information flow.