Has it ever crossed your mind that all purple liquids are really tasty, yet all solid purple food tastes like something only your Mother could persuade you to eat? I'd prefer to eat Chewbacca's Grandad's toenail clippings than Beetroot, purple cabbage or purple lettuce.
This is futher proven by the fact that blackberries are really nice 'cos they're black, not purple, but when they're changed into a liquid they're purple.
This may have a tie in with gases too. Have you ever seen a purple gas? It seems that purple things like to be in liquid form, refuse to be in gaseous form, and will taste really bad if forced to be in solid form