The cleaned artichoke bottom is a bit concave and should remain fairly white with the lemon juice on it. However, any dimpled choke that didn't get removed will turn brown quickly – if you see any, be sure to scrape it off.
Don't wash fresh artichoke bottoms until you're ready to cook them. Freeze them if you're not planning to use them shortly.
Frozen artichoke bottoms will keep well for several months. When using frozen artichoke bottoms in a recipe, I simply rinse them and add them, still frozen, directly to the dish for cooking.
