There is no objective scale to determine the sourest food. Youtubers Good Mythical Morning gave it a subjective taste test and gave the crown to umeboshi, a Japanese pickled plum-like fruit with second place going to Toxic Waste candy.
Taste of Home says tops is Warheads candy followed by kimchi. They put umeboshi in sixth place.
Sourest Food William Lawrence Sr Omnibit 2-27-20
