Symbolism, Imagery, Allegory
In The BFG, food is used as either a prize or a punishment.
The major problem the BFG has (besides his dismay that his fellow giants eat people) is that he has nothing good to eat. On top of being a vegetarian, he doesn’t believe in stealing. That means the only plant he can eat is the one that grows in Giant Country: snozzcumbers, which are compared to the taste of “frogskins,” (8.38) “rotting fish,” (8.38) “clockcoaches and slime-wranglers” (8.39). Only some of those things exist, but they all sound pretty gruesome. The BFG has been alive possibly since the earth began, and he somehow still hasn’t gotten used to them—that’s how bad they taste.
He is clever enough to use the snozzcumber as a tool to drive the Bloodbottler out of his cave, but only when he and Sophie enact their plan to tell the Queen about the giants is he rewarded with the prize of good food: a ridiculous amount of eggs, bacon, sausages, and fried potatoes. (Apparently even though he has trouble with human meat, bacon and sausages are okay). He also eats sponge cake, and doughnuts “ten at a time, like peas” (20.95).
Not a bad prize.
The giants, of course, are the opposite. They start out eating humans, who, to the giants, have many different, delicious tastes. In the end, they are punished with bad food. That’s how snozzcumbers save the day. Unless you’re one of the giants. Then it ruins the day.