Apple does not affect the taste after discoloration, and there is no solution after discoloration.
Apple meat contains an organic substance tannic acid. When peeling with a knife, the knife touches the apple, and the tannic acid in the apple meat reacts with the iron in the blade to form black iron tannic acid covering the surface of the apple meat. In addition to tannic acid, apples also contain an oxidase. When the apple skin is peeled off, the air meets the pulp. Under the catalysis of oxidase, the organic matter in the pulp is oxidized and discolored, so the peeled apple becomes discolored.