When fruits like strawberries, blueberries, raspberries, blackberries, cherries, plums, apricots, nectarines, peaches, pineapple, watermelon, cantaloupe, honeydew, grapes, figs, mangos, papayas, avocados, etc. are exposed to air moisture evaporates quickly causing the surface of the fruit to become moist. This causes oxidation reactions resulting in discoloration.