Why does fruit brown in the sun?

Great outdoor fun experiment with residents while enjoying the taste of a summer fruit salad!

Materials: Kiwi, apple, knife, sponge and scissors. Process: Peal and make a slice from the kiwi. Cut a piece of sponge the same size as a the kiwi slice. Cut the apple in half. Place the kiwi on the cut surface of one half of the apple. Place the sponge on the cut surface of the other half of the apple. Put both in direct sunlight. Observe for about one hour and then remove the sponge and kiwi.

Result: The enzyme called polyphenol oxidase in the apple interacts with oxygen and causes the fruit to turn brown. Cutting the apple releases the enzyme and starts the browning. Enzymes in kiwi interferes with the browning process.