Soak cut fruit for 10 minutes in 1 teaspoon of ascorbic acid per gallon of cold water; Penn State says vitamin C acts as an antioxidant to keep fruit from darkening

Cut fruit quickly turns brown due to an enzyme reacting with oxygen. A simple vitamin C solution effectively halts this undesirable darkening process. Pure ascorbic acid crystals or crushed vitamin C tablets work well. This inexpensive method offers a reliable way to preserve cut fruit. Food scientists continue to explore even more effective browning inhibition techniques.