A sliced apple for lunch is nutritious and flavorful, but after a couple of hours, enzymes in the exposed surface of the apple react with the oxygen in the air, turning your apple an unappetizing shade of brown before lunchtime rolls around. A slightly-brown apple is safe to eat, but the apple won't remain flavorful for very long, as browning is a sign that the apple is rapidly losing quality. Simple techniques, including treating the cut apples with acidic substances or keeping the fruit cool, prevent oxidation and maintain the color and crispiness of your apple.
Coat the cut edges of the apples with an acidic fruit juice. Fruit juice and other acidic solutions slow the browning process without affecting the flavor of the fruit. Use a pastry brush to brush the juice evenly on the apples. Use any citrus fruit juice such as lemon, lime, tangerine, orange or pineapple.
Place a mixture of water and cider vinegar or lemon juice in a small bowl. Toss the apples briefly in the solution, then pat the apples dry with a paper towel. This method may be easier if you are treating multiple cut apples.
Place cut apples in an airtight, leak-proof container. Add enough apple cider to cover the apples. Covering the apples with cider is another way to apply an acidic solution that slows browning and keeps your cut apples moist and fresh. After you eat the apples, you can drink the juice.