Certain fruits, such as apples and bananas, brown quickly after being sliced. This makes the fruit visually unappealing when added to fruit salads, or frozen, canned or dehydrated. One way to prevent browning is to treat the cut fruit with a bath of citric acid. Citrus fruits, such as oranges and lemons, contain citric acid, which is why they don't require such treatment, and why their juice is often used to prevent the browning of other fruit.
Combine 1 tbsp. of citric acid with 1 gallon of cold water in a bowl and mix.
Add pieces of cut fruit to the bowl immediately after cutting, completely submerging the fruit in the liquid solution.
Let the fruit set for 15 minutes in the solution before removing and draining off the liquid.
More efficient than citric acid is ascorbic acid.
If you don’t have citric acid, use lemon or orange juice to bath the fruit.