Preventing fruit browning

Cut fruit turns brown because of enzymatic browning, which is caused by the fruit being exposed to air, according to University of Illinois Extension. The fix is to coat the cut surface.

An ascorbic acid solution, made from powder or crushed vitamin C tablets, is the standard home method and does not change flavor. Citrus juices such as lemon can also slow browning, though they may alter taste, and a diluted lemon soak is a milder option. Citric acid alone is not a good replacement for ascorbic acid.

For pie fillings, Penn State Extension has apple slices placed in an ascorbic acid or lemon juice solution until they are used.