Oxidation Explained: Why Apples Turn Brown

Oxidation is a chemical reaction where oxygen interacts with other molecules.
When you cut an apple, enzymes inside the fruit are exposed to air.
The key enzyme is polyphenol oxidase, which reacts with oxygen.
This reaction produces brown-colored compounds called melanins.
Browning is harmless but changes the apple’s look and taste.
Lemon juice slows browning because its acidity blocks the enzymes.
Refrigeration also slows oxidation by reducing enzyme activity.
Some apple varieties brown less due to naturally lower enzyme levels.
Food industries use coatings and packaging to reduce browning.
Oxidation is the same type of process that causes rust on metal.