Lemon Juice Stops Apples from Turning Brown – Everyday Chemistry

 

Have you ever cut an apple only to see it turn brown after a few minutes? It looks unpleasant, right? But chemistry has the answer — and the solution!

The Science Behind Browning

When an apple is cut, the cells break open and release an enzyme called polyphenol oxidase (PPO).
This enzyme reacts with oxygen in the air and forms brown-colored compounds.This process is called enzymatic oxidation.

Cut Apple + Oxygen → Brown Pigments (Melanins)

How Lemon Juice Helps

Lemon juice contains citric acid and vitamin C (ascorbic acid).
These substances slow down the oxidation process by:

Lowering pH → Enzyme becomes less active
Acting as antioxidants → Prevent browning reaction

That's why apples stay fresh and white when sprinkled with lemon juice!