Why Do Sliced Apples Turn Brown?

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Why Do Sliced Apples Turn Brown?

You open yourِ lunch box toِ discover thatِ the lovely apple youِ sliced thisِ morning nowِ appears unsightly andِ brown.
This triggers anِ enzyme knownِ asِ polyphenol oxidase (PPO) to—wait forِ it—oxidize polyphenols inِ the apple’s flesh.
Different apple varieties containِ different amounts ofِ bothِ the initial enzyme andِ the polyphenols, andِ thus theyِ brown atِ different rates.

Enzymatic browning isِ not unique toِ apples.
Pears, bananas, andِ eggplants alsoِ turn brown fairlyِ quickly whenِ cut.
To reduce browning inِ apples, keepِ the slices refrigerated toِ slow theِ reaction.