Browning of the chopped apple can be minimized by :

using table sugar.

preserving in a container.

using lemon juice.

using milk of magnesia.

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This question was previously asked in

UPSC NDA-1 – 2023

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The correct answer is C) using lemon juice.

Browning of chopped apples is caused by enzymatic oxidation, specifically the action of the enzyme polyphenol oxidase when exposed to oxygen. Lemon juice contains citric acid and ascorbic acid (Vitamin C). The acidity lowers the pH, which inhibits the enzyme’s activity, and ascorbic acid is an antioxidant that preferentially reacts with oxygen, preventing the oxidation of phenolic compounds.

Other methods to minimize browning include using other acidic solutions (like pineapple juice or vinegar), covering the apple surface to reduce oxygen exposure, or blanching (briefly heating) to denature the enzyme, although blanching can alter texture. Using milk of magnesia (a base) would increase the pH and likely promote enzymatic activity, worsening browning. Sugar might help reduce water activity but is not effective against enzymatic browning.

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