BIOMOLECULES AND ENZYMES

Detailed explanation-1: -Oxygen in the air can cause sliced fruit to brown, a process called enzymic browning (an oxidation reaction). Phenols and the enzyme phenolase are found in the cells of the apple, and when these are exposed to oxygen in the air, for example through slicing, the oxygen causes a reaction.

Detailed explanation-2: -Oxidation occurs when a substance is exposed to oxygen. For fruit, oxidative browning occurs when enzymes interact with amino acids in the presence of oxygen, which then causes brown pigments to form. Pigments make up the natural coloring of plant and animal tissues.

Detailed explanation-3: -Its basically an oxidation reaction which involves chemical reactions so the phenomena is a chemical change.

Detailed explanation-4: -When fruit tissue is damaged because of heat, cold, age or mechanical stress, its cells break open and the phenolic compounds and the enzyme are released and mix with oxygen in the air. As a result the damaged tissue turns brown almost immediately.