Question

slice of apple acquires a brown colour if it is not consumed immediately explain

Answer 1

The brown colour is because your apple has rusted! That's because apples are rich in iron, which is present in all their cells. When you cut an apple, the knife damages the cells. Oxygen from the air reacts with the iron in the apple cells, forming iron oxides. This is just like rust that forms on the surface of iron objects.

Hope it helps u.

Answer 2

Answer:

A slice of apple acquires brown colour if it is not consumed immediately because of the formation of new substances that triggers the oxidation response that causes enzymatic browning.

Explanation:

• A slice of apple acquires brown colour if it is not consumed immediately because of the formation of new substances.

• Cutting or biting additionally uncovers an apple's cells to air, which contains oxygen. This triggers the oxidation response that causes enzymatic browning.

• When an apple is cut (or bruised), oxygen in the outer environment is introduced into the injured plant tissue.

• When oxygen is present in cells, Polyphenol oxidase (PPO) enzymes in the chloroplasts rapidly undergo oxidation and oxidize phenolic compounds naturally present in the apple tissues to O-quinones, colourless precursors to brown-coloured secondary products.

• O-quinones then possess the well-documented brown colour by reacting to form compounds with amino acids or proteins, or they self-assemble to make polymers.

• This enzymatic browning is not unique to apples.

• PPO is a mixture of monophenol oxidase and Catechol oxidase enzymes.
• This is present in nearly all plant tissues and can also be found in bacteria, animals and fungi.

• Browning of apples because of the enzymatic activity requires three things:

• 1. Oxygen.

• 2. A special polyphenol oxidase (PPO) enzyme

• 3. Polyphenols, (also called phenolic compounds). These are complex organic molecules which contain at least one hydroxyl group (-OH) bonded to a hydrocarbon ring (C₆H₅).

• When a slice of apple is not consumed immediately, it reacts with the oxygen in the air around.

Hence, this change basically forms a sort of rust on the surface of the fruit. This chemical reaction results in the brown colour of the apple slice.  

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