Why do apples turn brown when the are left in the air?

Question

I think it has something to do woth oxidation but im not very sure. I need to know for a biology project thats due in tomorrow!

Answer 1

Apples and other produce (e.g., pears, bananas, peaches, potatoes) contain an enzyme (called polyphenol oxidase or tyrosinase) that reacts with oxygen and iron-containing phenols that are also found in the apple. The oxidation reaction basically forms a sort of rust on the surface of the fruit. You see the browning when the fruit is cut or bruised because these actions damage the cells in the fruit, allowing oxygen in the air to react with the enzyme and other chemicals.

The reaction can be slowed or prevented by inactivating the enzyme with heat (cooking), reducing the pH on the surface of the fruit (by adding lemon juice or another acid), reducing the amount of available oxygen (by putting cut fruit under water or vacuum packing it), or by adding certain preservative chemicals (like sulfur dioxide). On the other hand, using cutlery that has some corrosion (as is seen with lower quality steel knives) can increase the rate and amount of the browning by making more iron salts available for the reaction.

Answer 2

Any fruit release ethanol gas mixed with some other enzyme called polyphenol oxidase or tyrosinase that gas ripens the fruit. Brown apples are over riped. If you notice, when apples are left open, it will take longer to ripe them then if they are wrapped in newspaper or something. If they are left open the gas mixes with the air and doesnot ripe as fast as the newspaper. The newspaper keeps the gas in and ripens the fruit faster.

Answer 3

the colour brown is the result of oxidation of the polyphenols contained in the apple. there are other factors involved but it is complicated chemistry and i am not well prepared so i don't want to give you the wrong answer

Answer 4

Because they conatin an enzyme called polyphenol oxidase which turns brown when exposed to oxygen in the air.

Answer 5

Basicly, they rust. Oxidation it the technical term for a substance reacting with Oxygen.

Answer 6

oxydation