りんごが茶色くなる理由は？切ると酵素と酸素が出会います

Why Do Apples Turn Brown?

Have you ever cut an apple and left it on a plate?

Soon, the white part starts to turn brown.

Inside an apple, there is an enzyme called polyphenol oxidase.

An enzyme is a natural helper that makes a chemical change happen.

When you cut an apple, you break many of its cells.

Then the enzyme meets chemicals called polyphenols and oxygen from the air.

The enzyme changes the polyphenols into new chemicals.

Some of these new chemicals are brown.

They belong to the same family as melanin, which gives color to human skin.

The same thing happens to avocados and potatoes.

A food scientist at the University of Wisconsin–Madison says this change may help protect plants.

Some of the new chemicals may keep pests and germs away.

Not all apples turn brown at the same speed.

Different kinds of apples have different amounts of the enzyme and the polyphenols.

So how can you keep apple slices white?

One way is to use lemon juice.

It is acidic, and acid makes the enzyme work less.

Sugar or syrup on the apple also helps, because it lets less oxygen in.

Boiling apples for four to five minutes almost stops the enzyme, but it changes the texture.

Scientists have even made an apple that is slow to turn brown.

It is called the Arctic apple, and it makes less of the enzyme.

Next time you cut an apple, watch the color change.