Why do cut apples, pears, bananas and apples turn brown?


Along with the previews posted article, I found this other interesting article. It is about the reason why bananas, apples, pears and potatoes turn brown after a certain time of being cut.

This fruits contain 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.

This reaction that takes place could 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).

If you want to read more about this, here is the link

Hope you found it interesting!!

Nohora C. Duque

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