Why does a banana skin go brown really quickly after it's been opened?

It%26#039;s a weird and silly question, but can anyone tell me what the science behind it is?|||Good question =)





Bananas and other produce (e.g., pears, apples, peaches, potatoes) contain an enzyme (called polyphenol oxidase or tyrosinase) that reacts with oxygen and iron-containing phenols that are also found in the produce. The oxidation reaction basically forms a sort of rust on the surface of the fruit.





You also see the browning when the produce 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.|||It%26#039;s the same process as iron turning to rust: oxidation.





The liquids/substances in the skin react with the oxygen in the air, turning dark.|||Because of oxidation. By the way, if im not mistaken, that brownish thingy is already carcinogenic.|||I think Its the presence of air that does this. I could be wrong but I have heard this from other people and may its just a urban legend or something.|||It is oxidizing, been exposed to the air.|||i always wondered the same thing|||it is a racist reaction