After peeling and chopping, a banana goes quickly from an appealing yellow to a dark brown, and crucially, it takes other fruit down with it.

The reason they go brown in the first place is because of an enzyme – a chemical that causes reactions – called polyphenol oxidase. PPO is released when plant cells are damaged by cutting, PPO converts common chemicals called phenolics to quinones by the addition of oxygen in the air, and then joins these together to form various brown pigments.

Why do bananas appear to speed up the ripening process of other fruits too? Bananas make other fruit ripen because they release a gas called ethane. This gas causes ripening, or softening of fruit by the breakdown of cell walls, conversion of starches to sugars and the disappearance of acids.