Chlorophyll

Definition

Chlorophyll is the green pigment that captures light in leaves and unripe fruit. It fades as many fruits ripen, which is why a hard green banana, lemon or papaya slowly turns yellow: the yellow pigments underneath are unmasked as the green breaks down. A lemon that is still green-yellow is caught mid-transition. Some varieties stay green even when fully ripe, so a green skin alone does not mean a fruit is underripe. See also: Carotenoid, Ripening, Ethylene, and the guide "Why Fruits Are Yellow: The Pigments Behind the Color".