How do tomatoes turn red?
The primary red pigment in ripe tomatoes is lycopene. The predominant pigment in green tomatoes is chlorophyll. As the tomato fruit ripen they produce more lycopene, and lose the ability to make chlorophyll. As part of the process of sunlight being converted to stored energy in a plant, chlorophyll continuously breaks down and is “re-manufactured” by the plant, using up stored energy (sugars). The tomato, when ripe, does not need to grow any more, so the plant saves energy by not making chlorophyll. As the green chlorophyll breaks down, the red pigments can be seen, resulting in red.
