As the fruit matures the pigment changes from green to orange to red. The first pigment change is a fading of the green color due to the transformation of chloroplasts into chromoplasts resulting in a decrease in chlorophyll concentration. The initial increase in B-carotene concentration results in the orange pigment. The final red color is due to the subsequent high concentrations of lycopene.(Grierson and Kader 1986)

photograph courtesy of Dr. David