Most immature fruits are green: peppers, pine cones, plums, lots of them. I want to know if the green is from chlorophyll in the cells. Do the fruit cells perform photosynthesis? When you cover a green stem or leaf, it will turn pale and stretch. That is because the stems have little need for chlorophyll in the dark, which is why they are pale. They stretch because the auxins in the stems are not destroyed by the photons, and the stems stretch out and topple over. If a green fruit is covered, will it turn pale and stretch like that?
The green pigment is indeed chlorophyll, and the fruits do perform photosynthesis. It's not just "fruiting" plants that do this either. Some shading experiments i saw estimated that up to 30% of the sugars assimilated into the barley ears (basically the grain) can come from photosynthesis occurring in those organs.