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I hear that Oranges cultivated in tropical areas of the world tend to be greener when ripe, is that correct? Even the same type of Orange differs in color if cultivated in California or Florida. I hear that's because of the climate (colder nights == oranger oranges)

But, at the same time, oranges tucked in between the tree leaves tend to be greener, for they need more chlorophyll to make the most use of less access to sun rays.

Could someone correct my assumptions? Also, if possible, list the pigments and processes involved?

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Naturally, ripe orange skins are usually green-yellow. In colder climates, they will turn orange over winter, since in the cold the chlorophyll will start degrading and stop masking out yellow/orange carotenoids in the skin. If the fruit is picked in fall (and not let ripen or degreened) they will have green color.

Ehtylene gas, which is a natural plant hormone, is sometimes used to give them more uniform, orange color (degreening). Also, some oranges cultivated in the US are dyed with Citrus Red 2 to make their peels orange.

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