Here's a nice post about color vision from a blog TPP often enjoys In Defense of Plants. The two images are great because it shows you how fruit would look without color vision. The answers given here were always part of my lectures on fruits. But in modern grocery stores you still have to know how to pick fruit that is/will be ripe especially the tropical fruits. For example, in general you cannot go by color on mangos or papaya. The flesh should just give under moderate pressure, and in TPP's opinion both are better just a tad underripe.