When do Anthocyanins show their color?

[bughunter99]

I'm growing out several F3 plants from Seattle's Woolly Blue Mammoth. One one plant I noticed that the first couple of plants that ripened in the center of the plant did not get any purple striping, new fruit which has a ways to go until getting ripe already has purple stripes forming.

My question, if I remove fruit from the vine and let it ripen in the sun, will it get purple stripes or does it have to be on the plant?

Stacy