Used: Doman Plum x15, Cieldalaes Pineapple x6, Valfruit x12
I'm pretty sure there is a RNG element. Me and another player both used the same combination of food, feeding in the same order, all at once, and at the exact same time. We both received no messages about a feather change on the first 3 Doman Plums and received feather change messages on every other piece of fruit.
The first player's chocobo came out Rose Pink and I got Snow White. I have seen reports of Lotus Pink, Rose Pink, Bone White, and Snow White from the same fruit combination.