Got my Chocobo to Snow White today
started out from the default

> Desert Yellow
+ around 7 plums until feathers message
> Sylph Green
+ 9 plums until feathers message
> Celeste Green

I looked at the RGB-Values for Celeste Green the Blue was right but Red and Green were too low so I guessed that my blue was probably a bit higher than needed I fed it 15+ plums after all

Solution: Pineapple

+ 1 pineapple until feathers message
> back to Sylph Green
+ 2 Pineapples until feathers message
> Snow White

From what I've gathered each fruit you feed adds to the values until the color actually changes and you get the message. However the amount that is added/substracted is random (there is probably a certain range that it falls into but inside that range it's random, only my speculation). Because of that using only one type of fruit and stopping after the first message is, in my opinion at least, the best method to get to your desired color.

And now someone please tell me what color this is, it looks beautiful *_*