It took me ages too get mine to eat anything apart from seeds and apple, but kept at it and now they generally accept most things now, but I also make believe I eat it also and say "MMMMMmm thats nice" and other gestures too show them how yummy it is, and guess what.......... they want some,
In fact Charlie often says "MMMmmmm that is nice"

copied it from his early conversion times. Bless em.