Purple tint on my sprouts?

Hello all,
First time here and would love a bit of advice please.
I sprout chick peas in a jar, they sprout well and are tasty, everything is fine with them... except... after a day in the fridge they chick peas themselves seem to take on a purplish tint.
Their regular colour is golden brown but this purple tint concerns me - does anyone know what it is and if it is safe please?
Many thanks in advance.
Paul :-) Tweet