I used to see some pink/orange/black particle in Enfamil formula (Enfagrow). And I send them back to the company and send one to Canada Health for testing. I was told by the company that it is Vitamin B12 though I doubt about that. After a couple of months, I got feedback from Canada Health and they said it is not a harzard particle and they could not tell what it is. But at that time, I already discarded the left formula and changed to Similac.