I have a large jewel yam. I peeled, diced, and boiled it with sugars and some spices. When I peeled it, I noticed there were deep darkish furrows in the potato, like spots where sprouts had been but were knocked off. There were a bit dark around the corner. Against my better judgement, I didn't cut them out. After boiling, the dark black spots seemed to permeate the flesh. It doesn't taste different, but it looks unpleasant. Around them, the flesh is very fibrous.
Is it safe to eat? Next time should I cut these out or avoid buying potatoes that have them?