Some color questions: Are potatoes with green skins or sprouts poisonous? Should the whole potato be thrown out, or is it fine to use if I just cut off the green? Why do shredded potatoes sometimes turn pink? Why do boiled potatoes sometimes have a blue spot? Is either OK to eat?
Ken Sissley, Naples, FL
Potatoes with green skins have a high level of solanine, which is toxic in large amounts. You can eat potatoes that have some patches of green, though, as long as you peel them completely, being sure to remove at least 1/8 inch of the outer layer of flesh. It’s not enough to remove just the green patch, and most peelers don’t remove enough of the outer layer to get rid of the solanine.
Sprouts also contain high levels of solanine. If your potato has one or two sprouts, cut them out and peel the potatoes well. If many of the eyes have sprouted, chances are the potato has started to decay and just won’t make good eating. When you’re deciding if it’s worth your time to rescue a green or sprouted potato, keep in mind that many of the nutrients in potatoes are in and near the skin.
Shredded potatoes will turn pink, or even brown, as a result of oxidation. The discoloration is more unsightly than worrisome. The best way to avoid oxidation is to shred the potatoes immediately before preparing the dish.
That dark spot in your boiled potato is a bruise. The damage to the cells will result in bitterness, so I’d cut it out.