When I peel sweet potatoes for a meal, why do some go black? I peel them about 1 hour or half an hour before I cook them

  • Could be oxidation, although that would normally turn them brown rather than black. Can you try rubbing lemon juice on them after you Perl them? This works on apples, maybe it will help your problem too. – James McLeod Jun 20 '16 at 8:10
  • Are they going black instantly or gradually when they sit peeled? – rackandboneman Jun 20 '16 at 9:04
  • Mostly when I have not finished peeling them, some go black gradually. Could the problem be that I put them in water after I have finished peeling the ( the ones that go black gradually? – Alison Jun 21 '16 at 9:11

Potatoes of all kinds will blacken after peeling. Try putting each potato in cold water while you peel the rest. I do this with both whole and cut potatoes. You can add some acid to the water if you like, but it's not really necessary.


Starch from the potato will blacken/bruised when exposed to air.

Add a tea spoon of salt in a bowl of cold water. Immediately put the peeled potato into the water. Salted water help dissolve the starch preventing bruising.

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