When I steam or boil diced sweet potatoes, I find that some turn an unappealing brown color. Why is this?

Chef Jil
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5 Comments

Smaug March 20, 2018
I went through a period of trying to find something that would cook decently in the microwave-sweet potatoes cooked in it developed a weird color accompanied by a weird smell and a weird taste. Sausages, by the way, microwave reasonably well.
 
702551 March 20, 2018
There are a few scenarios that can cause discoloration (which should not affect nutritional value or safety).

Aluminum and iron pots can react with sweet potatoes and cause darkening. Best to use stainless steel when boiling sweet potatoes.

Also, if sweet potatoes are stored in low temperatures (believe around 45 degrees F), some of the starch is converted to sugar and can result in a darker color after cooking.
 
702551 March 20, 2018
The latter implies not to refrigerate your raw sweet potatoes.
 
Chef J. March 20, 2018
Thank you. This all makes sense. And the aluminum sheet pan must be doing the dirty work when I roast them and they discolor.
 
702551 March 20, 2018
Glad to hear we have solved your mystery.

To avoid this in the future, try lining the sheet pan with parchment paper or switching to another material (like borosilicate glass) for your oven roasting.

Best of luck.
 
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