This Is Why Your Steel Cut Oatmeal Keeps Turning Green

If your morning oats are turning a funky color, it doesn't mean you got a bad box—it's probably your water.

February 12, 2018
cooking oatmeal
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Maybe it’s happened to you: you’re in the midst of cooking some steel-cut oats when you look down and notice a faint blue-green color accumulating in the pot. It can be off-putting, to say the least. So what’s going on? What is this weird green stuff besmirching your beautiful breakfast?

Turns out this is a fairly common (and harmless) occurrence that’s been studied by food scientists—we reached out to Doug Doehlert, who authored a study called “The Green Oat Story” in the Journal of Food Science on just this phenomenon, to find out what’s up.

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These savory slow-cooker cinnamon rolls are great for breakfast:

Why is this happening to me?

Doehlert and his colleagues suspected that consumer complaints about oats turning green were mostly due to minerals in the water. If your water comes from a well, he says, it might contain enough iron to produce a greenish color during the cooking process.

“We also noticed that oats will turn green under alkaline conditions,” he says, due to compounds called avenantheramides, but is doubtful this is the culprit. “I have always thought it unlikely that people would prepare oats under the alkaline conditions required to get this reaction, but we documented the colors these compounds change at alkaline pH. Because we could never observe a consumer's oats turn green, the iron explanation seems more likely, because iron will neutralize itself in minutes out of the well.”

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Do I have to throw it out?

Though it might look unappetizing, the oats are perfectly fine to eat—and iron in your water won’t harm you. “Green oats should be safe to eat—although the people reporting the green oats were reluctant to eat them! But I cannot think of anything that would make the oats unsafe,” Doehlert says.

Does it happen with other kinds of oatmeal?

Theoretically, yes, but it more often occurs with steel-cut oats for unknown reasons. “Any cut of oat can turn green according to our theories,” says Doehlert. “But all of the reported instances of green oats that I am aware of have occurred with steel-cut oats.”

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How do I prevent it?

Try cooking your oats using filtered water and a non-reactive pot—or let the cooking water sit exposed to the air for about an hour before you mix it with the oats. “Letting water sit on a counter for an hour would prevent the green color from appearing,” Doehlert says, “but this assumes the individual is getting their water from a well and the well water contains iron. You would also want to avoid cooking at overly alkaline conditions, but I don't expect people normally add baking soda to their oats when they cook—I wouldn’t!” 

The article This Is Why Your Steel Cut Oatmeal Keeps Turning Green originally appeared on Rodale’s Organic Life.