Purple Sweet Potatoes: The Ancient Superfood

These richly colored tubers shouldn’t be underestimated. Learn about their growing reputation, health benefits, and global history.

| Spring 2018

“It’s definitely not your typical sweet potato,” says Mary Landis, recounting an episode in which her microwave nearly erupted in flames. She’s a former “forager” for Frieda’s, a specialty produce company based in California that introduces unusual fruits and vegetables to American tables, including kiwi and dragon fruit. Companies like Frieda’s that specialize in exotic produce make it their priority to supply community supermarkets that would otherwise go without access to unique produce items.

These businesses have helped spark the appearance of more recent and now-familiar items, such as persimmons, rambutan, and cucamelon. Fruits aren’t the only products that have gained in popularity, though — specialty vegetables have also been attracting attention, particularly an unusual variety of sweet potato. Unbeknownst to some consumers, sweet potatoes come in a variety of colors besides the traditional orange, including red, yellow, and white. Perhaps most striking is the purple sweet potato, offering unrivaled health benefits and rich color.

In 2010, a sweet potato supplier of Frieda’s, A.V. Thomas Produce, told Landis they’d planted a trial of a North Carolina sweet potato that had rich, nearly black-purple skin and flesh that turned brilliant violet in the oven. “It’s a gorgeous sweet potato,” says Landis. “And the antioxidants don’t cook out. Usually when you cook a vegetable with dark coloring, the color is lost. A purple bell pepper turns brown when you cook it, and a purple cauliflower doesn’t keep its color in the pot.” Jeremy Fookes, retail sales specialist for A.V. Thomas, says this sweet potato’s color retention post-cooking was “what we thought was quite special. It’s not lavender-y, but purple-purple.”

Gaining Recognition

Purple-fleshed sweet potatoes are rich in anthocyanins, the same antioxidant compound that turns blueberries blue and gives them a superfood reputation. The same year A.V. Thomas trialed the mysterious purple-purple sweet potato, TV personality Dr. Mehmet Oz listed another cultivar — pale-skinned, mauve-fleshed beni-imo from Okinawa, Japan — as No. 1 of his top five superfoods. A year earlier, in 2009, The Oprah Winfrey Show had featured beni-imo when she interviewed researchers about Okinawa Island’s many centenarians and their diet consisting of about 60 percent sweet potatoes. Americans started looking to put the ‘Okinawan’ purples on the table, but these tubers were hard to come by. “They’re only grown in Hawaii and on Japan’s Okinawa Island, and they have to be irradiated when they come into the U.S.,” says Landis. “A lot of people don’t like that.”

A.V. Thomas tried growing the Japanese sweet potatoes on its plot in Merced County, but the crop failed dismally. “The ‘Okinawan’ sweet potato can have a difficult time growing in California because it’s very susceptible to disease,” says Fookes.

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