The findings – presented at a meeting of the American Chemical Society – show that the sweet potato can be boosted in terms of nutritional content by using a simple, inexpensive electric current treatment that increases the levels of beneficial polyphenols by around 60%.
Led by Dr Kazunori Hironaka, from the University of the Ryukyus, Japan, the research team note their electrifying success to be the first to enhance the nutritional content of sweet potatoes – which have been a dietary staple since prehistoric times.
"Many people don't realise it, but sweet potatoes are one of the world's most important food crops," said Hironaka.
“More than 95 percent of the global sweet potato crop grows in developing countries, where it is the fifth-most important food, and malnutrition is a serious problem," said Hironaka. "Our discovery offers a way to further increase the sweet potato role in relieving hunger and improving nutrition and health."
“This study indicates that electric treatment can be useful for enriching antioxidant activity of sweet potatoes,” add the researchers, who have previously reported that passing a similar current through white potatoes enhances levels of polyphenols by around 60%.
Study details
Hironaka and his colleagues used the same approach as used for the white potato, putting sweet potatoes into a salt solution that conducts electricity, and then passing various amounts of electric current through the water and the potatoes for 5 minutes.
The electric current stresses the potatoes, which as a result produce more polyphenols as a protective measure. The team suspected that the same effect would occur with sweet potatoes, but until now, nobody had tried.
The team reported that the best results came with 0.2 amps of current, which increased antioxidant activity in the potatoes by 1.4 (40% increase) times and total polyphenol content by 1.6 times (60% increase) compared to untreated potatoes.
Hironaka also noted that the electrical zapping seems to have no effect on the flavour, and that steaming is the best method of cooking to retain the most antioxidants.
The electrical treatment method is inexpensive and simple enough to be used on small farms or in food distribution centers, he noted.