Shock treatment turns humble spud into superfood

Originating in the region of southern Peru and first being domesticated between 3,000 and 2,000 BC, the potato has spread to become an integral part of the world’s cuisine and the world’s fourth-largest food crop. Scientists have now discovered not one, but two simple, inexpensive ways to boost the amounts of antioxidants in the humble spud. One involves giving spuds an electric shock, while the other involves zapping them with ultrasound, high frequency sound waves.

"We found that treating the potatoes with ultrasound or electricity for 5-30 minutes increased the amounts of antioxidants – including phenols and chlorogenic acid – by as much as 50 percent," said Kazunori Hironaka, Ph.D., who headed the research. "Antioxidants found in fruits and vegetables are considered to be of nutritional importance in the prevention of chronic diseases, such as cardiovascular disease, various cancers, diabetes, and neurological diseases."

The ultrasound treatment consisted of immersing whole potatoes in water and subjecting them to ultrasound for 5 or 10 minutes. For the electrical treatment, the scientists immersed potatoes in a salt solution for 10 seconds and subsequently treated the spuds with a small electrical charge for 10, 20, and 30 minutes. The study team then measured antioxidant activity and the phenolic content and concluded that the stresses increased the amount of these compounds. The 5 minutes of ultrasound, for instance, increased polyphenol levels by 1.2 times and other antioxidants by about 1.6 times.

Hironaka, who is with Obihiro University in Hokkaido, Japan, indicated that the process could have widespread commercial application, due to growing consumer interest in so-called "functional foods." Those are products like berries, nuts, chocolate, soy, and wine that may have health benefits beyond traditional nutrition. Such foods may promote overall good health, for instance, or reduce the risk of specific diseases. Hironaka estimated that sales of such products in the United States alone now approach US$20 billion annually.

"We knew from research done in the past that drought, bruising, and other stresses could stimulate the accumulation of beneficial phenolic compounds in fresh produce," Hironaka explained. "We found that there hasn't been any research on the healthful effects of using mechanical processes to stress vegetables. So we decided in this study to evaluate effect of ultrasound and electric treatments on polyphenols and other antioxidants in potatoes."