Zapping potatoes to make “superfood”

The stress of being sonically blasted causes them to generate more antioxidants, which have been shown to combat heart disease and cancer. Researchers believe the techniques could be used to turn the humble potato into a "superfood".

Potatoes, the world's fifth most widely consumed plant food, are already a good source of antioxidants, including vitamin C and compounds called polyphenols.

Scientists built a laboratory "torture chamber" where they could subject spuds to high frequency ultrasonic sound waves or mild electric shocks.

The treatment almost doubled the levels of some antioxidants in the potatoes.

Plants create antioxidants to help them survive stressful events such as drought, and attacks by pests and infections.

The chemicals mop up destructive molecules and also influence growth and cell death.

When consumed in plant foods, they are believed to protect arteries, reduce the risk of diabetes and help prevent the DNA damage that leads to cancer.

Study leader Dr Kazunori Hironaka, from Obihiro University in Japan, said: "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.

"We found that there hasn't been much research on the healthful effects of using mechanical processes to stress vegetables. So we decided in this study to evaluate the effect of ultrasound and electric treatments on polyphenols and other antioxidants in potatoes.

"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."

For the ultrasound treatment, the researchers placed whole potatoes in water and subjected them to 600 watt blasts of high-frequency sound for five or 10 minutes.

Electrified spuds were immersed in a salt solution and given 15 volt shocks for 10, 20 and 30 minutes.

The scientists then measured antioxidant activity and polyphenol levels, comparing them with those of untreated potatoes.

Five minutes of ultrasound treatment was found to increase antioxidant activity 1.5 times, polyphenol content 1.2 times, and levels of other antioxidants 1.6 times.

A 10 minute electric shock boosted antioxidant activity 1.6 times, total polyphenols 1.2 times, and levels of a polyphenol called chlorogenic acid 1.7 times.

The findings were presented at the 240th national meeting of the American Chemical Society in Boston, Massachusetts.