The spray that keeps fruit fresh for weeks

Scientists at the Korea Advanced Institute of Science and Technology have developed a new technique for coating fruit with a spray that could prolong its shelf life by several weeks. The process takes just five seconds to apply and can keep certain fruit fresh for four weeks or more.

The new nano-coating spraying technique uses plant-derived polyphenols, a nontoxic food additive that also has antibacterial properties. Test results found that after 28 days of storing mandarin oranges at 25°C, 27% of the uncoated fruit were rotten, while all of the coated mandarins remained edible.

In a test with strawberries, over half of the treated fruit remained in good condition after 58 hours, while only 6% of the untreated strawberries had not become rotten.

Before the new research there have been practical limitations on the application of preservative sprays. However, with the new technique taking only five seconds, it is thought the time saved could allow for preserving sprays to be brought into the process of mass-harvesting fruit. The scientists have patented the product and are in the process of attempting to commercialise it.

Worldwide, 1.3 billion tons of food is thrown away each year, amounting to £580-billion (R10-trillion). An estimated two billion people could be fed by the food that is wasted.

Darren Reynolds, professor of health and environment at the University of the West of England in Bristol, developed a similar spray last year that increased the shelf life of tomatoes and cucumbers by a day.

He believes the sprays could help fight world hunger by reducing the waste around the whole food industry.

"With fresh produce, you have to drive it somewhere and treat it," he said. "The waste is not just the bits you put in the bin - the whole chain around waste is growing."

Investigative food writer Joanna Blythman this week tweeted her dismay: "Just what we don't need: nano-coating spray to extend the shelf life of fruit. Clever research; stupid goals."