New nano-coating technique could make your fruit last for four weeks without rotting

Scientists from the Korea Advanced Institute of Science and Technology (KAIST) 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 non-toxic food additive that also has antibacterial properties. Test results found that after 28 days of storing mandarin oranges at 25C, 27 per cent of the uncoated fruit were rotten while all of the coated mandarins remained edible.

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

Prior to 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 that 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 for widespread use.

Worldwide, 1.3 billion tons of food is thrown away each year, amounting to £580 billion. An estimated two billion people could be fed by the food that's 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 that 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."

However, the idea of dramatically prolonging the life of fresh fruit could have serious implications for shoppers and growers. Some social media users are concerned by the developments, believing that the sprays are an unnatural and unecessary innovation, and could diminish the quality and taste of fresh produce.

Investigative food writer Joanna Blythman took to Twitter this week to express her dismay, saying: "Just what we don’t need: nano-coating spray to extend the shelf life of fruit. Clever research/stupid goals."

People replied in agreement, with one user posting: "Another way for old food to masquerade as fresh. No thank you. Glad I froze some of the strawberries I grew."

While the taste quality of food that has undergone a coating of preserving spray is up for debate, the edible coatings used in the experiments were declared safe to consume by the US Food and Drug Administration.