New spray keeps fruit fresh for two weeks

Bananas that are just right 
By: David Ross 

The days of throwing away fruit because it has ripened too quickly are over.

A spray-on coating made of a substance found in the shells of crabs can prevent bananas from ripening too quickly, and keep them fresh for up to two weeks, scientists said.

When used to coat green bananas, spraying a substance derived from shrimp and crab shells stopped its maturation and kept it fresh for two weeks by forming a hydrogel coating on the surface.

Supermarket bought bananas often go brown in two or three days. It is believed that spraying could save millions of soft strip bananas daily.

"We found that by spraying green bananas with chitosan airgel, it will keep bananas fresh for up to 12 days. Once bananas begin to mature, they quickly become yellow and soft, and then, they perish," Dr. Li Xihong, who did the spraying, said.

"We have developed ways to keep bananas green for a while longer and inhibit rapid maturation that occurs. Such coatings can be used at home by consumers, in supermarkets or in transport of bananas," said Li.

The spray, which is being developed at Tianjin University of Science and Technology of China, is clear and tasteless and it's completely safe.

It works by killing bacteria and reducing the speed at which the fruit breathes. Bananas take in oxygen and releases carbon dioxide, but they do it through their skin.

The faster they breathe, they mature faster, until they start to become soggy.

Bacteria thrives on the skin and then the banana rots. A conference of the American Chemical Society that reviewed the recipe said it has to be refined to make it suitable for commercial use.

Bananas are usually transported while still green and are ripened in warm, humid conditions.

The ethylene gas is used to initiate the ripening process. Bananas also produce ethylene as they ripen, so the rot faster when kept in a bag, as the gas accumulates.