Inhibiting ripening in bananas

SCIENTISTS from China have developed a spray coating that will delay ripening in bananas, and slow down the tendency to soften and rot into an unappetising mush, seemingly in the blink of an eye.

In research presented in August at the annual meeting of the meeting of the American Chemical Society, study leader Xihong Li, Ph.D. said the spray coating is a hydrogel made from chitosan. “We found that by spraying green bananas with a chitosan aerogel, we can keep bananas fresh for up to 12 days,” he said.

Unlike many other fruits, the respiration rate in bananas does not slow down, and bananas do not ripen slowly. The banana’s pulp releases a chemical that boosts respiration, and the pulp converts into the sugars that produce that sweet, banana taste. As respiration continues, however, the process speeds up, and bananas become unpleasantly sweet and mushy. Bacteria on the banana skin start to thrive and cause the banana to rot.

“We have developed a way to keep bananas green for a longer time and inhibit the rapid ripening that occurs. Such a coating could be used at home by consumers, in supermarkets or during shipment of bananas,” said Dr Li of the Tianjin University of Science and Technology.

He said chitosan’s antibacterial property is attracting considerable attention in efforts to keep fruits and vegetables fresher longer. Until now, however, it has not been used to slow the ripening of bananas.

Banana lovers should not go bananas over the hydrogel coating just yet; Dr Li’s team is still on the trail of a new ingredient for producing the hydrogel that would replace an existing ingredient that would not be used commercially.