Overripe bananas Philadelphia - Arabstoday   A solution to the age-old problem of bananas quickly going overripe before they can be eaten may be at hand thanks to chemistry, U.S. researchers say. A spray-on coating could delay the ripening of America\'s favorite fruit, scientists told a meeting of the American Chemical Society in Philadelphia Wednesday. The coating, a so-called \"hydrogel\" or super-absorbent material, is made from chitosan, a substance derived from shrimp and crab shells. \"We found that by spraying green bananas with a chitosan aero-gel, we can keep bananas fresh for up to 12 days,\" researcher Xihong Li from Tianjin University of Science and Technology in China said. Chitosan can help keep fruits and vegetables fresher longer due to its action in killing bacteria that cause produce to rot, scientists said. \"Such a coating could be used at home by consumers, in supermarkets or during shipment of bananas,\" Li said. Americans consume 6.4 billion pounds of bananas annually, a release from the society said. From : UPI