A spray made from a substance found in the shells of shrimps and crabs can prevent bananas ripening too fast and keep them fresh for up to 12 days, scientists report, in a discovery that offers relief to the more than 400,000 smallholder banana farmers in Kenya whose biggest headache is rotting bananas that cost them and the economy an average Sh200m a year in losses.
The spray, dubbed chitosan aerogel, which has been developed at Tianjin University of Science and Technology in China, works by slowing down the ripening of the bananas. Like people, bananas breathe, taking in oxygen and releasing carbon dioxide, but through their skin. The more a banana breathes, the quicker it ripens. Unlike many other fruits, the breathing rate in bananas does not slow down when they're picked, and bananas continue to ripen.
For that ripening process, the banana's pulp releases a chemical that boosts breathing, or what is called 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. At that point, 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 lead researcher Dr Xihong Li. The spray is clear, tasteless and is said to be completely safe.
Before releasing the gel to market, however, the scientists say one of its current ingredients would have to be replaced with an alternative to make it suitable for mass production.
The supply of shrimp shells is unlikely to be sufficient, meaning the team is now looking for a replacement source that will be viable for mass production.
The timing of the replacement and product launch will, however, be critical for Kenyan farmers. According to Bridgenet Africa, an NGO working with farmers, about 1 million bananas are thrown away every day in Kenya primarily for rotting. “And this has particularly taken a toll on farmers' earnings since it takes a lot of energy to tend to bananas, so when they can't get to the markets in time the losses due to the rotting is unimaginable,” said Alfred Kinge, a programme officer at Bridgenet Africa.
In addition, the recent high uptake of the high yielding tissue culture bananas, by some 90,000 farmers, created a glut in the market, which saw farmers end up with thousands of kilos of rotten bananas.
However, over the mid-term, the market for bananas has been impressive in the country, with a recent study by TNS showing that banana is the most preferred fruit among Kenyans, drawing sales income of Sh30bn last year.
Written by Bob Koigi for African Laughter