Old false claims that it is easy for copper to spot whether bananas have become ‘chemically’ ripe are re-emerging, even though it is impossible to judge with the naked eye how a banana has aged. Brown spots occur on bananas, regardless of the ripening method. Black stems can be a sign of the fungus caused by the fruit.
Examples of the post, which contain side by side photos of allegedly different bananas, can be found here, here and here here
The claim that ‘green stalk with brown spots means that it has become chemically ripe. Black stalk … Naturally ripened ”dates back many years and has been labeled as false here and there by other fact-checking organizations.
Most bananas are exported from countries like Ecuador and the Philippines while still green and then ripening at their destinations.
To ripen, all bananas need the air hormone ethylene it produces alone. Throughout their history, people have found ways to cause ripening with banana dishes, such as trapping ethylene gas by placing the fruit in a sealed bag (here). In the United States, classically and organically grown bananas (here) are regularly placed in temperature-controlled “ripening chambers” that pump ethylene over the fruit, making it soft, sweet, and ready to eat. This is what most people mean when they are ‘chemically ripe’. Other ripeners such as acetylene (an ethylene analogue) or smoke from burning semi-dry leaves are available, but they are not nearly as popular and have a more limited use (here). Or you can ripen bananas “naturally” alone.
There is no way a consumer who goes through the clusters in the store could see which ripening method was used.
Bananas that have matured on their own look like those pressed to ripen, with a 2019 article in the International Journal of Food Science finding that ‘most studies suggest that there is no difference in biochemical composition and sensory quality in bananas treated with chemicals that cause ripening of natural ripe bananas. ”
Brown spots are merely an indication of ‘advanced ripeness’ and indicate that a banana, though mature, is ‘at the point of its sweetness’ (here). As the U.S. Department of Agriculture explains here, the spots can also occur if the bananas were in a high temperature and overheated. Crushed bananas can also have spots (here.)
Meanwhile, black stalks and stems do not show that a banana has ‘naturally ripened’. Photos published here by the Postharvest Center at the University of California at Davis, a leader in agricultural research, show that bananas with green stems are in the first four stages of ripeness. But bananas with black stems may experience ‘crown rot’, a disease caused by one of the four fungi. It is a disease that develops “while the fruits are being stored and ripened in the marketing chain” (here). The fungus can move into the fruit, but so far a direct link between crown rot and human pathogens has not been established (here).
VERDICT
Untrue. Consumers cannot judge whether bananas have become ‘chemically’ or ‘naturally’ ripe by looking at them.
This article was produced by the Reuters Fact Check team. Read more about our fact-checking work here.