What is the secret of brown spots on banana peel?

Scientists have explained through a recent study that the formation of brown spots can be slowed down, by reducing the levels of oxygen available to microscopic skin cells, as reported by "Russia Today".

Scientists have produced a new method for simulating spot patterns on bananas, which gives new insight into how the world's most famous fruit turns brown over time.

The study authors said that preventing banana peels from turning brown could be the key to reducing food waste.

And every year, 50 million tons of bananas end up as food waste, according to lead study author Oliver Steinbock of Florida State University.

"For 2019, the total banana production was estimated at 117 million tons, making it the world's leading crop," Steinbock said.

When bananas are ripe, they form many of the dark spots that are familiar to most people and are often used as an indicator of ripeness.

However, the process of formation and growth of these spots and the resulting pattern remain poorly understood until now."

And the pulp of many fruits turns brown when cut and not eaten right away - not just bananas, but apples too.

This happens because the enzymes in the fruit react with the oxygen in the air - a process known as enzymatic browning.

But the banana peel also gradually turns brown.

This is because banana peels contain a gas called ethylene, which breaks down chlorophyll, the chemical that keeps plants green.

The brown color comes from dark pigments, including melanin, found in human hair and skin.

These pigments form in bananas when oxygen reacts with natural chemical compounds called phenols in the peel.

When bananas turn brown, a lot of the starch is converted into sugars, making them an excellent natural source of sweetness.

Despite this, the public tends to throw brown bananas away, although they are still edible and ideal for use in baking recipes.

In the study, the researchers used a combination of time-lapse video clips and a computer model to reveal how banana brown spots develop.

The team's computer model was used to look at the oxygen concentration and browning of the peel in the videos.

Oxygen from the air enters the peel through small holes called stomata, which explains why small spots form and spread, rather than the whole skin becoming uniformly brown.

"Banana peels have a waxy outer layer that - if intact - does a very good job of keeping oxygen out," Steinbock said. "The result is brown spots on a yellow peel. But very slowly, oxygen eventually gets into the peel all over, so that the old bananas become Really quite brown."

The researchers found that the spots appear and expand rapidly before their growth mysteriously stops - all within two days.

"Our results strongly suggest that the small holes in the center of the brown spots are collapsing," Steinbock said.

It re-closes the cortex, cutting off the flow of oxygen, and thus stopping the growth of the macula."

The browning process can be prevented through genetic modifications, or better storage conditions, such as special containers with low oxygen levels.

Another mechanism to protect bananas is a thin film to prevent oxygen from the air from entering the peel in its small openings.

Contrary to belief, the refrigerator is generally not a great place to put bananas after they have been returned from the stores.

When we put unripe bananas that are still a little green in the fridge, the pulp will not ripen at all but the peel will turn black.

However, putting a ripe banana in the refrigerator will help it stay ripe (rather than overripe) for a few more days.