Bananas are one of the fruits that people love very much, but have you ever noticed that black spots appear on the surface after a few days of banana placement?
We invited the Shanghai Fruit Industry Association to introduce the reasons why bananas turn black and appear black spots, and share some tips to delay the blackening of bananas.
Banana why
So easy to have black spots?
There are three main reasons why bananas turn black: physiological changes in bananas themselves, microbial activity, and oxidation reactions.
First, the physiological changes of bananas lead to black spots
Bananas are very sensitive fruits, and they undergo a series of physiological changes during ripening. When bananas ripen, they release a gas called ethylene. This ethylene gas stimulates the starch inside bananas to be converted into sugar, making them sweeter and more delicious. However, over time, ethylene gas causes the sugar inside the banana to break down, causing the banana to become softer and softer, and black spots to form on the skin.
Second, black spots caused by microbial activity
In addition to the physiological changes of bananas themselves, microbial activity is another major factor contributing to the appearance of black spots. When the skin of a banana is damaged or scratched, microorganisms take the opportunity to invade the inside of the banana and use the sugar and other nutrients in the pulp to grow and reproduce. These microbial activities cause bananas to turn black and form black spots on the surface.
Third, blackening caused by oxidation reaction
In addition to the above two reasons, the oxidation reaction can also cause the skin of bananas to blacken. Bananas contain some phenolic compounds, such as tyramine and phenylethylamine, which undergo oxidation when these compounds are exposed to air. This oxidation reaction causes the banana skin to turn black and show black spots.
How to delay
The process of bananas turning black?
Although bananas can't completely avoid turning black, there are a few things we can do to slow down the process:
1. Storage environment: Keep unripe bananas at room temperature and they can continue to ripen. Once the desired level of ripeness is reached, placing bananas in the refrigerator can slow down their ripening rate and the process of blackening.
2. Isolated storage: Some fruits produce ethylene gas, which may accelerate the ripening and blackening process of bananas. Therefore, isolating bananas from other fruits can extend the holding time of bananas.
3. Cover the packaging film: Covering the banana skin with a plastic packaging film can reduce the contact of oxygen to the banana, thereby reducing the oxidation rate and blackening process.
4. Eat quickly: If you don't want bananas to turn black, it's best to eat them as soon as possible. When bananas ripen, they become more vulnerable to microbial invasion and quickly turn black.
Although we can't completely stop bananas from turning black, with proper storage environment and a few little tricks, we can delay the process of banana blackening. Eating fresh bananas in a timely manner is the best option, either as a snack or as a addition to your healthy diet.