Banana epidermal cells contain an oxidative enzyme. On weekdays, it is tightly wrapped by the cell membrane, and does not contact with the air. However, once it is bruised or frozen, the cell membrane breaks down, and the oxidative enzymes flow out. It oxidizes with the oxygen in the air to form a black compound, that is, 'ugly' black spots.
When the banana is laid flat, the whole weight is pressed on the contact surface, and the pressure here becomes greater. It is likely to crush some cell membranes of epidermal cells on the contact surface, causing the oxidation enzymes inside to flow out and produce black spots.
Methods:
1. It is estimated that the bananas can't be eaten for a while and can be rinsed several times with water.
2. Dry the skin with a clean cloth and keep it dry.
3. Wrap the banana with several old newspapers and put it in a cool and ventilated place indoors. Pay attention to the contact area as small as possible.
4. You can also hang the whole bunch of bananas directly, which can also prolong the storage time.
The best way to buy bananas is to hang them up to reduce the pressure area, so that bananas can be 'beautiful' for a long time. In addition, if you buy bananas, rinse them with water for several times immediately, which can reduce the corrosion of ripening agent. Under the same external conditions, the washed banana can be stored for 5-7 days without deterioration.
Bananas are best preserved at 8-23 degrees centigrade, which is easy to over ripen and discolor at high temperature; however, if the temperature is too low, it is easy to cause frostbite. Therefore, it is necessary to keep bananas in the refrigerator, otherwise the flesh will turn dark brown and taste bad. Therefore, when it is hot, it should be placed in a cool and ventilated place. When it is cold, it should be wrapped and preserved with newspapers and other articles.