Do not store vegetables and fruits in plastic bags
Storing vegetables and fruits in plastic bags is a common scientific method for preservation.
The principle behind this method is to reduce the oxygen concentration and increase the carbon dioxide concentration, which puts the produce in a dormant state and prolongs its storage life. However, the storage time should not be too long.
Because vegetables and fruits are organic foods, they have a high water content (60%--95%) and contain water-soluble nutrients and enzymes. Throughout the storage period, they continue to undergo intense respiration. Under normal circumstances, for every 10°C rise in temperature, the respiration rate doubles. In the presence of oxygen, sugars or other organic substances in the produce are oxidized and decomposed, producing carbon dioxide and water, and releasing a large amount of heat. In the absence of oxygen, sugars cannot be oxidized and can only be decomposed into alcohol, carbon dioxide, and a small amount of heat.
However, the carbon dioxide concentration cannot increase indefinitely; it can only be raised by 10%. The oxygen concentration cannot decrease by more than 5%, otherwise, the produce, in order to obtain sufficient energy for its life activities in an oxygen-deficient environment, must decompose more nutrients. At the same time, the alcohol produced by anaerobic respiration remains in the produce, causing it to rot and spoil. Therefore, fruits and vegetables should not be stored in plastic bags for too long.
If you want to store fruits and vegetables in plastic bags, please do not mind the trouble. Open the bag every two or three days to release carbon dioxide and heat, and then tie it up again. This will reduce the occurrence of rotting and spoilage.
Do not store tropical fruits in the refrigerator
Various tropical fruits such as dragon fruit, mango, lychee, longan, papaya, and rambutan, once put in the refrigerator after being brought home, will begin to have sunken peels and black-brown spots within a few days. This indicates that the fruit has been frost-damaged.
Most tropical fruits are sensitive to cold and are not suitable for refrigeration. Frost-damaged fruits not only have their nutrients destroyed but are also very prone to spoilage. In a few more days, the pulp will rot.
Generally speaking, temperate fruits such as grapes, apples, and pears can be preserved in the refrigerator. However, bananas and mangoes will have their peels turn black when stored at 10°C; pineapples stored at 6°C—10°C will not only have their peels change color but their pulp will also become water-soaked; lychees, longans, and rambutans stored at 1°C—2°C will have their outer peel color darken, and the inner peel will develop scald-like spots. Such fruits are often no longer edible.
Tropical fruits are best stored in a place that is away from light and cool. If you must put them in the refrigerator, they should be placed in the fruit and vegetable compartment with a higher temperature, and the storage time should not exceed two days.
The daily storage of fruits can be divided into the following four categories:
Category 1: Do not put in the refrigerator, otherwise they will be frost-damaged. Examples: bananas, starfruit, loquats, etc.
Category 2: Can be put in the refrigerator, but must be ripened first (i.e., unripe fruits should not be put in the refrigerator). Examples: durian, mango, sugar-apple, passion fruit, persimmon, papaya, etc.
Category 3: Must be put in the refrigerator to be stored for a long time. Examples: peaches, mulberries, plums, lychees, longans, rambutans, cherries, chestnuts, guavas, grapes, pears, strawberries, mangosteens, dragon fruits, melons, pomelos, etc.
Category 4: Can be stored at room temperature or refrigerated. Examples: lemons, pineapples, grapes, oranges, olives, jujubes, apples, watermelons, tangerines, coconuts, grapefruits, sugarcane, etc.