Vegetables and fruits are stored in food plastic bags, which is a scientific method commonly used by people in winter. The principle of food plastic bags is to reduce the concentration of oxygen, increase the concentration of carbon dioxide, make vegetables and fruits in a dormant state, and extend the storage period. So how to use food-grade plastic bags to store fruit correctly? Giant Packaging teaches you a trick.
First of all, we must use food-grade plastic bags.
Generally speaking, the main material of our special food bags is polyethylene, or PE for short, which is a polymer organic compound formed by the addition and polymerization of ethylene. Polyethylene is recognized as the best material in contact with food in the world. It is non-toxic, tasteless and odorless, and conforms to the hygienic standard of food packaging. In addition, the production process should be in a dust-free workshop to ensure the conformity of products. Ordinary plastic bags contain polyvinyl chloride, which is generally used in plastic materials such as plates, toys, stationery, etc. If it is used to hold food, especially after heating, it is easy to produce harmful substances and cause diseases of liver, kidney, central nervous system and blood system. That is to say, we'd better use formal special food bags to store fruit or other food in the future.
Secondly, the storage time should not be too long.
Because vegetables and fruits are organic food with high water content (60% - 95%), and contain water-soluble nutrients and enzymes. During the whole storage period, there is still strong breathing activity. Under normal circumstances, the respiratory intensity of food plastic bags will double every 10 ℃ rise. Under aerobic conditions, the sugars in fruits and vegetables or other organic substances in food plastic bags will be oxidized and decomposed, producing carbon dioxide and water, and releasing a large amount of ripening; Under the condition of nutrient deficiency, sugar cannot be oxidized, but can only be decomposed to produce alcohol and carbon dioxide, and emit a small amount of heat.
However, the carbon dioxide concentration cannot increase indefinitely, and the plastic bag for food can only increase by 10%. The decrease of oxygen concentration should not exceed 5%, otherwise, in order to obtain enough energy for life activities, Guoshu must decompose more nutrients during hypoxia. At the same time, the alcohol produced in the food plastic bag due to hypoxia breathing will be left in the fruit, which will cause the fruit to rot and deteriorate, so the storage time of fruit and vegetables in the food plastic bag should not be too long.
If you want to store fruits and vegetables in plastic food bags, please don't be afraid of the trouble. Open the mouth of the plastic food bags every two or three days to release carbon dioxide and heat, and then tie the mouth, which will reduce the occurrence of decay and deterioration.
When cold storage is required, attention should also be paid to the storage environment of different fruits. Vegetables and fruits that may be frostbitten during cold storage can be divided into several types:
1. Relatively sensitive varieties: banana and apple will be injured when the temperature is below 12 ° C. Under normal circumstances, it should not be suitable for placing in the freezer;
2. Mild and moderate sensitive species: The temperature of cold injury is between 5-10 degrees. According to whether they should be injured immediately in the low temperature, they can be divided into the following three types. Most of these kinds of commodities still need to be put in the frozen warehouse to prevent the aging caused by the continuous high temperature, but they need to be put in and out of the warehouse before the cold injury occurs.
3. Reduce the water shortage of new products: The basic principle of water shortage of vegetables and fruits should be: the higher the ambient temperature, the lower the air humidity, and the faster the evaporation rate; The longer the storage time is, the more water will be lost; The larger the area is, the weaker the skin structure is. For example, leafy vegetables are more prone to water shortage. Most vegetables and fruits only need to lose 5-10% of water, and the quality will be significantly reduced; When vegetables and fruits are put into the freezer for storage, they can be put into the plastic film first to prevent water shortage. Under normal circumstances, the fresh-keeping film should not need to be sealed (unless the vegetables and fruits have a strong taste), but the sealed bag should not be stretched out. Just disassemble the sealed bag and press it down, which can effectively reduce the accumulation of bad gas in the water-deficient bag. If there are water droplets in the food-grade plastic film that solidify, you can put some newspapers and magazines in the bag to digest and absorb the water vapor to avoid this situation.
