Why radiation can keep food fresh?

As early as 1930, the French obtained the patent of radiation food. However, because the effect of radiation on food is not clear, it has not been widely used for a long time, and it was not until the 1960 s that experiments began. Now it has been recognized that irradiating food with a certain dose of radiation can kill insects, sterilize, inhibit germination, delay ripening, prevent rot and mildew, and achieve the purpose of keeping fresh and prolonging storage period. As we know, most foods that provide people with protein, sugar and oil are edible parts of animals and plants. Radiation will cause a series of chemical and biological changes to food, affecting and destroying the destruction of various biochemical active substances in biological cells, such as deoxyribonucleic acid. Purification, reduction or even loss of biocatalytic activity of biological enzyme; Changes in other chemical components or biological tissues make life functions such as cell growth and reproduction abnormal, thus changing some original properties and characteristics of food. In addition, irradiation of food with rays can directly destroy harmful and toxic substances such as pests and bacteria, and protect food from pests and germs. Food treated by radiation is called irradiated food. Irradiating tuberous plant foods such as potatoes and onions with radiation can inhibit their germination; Irradiated fruits and vegetables can delay ripening, avoid and reduce mold breeding, decay and fermentation; Irradiation of high-protein animal foods such as fish, meat and poultry can achieve thorough sterilization and eliminate any harmful organisms that cause food decay and deterioration; Irradiated frozen meat, eggs, poultry and other easily contaminated foods can kill salmonella ... There are many kinds of foods that can be treated with radiation, and the effect is obvious. In particular, it is necessary to irradiate, transport and preserve food in tropical areas for a long time. For example, India is located in the tropics, with high temperature and humidity, and food is very easy to rot and deteriorate. More than 20% of the hard-earned grain is often lost due to decay. If radiation is used, the loss will be greatly reduced. In order to keep the nutrition and flavor of food unchanged or slightly changed as far as possible, and not to cause radioactive harm to food, we must first choose a suitable radiation source. At present, there are only a few radioactive isotopes such as cobalt -60, cesium-137 and (rays, etc. ) all of them are used. The second is to control the radiation dose, for example, in order to eliminate salmonella in fish and meat products, the radiation dose is 300- 1 10,000 rad; The dose of inhibiting potato germination is 20,000 rads. Rade is a practical radiation dose unit. The energy absorbed by 100 erg rays per gram of irradiated object is 1 rad, and the radiation dose of 1 rad is very small. 1 million rads can only heat food by 2 degrees. Therefore, compared with heating high temperature disinfection, food irradiation treatment can be called cold disinfection. Such a small radioactive dose will not destroy the nutrition and flavor of food, nor cause radioactive pollution, and certainly will not endanger people's health and safety. In the past twenty years, due to the development of science and technology and the needs of people's lives, many achievements have been made in the research of irradiated food. The World Health Organization has identified several kinds of foods that can be irradiated, and many countries have widely carried out the research and application of food irradiation.