Even visible light can damage microorganisms or kill them after prolonged irradiation, because all photosynthetic organisms contain light-sensitive pigments such as chlorophyll (or bacterial chlorophyll), cytochromes, and flavin proteins, and it absorbs light energy into an excited state or activated, and transfers the absorbed energy to oxygen, generating oxygen radicals to act on the cells, leading to mutation or death of the organism. The effect of radiation sterilization by other factors, such as light can make the pyrimidine dimer disintegration, reduce the effect of ultraviolet light, oxygen can improve the effect of X-rays or γ-rays. Radiation sterilization devices include microwave ovens, ultraviolet lamps, cathode ray tubes, X-ray generators, radionuclides, and so on. The radioactive sources used commercially to sterilize large quantities of items are cobalt-60 and cesium-137, which emit gamma rays and are relatively inexpensive. Radiation sterilization is used for a wide range of purposes, such as medical devices and appliances (e.g., syringe lights), food, many plastic products in the laboratory and a variety of media are sterilized by this method.
Food radiation (or irradiation) sterilization is the use of a certain dose of very short wavelength ionizing rays on food sterilization (including raw materials), the radioisotope cobalt 60, cesium 157 produced by γ- rays or low-energy gas pedal radiation of β- rays on packaged food irradiation treatment. Delay the development of certain physiological processes (germination and maturation) of fresh food, or food for insecticide, disinfection, sterilization, mildew and other treatments, to achieve prolonged preservation time, stabilization, improve the quality of food for the purpose of the operation process. In the food sterilization commonly used rays are χ - rays, γ - rays and electron rays. Electron rays are mainly obtained from the electron gas pedal, χ-rays produced by the χ-ray generator, γ-rays are mainly obtained from radioisotopes, commonly used radioisotopes are 60Co and 137Cs. γ-rays have a strong penetrating power, suitable for the Complete food and a variety of packaged food internal sterilization treatment, the penetration of electron rays is weak, generally used for small packaged food or frozen food sterilization, especially suitable for the surface of the food sterilization treatment. Irradiation sterilization technology originated in the United States in 1943, the Massachusetts Institute of Technology for the U.S. military engaged in "ray on hamburger processing" research began, so far there have been 63 years of development history. In 1970, by the United States, the Soviet Union, Britain, the Netherlands, China, France, Denmark, Germany, Canada, Japan, Italy and other 24 countries signed an agreement to develop the International Food Irradiation Program (IFIP), this plan by the FAO (Food and Agriculture Organization of the United Nations), IAEA (International Atomic Energy Agency) hosted the WHO (World Health Organization) to participate in the development of the results of international cooperation in six consecutive years according to the IFIP research results show that: food, According to the results of six consecutive years of international cooperative research conducted by IFIP, the irradiation process of food and pharmaceuticals is essentially a physical process, just like thermal processing and refrigeration. The conclusion was that "when the overall average absorbed dose of any food or drug does not exceed 10 kGy (1 million tera), no further toxicity test is required and it is nutritionally and microbiologically safe", and therefore it is called the "International Safety Line". 1984 The Codex Alimentarius Commission (CAC) recommends CAC standards for irradiated foods and recommended protocols for irradiated food facilities to member countries.
Energy-saving, safe, reliable, effective, low-cost packaging food sterilization technology has been developed and applied, greatly promoting the production and development of packaged food. Food is easy to deteriorate, so the food and meat products industry has been trying to find effective food preservation methods. Irradiation methods have been strongly recommended as the best sterilization or cold sterilization method to reduce pathogenic bacteria to levels safe for consumption.
Canada, Israel, France, Japan and other countries commonly use the radioactive substance cobalt 60, which radiates powerful γ-rays that can completely destroy bacterial genetic factors, completely destroying their physiological activity, and can virtually eliminate any bacteria when used in high doses.
Common pathogenic bacteria that contaminate food include Escherichia coli, Salmonella, Campylobacter, and the often-mentioned Listeria monocytogenes that contaminate meat and meat products. In order to more effectively inhibit pathogenic bacteria and production of food to meet hygiene standards, researchers and food engineers have been working hard to carry out the relevant research work. Existing methods have their own strengths and in some cases affect the quality, taste and flavor of the food.
For the meat industry, post-slaughter livestock carcasses are usually rinsed with a liquid formulated with acetic acid, lactic acid, or chlorinated water, and then cleaned with steam and vacuum methods to remove surface dirt. They are then skinned and soaked in brine. Processing of meat products may include high-temperature cooking, pasteurization, or ultraviolet irradiation treatment. Irradiation for Complete Sterilization
Irradiation of foods in sealed packages at 2,500 to 5,000 kilorads kills all pathogenic microorganisms that damage the food, thus sterilizing the commodity. Before irradiation can be added to the food salt and sodium triphosphate, etc., can reduce the loss of water in the food, but also can enhance the ray on the killing ability of bacteria. After irradiation completely sterilized beef, chicken, ham, pork, sausage, fish and shrimp, etc. at room temperature (21 ℃ ~ 38 ℃) can be stored for more than 2 years, can keep the color and flavor good.
Irradiation sterilization
Dose of 100 to 1000 kilorads, can effectively limit the growth of organisms and corrosive microorganisms detrimental to public health, can effectively remove the high protein foods such as meat, dairy products, egg products, the great danger of salmonella, irradiation with 500,000 rads, it can be made to hundreds of millions of times fewer, but also to kill the depth of the salmonella in frozen foods. Now more than 20 countries around the world have approved the application of irradiation sterilization of food for human consumption, such as chicken, pork, fresh fish, mushrooms, spices, potatoes, rice, onions, wheat and so on. Irradiated food is safe and reliable, as proven by more than 40 years of practice in various countries around the world, irradiated food has never been found to have radioactive material residues, and can maintain the original quality and color and flavor. In the United States, irradiated food has been taken to space, astronauts have proved harmless to the body after consumption. The advantage of irradiated food is a long shelf life, irradiation can be kept fresh for several years, not only to kill bacteria, but also inhibit and slow down the metabolism of the food itself, eliminating the root cause of food spoilage. Irradiation sterilization can save a lot of energy, any food sterilized by irradiation method can be stored using only ordinary packaging, eliminating the need for a large number of cans, refrigeration and other materials as well as energy to irradiation storage has been able to replace part of the refrigerator. Principle: in the irradiation process, gamma rays penetrate the irradiation of goods in the box, the role of micro-organisms, directly or indirectly destroy microbial ribonucleic acid, proteins and enzymes, thereby killing micro-organisms, to play the role of sterilization.
Advantages: Due to the strong penetrating power of the ray, it can kill the germs and pests inside the large and small packages, bulk, liquids, solids, dry goods, fresh fruits, and it is especially suitable for some food products which are not suitable to be heated, fumigated, or wet-cooked. Irradiation processing belongs to the cold processing, will not cause a significant increase in the internal temperature of food, and thus easy to maintain the flavor and appearance of food quality. For example, irradiation preservation of potatoes can inhibit sprouting, full and not wrinkled, hardness is good, there is no significant loss of nutrients, and refrigerated or chemically preserved potatoes, compared with a strong competitive edge. Food irradiation is a physical process, no need to add chemical drugs, no drug residues, and not found sensory radioactivity, no pollution of the environment, is a safe and environmentally friendly food processing method. Irradiation processing can improve the process quality of food. For example, irradiated beef is more tender, irradiated wine can improve the degree of aging, irradiated soybeans are easy to digest and absorb. Irradiated food can kill salmonella and parasites, improve food hygiene quality.
High-dose completion of the sterilization of food for hospitals, special needs patients, astronauts, sailing, mountaineering, exploration and geology team's special needs. Irradiated food can be stored at room temperature for a long time, to facilitate long-distance transportation and international trade. As irradiation can completely kill and sterilize pests, it can be used as a special quarantine measure to prevent the spread of pests and diseases. 1, can be carried out at room temperature or low temperature, treatment process food temperature rise is very small, is conducive to maintaining the quality of food;
2, rays (such as γ-ray) penetrating power, can be in the packaging and without thawing irradiation of food, kill pests, parasites and micro-organisms hidden deep inside the food;
3, irradiated food does not leave any residue;
4, irradiated food will not leave any residue;
5, irradiation can be a special quarantine measures to prevent the spread of pests and diseases, and to prevent the spread of food.
4, and food freezing and storage methods, compared to irradiation storage methods can save energy;
5, can improve the process and quality of certain foods;
6, requires a large investment and specialized equipment to produce radiation (radiation source) and provide safety measures to ensure that the radiation is not leaked;
7, for different products and Different irradiation purposes to choose and control the appropriate dose of irradiation, in order to obtain the best economic and social benefits.
8, irradiated food labeling to be marked.