# Novel Techniques for Microbiological Safety in Meat and Fish Industries
## 6 Non-Thermal Preservation Techniques
### Irradiation  
Irradiation involves applying low-level energy radiation to the material [78]. Irradiation is an electric energy emission to waves or ionizing moving particles if it has adequate energy to remove the electrons from the atom or molecule [79]. The USDA and FDA have approved food irradiation since 1989, and around 30% of countries around the world have adopted it as a commercial method of food preservation, followed by the United States, China, the Netherlands, Belgium, Brazil, Thailand, and Australia [80]. Under the new FSSAI regulations in 2016, the irradiation of foods is now called 'Radiation processing of food'. The benefits of this technology include the fact that it is a physical, cold, and non-additive process that results in minimal food changes. The ultrasound method is highly effective when compared to chemicals and fumigants and can be used on pre-packaged food. A rise in the occurrence of food-borne diseases, especially those of animal origin, has been observed in both developed and developing countries [81]. Gamma rays, X-rays and electron beams are radiation sources that can be used to irradiate foodstuffs [82]. Gamma rays, X-rays or electrons can lead to electrons being released from their orbits and producing ions. Free electrons collide to create a radical electron beam. The ionizing mechanism of radiation may disrupt the chemical bonds of DNA and other biomolecules and hence interrupt cell insect infestation. Radioisotopes of Cobalt-60 and Cesium-137 are permitted in foodstuffs for gamma radiation. Machines using the electricity to produce electrons beam up to 10 MeV [79]. X-rays with up to a 5 MeV energy level are allowed in foodstuffs; however, radiation from X-rays is expensive [78]. The wavelength of the X-ray is below 100 nm. It requires no radioactive source, has a high penetration rate and a high dosage reliability. X-rays have extremely short wavelengths from 8-12 m and a high frequency from 1016-1020 Hz [79]. The X-ray (high-energy particulate matter) produced by the radiation source machine has an energy level of 5 to 10 MeV, which can be used for food irradiation. X-rays can penetrate 30-40 cm into thick materials, with this property allowing them to be used in packed products [83]. One of the most serious issues is the microbiological safety of irradiated foods. The macronutrients are unaffected; however, certain vitamins may be affected. Irradiation doses should not exceed the recommended dose, which is 10 KGy [84]. Irradiation between 1-10 kGy is a documented method for lowering the microbial load in foodstuffs. _Salmonella_, Listeria, and other pathogenic bacteria can contaminate poultry, meat, and eggs. UV (ultraviolet) rays are a form of non-ionizing radiations that can be used to kill pathogenic microbes with a wavelength of 100-400 nm, which is shorter than the wavelength of visible light, 400-700 nm [85]. The irradiation of fresh meat and meat products is thought to be a healthy and reliable way to prolong their shelf life. The Food and Drug Administration (FDA) has approved the use of irradiation to contain food-borne pathogens and extend shelf life in poultry and red meat [81]. Irradiation is a successful preservation technology; however, its use in meat and meat products causes physicochemical and biochemical changes that affect nutritional and sensory properties. Radiation processing of muscle foods produces free radicals and accelerates lipid and protein oxidation, resulting in negative changes. Ionizing radiation produces free radicals, which promote lipid peroxidation and other changes while also influencing meat sensory quality [81]. Beef treated at a temperature of 20 \({}^{\circ}\)C with a 2 kGy dose of radiation with a modified air package did not lead to additional oxidation [86]. The factors influencing irradiation oxidation of meat products are mainly the composition, storage and packaging of fatty acids and the proportion of polyunsaturated fatty acids.