Food sterilization by ionizing radiation

Abstract

In addition to the usual methods for food preservation, the use of radiation is increasingly widespread. The beginnings of radiation use date from the end of the 19th century, but more intensive application is noticed only after the Second World War [1]. Most of the research was carried out to determine the stability and food safety. Compared to the thermal sterilization, the radiation technique was developed later, and found less or limited application in the conservation of foods [2]. It should be noted that electromagnetic radiation is used not only for the destruction of microorganisms, but also for:  destruction of insects,  culinary food processing (microwave ovens),  slowing down certain biochemical activities (preventing germination)  improving certain technological parameters of some foods (improving the rehydration of dried fruits and vegetables). The radiation of a short wavelength (approximately 30 nm) is characterized by high energy, so it has a pronounced mutagenic and lethal effect. This radiation acts in two ways, either directly with nucleic acids or by forming the very reactive radicals that can react easily with various organic compounds, making them unavailable to microorganisms. Free radicals are ionized molecules - most commonly water molecules. Besides electromagnetic radiation (X - rays, gamma rays and cosmic rays), alpha and beta - (corpuscular) radiation can also perform ionization of molecules. By using ionizing radiation, only a small part of the energy is transformed into heat. Compared to thermal sterilization, this amounts to less than 2%, i.e. the temperature of the food does not rise more than 2 ° C, which is why this treatment is called cold sterilization.