Principle of food irradiation process

Generally, irradiation is the practice of exposing food a controlled amount of radiant energy to increase the safety of the food and to extend shelf life of the food. Treating food with ionizing radiation can kill bacteria and parasites that would otherwise cause foodborne disease.

It was first suggested in 1897, 1-year after Roe¨tgens discovered X-rays and it was patented in England in1905. From 1940 to 1960, research was conducted at the quartermaster laboratory of the US Army to provide sterilized cans to the US army.

In 1962, the first food irradiation facility was built for the army and the USDA issued the first food irradiation rules in 1963 to decontaminate wheat and wheat powder.

Sources of Ionizing irradiation are: Gamma rays, X-rays, Electrons (Radura). When radiation strikes other material, it transfers energy, it knocks electrons out of the material bombarded, breaking the molecular structure-thus leaving ions (free radicals) hence the name ionizing radiation. It kills microorganism by destruction of DNA and by creating toxic reactive compounds in a medium and in microbial cells. Irradiation kills bacteria, spores and insects as well as inactivates enzymes.

Advantages of irradiation:
*Less nutritional losses
*The chemical reactions associated with food irradiation do, in fact, produce very small amounts of new compounds called radiolysis products.
Principle of food irradiation process

Irradiation sterilization

Irradiation or ionizing radiation is a type of ‘cold’ sterilization, where the piece being sterilized is not exposed to heat. However, due to the poor heat transfer properties of many types of products, small increases in temperature above ambient can occur in the irradiated product.

Similar to sterilization by heat that requires high temperatures for specified times, sterilization of foods by irradiation requires high enough radiation doses to inactivate bacterial spores.

Radiation sterilization can be accomplished using one of three forms of radiation: gamma sterilization using radioisotopes, electron beam using electron accelerators, or beta radiation using an electron accelerator.

The irradiation sterilization process extends beyond treatment of health care products to commodities and irradiation of food to destroy pathogens such as salmonella and E. coli to make our food safer to eat.

Irradiation sterilization of foods, including meats and poultry, was extensively studied in the 1950s and 1960s, mostly by the US government. Irradiation sterilization effectively kills microorganisms because of its ability to break the chemical bonds of organic compounds, producing highly reactively species known as free radicals.
Irradiation sterilization