Food Irradiation

Irradiation of food refers to a food safety technology that protects food items from infestation by insects, bacteria and other microorganisms, through the method of controlled ionizing radiation, ultimately enhancing food safety and durability. The list of irradiated foods includes fruits, vegetables, meat, poultry and spices, among others. It delays the ripening of fruits, prevents sprouting in certain vegetables, sterilizes spices and herbs and reduces the growth of bacterial pathogens in meat and poultry - eliminating the risks associated with food borne illnesses, while preserving the freshness of food items. Irradiation of foods is a promising technology in that it retains the nutritional goodness of foods, while eliminating the harmful disease-bearing pathogens that can develop in various foods. The safety of the process lies in controlled doses of radiation by X-rays, gamma rays and accelerated electrons, so that there is no radioactive residue in the food items post-treatment, making it an effective method for de-contaminating food.


The methods of food irradiation

The approved sources for irradiation of food include gamma rays, X-rays and electron beams. The type of radiation used for irradiation of food is termed as“ ionizing radiation”, because the high energy sources of radiation convert the electrons of atoms and molecules into electrically charged ions. In the electron beam method, the electron accelerator sets in motion a stream of high energy electrons, to treat the food. There is no radioactive material involved in this method. The energy level of electrons produced is to be lower than 10 Mega electron volts. The streams of accelerated electron beams can gain access into foods till the thickness of three centimeters. Food irradiation by gamma rays uses the radionuclide cobalt-60, as a norm. In rare instances, the radionuclide cesium-137 is used. For food irradiation, the radionuclide is placed in a shielded chamber. The food to be processed is transported to the chamber and exposed to the radioactive rays from the radionuclide, for a specified period of time. The radiation doses for food irradiation are restricted to 10,000 Gray, in compliance with international policies for food safety, during the procedure of irradiation of foods. X-rays are lower in energy than gamma rays, typically restricted to 5000 Mega electron volts. For food irradiation, X-rays are generated from X-ray irradiation units that can be turned on, as per requirements. There are no radioactive materials involved in food irradiation by X-rays. X-rays are powerful enough to penetrate thick foods. The controlled radiation from these sources destroys the DNA structures of microbes, parasites, bacteria and other pathogens present in foods. The quantity and effectiveness of irradiation of food is dictated by the organism's sensitivity to irradiation, its ability to repair the damaged DNA and the amount of DNA present in the organism.


Above, irradiation using a radionuclide.

Purposes of food irradiation

The safety technology of irradiation of food is used to eliminate the disease bearing microorganisms in foods, effectively warding-off fatal diseases caused by the presence of pathogens such as salmonella, E.coli, and rendering foods safe and contaminant free. Food irradiation prevents food spoilage by rooting out parasites, insects and bacteria, sensitive to the processes of irradiation, through destruction of bonds in their DNA molecule, so that the microorganisms and insect pests are unable to thrive. By impairing the constitution of these microorganisms, food irradiation efficaciously preserves foods, preventing decomposition of food particles and extending their shelf life. Food irradiation has an edge over methods of preservation by canning in that the textures and flavors of foods are essentially unaltered. The natural compositions of the food items remain unchanged for no artificial ingredient, preservatives, additives, or pesticides are used in the process of food irradiation. This method can be used to preserve packaged and frozen foods. Food irradiation also delays ripening of fruits, and prevents sprouting of vegetables such as potatoes, thereby stalling food damages and promoting an extended shelf-life. The only drawback in the method of treatment of food by irradiation is the likelihood of re-growth of insects and pests on the food items in the absence of residues from treatment. The technology of irradiation of food is also used for sterilization of food items, adding to their longevity and making them more shelf-stable. Sterilized foods are used in medical facilities, for consumption by patients with extremely impaired immune systems, to rule out life-threatening infections. Sterilized foods are also used in space by astronauts and by military personnel in inhospitable regions. However, the foods treated for sterilization are exposed to higher doses of irradiation than the approved limits for standard food irradiation.

Impact of irradiation on food

The products that can be treated by food irradiation include fruits, vegetables, seasonings, spices, meat and poultry. Dairy products and eggs are excluded from the list of irradiated items because food irradiation has been observed to change the texture of these products. Food irradiation kills the microorganisms and insects found in food items by destroying the constitution of their DNA. Parasites and pests are easily destroyed with low doses of irradiation. However it is more difficult to kill the formidable bacteria, requiring more irradiation. Food irradiation does not kill viruses. The World Health Organization maintains food irradiation to be a safe technology for processing foods, stating that it does not significantly alter the nutritional contents of foods. The composition of food, with its vitamins and nutrients remains almost intact, with a slight reduction in vitamin B levels. However the change is minimal, precluding the possibilities of nutritional deficiencies. Chemical changes are not perceptible, and could be related to insignificant changes subsequent to the process of cooking or the more conventional preservation methods such as canning. Since food irradiation takes place under controlled levels, the food items remain raw, maintaining the texture and integrity of the food. Contrary to popular beliefs, food irradiation does not induce radioactivity in food, making it perfectly safe for edible purposes. Irradiated foods rule out the use of toxic chemicals, making them a sound choice. Irradiated foods eliminate the risks associated with food poisoning and food borne severe diseases.

Food irradiation: an underutilized tool

Despite being a potent weapon in the battles against food-borne illness and ensuring food safety, food irradiation has so far been an underutilized tool. The scientific community is unanimous about the beneficial impact of food irradiation in rooting out food-borne diseases and eliminating the risks associated with toxic chemicals used in alternative processing methods. However there are major obstacles ranging from consumer perceptions to industrial disinclination, retarding the growth in the markets for irradiated foods and hindering the popularity of this technology. A major roadblock for irradiation of food is the lack of sufficient irradiation facilities, which limits processing capacities. This significantly affects the supply of irradiated foods in the markets and the availability of “irradiated” brand of foods for consumers. There are also speculations and doubts among processors regarding consumer attitudes and preferences regarding irradiated foods. This makes the processors and industries engaged in food irradiation apprehensive about the demands for such food items. Market studies insinuate at the possibilities of a wider acceptance and a significant increase in demands for irradiated foods, with consumer education about the beneficial aspects and safety features of food irradiation technology. Knowledge about irradiated foods will guide the consumers to make an informed decision while purchasing foodstuffs. Also people are skeptical about the possible relationship between food irradiation and cancer, while others are worried about the vitamin depletion in irradiated foods. Industries are apprehensive that the expenses entailed in the food irradiation technology will reduce their profit margins.


Food irradiation has been authorized by 50 countries, with approvals granted to a range of food items including, meat, poultry, fruits, herbs and vegetables. Food irradiation could be an effective weapon in the battle against life-threatening, food-borne diseases. Food irradiation could assist us in bypassing the adverse effects of chemical pesticides on human health and the environment. However, irradiation of food is not a replacement for complete food safety in the production/distribution/consumption chain. Sanitation and hygiene is imperative at all stages of food handling to ensure safety. Knowledge about food irradiation could affect changes in consumer perceptions and preferences, which in turn, could create a boom in the markets for irradiated foods, reduce expenses on the manufacture of irradiated foods due to “economies of scale”, promote an increase in supply of such foodstuffs, and ultimately reduce microbial contamination and food-borne diseases.


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