Introduction
Is food preservation through radioactive materials possible? How can this technology prolong the freshness of foods? Will there be a possibility that the irradiated food products be radioactive? What are advantages and disadvantages of this technology? Food irradiation technology is used to control spoilage and to eliminate disease-causing bacteria in foods. This process can also be compared to cold pasteurization or irradiation pasteurization. Irradiation and pasteurization differ only in the source of energy that kills pathogens in foods. Food irradiation uses ionizing radiation while a typical pasteurization relies on heat (“Food Irradiation,” n.d.). Food irradiation annihilates not only microorganisms, fungi, insects and other pests to inhibit the food spoilage, but it also hinders the untimely sprouting of potatoes and onions (Backgrounder, 2000).
Cobalt-60
Cobalt-60 is a typically used radioisotope in food irradiation. The non-radioactive cobalt is naturally present in various minerals and is commonly used in the production of blue-coloured ceramic and glasses. On the other hand, cobalt-60 is produced either in linear accelerators or as a by-product of structural material’s exposure to neutron radiation. It gives off intense gamma rays, a non-particle and highly ionizing radiation. The use of cobalt-60 has several advantages: 95% of its emitted energy can be directly utilized and deeply penetrated on the sample; results to even distribution of radiation on food products; decays to non-radioactive nickel; and poses low environmental risk. Thus, it has a lot of industrial applications such as in levelling devices and thickness gauges, radiotherapy, and sterilization of food products.
Principles of Food Irradiation
Bulk or packaged food passes through radiation stream in a chamber on a conveyor belt (“Food Irradiation,” n.d). Gamma rays emanated from cobalt-60 can kill bacteria and other pathogens but are not dangerous to the food products. After the food irradiation, the product is left free of radioactive substance (“Cobalt,” n.d.). The food is only exposed to decaying cobalt-60 which in turn transforms into a non-radioactive nickel (Roberts, 1998). Hence, no harmful waste is produced in the food irradiation plant.
When the biomolecules of microorganisms are subjected with gamma rays, their electrons cleave away from them which cause ionization or formation of positive net electrical charge. This will result to the disruption of molecular structure and functions of the biomolecules specifically the DNA molecules that control the synthesis of other biomolecules. With these, the pathogens are harmed and thus their growth and reproduction are hindered (“Backgrounder,” 2000).
In addition, the type of food determines its length of exposure to radiation. The amount of radiation in food is measured by dosimeters in the food containers. Electron beam and x-ray accelerators as gamma rays sources are also utilized in food irradiation (“Food Irradiation,” n.d.). The amount radiation in foods is expressed in kilogray unit (kGy) that is qualitatively described: (0-1 kGy) kills pests or prevents maturation of Trichinella; (1-10 kGy) kills food-poisoning bacteria; and (10 + kGy) sterilizes meat and other foods (“Facts About Food Irradiation,” 1999).
Technological Development and Feedback
In 1930, a French scientist patented irradiation while the United States has started research on this technology in 1940’s. The proponents of this technology stated some of its advantages as safe and more abundant food products that are free from disease-causing bacteria such as Salmonella, E. coli O157:H7, Campylobacter jejuni and Listeria monocytogenes; reduction of post-harvest losses due to spoilage and pestilence; and prolonging the shelf life of food (“Backgrounder,” 2000). Foods irradiation also provides an alternative way on the use of poisonous pesticides or fumigants in food processing. Hence, it improves the safety of foods for health-risks individuals such as diabetics, transplant and cancer patients, and HIV-AIDS patients. However, antagonists of this technology argued that food irradiation not only destroys nutritive value of foods, it also generates poisonous substances such as benzene and formaldehyde. In addition to this, this technology may pose a threat to both public and workers during the transport and actual use of the radioactive materials (“Backgrounder,” 2000).
Safety of Irradiated Foods
More than 40 years of scientific research showed that food irradiation is safe and does not alter the flavor, aroma, and texture of food products. For instance, the United States supported a research that fed 600, 000 pounds of irradiated poultry products to animals for a six-year period and found non-toxic effects. Another study was conducted on animals wherein they were given dry powder milk irradiated at four and a half time greater than the allowed level of radiation (45 kGy) but did not cause any tumor or mutation to its 9 consecutive generation. Moreover, there were no harmful effects observed on 400 Chinese volunteers who were fed 60% to 66% irradiated foods in their diets for over a 15-week period (Roberts, 1998).
Opponents of this technology stated that radiation produces toxic by-products in foods. The International Consultative Group on Food Irradiation (ICGFI) contradicted this hypothesis by declaring that those by-products are produced by heat processing and are naturally present in foods (Roberts, 1998). In fact, the United States Food and Drug Administration affirmed that more than 90% of these by-products are similar to those present in foods that were processed through conventional methods such as freezing, drying, or heating. The FDA Bureau of Foods Irradiated Food Committee (BFIFC) even added that foods irradiated at 1 kGy would not yield a significant amount of these compounds (Roberts, 1998).
Benefits of Irradiation
Food spoilage is ubiquitous in a lot of developing countries. This may result to food shortage and health problems. For farmers, food is a threat on their financial status for spoilage may cause a large reduction in their harvested agricultural products. More than 40 countries are now using this technology in preserving around 40 food product varieties (“Food and Agriculture,” n.d). In this case, food irradiation may benefit not only the consumers but most especially the agricultural sector. This technology can prolong the shelf-life of meat, poultry and seafood. For instance, strawberries may rotten in just a week but irradiation can maintain its freshness for about three weeks. More than this, by exposing grains and spices, fresh and dried fruits, legumes and condiments to radiation, insects and pests are eliminated, thus, replacing the poisonous chemical fumigants. For example, in order to meet the quality requirements of the US mainland, irradiation in Hawaii has replaced chemical fumigation or vapor heat processes in the treatment of fruits. However, the spores of toxins, viruses or bacteria can withstand irradiation. Hence, it is crucial to use this technology parallel with other standard manufacturing processes (“Food Irradiation: A Global Safety Tool,” 2002).
Conclusion
Food irradiation, through longitudinal studies, is proven to be safe in the preservation of different food products. This technology annihilates pathogens and pests but not the spores of the disease-causing microorganisms. Thus, it is recommended to use food irradiation in parallel with other standard manufacturing processes. It is foreseen that by using this technology, both consumers and farmers will be benefited.
References
Backgrounder. (2000). Food Marketing Institute. Retrieved October 23, 2008, from http://www.fmi.org/media/bg/foodirradiation.pdf
Cobalt. (n.d.). U.S. Environmental Protection Agency. Retrieved October 23, 2008, fromhttp://www.epa.gov/radiation/radionuclides/cobalt.html#discovered
Facts about Food Irradiation. (1999). International Consultative Group on Food Irradiation. Retrieved October 24, 2008, from http://www.iaea.org/nafa/d5/public/foodirradiation.pdf
Food and Agriculture. (n.d.). Nuclear Energy Institute. Retrieved October 24, 2008, from http://www.nei.org/howitworks/foodandagriculture/
Food Irradiation. (n.d.). U.S. Environmental Protection Agency. Retrieved October 23, 2008, from http://www.epa.gov/radiation/sources/food_irrad.html
Food Irradiation: A Global Food Safety Tool. (2002). International Food Information Council (IFIC) Foundation. Retrieved October 24, 2008, from http://www.ific.org/publications/brochures/irradiationbroch.cfm
Roberts, T. (1998). Cold Pasteurization of Foods by Irradiation. Retrieved October 23, 2008, from http://www.ext.vt.edu/pubs/foods/458-300/458-300.html
