Irradiated foods

The bactericidal effects of ionizing radiation have been known for a century, and for over 80 years it has been known that ionizing radiation kills the Ttichinella spiralis parasite, which infects raw pork. By the mid-1970s, international experts had concluded that irradiating foods preserves them without creating any toxicological hazards. Only in the last decade, however, has preservation by irradiation been applied commercially. 

Opposition to irradiated foods arises from two main concerns. In the process of killing microorganisms, irradiation might also destroy important nutrients such as vitamins. Secondly, irradiation produces ions and free radicals such as OH that may react with foodstuffs to generate harmful compounds such as... 

Karam, L.R and Simic, M.G. (1986). Methods for the identification of irradiated chicken meat. Presented at the WHO Working Group on Health Impact and Control of Irradiated Foods, Neuherberg, Germany, November. 

Unique radiolytical products (URP) in irradiated food are usually formed by the secondary reactions of water radicals, eh, H, and OH, and to a lesser extent by the direct action of radiation, especially for foods with considerable water content. Due... 

Denaturation of proteins by irradiation can occur in small amounts at moderate or high doses. Some reduction in the availability of certain amino acids (lysine, methionine, etc.) has been reported in the proteins of irradiated foods. However, these effects are rather small, even at high radiation doses. 

By wholesomeness is generally implied safe consumption. In this respect, irradiated foods have made great progress (vide supra). On the other hand in most countries there are additional demands on the color, texture and the like, of the... 

Some 40 countries have cleared irradiated foods of certain types for human consumption, or have given provisional clearance. Large scale ( 104 tons per year) irradiation of potatoes has been approved in Japan, and very large scale ( 105 tons per year) irradiation of grains has been reported from the former Soviet Union for insect control. However, it must be admitted that clearances with associated legal complications have come slowly in most countries, and even today there are ongoing debates regarding the ethics and economics of food irradiation. 

The National Centre for Food Safety Technology, is spearheading several packaging related efforts to expand the fist of polymers that can be used for packaging in food irradiation applications. This comprehensive article explains and describes the current situation in the field of irradiated foods and packaging and provides an update on impending approval for processed and red meats. The industry is concerned to uphold and maintain public confidence in the processed food and irradiated food supply. 

Detection of irradiated food containing bone - Method by ESR-spectroscopy... 

Detection of irradiated food from which silicate minerals can be isolated - Method by thermoluminescence... 

Detection of irradiated food containing fat - Gas chromatographic analysis of hydrocarbons... 

The radioisotope cobalt-60, with a half-life of 5.27 years (1925.3 days) through beta ((3) emission, decays to form the stable element nickel-60. It is used to test welds and metal casts for flaws, to irradiate food crops to prolong freshness, as a portable source of ionizing gamma (Y) radiation, for radiation research, and for a medical source of radiation to treat cancers and other diseases. 

In the field of muscle foods, the use of marination before irradiation reduced the dose necessary to eliminate Salmonella in poultry [113]. Some antimicrobial additives, especially the natural ones (e.g., bacteriocins) [94] and GRAS (generally recognized as safe) preservatives [114] can be usefully combined with irradiation to reduce dose requirements. Some antioxidants have also been used to prevent the undesirable oxidative effects in irradiated foods. 

Wholesomeness (toxicological innocuity, nutritional adequacy, and microbiological safety) of irradiated food has been carefully evaluated by an unprecedented width of research and testing over more than 50 years. All scientifically acceptable evidence resulted from these studies supports the safety of irradiated foods for consumption [14,118-121]. 

At low and medium doses, it is well established that the nutritional value of proteins, carbohydrates, and fats as macronutrients are not significantly impaired by irradiation, and neither the mineral bioavailability is impacted. Like all other energy depositing process, the application of ionizing radiation treatment can reduce the levels of certain sensitive vitamins. Nutrient loss can be minimized by irradiating food in a cold or frozen state and under reduced levels of oxygen. Thiamin and ascorbic acid are the most radiation sensitive, water-soluble vitamins, whereas the most sensitive, fat-soluble vitamin is vitamin E. In chilled pork cuts at the 3 kGy maximum at 0-10°C, one may expect about 35 0% loss of thiamin in frozen, uncooked pork meat irradiated at a 7 kGy maximum at —20°C approx., 35 % loss of it can be expected [122]. 

Working on the subject between 1986 and 1998, the EU Scientific Committee of Food (SCF), an independent expert body advising the European Commission on health matters, concluded that the food irradiation process posed no problem for health over a wide ranged of uses, if used under prescribed conditions and endorsed for authorization of 17 irradiated foods/food classes [129]. The Commission proposal in December 1998 for an EU directive contained eight food categories and three products. 

Regarding packaging materials for irradiated foods, most commonly used food packaging material are suitable for the purpose. However, irradiation of prepackaged food requires approval of its packaging material [132]. 

FOOD IRRADIATION PROCESS CONTROL AND DETECTION OF IRRADIATED FOODS... 

Significant progress has been made in the field of analytical detection of irradiated food to improve consumers confidence and to assist international trade of irradiated food [135,136]. Due to national and international programs and activities of the European Committee for Standardization (CEN), five validated and standardized detection methods are now available. The CEN is also considering the adoption of further five detection methods three will be screening methods (positive results from a screening method must be confirmed using a standardized method) [136]. 

Codex General Standardfor Irradiated Foods and Recommended International Code of Practice for the Operation of Radiation Facilities Used for the Treatment of Food, CAC/Vol. XV-Ed. 1, Food and Agriculture Organization of the United Nations Rome, 1984. 

Loaharanu, P. Trends on the Use of Irradiation as a Sanitary and Phytosanitary Treatment for Food and Agricultural Commodities. Paper presented at ICGFI Workshop on Trade Opportunities for Irradiated Food, Kona, Hawaii, 22-24 May 2000. 

Wholesomeness of Irradiated Food, Report of a Joint FAO/IAEA/WFIO Expert Committee, WFIO Technical Report Series 659, World Health Organization, Geneva, 1981. 

---