Irradiation as a method for decontaminating food. A review.
Despite substantial efforts in avoidance of contamination, an upward trend in the number of outbreaks of foodborne illnesses caused by nonsporeforming pathogenic bacteria are reported in many countries. Good hygienic practices can reduce the level of contamination but the most important pathogens cannot presently be eliminated from most farms nor is it possible to eliminate them by primary processing, particularly from those foods which are sold raw. Several decontamination methods exist but the most versatile treatment among them is the processing with ionizing radiation. Decontamination of food by ionizing radiation is a safe, efficient, environmentally clean and energy efficient process. Irradiation is particularly valuable as an endproduct decontamination procedure. Radiation treatment at doses of 2-7 kGy--depending on condition of irradiation and the food--can effectively eliminate potentially pathogenic nonsporeforming bacteria including both long-time recognized pathogens such as Salmonella and Staphylococcus aureus as well as emerging or "new" pathogens such as Campylobacter, Listeria monocytogenes or Escherichia coli O157:H7 from suspected food products without affecting sensory, nutritional and technical qualities. Candidates of radiation decontamination are mainly poultry and red meat, egg products, and fishery products. It is a unique feature of radiation decontamination that it can also be performed when the food is in a frozen state. With today's demand for high-quality convenience foods, irradiation in combination with other processes holds a promise for enhancing the safety of many minimally processed foods. Radiation decontamination of dry ingredients, herbs and enzyme preparations with doses of 3-10 kGy proved to be a viable alternative to fumigation with microbicidal gases. Radiation treatment at doses of 0.15-0.7 kGy under specific conditions appears to be feasible also for control of many foodborne parasites, thereby making infested foods safe for human consumption. Microorganisms surviving low- and medium-dose radiation treatment are more sensitive to environmental stresses or subsequent food processing treatments than the microflora of unirradiated products. Radiation treatment is an emerging technology in an increasing number of countries and more-and-more clearances on radiation decontaminated foods are issued or expected to be granted in the near future.