15-01-2013, 01:05 PM
Safety of Irradiated Food
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Abstract
Food irradiation is the processing of food products by ionising radiation in
order to control foodborne pathogens, reduce microbial load and insect
infestation, inhibit the germination of root crops, and extend the durable life
of perishable produce. The use of irradiation has been approved for about 50
different types of food and at least 33 countries are using the technology
commercially. Despite the fact that irradiation has been used for decades for
food disinfection that satisfies quarantine requirements in trade, health
concerns over the consumption of irradiated food continue to attract attention.
This study reviewed the basic principles, applications and the associated
potential health risk, if any, posed to consumers as a result of consumption of
irradiated food. Review of the available evidence showed that although
irradiation processing leads to chemical changes and nutrient losses, the safety
and nutrient quality of irradiated foods are comparable to foods that have been
treated with other conventional food processing methods such as heating,
pasteurisation and canning when the technology is used as recommended and
good manufacturing practices are followed.
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Risk Assessment Studies –
Irradiation Treatment of Foods
OBJECTIVES
This study aimed to provide an overview of the basic principles
of food irradiation technology and its application; and to have a review in the
safety of irradiated food.
INTRODUCTION
2. Food irradiation is the processing of food products by ionising
radiation in order to control foodborne pathogens, reduce microbial load and
insect infestation, inhibit the germination of root crops, and extend the durable life
of perishable produce.1
3. According to the International Atomic Energy Agency (IAEA),
more than 50 countries have approved the use of irradiation for about 50 different
types of food, and 33 are using the technology commercially [Annex I].2 The
positive list of irradiated products varies between countries but is often limited to
spices, herbs, seasonings, some fresh or dried fruits and vegetables, seafood, meat
and meat products, poultry and egg products. Despite the fact that irradiation has
been used for decades for food disinfection and satisfying quarantine requirements
in trade, there is considerable debate on the issue of health concerns over the
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consumption of irradiated food. These include concerns over the toxicity of the
chemicals generated and the change in nutritional quality of food products after
irradiation.
PRINCIPLES OF FOOD IRRADIATION
Ionising radiation and their sources
4. According to the Codex General Standard for Irradiated Foods,
ionising radiations recommended for use in food processing are: (I) gamma rays
produced from the radioisotopes cobalt-60 (60Co) and cesium-137 (137Cs), and (II)
machine sources generated electron beams (maximum level of 10 MeV) and X-ray
(maximum level of 5 MeV).3
(I) Gamma rays produced from radioisotopes cobalt-60 and cesium-137
5. Cobalt-60 is produced in a nuclear reactor via neutron
bombardment of highly refined cobalt-59 (59Co) pellets, while cesium-137 is
produced as a result of uranium fission. Both cobalt-60 and cesium-137 emit
highly penetrating gamma rays that can be used to treat food in bulk or in its final
packaging. Cobalt-60 is, at present, the radioisotope most extensively employed
for gamma irradiation of food.4
(II) Electron beams and X-ray generated from machine sources
6. A major advantage of machine-sourced ionising radiation is that
no radioactive substance is involved in the whole processing system. Powered
by electricity, electron-beam machines use linear accelerators to produce
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accelerating electron beams to near the speed of light. The high-energy electron
beams have limited penetration power and are suitable only for foods of relatively
shallow depth.4
7. Electron beams can be converted into various energies of X-rays
by the bombardment with a metallic target. Although X-rays have been shown to
be more penetrating than gamma rays from cobalt-60 and cesium-137,4 the
efficiency of conversion from electrons to X-rays is generally less than 10% and
this has hindered the use of machine sourced radiation so far.5