Gamma rays are used industrially to ensure standards of hygiene in the food we consume. Over 20,000 tonnes of produce get sterilized every year in France, either by gamma irradiation or accelerated electrons.
Such types of radiation are an ideal tool for the elimination of microorganisms, bacteria, fungi and parasites at low temperatures and high reliability.
During the process, it is the atoms and molecules that feel the effects of radiations. Unlike what would happen under a neutron irradiation, the atoms nuclei remain untouched. All effects also stop as soon as the irradiation is finished. No radioactive element is produced: from this point of view, the consumption of sterilized food products presents absolutely no danger.
The effects depend on the dose of irradiation (expressed in grays (Gy)). By moderating the dosage, it is possible to inhibit plant growth (40-100 Gy), sterilize insects (30-200 Gy) or kill them (1,000 to 3,000 Gy). Higher doses are needed to eliminate microbes (1,000 to 4,000 Gy) and pathogenic bacteria (1,000 to 6,000 Gy), or to achieve complete sterilisation (15,000 to 50,000 Gy).
Numerous countries authorise the sale of irradiated produce, whereas others remain firmly opposed, fearing the fallout the association of ‘nuclear’ with ‘food’ could have in the minds of the ill-informed.
In another domain, gamma rays can contribute to the visual appeal of fruit and vegetables by eradicating the flies which spoil harvests in sunless countries. Irradiating larvae induces sterility in the adult insects, which eliminates the need for harmful insecticides. The fact that the process is radioactive also poses no danger: the technique is clean and biologically safe.
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