Preservation of food is a permanent defying target due to the continuous growth of
population, scarcity of soil, and health food safety aspects. Different processing technologies
are currently used to preserve food; irradiation processing based on the use
of ionizing radiation is used to extend the shelf life of the products, that is, stopping
the maturation process; decontamination, that is, lowering the presence of bacteria
and fungi; or sterilization of food products, that is, eliminating all the microorganisms.
This process is also called “cold pasteurization,” as it does not increase the
temperature of the irradiated products significantly. By using this technology, food components that are particularly sensitive to thermal treatments, like aromatic compounds
in medicinal or edible plants, could be decontaminated.
Currently, three types of ionizing radiation are authorized for food irradiation processing:
gamma radiation, electron beam (e-beam), and x-rays (E.U., 1999a). Gamma
radiation comes from the spontaneous emission of the isotopes of cobalt-60 (Co-60)
or Cs-137; e-beam radiation is produced by accelerating electrons till the energy of
10 MeV (mega electron volt); and x-rays are produced by the impact of accelerated
electrons on a metallic target, with the consequent emission of radiation (photons), by
a physical phenomenon described as “bremsstrahlung.” The three types of radiation
have different characteristics, namely the depth of penetration, but all can be used for
food processing using the right configuration adapted to the type or volume of food
to be processed. X-rays were the first ionizing radiation tested for food preservation;
however, due to the low efficiency of conversion of electrons energy to x-rays only
recently, with the development of new machines, this technique regained interest.
Recently, food irradiation has been pushed by phytosanitary trade barriers, to
eliminate the presence of insects, or due to health issues with contaminated food,
for example, Salmonella or Listeria, demanding new approaches to guarantee food
safety, without compromising the quality of the processed product (Cabo Verde et al.,
2010; Antonio et al., 2013).
Ionizing radiation processing is an alternative to chemical fumigation that is harmful
for the environment as well as the operators and leaves residues in the products.
This technology is also particularly important in the preservation of aromatic compounds
in edible and medicinal plants that are particularly sensitive to other decontamination
processes, for example, vapor steam sterilization, due to its thermal
sensitivity.
However, as in other food processing methods, irradiation may preserve some
components and degrade others. The balance of advantages and disadvantages, in
comparison to other preserving processes, should be used to select or not this type
of processing technology, to provide to the consumer a product that fulfills the best
criteria of quality and safety.
