Irradiation to decontaminate herbs and spices 67
3.3 Application of ionizing radiation...................................................
Radiation processing involves controlled application of the energy of ionizing radiations
such as gamma rays, X-rays, and accelerated electrons to food commodities including
spices for achieving one of the following objectives:
∑ disinfestation
∑ shelf-life extension
∑ hygienization
∑ sterilization.
The technology holds considerable promise because in many cases it has an edge
over conventional methods. It could be applied judiciously where conventional methods
are inadequate, uneconomical, or pose potential health risks. It can also be used as a
complementary process with many new and emerging technologies. The process
helps in keeping the chemical burden on the commodities low and also increases the
packaging possibilities. These benefits accrue mainly from the cold nature of the
process and the high penetrating power of ionizing radiation. Being a cold process
the technology is particularly appropriate for spices that are valued for their delicate
aroma and flavor constituents.
Radiation technology offers several advantages for processing spices. These
advantages are listed below:
∑ It is a physical, non-additive process, causing minimal change in spices and
herbs.
∑ It is highly effective compared to chemicals and fumigants.
∑ It does not leave harmful residues.
∑ It can be applied to bulk as well as prepackaged commodities.
∑ It is a cold process and preserves spices in natural form.
∑ It does not destroy the heat-labile aroma and bioactive constituents of spices and
herbs.
∑ The process is safe to workers and friendly to the environment.
3.3.1 Ionizing radiations
Ionizing radiations are a part of the electromagnetic spectrum. They have relatively
short wavelengths and high energy. These radiations can eject electrons from an atom
of a molecule in food to form electrically charged species known as ions. The ejected
electrons cause further ionizations. Due to the short wavelength and high energy
associated with ionizing radiations, they are highly penetrating and effective. Therefore,
unlike other methods, foods for radiation processing can be pre-packed and treated to
get the desired effect.
In accordance with international regulations such as Codex General Standards for
Food Irradiation, the ionizing radiations that are permitted for irradiating foods are
limited to:
∑ Gamma rays from radioisotope cobalt-60 or cesium-137
∑ X-rays generated from machine sources operated at or below an energy level of
7.5 MeV
∑ Electrons generated from machine sources operated at or below energy level of
10 MeV.