ABSTRACT
“Soft-electron”, new term we have created means an electron with an energy of 300 keV or lower. Soft-electrons with extremely small penetration capacity will open a door to novel sanitary and phytosanitary treatments for the first century of next millennium. Use of soft-electrons can supplement food irradiation technology developed and commercialized in the last decades of this century. Irradiation can decontaminate spices, herbs, dehydrated vegetables with little adverse effects on flavor and color, and blood plasma and whey protein with little functional change. Radiation treatment, however, still has a few drawbacks; degradation of starch and oxidation of lipids, so irradiation can not apply to decontamination of grains with high starch contents and seeds (e.g. soy bean and sesame) with high lipid contents. Irradiation adversely affects germination of seeds, as well.
Soft-electrons can eradicate microorganisms on the surface of dry food ingredients such as grains, dehydrated vegetables, spices, pulses and tea leaves with little quality deterioration. The penetration depths of the soft-electrons are too small to cause detrimental effects on the ingredients. Treatment of seeds with soft-electrons results in extremely low levels of microbial contamination and the same extents of germination and growth, as compared with untreated seeds. Soft-electrons at lower dose inactivate eggs, larvae, pupae and adults of insects such as red flour beetle and Indian meal moth. Adults of adzuki bean weevil do not emerge from the beans which have been infested with the eggs and exposed to soft-electrons, while a lot of adults emerge from untreated beans infested with the eggs. Soft-electrons can inhibit sprouting of potatoes.
The portion of grains exposed to electrons are removed as husk and bran by dehusking and/or milling. Potatoes are usually peeled and then used for processing or cooking. Therefore, chemical compounds formed in food by electron exposure are removed by dehusking, milling or peeling, and no such compound resides in the edible parts, which suggests the safety of foods treated with soft-electrons.
Electrons with such low energies do not require a thick shield due to their low penetration capacity, which enables in-line decontamination at food processing plants. The total cost for construction of a facility with an accelerator and a shield is less than US$ one million, much cheaper than ordinary irradiation facilities with gamma-rays or high-energy electrons. The costs of soft-electron treatment are estimated at US$50-200/ton and US$10/ton for decontamination and sprout inhibition, respectively.
