ABSTRACT
Machine sources of ionizing energy for the irradiation of food include beams of energetic electrons and X rays (bremsstrahlung) generated when the electrons are intercepted with metallic targets. Electron energy requirements depend on the thickness and density of the products and cover a wide range from 0. 1 to 10 MeV. The lowest electron energies can be used for treating surfaces, fluids and granular materials while the highest energies can be used for fruits, vegetables and meats with thickness up to about 10 cm. X rays are capable of treating containers of such products which are more than 50 cm in thickness. Electron beam power requirements depend on the absorbed dose and the throughput rate of the treatment process and also cover a wide range from less than 10 to more than 200 kW. The dose for various applications can be as low as 0. 15 and as high as 30 kGy while the throughput rate can range from a few to hundreds of tonnes per hour. With such a variety of process specifications, the cost of irradiating food also varies substantially from one application to another. In this paper, estimates are given for the fixed and variable costs for typical applications. Fixed costs include capital amortization, utilities, maintenance and services for the facility (other than the irradiation equipment) and administration. Variable costs include utilities and maintenance for the irradiation equipment, labor and supervision for the treatment process, dosimetry, and consumable supplies. The total cost per unit of product decreases as the throughput rate increases because the fixed costs are then spread over a larger number of units.
