How do X-rays irradiate food?

• A. Energy comes from gamma rays emitted by a radioactive source.
• B. Energy comes from an electrical source that produces a beam of accelerated electrons that collide with a metallic target.
• C. Energy comes from sunlight passing through packaging.
• D. Energy is generated by the heat of the product.

Answer: (B)

X-ray irradiation relies on converting electrical energy into high-energy photons by accelerating electrons and smashing them into a heavy metal target. An electrical power source drives an electron beam in an accelerator; the electrons gain kinetic energy as they are accelerated and then strike a metallic target (like tungsten). The rapid deceleration of these electrons in the target produces X-ray photons (bremsstrahlung), which then pass through the food to deliver the irradiation dose. This explains why the energy source is electrical, producing a beam of accelerated electrons that collide with a metallic target, rather than using radioactive sources, sunlight, or heat.