Final answer:
Food irradiation involves exposing food to ionizing radiation, creating free radicals that destroy harmful organisms, and it does not cause the food to turn brown. While long-term effects are still being studied, there have been no observed short-term health risks associated with consuming irradiated foods, and the process is considered generally safe by health organizations.
Step-by-step explanation:
The process of food irradiation works through ionization, where the food is exposed to ionizing radiation. This radiation creates free radicals and radiolytic products that can break apart cell membranes and destroy harmful bacteria and insects present in food. The ionization mentioned in the student's question is not the cause for food turning brown, which is typically a result of enzymatic browning or non-enzymatic processes such as oxidation, not ionization.
Cobalt-60 and cesium-137 are common sources of radiation used for food irradiation. The food does not become radioactive itself because it does not directly contact the radioactive material. Despite concerns, the safety of irradiated food is generally endorsed by authoritative organizations, such as the World Health Organization, because it does not result in significant chemical alterations at low levels of radiation, and there have been no observable negative short-term effects on human health from consuming irradiated food. Nevertheless, long-term effects are still being studied.