The purpose of food irradiation is to improve the quality of the food being irradiated, either from a microbiological, physical, or organoleptic perspective. Very low doses (< 1 kGy) are used to prevent sprouting in potatoes or delay the ripening of fruits. These doses can also be used to disinfect foods by killing insects in grains and fruits or inactivating parasites (trichinae) in meat. Slightly higher doses (1–5 kGy) can be used to pasteurize foods. Radiation pasteurization, or radurization, significantly reduces or eliminates bacteria of public health significance in the food while also decreasing the total number of bacteria in the food. As with pasteurization by heating, this reduction in the total number of bacteria in a food also results in an increase in the shelf life of the food. Finally, very high doses, on the order of 25 kGy or greater, can be used to sterilize foods. In practice, most of the current interest and research has focused on the low doses commonly used in pasteurization.

One of the main interests in food irradiation is that it can be used as a "cold" pasteurization technique. Many food-borne disease bacteria, including Salmonella, Escherichia coli O157:H7, and Listeria monocytogenes, are very sensitive to irradiation. Although there are some variations in sensitivity among the previously listed bacteria, a dose range of 1.5–3.0 kGy is sufficient to eliminate all these bacteria as they naturally occur in foods.

An advantage of irradiation is that it can penetrate packaging material. Foods can be prepackaged and then irradiated, eliminating the potential for contamination during packaging. In addition, irradiation can be used as a replacement for many food additives that are used to inhibit bacterial growth. Irradiation can also be used as a quarantine treatment for imported fruits and vegetables, which eliminates the need for the use of toxic fumigants.