Which of the following processes is used in food preservation in an industry?

The process used in food preservation in an industry is the irradiation of gamma rays. Gamma irradiation is a process that exposes food to a controlled amount of ionizing radiation to eliminate bacteria, fungi, and other microorganisms that cause food spoilage and foodborne illness. The gamma rays penetrate the food, disrupting the genetic material of microorganisms and rendering them unable to reproduce. This process does not make the food radioactive and does not significantly change the taste, texture, or nutritional value of the food. Therefore, the correct option is "Irradiation of gamma rays".