Improving the Safety of Our Local Fruits and Vegetables by X-Ray Irradiation

Gamma irradiation is a “frightening” word for many consumers because of its association with radioactive materials. In spite of tremendous efforts made to educate the consumers about the safety of gamma irradiation technology for food protection, the lingering doubts and skepticism make it difficult to adopt this as an industry standard. For example, the U.S. Food and Drug Administration (FDA) approved the use of gamma irradiation (radionuclides Cobalt-60 or Cesium-137) in 1963; however, a recent survey has shown that consumers remain suspicious of gamma irradiation technology. People are more familiar with X-rays as thousands of X-ray machines are working in hospitals all over the world as diagnostic tools, and using same machine for food preservation may find ready acceptance. X-rays are different from gamma rays as no radioactive materials are involved. X-ray can be as effective as gamma rays. We believe that development of the X-ray system and educating the public could help ease public anxiety over the use of irradiation as an effective method for ensuring the safety of our fresh produce. Also, the increasing threat of microbial contamination of fruits and vegetables is forcing us as food scientists to carry out more studies on using X-rays for produce. In the last three years, we (at Mississippi State University) have been testing the capability of the RS 2400 X-ray machine (Rad Source Technology, Inc.) for elimination of the most food-associated outbreaks pathogenic bacteria in the U.S./worldwide such as Escherichia coli O157:H7, Listeria monocytogenes, Salmonella enterica, and Shigella  spp. in  different fresh produce including cantaloupes, green peppers, lettuce, mangoes, parsley, spinach, and  tomatoes. We were also examining the effect of X-ray treatments on the quality and shelf life of these produce. The 2400 X-ray machine showed high reduction (6–7 log reduction) of all tested pathogenic bacteria even at low doses. Moreover, treatment with X-ray did not alter the visual quality of the treated produce and extended the shelf life by more than 30 days at refrigerated temperature.