First recognized in 1895, X-ray irradiation soon became a breakthrough diagnostic tool for the dental and medical professions. However, the food industry remained slow to adopt X-ray irradiation as a means for controlling insects and microbial contaminants in food, instead using gamma and electron beam (E-beam) irradiation. However, the reinvention of X-ray machines with increased efficiency, combined with recent developments in legislation and engineering, is now allowing X-ray to actively compete with gamma irradiation and E-beam as a microbial reduction strategy for foods. This review summarizes the historical developments of X-rays and discusses the key technological advances over the past two decades that now have led to the development of several different X-ray irradiators capable of enhancing the safety and shelf life of many heat-sensitive products, including lettuce, spinach, tomatoes, and raw almonds, all of which have been linked to high profile outbreaks of foodborne illness.
Low-energy X-ray irradiation was assessed as a means of eliminating Escherichia coli O157:H7 on lettuce. Round-cut iceberg lettuce samples (2.54-cm diameter) were dip or spot inoculated with a three-strain cocktail of E. coli O157:H7, stored for 24 h at 4 degrees C, and then irradiated at four dose levels up to 0.25 kGy using a prototype low-energy (70 kV) X-ray irradiator. E. coli O157:H7 survivors were quantified by plating on sorbitol MacConkey agar containing cefixime and tellurite. Dip inoculation yielded a D(10)-value of 0.040 +/- 0.001 kGy, which is 3.4 times lower than a previously reported value of 0.136 kGy using gamma radiation. The D(10)-value for E. coli O157:H7 on spot-inoculated samples was 0.078 +/- 0.008 kGy, which is about twice that of dip-inoculated samples. When 10 stacked leaves were irradiated from both sides, a dose of 0.2 kGy was achieved at the center of the stack with a surface dose of 1 kGy, corresponding to a approximately 5-log reduction of E. coli O157:H7 at the center of the stack. Based on these findings, low-energy X-ray irradiation appears to be a promising microbial inactivation strategy for leafy greens and potentially for other types of fresh produce.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.