Utilization of pulsed UV light for inactivation of Salmonella Enteritidis on shelled walnuts

Due to their nutritional value, walnut consumption has been increasing worldwide, however outbreaks caused by walnuts are still of concern. Current chemical methods in walnut industry to prevent pathogenic microorganisms are not preferred by the consumer while thermal treatments may cause undesired flavor. UV light is the portion of the electromagnetic spectrum with wavelengths of 100–400 nm. UV light in the 100–280 nm range has germicidal capabilities. Walnut halves and pieces were inoculated with Salmonella Enteritidis and treated in a pulsed UV light system chamber at three different distances for varying treatment times. Maximum log reduction of 3.18 CFU/g was obtained after pulsed UV treatment at 8 cm for 45 s. Measurement of energy levels revealed an increase in energy and temperature with longer treatment time and shorter distance from the strobe to the sample. Furthermore, quality parameters were assessed to determine the influence of pulsed UV light treatment on the quality of walnuts. The quality results showed no significant differences between control and pulsed UV treated samples. Overall, this study demonstrated that pulsed UV light technology is a promising method to decontaminate walnuts without using any chemicals, which will open doors for the food industry.