Application of water-assited ultraviolet light processing on the inactivation of Salmonella on fresh produce
Date
2017
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
University of Delaware
Abstract
Fresh fruits and vegetables such as strawberries, tomatoes and lettuce have become a primary cause of foodborne illness outbreaks. One of the major pathogens lead to outbreaks associated with fresh produce is Salmonella. The low decontamination efficacy and harmful by-products caused by various sanitizers arise the concern about using chemical sanitizers. In this study, a non-thermal water-assisted UV processing was developed and evaluated its effect on the inactivation of Salmonella in wash water on fresh produce. The effect of wash water quality on the decontamination effect of water-assisted UV processing was also evaluated. Water-assisted UV treatments with intensity ≥ 2mW/cm2 and treatment time ≥ 45s achieved higher Salmonella inactivation in tap water than the 10 ppm chlorine treatment. Increasing UV intensity or treatment time could significantly increase the Salmonella log reduction. Higher Salmonella decontamination effect was achieved on blueberries and tomatoes than on other fresh produce. 10min water-assisted UV treatments with intensity of 29mW/cm2 reduced Salmonella spot-inoculated on blueberries and tomatoes by 4.54 and 5.06 log CFU/g, while only 2.4, 3.2 and 2.91 log CFU/g reductions were achieved on strawberries, spinach and lettuce, respectively. Increasing the organic load and turbidity in wash water did not significantly change the efficacy of water-assisted UV treatment on the inactivation of Salmonella on fresh produce (P>0.05). When compared the water-assisted UV treatment (samples immersed in agitated water during the UV treatment) with Dry UV (UV treated directly) or Wet UV (samples were immersed into water and get out quickly, then treated by UV directly with small water droplets on the sample surface) treatment, water-assisted UV treatment achieved higher decontamination effect than dry and wet UV treatments for Salmonella spot-inoculated on fresh produce. 1.32, 1.23 and 2.79 log reductions of Salmonella spot-inoculated on lettuce were achieved by dry, wet and water-assisted UV treatments, respectively. 10ppm free chlorine and 1%H2O2 were combined with water-assisted UV treatment. However, no significant improvement in Salmonella inactivation was found (P>0.05). Based on this study’s findings, the water-assisted UV system developed could be a good choice for decontamination of fresh produce.
Description
Keywords
Fresh produce, Salmonella, Ultraviolet light, Water-assisted