Advanced Oxidation Technology with Photohydroionization as a Surface Treatment for ControllingListeria monocytogeneson Stainless Steel Surfaces and Ready-to-Eat Cheese and Turkey

Abstract

Listeria monocytogenes is difficult to control in food and processing environments due to its widespread nature and ability to survive in a range of adverse conditions, including low temperatures, pH, and high salt concentrations. The objective of this study was to evaluate the efficacy of Photohydroionization™ (PHI; RGF Environmental Group, Inc., Riviera, Beach, FL), a novel advanced oxidation technology, as a surface treatment to control L. monocytogenes on food-contact surfaces, sliced American cheese, and ready-to-eat (RTE) turkey. A five-strain cocktail of L. monocytogenes was used to inoculate sample surfaces. Food-contact surfaces were exposed to ultraviolet and other oxidative gases produced by the PHI system for 10, 20, 30, 45, 60, and 120 s and 5, 10, and 15 min; cheese and turkey samples were treated for 30, 60, and 120 s and 5 min. For each matrix at each time point, seven samples were treated and enumerated by plating appropriate dilutions onto modified oxford medium and thin-agar-layer modified oxford medium. Results showed reductions (p<0.05) in L. monocytogenes: 4.37 log colony-forming units (CFU)/coupon on stainless steel after 15-min treatment. A 1.39 and 1.63 log CFU/sample after 120 s and 2.16 and 2.52 log CFU/sample after 5 min were seen on American cheese and ready-to-eat turkey, respectively. Lipid oxidation analyses performed on cheese and turkey samples indicated that PHI treatment did not affect (p>0.05) thiobarbituric acid-reactive substances values. This study demonstrates the efficacy of PHI treatment to reduce L. monocytogenes on stainless steel and RTE foods and may serve as a processing intervention to ensure safe production of food.

The effectiveness of radiant catalytic ionization in inactivation ofListeria monocytogenesplanktonic and biofilm cells from food and food contact surfaces as a method of food preservation

“…Our previous study (Skowron et al 2018) confirmed the effectiveness of RCI towards many microbial species, including L. monocytogenes, applied in planktonic form on abiotic surfaces. The effectiveness of photo-oxidation towards L. monocytogenes on the steel surface was also shown by Saini et al (2014) (4Á37 log CFU/coupon on stainless steel after 15-min treatment).…”

“…The effectiveness of photo‐oxidation towards L. monocytogenes on the steel surface was also shown by Saini et al . () (4·37 log CFU/coupon on stainless steel after 15‐min treatment).…”

“…Saini et al . () showed the effectiveness of photo‐oxidation towards L. monocytogenes applied on food fragments. They showed reductions in L. monocytogenes : 1·39 and 1·63 log CFU/sample after 120 s and 2·16 and 2·52 log CFU/sample after 5 min were seen on American cheese and ready‐to‐eat turkey respectively.…”

“…The differences are most probably due to the completely different properties of food products, which allow the penetration of bacteria suspended in aqueous solution into the raw material, and thus the protection against bactericidal ions generated during radial catalytic ionization. Saini et al (2014) showed the effectiveness of photo-oxidation towards L. monocytogenes applied on food fragments. They showed reductions in L. monocytogenes: 1Á39 and 1Á63 log CFU/sample after 120 s and 2Á16 and 2Á52 log CFU/sample after 5 min were seen on American cheese and readyto-eat turkey respectively.…”

Using UVC Light-Emitting Diodes at Wavelengths of 266 to 279 Nanometers To Inactivate Foodborne Pathogens and Pasteurize Sliced Cheese

“…In a pulsed UV system in which 3,800 V of input was used to generate 1.27 J/cm 2 per pulse for a lamp with a frequency of three pulses per s, L. monocytogenes inoculated onto unpackaged white American cheese slices (9 by 9 cm) was reduced by 1.1-to 3.08-log CFU/cm 2 at distances of 13 and 8 cm at intervals from 5 to 40 s (17). Another promising disinfection method of cheese, photohydroionization technology, consisting of a combination effect of plasmas, 16.65- mJ/cm 2 UV lamp irradiation, ozone, and hydrogen peroxide, decontaminated L. monocytogenes on sliced American cheese by slightly Ͼ2-log CFU/sample after 5 min of treatment (18). As shown by these earlier studies, UVC is obviously an effective sterilization technology available to the food industry and potentially useful for pasteurizing cheese using UV-LEDs as a highly competitive and promising novel intervention.…”