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The effect of the pre-growth temperature of bacterial cultures on their subsequent survival kinetics in fresh-cut produce during refrigerated storage was investigated in this study. Three-strain cocktails of Listeria monocytogenes and Salmonella enterica, cultured at different growth temperatures (4, 21, and 37 °C) were inoculated on fresh-cut mixed salad and on individual produce in the mixed salad. The inoculated samples were stored at 4 °C and 80 ± 2% relative humidity (RH) for up to 72 h and the growth, survival, or death kinetics were determined at regular intervals. The results indicate that depending upon the type of pathogen tested, the pre-growth temperature(s) and the type of produce showed a significant (p ≤ 0.05) effect on the survival kinetics. Among the tested produce, mixed salad showed the highest reduction in L. monocytogenes pre-grown at 37 °C (1.33 log CFU/g) followed by red cabbage (0.56 log CFU/g), iceberg lettuce (0.52 log CFU/g), and carrot (−0.62 log CFU/g), after 72 h, respectively. In the case of Salmonella, carrot showed the highest reduction (1.07 log CFU/g for 37 °C pre-grown culture) followed by mixed salad (0.78 log CFU/g for 37 °C pre-grown culture), cabbage (0.76 log CFU/g for 21 °C pre-grown culture), and lettuce (0.65 log CFU/g for 4 °C pre-grown culture), respectively. Among the tested ComBase predictive models, the Baranyi–Roberts model better fitted the experimental data. These findings indicate that the appropriate selection of pre-growth environmental conditions is critical to better understand the kinetics of foodborne pathogens.

Fresh and fresh-cut fruits and vegetables have been associated in several foodborne illness outbreaks. Although investigations from those outbreaks reported that the contamination with pathogenic microorganisms may occur at any point in the farm to fork continuum, effective control strategies are still being widely investigated. In that direction, the concept of hurdle technology involving a sequence of different interventions have been widely explored. Among those interventions, ultraviolet (UV) light alone or in combination with other treatments such as use of organic acids or sanitizer solutions, has found to be a promising approach to maintain the microbiological safety and quality of fresh and fresh-cut produce. Recent advances in using UV as a part of hurdle technology on the safety of fresh produce at different stages are presented here. Furthermore, this review discusses the mechanism of UV induced antimicrobial activity, factors that influence antimicrobial efficacy and its effect on produce. In addition, the challenges, and prospects of using UV irradiation as an intervention treatment were also discussed.

The purpose of this study was to determine the effect of sanitizer use conditions on the susceptibility, biofilm forming ability and pathogenicity of Listeria monocytogenes. Two different strains of L. monocytogenes and a non-pathogenic L. innocua were exposed to sodium hypochlorite, benzalkonium chloride and peroxyacetic acid at different concentrations (4 to 512 ppm) and treatment times (30 s to 5 min), respectively. Under the tested conditions, no significant difference (p > 0.05) in reduction was observed among the three tested sanitizers. A reduction of 1 to 8 log CFU/mL was observed depending upon the sanitizer concentration and treatment times. The survived cells at the highest sublethal concentration and treatment time of a particular sanitizer upon re-exposure to the same or different sanitizer showed either no change or increased susceptibility when compared to parent strains. Upon repeated exposure to sanitizers at progressively increasing concentrations from 1 to 128 ppm, L. innocua was able to survive concentrations of up to 32 ppm benzalkonium chloride and 64 ppm peroxyacetic acid treatments, respectively. At the tested sub-lethal concentrations, no significant difference (p > 0.05) in biofilm formation was observed among the tested strains. Caco-2 interaction with L. innocua showed a reduction in invasion ability with sublethal concentrations of sanitizers.

Foodborne pathogens such as Salmonella, E. coli O157:H7, and Listeria monocytogenes are known to survive under different environmental stresses with an effect on their physiological properties. The purpose of this study was to determine the effect of different environmental stresses on the foodborne pathogens response to subsequent chemical treatments. Three types of pathogens Salmonella, E. coli O157:H7, and Listeria monocytogenes were subjected to different environmental stresses: (i) Desiccation (ii) high salt (iii) low pH, and (iv) temperatures (14, 23, and 37 °C) during their growth. The cells harvested at their early stationary growth phase were subsequently subjected to chlorine (100 or 200 ppm), peracetic acid (40 or 80 ppm), and 0.5% lactic acid treatments. The results showed that pre-growth stress conditions have significant effect on the reduction of tested pathogens depending upon the type of chemical treatment. Salmonella showed the highest sensitivity against all these treatments when compared to E. coli O157:H7 and Listeria monocytogenes. In addition, Listeria monocytogenes showed the highest percentage of sub-lethally injured cells. These findings highlighted the need to consider pre-growth conditions as an important factor for the validation of physical and chemical intervention treatments.