Evaluation of ultraviolet light (UV), non-thermal atmospheric plasma (NTAP) and their combination for the control of foodborne pathogens in smoked salmon and their effect on quality attributes

The effectiveness of UV-C and Non-Thermal Atmospheric Plasma (NTAP) treatments, applied individually or in combination, for the inactivation of Listeria monocytogenes, Listeria innocua, Salmonella enterica serovar Typhimurium, Salmonella enterica serovar Enteritidis, Staphylococcus aureus, Escherichia coli O157:H7, Aeromonas hydrophila and Plesiomonas shigelloides on smoked salmon, compared to an abiotic surface (BHI agar), was evaluated. The impact of these technologies on the color, external appearance and degree of lipid oxidation of vacuum-packaged smoked salmon during refrigerated storage (4 +/- 1 degrees C) for up to 28 days was also determined. D values (mJ/cm(2)) required to reduce the microbial population in 1 log cycle ranged from 3.12 (S. Enteritidis) to 1.00mJ/cm(2) (P. shigelloides) and t(99%) values (time of exposure to NTAP needed to inactivate the 99% of the population) ranged between 2.48 (P. shigelloides) and 0.48 (L. innocua) min. Although all microorganisms exhibited a higher resistance to UV-C and NTAP treatments on smoked salmon, the application of a a 900 mJ/cm(2) UV-C or a 15 min NTAP treatment allowed the inactivation of - 0.5-1.3 log CFU units of the microbial population, with no significant changes in the sensory quality properties of the treated products. The sequential application of UV-C and NTAP resulted in an additive lethal effect, except in combined treatments involving high UV-C energies (500 mJ/cm(2)) and long ( >= 4 min) NTAP exposure times, which showed an antagonistic interaction. In addition, these latter combined treatments induced lipid oxidation and adverse changes in appearance. In conclusion, UV-C and NTAP can be considered as promising surface decontamination technologies against foodborne microorganisms of concern in fishery industries, especially for their application on abiotic materials. In addition, they cause minor effects on quality properties of smoked salmon, achieving log reductions ranging from 0.1 to 1.57 when applied in combination, what evidences their potential within hurdle technology approaches aimed at maintaining smoked salmon quality and safety.