Inactivation of Salmonella on black peppercorns using an integrated ultraviolet-C and cold plasma intervention

A nonthermal process that applies ultraviolet (UV)-C and helium cold plasma (CP) simultaneously (UV-CP) has been investigated as an intervention technology to inactivate Salmonella on black peppercorns. The optimum CP treatment voltage and UV-CP treatment time for inactivating Salmonella on black peppercorns were predicted using a model equation as 9.7 kV and 22.1 min, respectively, which non-thermally inactivated Salmonella by 3.7 log CFU/g. UV-CP treatment yielded a stronger bactericidal activity than UV treatment alone, without inducing photoreactivation. In addition, UV-CP-induced reactive species were similar to those found in individual UV and CP treatments. Furthermore, UV-CP treatment caused a profound deformation of Salmonella morphology and a greater extent of DNA damage than UV or CP treatment did alone. UV-CP treatment did not alter the color or 2,2 '-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) radical scavenging activity; however, it lowered the 2,2-diphenyl-1-picrylhydrazyl radical scavenging activity and piperine concentration in the peppercorns. The findings of this study demonstrate the potential application of UV-CP treatment for decontamination of black peppercorns.