Microbial decontamination of dried laver using corona discharge plasma jet (CDPJ)

In the present study, atmospheric pressure corona discharge plasma jet (CDPJ) was used for surface microbial decontamination of thin sheets of dried laver, which is commonly used in ready-to-eat Korean rice roll, gimbap (kimbab). Microbial contaminants namely aerobic bacteria, molds, and marine bacteria were found on the surface of commercial dried laver sheets. CDPJ was generated at an output voltage of 20 kV DC and frequency of 58 kHz. Upon exposure to the CDPJ, greater than 2 log (99%) unit reductions in viable cell count of aerobic bacteria was observed over a 20 min period. The inactivation pattern fitted well to Singh-Heldman model or pseudo-first order kinetics. Compared to plasma-unexposed laver, no changes in color characteristics, total phenolic content and DPPH radical scavenging activity were observed in plasma-exposed laver. Furthermore, CDPJ-exposed laver sheets had exerted minimal to no impact on sensory characteristics of gimbap (kimbab), while extending the shelf life of the product. In conclusion, CDPJ can be used for surface decontamination of dried laver without adversely affecting its physical as well as functional properties.