Dielectric barrier discharge plasma for microbial decontamination of dried laver: effects on physicochemical characteristics

Dielectric barrier discharge (DBD) plasma in atmospheric pressure air was used for microbial decontamination of thin sheets of dried laver, which are commonly used in kimbab preparation. Microbial contaminants namely aerobic bacteria, moulds and marine bacteria were found in sun-dried laver sheets. DBD plasma was generated at an output voltage of 30 kV AC and a frequency of 30 kHz. Upon the plasma treatment of laver, 2.5-log (99.68%), nearly 1.5-log (96.84%) and above 1.0-log (90%) unit reductions in viable counts of aerobic bacteria, marine bacteria and moulds were observed over a 10-min period, respectively. The inactivation pattern fitted well to Singh-Heldman model or pseudo first-order kinetics. Compared to control laver, no significant (P > 0.05) changes in the colour characteristics, total phenolic content and 2,2-diphenyl-1-picrylhydrazyl radical scavenging activity were observed in plasma-treated laver. Furthermore, DBD plasma-treated laver sheets had exerted no negative impact on the sensory characteristics of kimbab and can extend the shelf life.