Effect of low-pressure air plasma on the microbial load and physicochemical characteristics of dried laver

Pradeep Puligundla, Je-Wook Kim, Chulkyoon Mok

Department of Food Science & Biotechnology, Gachon University, Seongnam 461-701, Republic of Korea.

Abstract

Low-pressure air plasma (LPAP) has not been widely used for food products surface bio-decontamination. In the present study, LPAP was used as inactivating agent against surface microbial contaminants of sun-dried laver sheets. Microbial inactivation kinetics and physicochemical characteristics of LPAP-exposed laver sheets were determined. Also, the sensory properties of kimbab (rice rolled in laver), which was roll wrapped using plasma-treated dried laver, were evaluated. LPAP was generated at the vacuum pressure of 133.3 Pa or 1Torr, and a power density of 54.1 mW/cm³. Upon LPAP-exposure, over 1-log reduction in viable cell count of aerobic bacteria was observed over a 20 min period. The microbial inactivation pattern fitted well to Singh-Heldman model or pseudo-first-order kinetics. Compared to plasma-unexposed laver, there were no changes in color characteristics, total phenolic content, and 2, 2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity of plasma-exposed laver. Furthermore, the use of LPAP-exposed laver sheets exerted minimal to no impact on sensory characteristics of kimbab.

Keywords: Low-pressure air plasma; Dried laver; Microbial inactivation; Kinetic modeling; Kimbab.