Inactivation of Human Norovirus GII.4 and Vibrio parahaemolyticus in the Sea Squirt (Halocynthia roretzi) by Floating Electrode-Dielectric Barrier Discharge Plasma

Human norovirus (HNoV) GII.4 and Vibrio parahaemolyticus may be found in sea squirts. Antimicrobial effects of floating electrode-dielectric barrier discharge (FE-DBD) plasma (5–75 min, N(2) 1.5 m/s, 1.1 kV, 43 kHz) treatment were examined. HNoV GII.4 decreased by 0.11–1.29 log copy/μL with increasing duration of treatment time, and further by 0.34 log copy/μL when propidium monoazide (PMA) treatment was added to distinguish infectious viruses. The decimal reduction time (D(1)) of non-PMA and PMA-treated HNoV GII.4 by first-order kinetics were 61.7 (R(2) = 0.97) and 58.8 (R(2) = 0.92) min, respectively. V. parahaemolyticus decreased by 0.16–1.5 log CFU/g as treatment duration increased. The D(1) for V. parahaemolyticus by first-order kinetics was 65.36 (R(2) = 0.90) min. Volatile basic nitrogen showed no significant difference from the control until 15 min of FE-DBD plasma treatment, increasing after 30 min. The pH did not differ significantly from the control by 45–60 min, and Hunter color in “L” (lightness), “a” (redness), and “b” (yellowness) values reduced significantly as treatment duration increased. Textures appeared to be individual differences but were not changed by treatment. Therefore, this study suggests that FE-DBD plasma has the potential to serve as a new antimicrobial to foster safer consumption of raw sea squirts.