Inhibitory effects of atmospheric dielectric barrier discharge plasma against Bacillus cereus and Staphylococcus aureus on Gwamegi (semi-dried Cololabis saira)

Abstract

The current study was conducted to investigate the effects of atmospheric dielectric barrier discharge (DBD) plasma on the reduction of B. cereus and S. aureus, both potential hazardous bacteria on Gwamegi. DBD plasma devices (1.1kV, 43kHz, 5-60min, N2 : 1.5lpm for 5, 10, 20, 30 and 60min) were used to investigate the reduction effect. In the B. cereus by DBD plasma treatment, the 5-60min indicated a reduction of 0.2-1.2 log CFU/g. The reductions of S. aureus at the same duration time of DBD plasma were 0.1-1.1log CFU/g. The D-values for B. cereus and S. aureus were 49.0 (R2 =0.98) and 61.0 (R2 =0.94) min, respectively. The pH values for 0-30min (6.00-6.01) were not significantly different, but significant differences at 60min (6.09). There were no significant sensorial differences in colour (6.4-5.2) and flavour (6.2-5.3), but showing significant differences in appearance (6.6-5.2), texture (6.3-5.1) and overall acceptability (6.5-5.5). This study indicates that the 60min of DBD plasma treatment resulted in >1log CFU/g of B. cereus and S. aureus without concomitant adverse changes in pH and most sensory properties in semi-dried Gwamegi. This novel DBD plasma technology can be applied in semi-dried food production and distribution processes to enhance dried fishery food hygiene and safety.