Application of dielectric barrier discharge plasma for the reduction of non-pathogenic Escherichia coli and E. coli O157:H7 and the quality stability of fresh oysters (Crassostrea gigas)
Man-Seok Choi, Eun Bi Jeon, Ji Young Kim, Eun Ha Choi, Jun Sup Lim, Jinsung Choi, Shin Young Park
Abstract
This study focuses on the efficacy of dielectric barrier discharge (DBD) plasma treatment (1.1 kV, 3 mm distance, N2 1.5 L/min) as a non-thermal intervention to reduce non-pathogenic Escherichia coli and E. coli O157:H7 in oysters (Crassostrea gigas). Exposure times of 10–30 min by the plasma against non-pathogenic E. coli and E. coli O157:H7 resulted in a log reduction of 0.31–1.01 and 0.18–0.62, respectively, in fresh oysters. In particular, exposure to DBD plasma for 60 min indicated 2.14 log reduction (99.28% reduction) of non-pathogenic E. coli and 1.19 log reduction (93.54% reduction) of E. coli O157:H7. D1-values for non-pathogenic E. coli and E. coli O157:H7 were 27.78 min and 50.08 min, respectively (R2 ≥ 0.98 by using a first-order kinetic model). The glycogen content (1.10–1.20 g/100 g) and texture profile (hardness, springiness, cohesiveness, resilience) of samples treated with DBD plasma did not differ significantly from that of the control (p > 0.05). Therefore, exposing oysters to DBD plasma for at least 60 min could be useful for reducing >99% of non-pathogenic E. coli and 90% of E. coli O157:H7 without causing any deleterious changes to the glycogen content and overall texture of fresh oyster.