Effect of inkjet-printed flexible dielectric barrier discharge plasma on reduction of pathogen and quality changes on sliced cheese

Abstract

The objective of this study was to investigate pathogen reduction and quality changes in sliced cheddar cheese treated with inkjet-printed flexible dielectric barrier discharge (FXDBD) plasma. The samples were treated with plasma for 0, 5, 10, 15, and 20 min. The surviving populations of Escherichia coli O157:H7, Salmonella Typhimurium, and Listeria monocytogenes were significantly reduced by 2.65, 2.80, and 2.03 log CFU/g, respectively, after 20 min. The main reactive species that could be involved in bacterial inactivation were ozone (O-3) and nitrogen oxides (NOx), which were produced at concentrations of 298.19 and 28.08 ppm, respectively, after 20 min plasma treatment. The pH of the plasma-treated sample was lower than that in the control group (P < 0.05), whereas there was no significant difference among treatment times. With increasing plasma treatment time, the L* value decreased, while the b*, total color difference, and 2-thiobarbituric acid reactive substances values increased (P < 0.05) while the redness (a*) value remained unchanged. These results indicate that inkjet-printed FXDBD plasma can effectively inactivate pathogens in cheese; however, it causes an increase in lipid oxidation. Plasma treatment with newly developed inkjet-printed FXDBD showed improved microbiological safety with minimal effects to the physicochemical quality of cheese.