Feed gas effect on plasma inactivation mechanism of Salmonella Typhimurium in onion and quality assessment of the treated sample

A submerged dielectric barrier discharge (DBD) plasma reactor was used to inactivate artificially inoculated reference strains of Salmonella Typhimurium ATCC 14028 on sliced onion (3 cm × 3 cm). Salmonella Typhimurium reductions obtained after 10 min of treatment were 3.96 log CFU/slice and 1.64 log CFU/slice for clean dry air and N(2) feed gas, respectively. Variations observed in Optical Emission Spectra (OES) for different feed gases are responsible for the inactivation level variations of Salmonella Typhimurium. The physiochemical properties of the onion slices, such as quercetin content, ascorbic acid content and color parameters, were monitored before and after treatment and the changes that occurred were measured to be in the acceptable range. Quercetin content was reduced only 3.74–5.07% for 10 min treatment, higher reduction was obtained for the use of clean dry air than that of N(2) feed gas. Ascorbic acid loss was measured to be 11.82% and 7.98% for a 10 min treatment with clean dry air and N(2) feed gas, respectively. The color parameters did not show significant changes upon treatment (p > 0.05) of the same duration for the uses of different feed gases.