Low-temperature argon plasma jet with cascading electrode technique for biological applications.

In this study, the design, performance, and characteristics of a low-temperature argon plasma jet with cascading electrode technique (APJCE) are presented. APJCE is designed based on a tip-ring structure with a cascading ring. The effect of plasma jet driven by repetitive high-voltage microsecond pulses in APJCE structure was measured qualitatively in local surface temperature detection system. Then, by applying the generated plasma jet to biological surface and measuring and characterizing the electrical parameters, we obtained a plasma jet, which is electrically and thermally in the cold plasma regime. Simulation of the electric field distribution in the nozzle also yielded similar results to the experimental results. Finally, by cascading electrodes, we guided the plasma column to the nozzle output so that the plasma temperature within four centimeters of the nozzle output is 37 °C. The resulting plasma jets were studied by atomic emission spectroscopy and the intensity of the spectral lines of the atmospheric argon plasma jet spectra was obtained as a final experimental result at the output.

Enhancement of polyphenolic content extraction rate with maximal antioxidant activity from green tea leaves by cold plasma.

A dielectric barrier discharge (DBD) atmospheric cold plasma was evaluated as a tool to increase the extraction rate of total phenolic content (TPC) and antioxidant activity from green tea leaves. The effects of nitrogen DBD cold plasma on changes of color and surface morphology were investigated. Optimum conditions of cold plasma treatment (treatment time and generation power) were obtained by response surface methodology. After the nitrogen DBD cold plasma at 15 W of the generation power for 15 min, the TPC and antioxidant activity of green tea increased by 41.14% and 41.06%, respectively. The catechin also increased by 103.12%. The scanning electron microscopy results showed cell ablation and ruptures of the green tea leaf surface after nitrogen DBD cold plasma treatment. PRACTICAL APPLICATION: The developed DBD cold plasma source fed by nitrogen gas can be a suitable procedure for green and useful extraction of phenolic compounds from natural sources in the food industries.