Combined antibacterial activity of green tea extract with atmospheric radio-frequency plasma against pathogens on fresh-cut dragon fruit

- We use atmospheric plasma jet to enhance antibacterial activity of green tea extract.
- Plasma jet could increase the total phenolic content of fresh-cut dragon fruit.
- Green tea extract activated with plasma jet extends 3-fold shelf-life of fresh-cut fruit.

The objective of this research was to observe the combined effect of green tea extract (at a tea: water; g ml−1, ratio of 2.5-10.0%) and cold plasma (20 W and 40 W) against bacteria pathogens (Escherichia coli, Salmonella typhimurium, and Listeria monocytogenes) that can be found on the fresh-cut dragon fruit. The change in pathogens after plasma treatment of a fresh-cut dragon fruit treated with green tea at 4 ± 1 °C was also investigated. Dragon fruit's nutritional value, mineral, total phenolic content, and sensory within and without plasma and green tea was determined. It was found that atmospheric radio-frequency (RF) plasma at 40 W could extend the protection against all pathogen growth on the surface of fresh-cut dragon fruit treated with at a 5.0% of green tea to at least 15 days. Without the plasma treatment, green tea of 2.5-10.0% could not inhibit all bacterial growth. In addition, higher values of total phenolic content, crude protein, crude fat and crude fibre were observed in the fresh-cut dragon fruit with green tea after the plasma (p < 0.05) treatment; however, no change was found (p > 0.05) regarding the minerals Fe, Cu, and Mn and the sensory test. The research indicated that green tea extract and atmospheric RF plasma in combination could protect against the growth of pathogens on fresh-cut dragon fruit and extend its shelf-life.