Combined antibacterial activity of green tea extract with atmospheric radio-frequency plasma against pathogens on fresh-cut dragon fruit
Authors: Narumol Matan and Kanockwan Puangjinda and Saifon Phothisuwan and Mudtorlep Nisoa
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.
