Inactivation of spoilage organisms on baby spinach leaves using high voltage atmospheric cold plasma (HVACP) and assessment of quality

Abstract

Cold plasma technology has previously shown potential as a novel, non-thermal technology for decontaminating foods and improving food safety. The study explores the potential of a nitrogen gas-based high voltage atmospheric cold plasma (HVACP) system to eliminate native microbiota from baby spinach leaves using a high purity (99.99%) nitrogen gas. The effect of HVACP was also evaluated over a storage period of 7 days at 4 °C. Up to 2.6 and 3.5 log10 CFU/sample of microbiota were eliminated until 7 days of refrigerated storage after 2.0 and 5.0 min (mins) of cold plasma exposure, respectively. 16 s rRNA sequencing revealed the presence of persistent Pseudomonas strains such as P. fluorescens, P. libanensis and Pseudomonas gessardii and elimination of other competitive microbial strains such as Bacillus spp., Exiguobacterium spp., and Pantoea spp. A five-minute, indirect, 80 kV HVACP treatment reduced 3.51 log10 CFU/sample after 7 days of refrigerated storage at 4 °C, compared to an untreated control with 7.50 log10 CFU/sample, without significantly affect the texture profile, color or moisture content of the leaves, serving as a promising non-destructive decontamination technology.