INNOVATIVE NON-THERMAL TECHNOLOGY TO IMPROVE SAFETY AND QUALITY IN READY-TO-EAT VEGETABLES

Chemical sanitizers are widely used for ready-to-eat vegetables (REVs) decontaminating in the food industry but can compromise quality, pose environmental and health risks. Cold plasma has emerged as a promising nonthermal alternative, generating reactive species (ROS and RNS) that effectively reduce microbial loads, while preserving nutritional and sensory qualities. This study evaluated the efficacy of cold plasma processes, specifically Plasma-Activated Water (PAW), as decontamination method for REVs, e.g. baby leaf lettuce and shredded carrots, at various treatment times in comparison with a conventional sanitizer (sodium hypochlorite). In baby leaf lettuce, PAW significantly reduced coliforms, total mesophilic and psychrotrophic bacteria and Pseudomonas spp., especially after 10 minutes of washing; reductions in spoilage Pseudomonas spp. and coliform populations were over 2 log CFU/g. Gas chromatography-mass spectrometry (GC/MS) analysis also revealed that PAW-treated lettuce presented higher levels of green aroma compounds (3,3,5-trimethylcyclohexyl acetate and cis-2-pentenol) and lower levels of aldehydes (hexanal, methyl butanal) than chlorine-washed samples, thus suggesting improved sensory attributes. Follow-up experiments tested PAW’s decontamination effect on shredded carrots deliberately contaminated with two strains of Escherichia coli, Salmonella Enteritidis, or Listeria monocytogenes. The results indicated 2-Log reductions for Escherichia coli and Salmonella Enteritidis (both strains), while Listeria monocytogenes was more resistant. PAW treatment likewise reduced the total spoilage microbial load on uninoculated carrots, including Enterobacteriaceae, mesophilic and psychrotrophic bacteria, Pseudomonas spp., lactobacilli, yeasts, and lactococci. Throughout the storage, the microbial load of total coliforms, lactobacilli and Pseudomonas spp. were below the 10^7 CFU/g threshold after 5 days. Physicochemical analyses showed that PAW slightly decreased pH with increasing treatment time and did not induce significant changes in lightness parameters throughout the storage period. Overall, PAW can potentially be an effective decontamination method in both matrices tested and improved sensory quality, providing a sustainable alternative to conventional chemical treatments.