Application of cold plasma on fresh cut carrots for the inactivation of Arcobacter spp., an emerging food-borne zoonotic pathogen

Cold plasma is a promising non-thermal technology that has the potential to inactivate microorganisms in food. In this study, the inactivation of two strains of Arcobacter butzleri (BZg74 and BZs206) artificially inoculated onto freshly cut carrots was investigated using two different configurations: Cold Atmospheric Plasma (CAP), Plasma Activated Water (PAW). Contamination levels of both the strains were significantly reduced. A. butzleri BZg74 showed a higher sensitivity, with a reduction of more than 2 log CFU/g after 20 min and values below the detection limit reached after 30 min of CAP treatment. On the other hand, a maximum reduction of 2 log CFU/g was achieved for the strain BZs206 after 30 min. As for the indigenous microbiota, CAP treatments resulted in a significant reduction of 1.5 log for mesophiles (20 min) and for Enterobacteriaceae (30 min). In contrast, washing with PAW led to an immediate (5 min) and significant effect of 1.3 log CFU/g reduction against the mesophilic population. In terms of product quality, the CAP treatment showed a stronger effect, reflected in a deterioration of colour, pH and dry matter with longer treatment times, while the PAW treatment allowed better preservation. The inactivation of peroxidase activity was strongly dependent on the type of configuration, confirming the complexity of the interaction of plasma reactive species with food matrices and the need for specific adaptation of processing parameters depending on the impact on the quality characteristics of the product.