Cold atmospheric pressure plasma decontamination of allspice berries and effect on qualitative characteristics

Abstract

The effect of low-temperature plasma generated at atmospheric pressure was studied in term of reduction of bacterial contamination and influence on nutritional characteristics of allspice (Pimenta dioica). The low-temperature plasma was generated in ambient air using Diffuse Coplanar Surface Barrier Discharge (DCSBD). The bacterial species inoculated on the surface of samples were reduced in dependence on exposure time. Plasma treatment time of 240 s led to log10 CFU/g of Salmonella Enteritidis to below detection level (1.0 log10 CFU/g) from initial population of 7.64 log10 CFU/g. After treatment with DCSBD plasma for 300 s, the populations of Bacillus subtilis and Bacillus subtilis endospores were decreased by 2.85 log10 CFU/g and 1.70 log10 CFU/g, respectively. The parameters related to the decontamination effect were measured. Temperature of samples does not exceed the value declared as low-temperature limit and water activity decreased after plasma treatment. The effect of plasma on the qualitative properties of allspice studied by infrared spectroscopy showed no changes in characteristic chemical bonds on the surface and also inside the samples. Measurements of polyphenolics content in allspice showed that plasma has negligible impact on these main constituents affecting taste and flavor. The experiments demonstrated an efficient reduction in microbial contamination and minimal influence on the aroma profile of treated and stored spice.