Efficacy of Gliding Arc Plasma Discharge Remote Treatment on Microbial Decontamination of Black Pepper (<i>Piper nigrum</i>) Seeds

Cold plasma technology is experimentally investigated globally as a green approach to microbial decontamination. Gliding Arc Plasma Discharge is one cost-effective design among many cold plasma configurations. The present study aimed to investigate the efficacy of Gliding Arc Plasma Discharge treatment for decontaminating black pepper seeds. Samples of black pepper seeds were washed, dried, packed and drawn from a processing facility in Padukka, Sri Lanka, and selected for the study. The study isolated and genetically identified the microflora associated with black pepper seeds. Reductions occurring in the microflora after Gliding Arc Plasma Discharge treatment and respective changes in the black pepper seeds' physical, chemical, and structural parameters were studied. Three bacterial species, namely, <i>Bacillus safensis, Bacillus firmicutes, </i>and<i> Bacillus siamensis</i>, and seven fungal species, five of which were<i> Aspergillus spp., </i>one of<i> Talaromyces spp, </i>and<i> Cladosporium spp., </i>were isolated, and genetically identified. A few identified molds can cause the physical degradation of black pepper seeds. Results showed a reduction in aerobic bacteria by 51%, 69%, and 73%, and yeast and mold count by 58%, 92%, and 93% with Gliding Arc Plasma Discharge treatment time of 5,10, and 15 minutes respectively. When a known quantity of a reference strain, namely Bacillus cereus American Type Culture Collection 11778, was subjected to Gliding Arc Plasma Discharge treatment to analyze the performance of a single pathogenic microbe, a reduction of 99.9% was achieved after 15 minutes. Even though a significant decrease in moisture content and water activity levels was observed after Gliding Arc Plasma Discharge treatment, piperine content and volatile oils reduction were not significant at p<0.05 with treatment time. Scanning Electron Microscopic images showed surface changes in all treatments, while Attenuated Total Reflectance Fourier Transform Infrared spectra also confirmed chemical structural changes of piperine. The study concludes that Gliding Arc Plasma Discharge treatment is an effective method for decontaminating microbes present in black pepper seeds.