Effect of Low-Pressure Cold Plasma Treatment on Microbiological and Physicochemical Properties of Black Peppercorns

Abstract

Spices contaminated with microorganisms can cause food spoilage and food borne diseases. Cold plasma is an emerging nonthermal sterilization method that can be used in place of wet or dry heat sterilization. This study was carried out to evaluate the efficacy of Low-Pressure Cold Plasma (LPCP) as a sterilization method and the potential changes in quality of black peppercorns after the treatment. LPCP (300 W, 30-liter, 0.3 mbar, 13.56 MHz) generated from oxygen fed at 2 cm3/s was used to treat commercially available peppercorns for 10 and 20 min at 150 and 250 W. Log reduction in Aerobic Plate Count and Yeasts & Moulds Count after treatment were 0.88 and 3.66, respectively. Water activity of peppercorn was significantly reduced due to treatment. The highest level of decontamination was observed at 250 W for 20 min; however, there was no change in the quality of volatile oils in black peppercorn. SEM images confirmed modifications of the surface of peppercorns and ATR-FTIR spectra confirmed there were no chemical changes in the functional groups on the surface of peppercorns with respect to piperine content. This study shows the potential in reducing natural fungal counts of black peppercorns using LPCP with minimum adverse effects to its quality.