Low-Pressure and Atmospheric-Pressure Cold Plasma Treatment as a Pretreatment for Extracting Volatile Oils from Black Pepper (Piper nigrum) Seeds

Abstract

Volatile Oils (VOs) are essential contributors to the aroma and flavor of black pepper seeds, making their analysis crucial after sterilization processes. This study aimed to qualitatively and quantitatively analyze VOs in black pepper seeds that have been subjected to the following two modes of Cold Plasma (CP) treatments to evaluate its efficacy as a pretreatment for hydro distillation. CP generating setups, Low-Pressure Cold Plasma (LPCP) and Gliding Arc Plasma Discharge (GAPD) were used for the study. A commercially available black pepper (Piper nigrum)variety (MB12) underwent CP treatments with varying time durations (5, 10, and 15 minutes). The VOs were extracted using hydro-distillation and identified and quantified by GC-MS and GC-FID respectively. The study examined 12 major components of VOs, including α-pinene, β-caryophyllene, and D-limonene. Results revealed that LPCP at 5 minutes and GAPD at 10 minutes yielded the highest VO content, while prolonged treatment times led to decrease oil yields in both treatments. No significant differences were observed in individual VO components between the two CP treatments. The refractive index of VOs after LPCP and GAPD treatments did not significantly differ, affirming the GC-FID results. Importantly, the study concluded that both 5-minute treatment time of LPCP and10-minute treatment time of GAPD did not adversely affect the quality of VOs in black pepper seeds. The results of the study highlighted the necessity of insights into optimal processing conditions and highlighting the utility of LPCP and GAPDas pretreatments for VO extraction.

Keywords: black pepper seeds, volatile oils extraction, cold plasma, gliding arc plasma, low pressure plasma