Qualitative changes of Blue eryngo (Eryngium planum L.) phytochemicals as affected by different drying methods

Eryngium planum L. known as Blue eryngo is used as fresh and dried ornamental plant along with medicinal applications. It is used in folk medicine in Europe as Eryngii plani herba and Eryngii plani radix. The purpose of this study was to investigate the effect of different natural (shade (SHD11Shade Drying) and sun (SD22Sun Drying) drying) and artificial drying methods (oven (OD33Oven Drying), vacuum oven (VOD44Vacuum-Oven Drying), infrared (ID55Infrared Drying), freeze (FD66Freeze Drying) and microwave (MD77Microwave Drying) drying) on the essential oil (EO) content and composition, total phenolic and flavonoid content and also antioxidant capacity (DPPH) of Blue eryngo. The energy consumption of drying in SHD, SD, FD, OD at 40, 50 and 60 ℃, VOD at 40, 50 and 60 ℃, ID at 125, 132 and 220W/cm2 and MD at 100, 200, 300, 400 and 500W were also calculated. The isolation of EOs was done by hydro-distillation method and their components were identified by gas chromatography (GC) and gas chromatography/mass spectrometry (GC-MS). The results disclosed that the highest (0.19g/100g D.M.) and lowest (0.08g/100g D.M.) essential oil content related to VOD at 60 ℃ and fresh plant, respectively. The highest (30.8%) and the lowest (14.7%) β-Elemene (as a main compound) was obtained by OD at 60 ℃ and SD, respectively. SHD needed the highest drying time (70.7h) whereas the lowest one (0.2h) related to MD at 500W. The highest (44.8kW.h) and the lowest (0.1kW.h) energy consumption were related to FD and MD at 500W, respectively. Different drying treatments showed different total phenolic and flavonoid content, and the highest total phenolic content related to ID at 220W/cm2 with 66.62mg GAE/g dry weight of extract. The OD at 50 ℃ showed the highest total flavonoid content with 6.5mg QE/g dry weight of extract and the highest antioxidant capacity related to OD 50 ℃ with IC50 192.66µg/ml. In conclusion, the best drying methods based on energy consumption, time of drying, EO content and composition for E. planum are MD 500W, OD 60 ℃ and VOD 50 and 60 ℃.