Effect of drying methods on the chemical composition and biological activity of parsley herb essential oil

Abstract

Background and Objective: This study was used to identify the effect of different drying methods on chemical composition and biochemical activities of parsley herb. The main objective was to study the benefits and harms of drying process for aromatic herbs that some factories perform to increase the yield of essential oil from each distillation batch. Materials and Methods: Fresh parsley herb was dried by one of two methods: an electric oven or a solar drying unit. The essential oil separated from dried herb was inspected for the changes that occurred in its chemical composition using by GC/MS technique. Moreover, the antioxidant and antimicrobial activities of parsley oil were determined using DPPH assay and the agar-well diffusion method, respectively. Results: The results indicated that, solar drying (sd) of parsley herb led to slight increment of oil yield, while oven drying (od) slightly decreased oil yield. The concentration of p-Mentha-1,3,8-triene (the major) was changed by decrease or increase after sd or od, respectively. The oil of sd had the highest antioxidants activity compared to that of od. The antimicrobial activity of parsley oil of od was significantly higher than that of sd. Conclusion: It is better to separate parsley oil by distillation from fresh herb without drying, which causes undesirable changes in the structure and properties of the oil.