Comparison Extraction Methods of Essential oils of Rosmarinus officinalis L. in Iran By Microwave Assisted Water Distillation; Water Distillation and Steam Distillation

Rosmarinus officinalis L. is a perennial herb that belongs to the Lamiaceae family. It is used as a food flavouring agent, and well known medicinally for its powerful antimutagenic, antibacterial and chemopreventive properties. The most applicable method for extraction of essential oil is water distillation (WD) and steam distillation (SD). It is a traditional technique which is used in most industrious companies. The essential oil from the leaves rosemary obtained by Microwave assisted water distillation (MAWD) on 440W, 770W and 1100W has been compared with those obtained by conventional WD and SD. The total yield of the volatile fractions obtained through WD was 1.30%, SD was 0.54% and MAWD in 440W was 0.45%, 770 W was 0.50% and 1100 W was 0.55%, respectively.Essential oils samples were analyzed by GC and GC-MS, the oils revealed the presence of 28 to 35 compounds in the essential oils obtained through HD, SD and MAWD, respectively. Main components in WD method were camphene 33.08%, γ-terpinene 8.62% and verbenene 8.57%, in SD were camphene 31.71%, WD, γ-terpinene 8.92%, and verbenene 8.74%, and by Microwave-assisted water-distillation (MAWD) on 440W were linalool acetate 28.67% cis-sabinene hydrate acetate 20.59% and terpin-4-ol 11.56%, on 770W were camphene 15.88%, γ-terpinene 14.61% and cis-sabinene hydrate acetate 10.28%, and on 1100W were camphene 28.22%, γ-terpinene 13.66% and β-pinene 8.42%, respectively.