Background: Rosemary (Rosmarinus officinalis) is a plant belonging to the mint family that it's antimicrobial, anti-oxidant and anti-mutagenic features caused it to be extensively used in the medical, pharmaceutical and food industries.

Objective: In this study, the identification and determination constituents of the essential oil of rosemary and minimum inhibitory concentration of the rosemary essential oil and determine the efficacy of the microencapsulated in chitosan coating was investigated.

Methods: To extract the essential oil, water distillation method using clevenger was applied. After forming the oil, compounds were segregated using gas chromatography-mass spectrometry (GC-MS). The compounds were identified by Kovats index and retention time. In addition to do the encapsulation in chitosane coating emulsification method was applied. To determine the minimum inhibitory concentration of rosemary essential oil, agar dilution method has been applied.

Results: The results show that most compounds in rosemary essential oil obtained from the leaves and stem cultivated in the Shiraz and harvested in the month Khordad include: α-Pinene 12.3%, 1,8-Cineole 12.02% and Camphene 9.2%. Moreover the efficiency of oil extraction and encapsulation were 1.4 % and 39.33% respectively and also the minimum inhibitory concentration of rosemary oil against Staphylococcus aureus and Escherichia coli were 8.5 and 3.5 mg/mL.

Conclusion: Rosemary has antibacterial and antioxidant features due to existence of some compounds such as α-Pinene and linalool. On the other hand, the efficiency of oil extraction has raised because of the great amount of biologically active compounds and volatile oils.