Nowadays, the use of natural preservatives, such as essential oils, has atracted increasing attentions. Among the essential oils, Shirazi thyme and Trachysper ammi with phenolic compounds have antimicrobial and antioxidant properties. While natural essences are a complex mixture of several substances that are very sensitive to light, oxygen, humidity and high temperatures, and are not water-soluble. Therefore, it is necessary to protect them for their utilization. Encapsulation technology with nanometric size has been remarkably developed for the design and formulation of food products to increase stabilization, solubilization and delivery of bioactive components. Among the various nanostructures, nanofibers with diameter smaller than 100 nm have been shown to possess excellent mechanical, thermal and electronic properties. Electrospinning is the simplest method for producing nanofibers. Recently, nuzzle-less electrospinning device has been introduced as a noveltechnology, with the aim of producing nanofibers in large scale. In this study, nanofibers were prepared by solution of gelatin/chitosan in ratios of 1:6, 1:8 and 1:10 and essence concentrations of 20 and 40%. Solution properties (viscosity and electrical conductivity) were measured and process parameters (voltage, disk-collector distance and rotation speed) were optimized as 25 kV, 5 cm and 20 rpm. Results showed that encapsulation efficiency values were more than 92% and loading capacity enhanced with increasing essence concentration. Diameter and morphology were measured by scanning electron microscopy (SEM). To investigate chemical structure and functional groups of applied and produced materials, Fourier transform infrared (FT-IR) was used and data approved that not any chemical reaction was accoured between ingredients during electrospinning. In order to study the thermal profile, differential scanning calorimetry (DSC) was applied and it was showed that thermal stability of the essential oils enhanced by encapsulation. Antioxidant properties of the free and encapsulated essential oils were compared with the DPPH method during the 18-day period. The results demonstrated that at the beginning the free essential oils had higher antioxidant activity, while at the end of period, due to protection of phenolic compounds against unfavorable condtions, the encapsulated essential oils has power against oxidation. Antimicrobial activity of different concentrations of free and encapsulated thyme essential oil were investigated against inoculated 10 5 colonies of clostridium perfringens for 17 days. The results proved destruction of the colonies after 48 hr. Finally, nanofiber containing essential oil of thyme were used to reduce nitrite in 50% meat samples of sausages and their microbial properties, moisture content, pH, color, texture and sensory properties were evaluated. The results showed that the encapsulated essential oil of thyme had no significantly differences antimicrobial activiety against clostridium perfringens , color and sensory properties with 120 ppm nitrite containing sample. Therefore, nanofiber containing essential oil could be a suitable substitute for nitrite consumption for meat products. Key Words : Ammi essential oil, Antimicrobial, Thyme essential oil, Clostridium perfringens , Disk nuzzle-les electrospinning, Sausage.