Nowadays, using the chemical preservatives has become widespread in different food industries and there are few products produced without using the preservatives. So, preservatives play an important role in food industry and consequently on public health of the society. On the other hand, bad effects of chemical preservatives on consumer's health have become apparent. As a result, people have more tendencies towards using natural material. In recent years, numerous studies have been done in order to find a substitute for chemical preservatives. The best substitute for chemical preservative is natural preservative. Natural preservatives, not only don’t have a bad effect on consumers' health, but also, has a good effect on human health. In addition, they increase the nutrition value of the product. The most important natural resource for producing the preservatives is plant. Flavenoids are a group of material with phenol structure which is abundant in plants. Some of the combinations of this group have antioxidant and antimicrobial properties and even they are anticancer, antifungal and anti-inflammation and they can decrease the heart diseases. Using essential oils in foods have some problems problems which in action makes using them impossible. A number of theses problems are: sensitivity to light, oxygen and heat; insolvability in water, problems in storage and traortation and lack of appropriate distribution in the food. So, we should try to find a way for using these materials in the foods industry. Microencapsulation is a proper way to solve this problem. Microencapsulating the essential oils can result in protection to prevent bilateral environmental effect and not to lose them. During microencapsulation process, oil essence, as the core material are covered by the wall material as the protection. In this case, the materials are not exposed to the environment and environmental changes. Furthermore, during this process essences are converted to solid material and powder which doesn’t require special condition for storage. In addition, by using the soluable material in the water – as the wall – we can increase the ability of spread and solubility of the essential oil in the food environment. During microencapsulation process, the essence doesn't encounter major damage because of using low temperatures and short time. So, we hope that this method will help us to solve the problem and will make it possible to use the plant essential oils in the food. The purpose of this project is to determine the antioxidant and antimicrobial property of the oil essences during the microencapsulation process. In this project, at first we prepared the essential oils of two native plants of Iran, include lemon balm and ajotva seeds, by clevenger. Then, we studied the antioxidant and antimicrobial property of the essences. In the second phase, these essences were converted to microencapsulate material and the antioxidant and antimicrobial property of the capsules was studied to determine the effect of microencapsulation on protecting these properties. The results of this project showed that microencapsulation will increase the antioxidant and antimicrobial property of these two essential oils.