Abstract: In this study,microwave-assisted steam distillation extraction technology was developed and optimized for the extraction of essential oil from Yongzhou Mentha haplocalyx and a formulation of air refreshing agent with mosquito repelling function was developed.Results showed that,(1) the optimal extraction process of essential oil from Yongzhou M.haplocalyx were solid/liquid ratio of 1:8,microwave time of 250 s,microwave power of 300 W,distillation time of 2-5 h,the maximum yield of essential oil were 3.3% under the optimized conditions.(2) A air freshener was developed based on essential oil extracted from Yongzhou M.haplocalyx and R.zingiberis which was another local dominant plant resource,the formula showed the best performance of air freshing when the essential oil ratio was 2:1 (mint:ginger) and the total volume fraction of essential oil was 6%.In addition,it had an efficient and lasting mosquito repelling effect.The results indicated that,a higher extraction rate of essential oil from Yongzhou M.haplocalyx can be obtained by microwave-assisted extraction and the development of multi-functional air freshener based on the plant essential oil was feasible and effective.The results of this study can provide some reference for the comprehensive utilization of local plant resources in Yongzhou of Hunan province.

Key words: Yongzhou Mentha haplocalyx, essential oil, microwave assisted, steam distillation, air freshener