Evaluation of the storage and drying processes of Melissa officinalis L. leaves

Abstract

Melissa officinalis L. (Lamiaceae), medicinal plant used as sedative commercialized in natura and as dry plant in Brazil. The aim of this study was to determine the postharvest life and drying processes of Melissa leaves in function of essential oil contents. Leaves (10 g) were stored at room temperature (RT=19.6°C) and refrigeration temperature (10°C, AR), measured daily loss of fresh mass. In the evaluation, the drying processes used were microwave equipment (MW), thin-layer drying (TLD) and conventional oven (CO). The essential oil was obtained by the Clevenger apparatus. All treatments were done with four replicates and the data compared at 5% significance. The efficiency of the storage process was more effective in RT (A·=9.5222x2-51.271x+98.981; R2=0.99) with shelf-life of three days. AR had chilling causing a loss of essential oil and making commercialization impossible. The ideal wet mass was estimated to be between 2.70 and 2.83 g (ideal theoretical drying point) and the best dryings occurred in CO and TLD. The essential oil contents decreased in function of inadequate drying (MW), in relation to TLD and CO. The most suitable drying was in conventional oven (CO) and the major shelf-life time at room temperature (RT) and both processes had the best biomarker preservation. Key words: Postharvest, shelf-life, medicinal plant, drying process, quality control, bio-actives.