| Resumo: | Due to the great demand ofconsumers for an increasingly healthy diet, the food industry hás been interested in natural alternatives, namely from plant kingdom, in view of replacing artificial additives [1,2]. Thus, the development ofthese natural ingredients requires preliminary studies that evaluate the best extraction methodologies and conditions, in order to obtain the highest leveis ofthe target compounds [3,4]. The aim of this study was to optimize the extraction of rosmarinic acid from Melissa officinalis L. (lemon balm), comparing three dififerent techniques: maceration, microwave assisted extraction and ultrasonic assisted extraction. The response surface methodology was applied to obtain the conditions that maximize the extraction of rosmarinic acid, using a circumscribed central composite design with three variables and five leveis, being the relevant variables time, temperature or power, and ethanol concentration. The amount of rosmarinic acid (obtained by HPLC-DAD) and the extraction yield were used as responses. Ultrasonic extraction proved to be the most efficient technique, leading to 86 ± 4 mg ofrosmarinic acid/g ofplant (dryweight) under optimal extraction conditions: 33 ± 3 min, 372 ± 19W and40 ± 1% ethanol. The results obtained highlight that M. officinalis species is a source ofrosmarinic acid and reveal the best extraction conditions to obtain the highest leveis ofthis molecule, with great interest for the food industry.
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