Enrichment of antioxidant compounds from lemon balm (Melissa officinalis) by pressurized liquid extraction and enzyme-assisted extraction

Abstract

The search of new natural sources of bioactive compounds to be employed in the food industry is a hot topic in the field of functional foods. Besides, the use of environmentally respectful technologies focused on the extraction of bioactives from natural matrices is of great importance nowadays. Pressurized liquid extraction (PLE) is a novel extraction method that allows obtaining higher extraction efficiencies while minimizing both, the amount of solvents and the time. On the other hand, enzyme assisted extraction (EAE) can be seen as a way to further improve the extraction mass transfer kinetics when dealing with plant-based materials. In fact, the use of enzymes to break down cells walls might offer new possibilities because the potential bioactive compounds found in cells will be more available to the extraction solvent. In these work, the two extraction mechanisms are studied and tested for the extraction of natural antioxidant compounds from lemon balm (Melissa officinalis). Different PLE extraction conditions are tested using ethanol or water as extracting solvents. Besides, the use of different enzymes, namely cellulose, xylanase and pectinase, alone or in combination, is also studied. Best results in terms of total antioxidant activity and extraction yield were obtained when using PLE using water as extracting solvent at 150 °C. Besides, the obtained extracts were chemically characterized using an HPLC-DAD-MS method. Thanks to the combination of these techniques, several interesting phenolic compounds could be identified in the obtained extracts, among which rosmarinic acid is highlighted.