Enzymatic and Microwave Pretreatments and Supercritical CO(2) Extraction for Improving Extraction Efficiency and Quality of Origanum vulgare L. spp. hirtum Extracts

The goal of the study was to establish a procedure for improving the efficiency of supercritical carbon dioxide (scCO(2)) extraction of Origanum vulgare L. spp. hirtum (Greek oregano) and enhancing the quality of obtained extracts. Microwave and enzymatic pretreatments of the plant material were applied prior to the scCO(2) extraction. It was determined that the microwave pretreatment with irradiation power 360 W during 2 min accelerated the extraction of lipophilic compounds and provided a twofold higher extraction yield compared to the control. Moreover, this pretreatment also led to an increase in oxygenated monoterpenes content and the most dominant component carvacrol, as well as the extracts’ antioxidant activity. The enzymatic pretreatment caused a significant increase in the extraction yield and the attainment of the extract with the most potent antioxidant properties. Coupling the pretreatments with scCO(2) extraction improves the process of obtaining high value lipophilic products of oregano in terms of utilization of the plant material, acceleration of the extraction with the possibility to adjust its selectivity and quality of extracts, and enhancement of biological activity.