Microwave-Assisted Extraction of Pumpkin Compounds

The extraction procedure was carried out following the conditions of previous papers [16 (link),17 (link)] with slight modifications. A dried pumpkin sample (1 g) was extracted with 20 mL of solvent (hexane:isopropanol, 60:40 v/v or hexane: acetone: ethanol, 50:25:25 v/v/v) for 15 min or 30 min at 45 °C using a closed vessel system microwave (Model Initiator 2.0, version 2.3, Biotage AB, Uppsala, Sweden) under controlled conditions. The temperature was the preferred controlled variable to avoid degradation of the target compounds and to achieve maximum efficiency. The other parameters were directly dependent on the temperature, such as the magnetron power (maximum 40 W) and pressure (maximum 5 bar). At the end of the treatment, the vessel used was cooled to room temperature. The extracts were filtered through a paper filter (MN 615, Macherey–Nagel, Düren, Germany), collected in amber glass vials, and kept at −20 °C until further analysis. The extraction was repeated three times.