Optimization of Focused Ultrasound Extraction and Supercritical Fluid Extraction of Volatile Compounds and Antioxidants from Aromatic Plants

Abstract

In this work, we have accomplished the optimization of focused ultrasound extraction and supercritical fluid extraction (SFE) of volatile oils and phenolic compounds from aromatic plants such as rosemary, oregano, and chamomile. The response surface analysis was the overall procedure to tackle this work. On the one hand, the focused ultrasound extraction method of volatile compounds was studied based on the use of cyclohexane as extractant (chamomile required cyclohexane:isopropanol (95:5)), and three parameters were optimized (cycles, amplitude, and time) for each plant. The quantification of the volatile compounds was performed by means of GC × GC-MS analysis and the volatile oil concentration rounded 10–310 μg/g for the oregano; 7–2,920 μg/g for the rosemary, and 0.8–244.2 mg/g for the chamomile. In the SFE method, four parameters were studied (oven temperature, pressure, CO₂ flow, and EtOH %). The total polyphenol content was determined by Folin–Ciocalteu obtaining values from 1,000 to 12,000 mg gallic acid equivalent (GAE)/g plant. The antioxidant capacity was measured by Trolox equivalent antioxidant capacity obtaining values from 1.1 to 46.7 μmol Trolox equivalent/g plant.