Extraction of anthocyanins from purple sweet potato using supercritical carbon dioxide and conventional approaches

This research investigates the potential of supercritical carbon dioxide (SCCO₂) technology as a green and sustainable approach to improve anthocyanin extraction from purple sweet potatoes (PSP). The study explored different extraction parameters (i.e., temperatures of 35–55 °C, cosolvent concentrations of 10–30 % (w/w), ethanol ratios of 30–70 % (v/v), pressures of 30–40 MPa, extraction times of 120–180 min, and solvent: sample ratios of 25:1–45:1(v/w)), to optimize the total phenolic content (TPC), anthocyanin content (ANC), and antioxidant activity (AA). Additionally, conventional extraction methods using different solvent (ethanol and methanol) mixtures, solvent: sample ratios (15:1; 45:1; 6:1 (v/w)), temperatures (35–50 °C), and extraction times (50–60 min) were performed for the extraction of phenolic compounds from PSP. The highest TPC (340 mg GAE/g dry PSP), ANC (136 mg C3G/100 g dry PSP), and AA (ABTS (7.3 mg TEV/g dry PSP), DPPH (18.2 mg TEV/g dry PSP), and FRAP (1399 mg GAE/100 g)) were achieved with 30 MPa, 35 °C and 20 % cosolvent concentration operated for 180 min. These findings underscore the use of SCCO₂ extraction to obtain anthocyanin extracts that can potentially be used as a coloring agent in the food industry. The proposed SCCO₂ extraction method provides an eco-friendly alternative to conventional methods for extracting phenolic compounds.