Effect of supercritical CO₂ extraction and the Soxhlet method on the content of curcuminoids, phenolic compounds, and antioxidant activity in Curcuma longa L

Turmeric roots from the tropical regions of Peru's Junín province were used. These roots are important in both gastronomy, due to their flavour and colour, and traditional medicine, due to their bioactive properties. This study involved a physicochemical analysis of fresh turmeric rhizomes to determine their degree of maturity. The study aimed to evaluate the effect of supercritical CO₂ (Sc-CO₂) pressure and temperature on the extraction of turmeric extract (TE), its curcuminoid content and its antioxidant activity. The rhizomes were prepared for extraction using both Sc-CO₂ and the Soxhlet method. The extracts were analysed by HPLC to quantify the curcuminoids, and by spectrophotometry to determine the total phenolic content (TPC) and the antioxidant activity (AA). Significant differences (p < 0.05) were observed in the extracts obtained with Sc-CO₂ at 50°C and 25 MPa, which exhibited higher levels of demethoxycurcumin (DMC), curcumin (CC) and total curcuminoids (TC). Soxhlet extraction resulted in higher curcuminoid yields. The TPC and AA (DPPH method) of the Sc-CO₂ extracts at 50°C and 25 MPa were higher than those of the Soxhlet extracts. These results highlight that supercritical CO₂ extraction is an environmentally friendly technology that prevents the degradation of curcuminoids, as demonstrated by higher DPPH free radical scavenging activity than that observed in Soxhlet extracts.