Solvent and supercritical carbon dioxide extraction of color from eggplants: Characterization and food applications

Extractions of anthocyanins from peels of eggplant (Solanum melongena L.) using GRAS solvents and supercritical carbon dioxide (SC-CO2) were investigated. Conditions of solvent extraction that provided maximum yield of anthocyanin were water–ethanol (1:1, v/v) in 10% citric acid at 60 °C. The highest yield of the same by SC-CO2 was a sample size of 10 g of peels at 60 °C, 10 MPa, 1.5 h extracting time and 2 L min−1 of CO2. Delphinidin-3-glucoside and delphinidin-3-rutinoside were tentatively identified as the major anthocyanins in the extracts. The total phenolics, proanthocyanidin content and antioxidant activity of the solvent-extracted color were significantly higher than those in the SC-CO2 extracted color. Stability studies concluded that the former was more stable at high temperature regimes. Trace metal content in the SC-CO2 extracted color was significantly lower. Usage of the SC-CO2 extracted color in non-thermal food applications is recommended owing to its higher stability and low metal contamination.