Process development for the enrichment of curcuminoids in the extract of ionic type of NADES

Abstract Curcuminoids were successfully extracted from Curcuma zeodaria powder with Natural Deep Eutectic Solvents (NADES) as solvent. Ionic types of NADES such choline chloride-citric acid-water (CCCA-H2O = 1:1:18, mole ratio) and choline chloride-malic acid-water (CCMA-H2O = 1:1:18, mole ratio) gave the highest yield of extracted curcuminoids, ca. 0.270±0.025 and 0.355±0.055 mg/g respectively for CCCA and CCMA. However, the final product of the extracted curcuminoids was mixed in the NADES matrix. Hence, a separation process by means a solidification was mandatory. Isopropanol-n-hexane in both volume and molar ratio, i.e. 1:1, 1:1.5, 1:2, 2:1, and 2.5:1, were observed as a solvent in the solidification process as well as the solubility of curcuminoids in both isopropanol and n-hexane. Unfortunately, both of CCCA-H2O (1:1:18) or CCMA-H2O (1:1:18) and curcuminoids form a homogenous mixture with isopropanol. Therefore, all NADES constituents, i.e. choline chloride, citric acid/malic acid, and water, should be first removed before solidification process. Solubility of curcuminoids in isopropanol and n-hexane was, respectively, 3.2 mg/mL and 0.4 mg/mL at 40 °C. Isopropanol-hexane (1:1.5, v/v) give the highest recovery of curcuminoids, ca. 74.29%, by solidification process.