Effectiveness of cholinium amino acid ionic liquids for the extraction of phytonutrients from palm oil

Abstract

Palm oil is the most widely consumed vegetable oil globally, owing to its high yield and cost-effectiveness. Beyond its primary use, palm oil is rich in valuable phytonutrients such as tocols (tocopherols and tocotrienols) and carotenoids, which hold significant economic value. Solvent extraction is a promising method to recover phytonutrients from palm oil; however, the use of flammable and toxic organic solvents raises concerns about environmental sustainability and infrastructure costs, necessitating the development of safer and more efficient solvent systems. This study investigates the potential of ionic liquids (ILs), specifically cholinium (CH) amino acid (AA) ILs ([CH][AA] ILs), as environmentally friendly and biocompatible solvents for extracting tocols and β-carotene from crude palm oil. Six [CH][AA] ILs, derived from alanine, serine, proline, glycine, leucine and lysine, were synthesized and evaluated for their extraction efficiency. Most of these ILs demonstrated significant efficacy in extracting tocotrienols and tocopherols, with the lysine-based IL showing the highest performance, extracting over 200 mg kg⁻ ¹. In terms of extraction efficiency, the ILs ranked as follows: lysine > proline > glycine > serine > leucine > methanol (not an IL) > alanine. Notably, none of the [CH][AA] ILs were able to extract β-carotene, highlighting their selectivity for tocols.