Sustainable Recovery of Actinidin From Actinidia deliciosa Peel Using Biocompatible Cholinium-Based Ionic Liquids

Abstract

Food waste valorization has emerged as an important strategy to recover high-value biomolecules from underutilized agro-industrial waste. Among them, actinidin, the major protease of Actinidia deliciosa, has attracted considerable interest due to its broad proteolytic activity and potential applications in food processing, nutrition, and biotechnology. In this work, actinidin was extracted from kiwifruit peel using aqueous solutions of cholinium-based ionic liquids (ILs). An initial solvent screening identified cholinium bitartrate [N_111(2OH)][Bit] as the most effective extraction medium. Molecular docking studies revealed that the interactions between actinidin and IL ions depend strongly on ion identity, particularly the anion. Process optimization identified 500 mM [N_111(2OH)][Bit], a solid-to-liquid ratio of 1:10 w/w, 600 rpm, 45°C, and 30 min as the most favorable extraction conditions, yielding a proteolytic activity of 5.388 U L⁻¹, a protein concentration of 1115.3 mg L⁻¹, and a specific proteolytic activity of 0.00483 U mg⁻¹ protein. The process achieved a Path2Green score of 0.392, indicating moderate sustainability potential, and a process for IL recyclability was proposed. These results support the potential of aqueous cholinium-based ILs for the valorization of kiwifruit peel while defining solvent recovery, toxicological assessment, and technoeconomic evaluation as priorities for further process development.