Enhanced extraction of astaxanthin using aqueous biphasic systems composed of ionic liquids and potassiumphosphate

Shrimp waste containing a substantial amount of valuable nutrients presents a challenge for food industry. In this work, extraction of astaxanthin from shrimp waste via aqueous biphasic systems (ABS) composed of ionic liquids (ILs) and potassiumphosphate (K₃PO₄) was investigated. The influence of phosphonium- and ammonium-based ILs and temperature on the phase behavior and astaxanthin extraction was evaluated. The hydrogen-bond basicity of each IL studied shows a negative linear correlation with tie-line lengths of ABS and a positive linear correlation with extraction efficiency (EE_Ast). In general, lower temperature are favourable for astaxanthin extraction. Tributyloctylphosphonium bromide ([P₄₄₄₈]Br) resulted in the strongest ABS formation ability and bonding interactions between the anion and astaxanthin. Compared with organic solvents, [P₄₄₄₈]Br + K₃PO₄ ABS achieved higher EE_Ast of 93.08% at 308 K. The chemical properties provide the possibility of prescreening appropriate ILs for ABS formation and predicting the partition of a target molecule.