Fractionation of Squid Pens with Ionic Liquids-An Upgraded β-Chitin and Shellfish Protein Production.

This study investigates the utilization of squid pen waste through a biocompatible ionic liquid approach, focusing on choline acetate, [Ch][OAc]. This ionic liquid effectively extracts over 80 wt % of protein from squid pen waste. To optimize the extraction process, a factorial design of experiments was employed to achieve a protein recovery of 75% at an estimated purity of 86%, along with highly acetylated, crystalline β-chitin with a purity of up to 95%. The extracted protein was subsequently used to create biocomposite films from α- and β-chitosan, demonstrating impressive tensile strengths of 93.15 ± 7.9 and 83.5 ± 6.2 MPa, respectively, while maintaining hydrophilic properties (θ < 90°). Molecular dynamics simulations revealed that the anion [OAc] exhibits a stronger affinity for protein surfaces compared to other anions, while its combination with the cation [Ch] optimally facilitates protein recovery. A material mass balance indicated that from 1 kg of dry squid pen, 0.526 kg of protein and 0.34 kg of chitin were recovered. However, high solvent usage significantly impacts energy demands and CO emissions, generating approximately 4.27 kg of CO per kg of product, with 61% attributed to protein production. Technoeconomic analysis demonstrated that solvent costs account for nearly 65% of the minimum selling price of the protein, estimated at $9 kg, which decreases to $0.6 for each kilogram of coproduced β-chitin. Technoeconomic analysis showed that solvent costs comprise nearly 65% of the minimum selling price of the protein, which can reach $9 kg, but this price decreases to $0.6 for each kilogram of coproduced β-chitin. This research underscores the potential of squid pen waste as a valuable resource while highlighting the need for sustainable solvent management strategies.