Menthol-based deep eutectic solvent-water biphasic extraction of cinnamon bioactives for biodegradable active films used in shrimp preservation.

Conventional extraction methods for cinnamon bioactive compounds generally target either hydrophobic or hydrophilic components, limiting their integrated utilization. In this study, a menthol-based deep eutectic solvent (DES)-water biphasic system was developed for the simultaneous extraction, selective partitioning, and direct utilization of cinnamaldehyde (CA) and proanthocyanidins (PC) in biodegradable active packaging. The DL-menthol/hexanoic acid system (DES3-H₂O) achieved the highest CA extraction rate (52.57%) with a partition coefficient of 94.55 and a selectivity coefficient of 27,014.29, while the DL-menthol/acetic acid system (DES1-H₂O) exhibited the highest PC extraction rate (78.52%). Mechanistic analyses demonstrated that polarity differences, hydrogen-bond interactions, and micellar aggregation collectively governed the selective partitioning of CA and PC. The selectively recovered extracts retained excellent biological activity and were directly incorporated into chitosan/pullulan films, significantly improving moisture barrier performance, flexibility, UV-shielding ability, and biodegradability. The CA-rich upper-phase film exhibited the strongest antibacterial activity, with inhibition rates of 78.37% against Escherichia coli and 58.33% against Staphylococcus aureus, and extended the refrigerated shelf life of shrimp from 1 day to 4 days. Weighted K-nearest neighbor evaluation further identified the film incorporated with the cinnamon extract recovered from the DL-menthol/octanoic acid biphasic system (designated as DES4-H2O(T)-F) as the formulation closest to the ideal multifunctional packaging material. This work establishes an integrated strategy coupling selective extraction with direct fraction utilization, providing a sustainable approach for the high-value utilization of cinnamon bioactives and the development of multifunctional biodegradable food-packaging materials.