Pressurized Deep Eutectic Solvent Extraction of Peptides and Amino Acids from Periplaneta americana: A New Separation Strategy for Phase-Switchable System

Periplaneta americana (American cockroach) is a traditional medicinal insect rich in bioactive peptides and amino acids, yet its efficient and green extraction remains challenging due to its complex matrix and the thermolabile nature of its active components. This study developed a novel pressurized deep eutectic solvent (DES) extraction method using a “sandwich” system with a phase-switchable feature for the efficient enrichment of total amino acids and peptides from P. americana. A choline chloride-phenylacetic acid (ChCl-PA, 1:2 molar ratio) DES was selected for its suitable melting point (~25 °C), strong intermolecular interactions with the targets, and ease of recovery via phase switching. The extraction was performed in a stainless-steel mold under mild conditions under 8 MPa for 2 h without extra liquid organic solvents. Key parameters including solid-to-solid ratio, pressure, temperature, and time were systematically optimized, achieving a maximum total yield of 120.2 mg/g, higher than conventional stirring, ultrasound-assisted, microwave-assisted, or ethanol reflux extraction. The kinetic study showed that the extraction process of the experimental method could be better described by the pseudo-second-order kinetic model (R2 = 0.9791). The fitting trend of the experimental data generally conformed to the mass transfer behavior similar to chemical adsorption. Theoretically, it is speculated that potential intermolecular interactions including electrostatic attraction, π-π stacking and ion exchange may occur between DES and target components. The DES could be efficiently recovered (>86% recovery) and reused for at least four cycles with acceptable performance. Scanning electron microscopy confirmed pronounced structural disruption of insect powders after extraction, facilitating target release. Greenness assessment using ComplexGAPI and AGREE tools validated the method’s environmental friendliness, with minimal solvent consumption, low energy input, and reduced hazardous waste. Overall, this pressurized DES strategy provides a simple, economical and sustainable laboratory-scale alternative for the extraction of thermosensitive bioactive components from soft biomaterials. It has certain reference significance in laboratory-scale analysis pretreatment and future amplification research in natural product research.