Environmentally friendly solvents: the strategic and frontier fields of natural product extraction

Driven by global sustainability and circular economy initiatives, conventional extraction techniques reliant on volatile organic solvents and strong alkalis, which lead toenergy-intensive, environmentally detrimental, and subject to stringent regulatory scrutiny, making them ill-suited for contemporary industrial demands. In response, environmentally friendly solvents (EFSs), such as deep eutectic solvents, supercritical fluid, and ionic liquids, characterized by low toxicity, biodegradability, and renewability, have emerged as pivotal enablers of sustainable and efficient extraction processes. However, the wide diversity of EFSs give rise to a persistent "solvent selection dilemma." Meanwhile, current research lacked a comprehensive framework that integrates solvent design, process compatibility, and scalability, thereby failing to provide systematic guidance. To bridge this gap, this study presents a systematic review of advances in EFS research over the past decade. Through a comprehensive analysis of relevant literature, it outlines the classification, intrinsic properties, and molecular interaction mechanisms of EFSs. The review synthesizes their applications and compatibility principles in the extraction of key bioactive components, including polyphenols, carotenoids, and polysaccharides, and critically assesses core technical challenges such as the trade-off between extraction efficiency and environmental impact, cost management, and solvent recyclability, along with their underlying causes. By moving beyond solvent-specific descriptions toward multicriteria decision-making and closed-loop process design, this review provides a science-based route for selecting, optimizing, and industrializing sustainable extraction systems for food and natural-product applications.