Deep eutectic solvents (DESs) with tunable hydrogen-bond network and solvation capacity and acid–base properties are a promising medium for selective fractionation of lignocellulose and valorization of lignin. However, efficient lignin removal and depolymerization, together with the cleavage of lignin–carbohydrate complexes (LCCs), remain critical challenges in DES-mediated lignin-first biorefining. Reactive lignin intermediates may become temporarily stabilized within the solvent environment and subsequently undergo recondensation. Recent developments in DES-assisted selective lignin fractionation, structural regulation, catalytic depolymerization and high-value utilization are critically summarized, and the relationship among molecular structures, the reaction microenvironment, conversion pathways and functional performance are emphasized. The impacts of DES composition, H-bond donors/acceptors, acidity/basicity and solvation parameters on lignin dissolution, LCC bond cleavage, and the stability of major linkages such as β-O-4 are highlighted, along with the intensifying effects of ultrasound and microwave fields. DESs are also regarded as multifunctional reaction platforms with capabilities for selective fractionation, in situ stabilization, and chemical functionalization. Bond cleavage, reactive-intermediate evolution, and radical regulation under thermal, photocatalytic, and electrocatalytic conditions are analyzed, along with strategies to suppress lignin recondensation and enhance aromatic monomer yields. High-value applications in nanomaterials, functional and stimuli-responsive materials, energy materials, and high-energy-density bio-oils are also reviewed. Finally, techno-economic analysis and life-cycle assessment are discussed to identify challenges in DES recovery, stability, mass transfer, energy consumption, and scale-up integration, providing guidance for rational DES design and sustainable lignin-first biorefining.

Growing demand for safe, sustainable, and minimally processed foods has increased interest in emerging non-thermal preservation technologies capable of reducing environmental impact while maintaining nutritional and sensory quality. Among these technologies, cold plasma-activated water (CPAW) has gained considerable attention as an eco-efficient and versatile processing medium for food applications. CPAW is generated through the dissolution of plasma-induced reactive oxygen and nitrogen species (RONS) in water, producing a chemically active solution with antimicrobial, oxidative, and enzyme-modulating properties. Depending on its reactive-species composition and storage conditions, CPAW may retain activity for delayed application, offering greater operational flexibility than direct plasma treatment. Building on established plasma–liquid applications in water purification, this review critically examines current knowledge on the generation of CPAW, its physicochemical characteristics, and mechanisms of action, with emphasis on its interactions with microorganisms, food macromolecules, and enzymes. It also covers recent advances in analytical characterization, application strategies, safety assessment, and sustainability considerations, discussing how plasma operating conditions, gas composition, and storage parameters shape CPAW stability and performance. The review highlights the limitations of treatment-time-based reporting and the need for standardized physicochemical dose descriptors to improve reproducibility and cross-study comparison. Although CPAW offers potential as a low-residue technology with promising sustainability advantages, challenges related to mechanistic understanding, scalability, process standardization, regulatory acceptance, and consumer acceptance remain significant barriers to industrial adoption. Addressing these limitations through interdisciplinary research and technological optimization will be necessary for the successful integration of CPAW into next-generation sustainable food-processing systems.