Fabrication of cellulose nanofibers from Rosa roxburghii pomace via ultrasonic-assisted extraction

To promote the valorization of Rosa roxburghii pomace (RRP), a typical lignocellulosic agricultural waste, lignin-containing cellulose nanofibers (LCNFs) were fabricated via an eco-friendly ultrasonic-assisted deep eutectic solvent (DES) strategy. Choline chloride-formic acid (ChCl-FA) was selected as the optimal DES, and extraction parameters were optimized using single-factor experiments and Box–Behnken response surface methodology. Under the optimal conditions (9 mL/g liquid-to-solid ratio, 42°C, 35% DES water content, the cellulose retention rate reached 91.87 ± 0.14%, with efficient hemicellulose removal. Comparative analysis verified that ultrasonic-assisted ChCl-FA treatment improved the microstructure of cellulose-rich solids, yielding LCNFs with the smallest particle size (150.47 ± 2.68 nm), the highest absolute zeta potential (−25.13 ± 0.60 mV) and superior emulsifying activity index (EAI) and emulsifying stability index (ESI). Characterizations revealed the obtained LCNFs possessed a 3D porous network structure, moderate crystallinity, enhanced hydrophobicity and typical shear-thinning behavior. Stability tests indicated that LCNFs-stabilized emulsions exhibited favorable stability under pH 4–9, thermal stability up to 90°C, NaCl concentration ≤ 50 mM, and 16 d of storage at 4°C. Moreover, LCNFs exhibited prominent concentration-dependent antioxidant capacity and favorable antibacterial effects against Staphylococcus aureus and Escherichia coli. This study achieves efficient recycling of RRP. The multifunctional LCNFs with excellent emulsifying, antioxidant, antibacterial and stable performances are promising green biodegradable additives, providing a sustainable approach for high-value utilization of lignocellulosic wastes and functional food development.