Mechanistic insights into the interfacial rheology of cellulose nanofibers from rice bran for stabilising pickering emulsions

This study optimised a sequential extraction process that includes alkali treatment, bleaching, and acid hydrolysis to produce cellulose nanofibers (RBNF) from defatted rice bran and examined their functionality as Pickering emulsion stabilisers. The optimised conditions (5% KOH for 15 h, 1% NaClO 2 , and 10% H 2 SO 4 yielded 13.88% nanofibers containing 60.5% cellulose with 55% crystallinity. Structural analyses (SEM, AFM, MIR, XRD) confirmed progressive removal of lignin and hemicellulose and formation of fibrillar morphologies (42 nm diameter), while zeta potential (< −26 mV) and DSC data indicated good colloidal and thermal stability. Interfacial rheology demonstrated that RBNF powders and gels exhibit similar diffusion, adsorption, and rearrangement kinetics at air–water and oil–water interfaces, forming elastic interfacial films described by first-order behaviour. Pickering emulsions prepared via ultrasonication, or high-pressure homogenisation displayed comparable droplet sizes (∼3–4 μm), shear-thinning flow, and gel-like viscoelasticity (G′>G″). Microscopy (CLSM, SEM, Cryo-SEM) revealed stabilisation mechanisms involving strong RBNF adsorption at the oil–water interface, entrapment of droplets within a three-dimensional fibre network, and bridging them. Overall, this work demonstrates that rice bran is a promising source of nanocellulose and provides mechanistic insights into RBNF-stabilised emulsions, highlighting the practical advantages of using powder-form nanofibers for scalable, food-grade Pickering systems. • Cellulose from rice bran is optimal with 5% KOH soak (15h), bleach and acid hydrolysis. • Sequential chemical treatment increased the stability and crystalline regions of nanofiber. • Ultrasonication (4 min, 90%) yielded interfacial rheology like initial RBNF gel. • High pressure homogenization at 150 bar demonstrated stable and high viscous emulsions. • Diffusion, adsorption, rearrangement and entrapment in RBNF network resulted stable PEs.