Regulation mechanism of nanocellulose with different morphologies on the properties of low-oil gelatin emulsions: Interfacial adsorption or network formation?

In this work, cellulose nanocrystals (CNCs), cellulose nanospheres (CNSs) and cellulose nanofibrils (CNFs) were prepared and compared, and then the effect of nanocellulose with different morphologies and concentrations (0.2–0.6%, w/v) on the interfacial properties and emulsifying properties of gelatin (G, 2.0%, w/v)/nanocellulose complexes (G-CNCs, G-CNSs, G-CNFs) was investigated systemically. The results showed that the addition of nanocellulose increased the surface hydrophobicity (H 0 , 7.45–9.93) and apparent viscosity (17.75–60.94 Pa s) of complexes due to the generation of intermolecular hydrogen bonds, hydrophobic interactions and bridging structures. Among them, the promoting effects of CNCs and CNSs were the strongest and weakest, respectively, and the effects of CNFs were intermediate. The improved H 0 was beneficial to promote the adsorption of G-CNSs at the oil-water interface, corresponding to increased interfacial viscoelasticity and decreased droplet size (55.14–49.12 μm). However, the interfacial adsorption of the G-CNCs and G-CNFs was inhibited due to the energy barrier generated by molecular entanglement despite its high hydrophobicity, which made more complexes participate in the formation of the network structure in the continuous phase (CLSM), thus improving the water holding capacity (56.14–9.65%) and rheological properties of the emulsion, especially in the G-CNCs. Furthermore, the increased nanocellulose concentration further improved the interfacial stability and emulsion stability. Therefore, this study could provide significant guidance for regulating the properties of low-oil emulsions stabilized by gelatin/nanocellulose complexes.