Adjusting the interfacial property and emulsifying property of cellulose nanofibrils by ultrasonic treatment combined with gelatin addition

In this work, the effect of different ultrasonic power (0, 15%, 45%, and 75%) and different gelatin concentration (0, 0.5%, 1.0%, and 1.5%, w/v) on the interfacial property and emulsifying property of cellulose nanofibrils (CNF) obtained by ball milling treated were studied. Results showed that ultrasonic treatment destroyed the original structure and amorphous region of CNF, exposed more hydroxyl (0.692–0.736) and hydrophobic regions, and increased the crystallinity (61.40%–69.10%) and wettability (41.5°–65.6°) of CNF. The improved wettability promoted its adsorption at the oil-water interface, increased the interaction of CNF at the interface and then improved the stability of the interfacial film dominated by elasticity (5.78 mN/m-16.36 mN/m). Furthermore, gelatin was added by two step emulsification to further improve the stability of CNF-stabilized emulsion due to the poor stability. At a lower gelatin concentration (0.5%), the gelatin was mainly adsorbed in continuous phase and accompanied by slight interfacial adsorption. With the increase of gelatin concentration (1.0%–1.5%), the more gelatin was gradually adsorbed on the interface to replace CNF, formed the gelatin dominated interfacial film, and accompanied by the formation of a tight three dimensional network structure due to the improvement of the entanglement between gelatin and CNF (CLSM), and then significantly (p < 0.05) increased the rheological properties, water holding capacity (WHC, 58.81%–73.28%) and stability of the emulsion. Therefore, this study could provide a theoretical basis for the regulation of interfacial property and emulsifying property of CNF.