Improvement of low-oil gelatin emulsions performance by adjusting the electrostatic interaction between gelatin and nanocellulose with different morphologies

This work investigated the effect of different pH values (4, 7, 11) and nanocellulose morphologies (cellulose nanocrystals (CNCs), cellulose nanospheres (CNSs), and cellulose nanofibrils (CNFs)) on the low-oil gelatin emulsions performance. Results showed the electrostatic complex (pH = 4) transformed into complexes in the form of free molecules (pH = 11), reduced the interaction between gelatin and nanocellulose. The emulsion showed smaller creaming index (CI, 0–49.55%) and larger D4,3 (30.47–44.63 μm) at pH = 7 in comparsion with pH = 4 (0–59.17%, 28.1–35.1 μm) and pH = 11 (0–58.54%, 21.3–29.47 μm). The microstructure showed the composition of interfacial film was changed from electrostatic complexes (pH = 4) to gelatin (pH = 7) due to competitive adsorption, and the nanocellulose was filled into the continuous phase to form a compact network. While the strong electrostatic repulsion (pH = 11) weakened the network strength, indicating the emulsion at pH = 7 has relatively high stability. Moreover, the nanocellulose morphologies also acted a crucial role in adjusting the properties and network structure of emulsions. The interfacial results displayed the interfacial adsorption of G-CNCs was restrained (84.12%) significantly (p < 0.05) at pH = 7, which reduced the interface stability, but formed a compact cellulose network, G-CNSs and G-CNFs could form relatively loose network due to small size or easy aggregation. It suggested the G-CNCs at pH = 7 was more conducive to the establishment of stable emulsions. Hence, this work would offer a guiding significance for the practical production of low-oil gelatin emulsions.