Properties and stability of water-in-water emulsions stabilized by microfibrillated bacterial cellulose

The stabilization of food-grade water in water (W/W) emulsions, as a potential candidate for encapsulating water-soluble functional components, remain a significant challenge in food science research. The main purpose of the work was to find a suitable particle for the preparation of the novel W/W emulsion. This system was composed of two immiscible water-soluble biopolymers (dextran and maltodextrin), and stabilized by using bacterial cellulose (BC) nanofibrils. The BC-stabilized W/W emulsions were successfully fabricated with the 20 wt% dextran (DEX) and the 10 wt% maltodextrin (MAL). There was no significant change in the droplet size of the emulsion with increasing BC surface charge from 0.41 mmol/g to 1.41 mmol/g dry cellulose. Meanwhile, the apparent viscosity, storage modulus (G′) and loss modulus (G″) of the emulsions were decreased with increasing BC surface charge. The stabilization mechanism of the W/W emulsion was due to the formation of viscoelastic network structure by BC nanofibrils. When the BC content increased from 0.04 wt% to 0.16 wt%, the emulsion droplet size was decreased from 3.78 ± 0.79 μm to 2.01 ± 0.40 μm. Furthermore, the obtained W/W emulsion did not demulsify within 7 d, it had better stability than that of the reported W/W emulsion. Moreover, the BC-stabilized emulsion was insensitive to the change of ionic strength concentration (0–200 mM) and pH (3–11). In brief, it was the first report to use BC nanofibrils to stabilize the W/W emulsion, which enriched the type of W/W emulsion.