Enhanced emulsification of cellulose nanocrystals by ε-polylysine to stabilize Pickering emulsions

This study provides a novel strategy for preparing bio-based antibacterial emulsions stabilized by cellulose nanocrystals (CNCs). Antibacterial ε-polylysine (ε-PL) with a positive charge was introduced into the aqueous phase to modulate the interfacial behavior of CNCs via electrostatic interactions. Pickering emulsions containing ε-PL/CNCs (ε-PL 0.07-0.1 g/L) had significantly better stability, larger emulsion ratio, smaller emulsion droplet diameter, and superior antibacterial ability than emulsions stabilized by CNCs alone. This could be attributed to the formation of a CNC-dense layer at the interface in the continuous phase caused by a reduction of electrostatic repulsion after adding ε-PL. This was confirmed by zeta potential measurements, rheological properties, and bio-freezing scanning electron microscopy. In addition, cinnamaldehyde was introduced into the oil phase to further improve the antibacterial properties of the emulsion, thereby avoiding easy evaporation into water. Our findings provide an innovative solution for preparing bio-based antibacterial emulsions stabilized by ε-PL/CNCs, which will benefit the development of food, medicine, and cosmetic lotions.