Insight into the stabilization mechanism of bacterial cellulose nanofibers/whey protein isolate complexes at the oil-water interface

Abstract

In this work, O/W Pickering emulsions stabilized by bacterial cellulose nanofibers (BCNFs) and whey protein isolate (WPI) electrostatic complexes were fabricated, and their stabilization mechanisms were investigated. The BCNFs/WPI complex particles were successfully formed at pH 3.0 under electrostatic and hydrogen-bonding interactions, and showed a “dot-line” network structure. The resultant Pickering emulsions progressively exhibited more uniform droplets size (approximately 15 μm), higher viscosity and viscoelastic moduli, increased interfacial protein adsorption, and reduced flocculation index with increasing BCNFs-to-WPI ratios, especially at a ratio of 1:5. The synergistic stabilization mechanism could be summarized as follows: Negative-charged BCNFs and positive-charged WPI formed electrostatic complexes that self-assembled into compact interfacial layers and entangled networks, preventing oil droplets flocculation or coalescence. Simultaneously, a moderate amount of BCNFs effectively enhanced the emulsions stability via fortified steric hindrance and bridging flocculation. This study builds a theoretical framework for constructing Pickering emulsions stabilized by protein-polysaccharide complexes.