Elucidating interfacial-function relationships of lactoferrin-cellulose nanofibril complexes via multidimensional spectroscopy and QCM-D: interfacial anchoring and bulk stabilization mechanisms in robust Pickering emulsions

Abstract

Pickering emulsions stabilized by natural biopolymers have garnered significant interest due to their safety and functionality. In this study, lactoferrin (LF) and cellulose nanofibril (CNF) were complexed via electrostatic interactions under varying pH conditions. Multidimensional spectroscopic and interfacial tension analyses revealed that LF dominates the interfacial behavior of the complexes. QCM-D demonstrated that LF-CNF complexes formed a denser interfacial layer (apparent adsorbed mass ∼ 287.0 ng/cm2), approximately 1.8 times higher than LF alone (∼159.4 ng/cm2) and 12 times higher than CNF alone (∼22.5 ng/cm2). When used as Pickering emulsion stabilizers, all emulsions exhibited shear-thinning behavior. The 1.0 wt% LF-CNF complexes provided the finest droplet size, highest uniformity, and longest storage stability (up to 28 days). This study clarifies the interaction mechanisms and interfacial behavior of protein-polysaccharide complexes, offering theoretical guidance for designing high-performance food-grade emulsifiers with natural origin.