Stabilization of Pickering emulsions with bacterial cellulose nanofibrils (BCNFs) fabricated by electron beam irradiation

Abstract

Bacterial cellulose (BC) had been considered as a promising Pickering stabilizer for its non-toxicity, high purity, and biocompatibility. The electron beam irradiation (EBI) technology had gained significant attention in the field of cellulose degradation due to its operational convenience and mild reaction conditions. Pickering emulsions using BC degraded by EBI as Pickering stabilizers were successfully prepared. Irradiated bacterial cellulose nanofibers (IBCNFs) exhibited a high aspect ratio(30–80 μm in length and 21–109 nm in width) and high absolute zeta potential (-50 mV). The optimal emulsification performance of IBCNFs was observed at an irradiation dosage of 100 kGy (IBC-100). The emulsions based on IBC-100 achieved an EI value of 96.15 ± 0.19%, while those based on IBC-500 obtained an EI value of 59.93 ± 1.47%. r. Stable Pickering emulsions were prepared when the concentration of IBC-100 stabilizer exceeded 0.3 wt% with a fixed oil phase of 30%, or when the rapeseed oil phase was below 50% while maintaining a fixed suspension of 0.5 wt% IBCNFs. Confocal laser scanning microscopy (CLSM) demonstrated that IBCNFs facilitated the formation of a dense interfacial layer at the oil-water interface and formed a three-dimensional network within the water phase. Which effectively hindered the aggregation and flocculation between individual oil droplets. Furthermore, rheological findings demonstrated that emulsions possessed primarily exhibited properties of elasticity, and their gel strength could be enhanced by adjusting the irradiation dosages of IBCNFs. Moreover, environmental stability experiments indicated that IBCNFs-based emulsions exhibited exceedingly high temperature (20–80 °C) and pH tolerance (4–12). Flocculation occurred under high acid (pH = 2) conditions and at high ionic levels (≥ 40 mM NaCl), without causing disruption to the emulsion droplet structure. This study provided an innovative approach to preparing cellulose nanofibers with high aspect ratio, which could be utilized as emulsion stabilizers. The study also demonstrated that Pickering emulsions based on IBCNFs exhibit excellent stability and rheological properties. IBCNFs have promising potential to serve as a natural Pickering emulsifier for stabilizing oil-in-water emulsions in various food applications, cosmetic and pharmaceutical formulations.