Genipin-crosslinked sugar beet pectin-bovine serum albumin nanoparticles as novel pickering stabilizer

Abstract

Food-grade polysaccharide-protein based nanoparticles receive considerable interest in food, pharmaceutical and cosmetic industries as Pickering emulsion stabilizer to satisfy the need of safety and emulsifying functionality. Here, we reported a type of novel sugar beet pectin-bovine serum albumin conjugate nanoparticles (S-BNPs) with a mean size of ~180 nm that were fabricated by the genipin-crosslinking strategy followed by facile ultrasonication. The as-prepared S-BNPs mainly consisted of 35.2% polysaccharide and 58.4% protein, showing a core-shell nanostructure with SBP chains surrounding the inner protein core, as unveiled by analyses of atomic force microscopy and transmission electron microscopy. S-BNPs had excellent colloidal stability under various pH (4.0–12.0) and ionic strength (μ, 0–500 mM) conditions. When used at a concentration (c) of 0.5 wt%, S-BNPs well stabilized Pickering emulsions (from creamed to gel-liked high internal phase emulsions/HIPEs) with different droplet characteristics and visual appearances with a maximum oil volume fraction (Ф) up to 0.84. At a lower c of 0.25 wt%, S-BNPs stabilized Pickering emulsions with a maximum Ф up to 0.70. Rheology measurements indicated that a higher c strengthened the stiffness of HIPEs (Ф = 0.80), thereby endowing the gel-like HIPEs with a self-supporting appearance. Owing to its unique nanostructure, S-BNPs displayed desirable emulsification properties at a wide range of pH (5.0–12.0) and μ (0–500 mM), whereas the two control samples, Crosslinked-BSA and SBP-BSA-Complex (electrostatically bound at pH 4.5), showed inferior emulsification properties in long-term storage, pH, and μ testings. In the repetitive freeze/thaw-induced demulsification cycles, a representative S-BNPs stabilized HIPE was re-emulsified 5 times. Altogether, this work demonstrates that the genipin-crosslinking is feasible to synthesize S-BNPs as an edible Pickering emulsion stabilizer for food and relating industries.