Food emulsifier based on the interaction of casein and butyrylated dextrin for improving stability and emulsifying properties

Green hydrophobically modified butyrylated dextrin (BD) was used to modulate casein (CN). The CN/BD complex nanoparticles were formed at different CN-to-BD mass ratios based on a pH-driven technology. The interaction force, stability, and emulsifying properties of complex nanoparticles were investigated. The nanoparticles had a negative charge and a small particle size (160.03, 152.6, 155.9, 206.13, and 231.67 nm) as well as excellent thermal stability and environmental stability (pH 4.5, 5.5, 6.6, 7.5, 8.5, and 9.5; ionic strength, 50, 100, 200, and 500 mM). Transmission electron microscopy demonstrated the successful preparation of complex nanoparticles and their spherical shape. Fourier transform infrared spectroscopy, fluorescence spectroscopy, and dissociation analysis results showed that the main driving forces of formed CN/BD nanoparticles were hydrogen bonding and hydrophobic interaction. Furthermore, the CN/BD nanoparticles (CN/BD mass ratio, 1:1; weight/weight) exhibited the lowest creaming index, and optical microscopy showed that it has the most evenly dispersed droplets after 7 d of storage, which indicates that the CN/BD nanoparticles had excellent emulsifying properties. Butyrylated dextrin forms complex nanoparticles with CN through hydrogen bonding and hydrophobic interaction to endow CN with superior properties. The results showed that it is possible to use pH-driven technology to form protein-polysaccharide complex nanoparticles, which provides some information on the development of novel food emulsifiers based on protein-polysaccharide nanoparticles. The study provided significant information on the improvement of CN properties and the development of emulsions based on CN.