Effect of black highland barley polysaccharides and low frequency-static magnetic field on casein-based coacervates:...

To evaluate the combination effects of highland barley polysaccharides (HBP) and low-frequency static magnetic field (LF-SMF) treatment on the structure and properties of acid-induced casein (CS) coacervates, this study conducted a comprehensive investigation at various stages- before, during, and after coacervation-for the first time. Compared with native CS, adding HBP caused CS to denature owing to hydrophobic and electrostatic interactions, and LF-SMF treatment further promoted these changes. During the acidification (pH 7.0-2.0) and coacervation processes, the integration of LF-SMF treatment with the addition of HBP enhanced the rate and extent of casein (CS) aggregation and crosslinking, attributable to alterations in the ζ-potential of CS. Among the formed coacervates, the yield and particle size of CS/HBP complex coacervates after being treated with LF-SMF (M-CS/HBP) increased from 67.9 % to 78.4 % and from 803.12 nm to 1253.43 nm, respectively. Additionally, M-CS/HBP demonstrated improved viscoelasticity and a more uniform, compact microstructure with denser packing. The alterations observed in CS-based coacervates were due to non-covalent interactions between CS and HBP, further promoted by LF-SMF treatment, leading to the unfolding and disordering of protein secondary structure. Consequently, M-CS/HBP complex coacervates demonstrated superior encapsulation efficiency for L. plantarum and provided enhanced protection for probiotics under adverse environments.