ABSTRACT This study focuses on the stability of whey protein isolate–dextran (WPI–D) complexes, exploring how their modification modes (covalent grafting/non‐covalent mixing) and drying processes (spray‐drying SD/freeze‐drying FD) regulate structural properties and stability. Covalent WPI–D grafts (WPI‐D‐G) exhibit a higher degree of glycosylation, with significant fluorescence quenching and red shift. Fourier transform infrared (FTIR) spectral analysis reveals reduced absorbance of amide bands, collectively forming rigid cross‐linked structures. Compared to non‐covalent WPI–D mixtures (WPI–D‐M), these structures exhibit superior emulsifying activity index (EAI), emulsion stability index (ESI), as well as stronger tolerance to environmental stresses (thermal stability: FD WPI–D‐G (WPI–D‐GF) maintain a particle size of 0.447 µm at 80°C, whereas SD WPI–D‐G (WPI–D‐GS) tend to aggregate; salt tolerance: stable at NaCl ≤ 20 mg/mL; pH stability: robust across pH 2–7). WPI–D‐GF retain intact cross‐linked structures, exhibiting enhanced emulsifying performance and colloidal stability (higher absolute zeta potential), whereas WPI–D‐GS, despite forming smaller uniform spherical particles, undergo partial structural degradation. Regarding comparative stability under different conditions: WPI–D‐GF outperforms WPI–D‐GS in thermal stability, whereas covalent grafts from both drying methods demonstrate comparable salt and pH tolerance. These findings elucidate the structure–stability relationship of WPI–D complexes, thereby providing a theoretical foundation for regulating their stability through process optimization.
Li et al. (Sun,) studied this question.