Ultrasound-assisted enzymatic construction of sodium caseinate-polyphenol-polysaccharide emulsion delivery system: Innovative strategy to improve curcumin retention and stability

Proteins and polysaccharides are widely used to construct drug delivery systems, while oat polyphenols exhibit strong antioxidant properties. Despite its antioxidant capacity, curcumin remains inherently unstable. In this study, sodium caseinate (SC) -polyphenol and SC-polysaccary-polyphenol conjugates were prepared by ultrasound-assisted enzymatic method, and the HIPE system was constructed to improve the stability of curcumin. Intrinsic fluorescence spectroscopy demonstrated a marked decrease in maximum emission intensity of SC-chitosan oligosaccharide (COS) conjugates, confirming fluorescence quenching through covalent SC-polysaccharide cross-linking. SC-CMC conjugates exhibited significantly higher surface hydrophobicity. In vitro digestion experiments demonstrated that HIPEs prepared with CMC achieved higher curcumin retention rates. Curcumin retention in HIPE systems showed no significant variation across pH 3.0–7.0, with polyphenol incorporation effectively mitigating pH-dependent retention fluctuations ( p  < 0.01). Notably, the pH sensitivity of curcumin was reduced by the addition of polyphenols. The HIPE-based system significantly enhanced curcumin stability and shows potential for the targeted delivery of bioactive conjugates.