Sulfate ester motifs of carrageenan govern the assembly and functional properties of tea protein carriers

Sulfate ester motifs of carrageenan modulate assembly properties of tea protein. • Carrageenan sulfate ester motif regulates the bioaccessibility of curcumin. • Sulfate ester motif of carrageenan influenced the functional properties of carrier. Incorporation of carrageenan (Car) offers an effective approach to modulate the assembly and functionality of protein-based nanocomplexes; however, the role of Car sulfate ester motifs has not been fully clarified. Here, κ-Car, ι-Car, and λ-Car with distinct sulfate content and distributions were used to construct Car/TP-Cur nanocomplexes. The sulfate ester motifs regulated intermolecular interactions and protein conformation, leading to distinct assembly structures. In κ-Car/TP-Cur and ι-Car/TP-Cur nanocomplexes, the interaction between TP and Cur was dominated by hydrogen bonding and hydrophobic interaction, whereas λ-Car/TP-Cur complex was mainly governed by hydrophobic interactions. Notably, ι-Car produced the most compact and stable structure, achieving curcumin encapsulation efficiency of 83.33% and bioaccessibility of 34.59%. Moreover, sulfate ester motifs significantly affected antioxidant activity and emulsion properties. These findings clarify how Car sulfate motifs regulate the assembly behavior and functional properties of protein-polysaccharide complexes and provide guidance for designing efficient natural delivery carriers. Download: Download high-res image (263KB) Download: Download full-size image