Stabilization and color protection of phycoerythrin hydrolysate through agarose oligosaccharide complexation

BACKGROUND: Phycoerythrin has limited applications due to its sensitivity to light and heat. To enhance phycoerythrin's stability and resistance to degradation, a complex was formed between bromelain-hydrolyzed phycoerythrin (PEH) and agarose oligosaccharides (AOs). RESULTS: ) with rising temperature, indicating that AOs and PEH undergo static quenching, which quenches the intrinsic fluorescence of PEH. Fourier-transform infrared (FTIR) analysis revealed an increase in α-helix content from 0.1568 to 0.1653, and hydrophobic interactions and hydrogen bonding drove the interaction between AOs and PEH. In addition, the DPPH radical scavenging rate of the AOs/PEH complex increased from 67.54% for PEH to 88.67%. The AOs/PEH (50:1, molar ratio) complex exhibited a stability 1.34 times that of the untreated PEH after 60 °C treatment. Moreover, at 80 °C, the AOs/PEH complex exhibited a smaller overall color variation (ΔE < 0.1) compared to that of free PEH. CONCLUSION: These results demonstrate that combining AOs with PEH enhances the stability of PEH, which offers new insights for the application of phycoerythrin and its derivative as a natural pigment in food and coloring sectors. © 2026 Society of Chemical Industry.