Structural, color, and stability properties of hydrogen peroxide-treated phycoerythrin-based colorant proteins from dried laver (Pyropia yezoensis).

This study aimed to develop a strategy for use of the water-soluble protein fraction extracted from laver biomass to establish a seaweed biorefinery system. By leveraging the oxidative reactivity differences of hydrogen peroxide (H₂O₂), a phycoerythrin (PE)-based colorant protein (PBCP) was produced from the water-soluble proteins of dried laver (Pyropia yezoensis). The highest a* value and PE/PC ratio (13.85) for PBCP were achieved after a 1.5 h treatment with 4.5 mol/L H₂O₂. The protein content (3.48 mg/mL) of the PBCP was approximately 1.5-fold to 2-fold greater than that of PE obtained through ammonium sulfate precipitation and ion-exchange chromatography. H₂O₂ treatment induced interactions between proteins and saccharides in the water-soluble protein, causing aggregation through β-structures primarily stabilized by disulfide bonds. These structural changes led to enhanced emulsifying properties and color stability under various temperature, light, and pH conditions. These findings establish PBCP as a stable, seaweed-derived protein pigment for food applications.