Egg white protein and transglutaminase synergistically improve the gel quality of frozen thawed damaged shrimp surimi

BACKGROUND: Freeze-thaw (FT) cycles often induce severe deterioration in the gel quality of Litopenaeus vannamei surimi, which poses a major challenge to the surimi processing industry. Egg white protein (EWP) and transglutaminase (TG) are widely recognized for their capacity to modify protein structures and enhance gel properties. However, the synergistic mechanisms by which EWP and TG mitigate FT-induced gel quality impairment in L. vannamei surimi remain insufficiently explored. RESULTS: The effects of 2% EWP, 0.2% TG, and their combination on the gel quality of FT-treated L. vannamei surimi were evaluated. Compared with the FT-treated group, individual addition of EWP or TG significantly increased gel strength and reduced cooking loss (P < 0.05). Notably, the EWP-TG combination exhibited the most pronounced synergistic improvements relative to single addition. Myofibrillar protein analysis revealed that FT treatment significantly elevated turbidity and surface hydrophobicity while decreasing free sulfhydryl group content. In contrast, the EWP-TG combination effectively reversed these FT-induced adverse changes, reducing turbidity and surface hydrophobicity by strengthening protein-water interactions and increasing free sulfhydryl group levels to preserve protein structural stability. Rheological measurements demonstrated that the combination markedly alleviated the FT-induced decline in apparent viscosity, indicating enhanced gel network integrity. Scanning electron microscopy observations confirmed that FT treatment resulted in a porous, rough gel microstructure with irregular fissures, whereas the EWP-TG combination yielded a smooth, uniform, and compact gel network by promoting crosslinking between protein molecules. CONCLUSION: The combination of 2% EWP and 0.2% TG significantly enhanced the gel quality of FT-damaged L. vannamei surimi through a synergistic mechanism. EWP acted as a structural modulator via hydrophobic interactions, while TG mediated covalent crosslinking to reinforce the protein network, collectively mitigating FT-induced structural damage. These findings provide valuable insights and practical implications for developing effective strategies to improve the stability and quality of FT-processed shrimp surimi in industrial production. © 2026 Society of Chemical Industry.