Phenolic acid-grafted chitin nanofibers improve frozen quality of frozen Litopenaeus vannamei: myofibrillar protein preservation and ice crystal control.

Frozen storage of Litopenaeus vannamei causes ice crystal-induced tissue damage and myofibrillar protein (MP) denaturation. Ferulic acid (FA), sinapic acid (SA), and caffeic acid (CA) were grafted onto chitin nanofibers (ChNFs) to prepare cryoprotective phenolic acid-grafted ChNFs (PC) conjugates. During 12 weeks of frozen storage. PC treatment significantly inhibited quality deterioration. SA-g-ChNF reduced TVB-N (8.07 vs 10.81 mg/100 g) and TBARS (0.23 vs 0.36 mg/kg) at 12 weeks; CA-g-ChNF maintained higher MP water-holding capacity (12.59 vs 6.69 g/g) and Ca2+-ATPase activity (2.20 vs 1.31 U/mg). PC conjugates preserved sulfhydryl content, limited surface hydrophobicity, and maintained α-helix content, indicating reduced MP unfolding. Smaller ice-crystal areas and better water distribution were observed. A working model is proposed: the ChNFs backbone mainly limits ice-crystal growth and mechanical damage, while grafted phenolic acids mainly inhibit oxidative denaturation and stabilize MP conformation, providing synergistic protection. These conjugates are promising bio-based cryoprotectants for frozen aquatic products.