Polyphenol-mediated stabilization of myofibrillar proteins: Effects of pomegranate peel extract on freeze-thaw stability and gelation.

Abstract

This study investigated the cryoprotective efficacy of pomegranate peel extract (PPE; 0.45%, w/w) against commercial cryoprotectant in silver carp myofibrillar proteins during repeated freeze-thaw (FT) cycles (0-4). Compared with the commercial cryoprotectant, PPE effectively mitigated FT-induced protein oxidation, exhibiting 25% lower carbonyl content, 18.96% higher sulfhydryl content, 16.55% lower disulfide bond formation, and maintained 20.24% higher Ca2+-ATPase activity. PPE also suppressed protein aggregation, as evidenced by smaller particle size (263 vs. 305 nm, respectively), lower turbidity, and higher absolute zeta potential. Consequently, PPE efficiently preserved the secondary structure and myosin heavy chain integrity, resulting in 15.13% higher protein solubility, 11.37% greater water-holding capacity, and 2.1-times higher gel strength after four FT cycles. SEM further confirmed a denser gel network with finer ice-crystal distribution. These findings highlight PPE as promising multifunctional natural alternative to conventional cryoprotectants for preserving the structural integrity and functionality of frozen aquatic food proteins.