Influence of soy protein and egg white powders on the stability of frozen fish balls (Chirocentrus dorab) during freeze–thaw cycles

Abstract Repeated freeze–thaw (FT) cycles commonly occur during frozen storage and distribution and are known to deteriorate the structural integrity, water-holding capacity, and sensory quality of surimi-based products. Therefore, the incorporation of functional protein binders has been proposed as an effective strategy to mitigate FT-induced quality loss. This study investigated the effects of binder addition on physicochemical and sensory qualities of frozen fish balls subjected to five repeated FT cycles. Frozen minced fish exhibited higher gel strength than fresh fish ( p ≤ 0.05), with no significant change in lightness ( L *) or whiteness (W) ( p > 0.05), supporting the use of frozen raw materials. The addition of soy protein (SP) and egg white (EW) powders at levels of 2%, 4%, and 6% reduced thawing, centrifugal, and cooking losses while maintaining texture attributes such as springiness, cohesiveness, and chewiness. SP improved gel strength at 4%–6% across all freeze–thaw cycles ( p ≤ 0.05), though 6% slightly reduced L * and W. EW better preserved brightness at 2%–4%, while both binders at 6% increased b *, indicating yellowness ( p ≤ 0.05). SEM analysis showed repeated FT cycles disrupted the internal microstructure of fish balls containing SP or EW, increasing porosity and pore size, reflecting moisture loss and protein matrix degradation. Overall, 4% binder addition for both SP and EW was identified as the optimal binder level based on instrumental textural evaluations without adversely affecting color attributes. EW formulations further enhanced water-holding capacity and delayed total volatile basic nitrogen (TVB-N) accumulation compared with SP ( p ≤ 0.05). Sensory evaluation confirmed that fish balls containing 4% EW after one FT cycle achieved the highest preference scores, consumer acceptance (90.74%), and purchase intention (79.63%), highlighting the practical potential of EW as an effective binder for improving the stability and marketability of frozen fish ball products. Graphical Abstract