Abstract

Freezing extends the shelf life of seafood, yet physicochemical and textural degradation persists. This study evaluated coho salmon (Oncorhynchus kisutch) fillets stored isothermally at 268, 264, 260, and 255 K, measuring total volatile basic nitrogen (TVB-N), salt-soluble protein (SSP), pH, and Texture Profile Analysis (hardness, cohesiveness, adhesiveness, springiness, gumminess, chewiness). Independent triplicate determinations were performed at each time-temperature point. TVB-N started at 11.58 +/- 1.48 mg/100 g and increased less at colder temperatures (45.5 % at 255 K vs. 60.8 % at 268 K). SSP declined markedly (76-80 % depending on temperature), while pH and total nitrogen remained stable. Texturally, hardness, adhesiveness, gumminess, and chewiness decreased significantly, with attenuated losses at lower temperatures, whereas cohesiveness and springiness were unchanged. A flexible phenomenological kinetic analysis showed that apparent rates consistently decreased with decreasing temperature. The temporal profile of deterioration remained comparatively stable for TVB-N, hardness, and gumminess, but became sharper for SSP, adhesiveness, and chewiness, indicating mechanism transitions linked to ice recrystallization, water redistribution, and microstructural reorganization. The novelty lies in an integrated multi-response design for O. kisutch and in validating a non-restrictive kinetic framework across a broad thermal range. Collectively, the results provide operational criteria to set time-temperature tolerances and estimate shelf life in the coho cold chain, with parameters that are readily transferable to non-isothermal profiles for quality management and process control.