Mechanisms of quality deterioration in noodle-shaped surimi gels: Insights from the impact of setting temperatures on protein structure

Quality deterioration in noodle-shaped surimi gels (NS) occurs when setting temperatures exceed 35°C, yet the underlying structural mechanisms remain unclear. This study investigated the effects of setting temperatures on protein structural transitions and NS quality. Rheological behavior, molecular chain integrity, protein conformation, and endogenous enzymatic activity were systematically evaluated under different setting temperatures. NS exhibited optimal gelling performance between 30 and 35°C, while rigidity, elasticity, and molding capability declined sharply at 40°C. During the chopping and setting, elevated temperatures led to a loss of hydrogen bonds and Ca 2+ -ATPase activity, while hydrophobic interactions intensified. A critical threshold at 35°C induced α-helix-to-β-sheet transitions and promoted excessive protein aggregation. Consequently, molecular chain integrity and viscoelastic properties were markedly compromised above 35°C. Quality deterioration of NS above 35°C is attributed to dual mechanisms: (1) the breaking of hydrogen bonds in fish pastes drives the transformation from α-helical to β-folded structure; (2) the burial of hydrophobic groups by protein aggregates weakens the molecular chain and rheological properties. These findings elucidate the protein structural basis of NS quality deterioration and provide theoretical guidance for optimizing NS processing. • NS quality deterioration mechanism caused by setting temperatures was revealed. • Hydrogen bonds in fish pastes were severely broken at temperatures above 35°C. • Protein aggregation in NS was promoted at setting temperatures above 35 °C. • Hydrophobic interactions in NS weakened sharply at setting temperatures above 35 °C.