Effects of Ultrasound Combined With Yeast Extract and Trehalose on the Structure and Gel Properties of Myofibrillar Protein Under the Low‐Salt Condition

Reducing sodium content compromises the texture and flavor of meat products. This study investigated the combined effects of ultrasonic treatment (UT), yeast extract (YE), and trehalose (TH) on myofibrillar protein (MP) gelation and molecular structure under the low-salt (1.5% NaCl) condition. Compared to low-salt control, the UT-YE-TH treatment markedly enhanced the gel functionality (p < 0.05). Water-holding capacity (WHC) improved from 69.76% (R) to 85.55% (R-UT-YETH), and gel strength increased from 94.75 to 173.54 g (p < 0.05). Microstructural analysis showed that the combined treatment generated a more continuous and homogeneous protein network. Circular dichroism revealed a decrease in α-helix content (from 13.6% to 2.0%) and an increase in β-turn (from 21.2% to 27.3%). Intrinsic fluorescence and surface hydrophobicity measurements further confirmed enhanced unfolding and intermolecular interactions, accompanied by elevated total and free sulfhydryl contents. Correlation analysis and principal component analysis (PCA) indicated that increased β-turn fractions and greater hydrophobic exposure were associated with improvements in WHC and gel strength. The combined application of UT, YE, and TH effectively improves MP gelation under the low-salt condition by promoting favorable structural transitions, which provides a practical strategy for producing reduced-sodium cured meat products with enhanced quality.