Regulation of Pickling Efficiency and Physicochemical Properties of Reduced-Sodium Chicken Breast Using Shiitake Mushroom Extract and Ultrasound-Assisted Marination

Reducing sodium in poultry products often compromises texture and water-holding capacity. This study investigated the interactive effects of shiitake (Lentinula edodes) mushroom extract (SME) and ultrasound (US) on mitigating these defects in reduced-sodium chicken breast. A standard 2.0% NaCl brine served as the control, while reduced-sodium formulations contained 1.4% NaCl supplemented with 0.2% or 0.6% KCl. SME (0.4–1.2%) and probe US (20 kHz, 300 W, 15 min) were applied. Independently, SME increased brine uptake (15% at 1.2% SME), while US accelerated chloride diffusion (~30%) via microstructural disruption. The synergistic treatment combining 0.8% SME with US was identified as the statistical optimum. Simple effect analysis confirmed this combination significantly reduced cooking loss (p < 0.01) and restored comprehensive textural attributes to levels comparable with the 2.0% NaCl control. As confirmed by LF-NMR and microstructural analysis (H&E staining), these macroscopic improvements were highly correlated with optimized immobilized water (P21) proportions and myofibrillar protein-matrix stabilization. Ultimately, this strategy provides a functional and microstructural basis for developing sodium-reduced poultry without compromising critical quality attributes.