Reducing sodium in meat products is nutritionally desirable, but salt reduction often weakens myofibrillar protein gelation and reduces texture quality and water retention. This study investigated the effects of L-lysine (Lys) and konjac glucomannan (KGM) on the physicochemical properties, gel characteristics, and structural changes of beef myofibrillar protein (MP) gels under low-salt conditions. The results indicated that reducing NaCl from 0.6 to 0.2 M decreased water-holding capacity (WHC), increased cooking loss, and produced a loose gel network. Compared with the 0.2 M NaCl group, the combined Lys-KGM treatment increased WHC from 28.53% to 56.70% and reduced cooking loss to 22.19% (p < 0.05). Texture analysis showed that Lys-KGM increased hardness and springiness by 69.40% and 80.43%, respectively (p < 0.05). LF-NMR indicated a higher proportion of immobilized water and reduced water mobility in the combined treatment. Lys increased reactive sulfhydryl content and surface hydrophobicity, whereas KGM reduced surface hydrophobicity and enhanced water immobilization. Lys-KGM slightly but significantly decreased α-helix and increased β-sheet contents (p < 0.05), accompanied by changes in the relative contributions of intermolecular forces and a more continuous gel network. Molecular docking and molecular dynamics simulations provided supporting evidence for different interaction patterns between myosin and Lys/KGM. These results suggested that Lys and KGM might help maintain the quality of low-salt meat protein gels and provide a formulation basis for reduced-sodium meat products.
Xiuyun Guo, Jinsheng Yang, Chao Fu et al.· Gels· 0 citations
Proteins are effective carriers for polyphenols, yet whether structural differences between plant- and animal-derived proteins influence the delivery and functionality of polyphenols in their nanocomplexes remains unclear. In this study, soy protein isolate-curcumin (SPI-CUR) and myofibrillar protein-curcumin (MP-CUR) nanocomplexes were fabricated via a pH-driven method, and their physicochemical properties, interaction mechanisms, and cryoprotective effects on surimi were investigated. Both nanocomplexes achieved high encapsulation efficiencies (90.63% for SPI-CUR and 83.29% for MP-CUR) and thus exhibited enhanced antioxidant activity. CUR loading induced conformational changes in the protein carriers, as evidenced by increased α-helix content and decreased β-sheet content, suggesting the formation of a more compact structure. Meanwhile, this conformational change was accompanied by a marked reduction in particle size, with SPI-CUR reaching 66.13 nm. Molecular docking further revealed that hydrophobic interactions and hydrogen bonding were the primary forces stabilizing both nanocomplexes. During freeze-thaw cycles of surimi, both SC and MC nanocomplexes were superior to commercial cryoprotectants in preserving product quality, evidenced by improved water-holding capacity, enhanced gel properties, and inhibited protein oxidation. Notably, the two nanocomplexes exhibited distinct protective profiles depending on the protein source. MP-CUR demonstrated superior preservation of gel texture by minimizing thawing loss to 0.53% and maintaining high hardness (425.50 ± 34.85 g) and springiness (0.81 ± 0.03), which facilitated the formation of a denser gel network. In contrast, SPI-CUR demonstrated superior viscoelasticity and yielded the highest storage modulus (G'). This study establishes a foundation for the rational design of natural and efficient surimi cryoprotectants derived from protein-polyphenol complexes.
Xiaoyun Liu, Yang Meng, Zhikun Yang et al.· Journal of Food Science· 0 citations
