Abstract:
This study aimed to elucidate the molecular mechanisms by which basic amino acids (L-arginine/L-Arg, L-lysine/L-Lys, L-histidine/L-His) regulated oxidation resistance and gel network formation in yak meat myofibrillar protein (MP). Different concentrations (0.08%, 0.15%, 0.30%, 0.60%, w/v) of each amino acid were added to the MP system. Changes in structural properties (solubility, turbidity, surface hydrophobicity, secondary and tertiary structures) and oxidation indicators (carbonyl content, total and active sulfhydryl content) of MP, as well as gel properties (water-holding capacity, cooking loss, whiteness, strength, rheological behavior), were systematically analyzed. Results demonstrated that basic amino acids synergistically improved gel performance by neutralizing charges to reduce intermolecular repulsion, inducing conformational unfolding to expose hydrophobic groups and active sulfhydryls, and regulating secondary structures (L-Lys/L-Arg promoted
α-helix to
β-sheet conversion, while L-His maintained concurrent increases in both), but their effects exhibited concentration and type dependencies. In beneficial aspects, L-Lys and L-Arg significantly enhanced solubility (86.38% for 0.60% L-Arg,~25% higher than control) and reduced turbidity (suppressing aggregation); these structural optimizations combined with disulfide crosslinking from exposed active sulfhydryls formed uniform gel networks, specifically increasing water-holding capacity by~25% (L-Lys/L-Arg groups at 0.30%) and reducing cooking loss (48% reduction for 0.30% L-Lys), while significantly enhancing storage modulus G' at high temperatures (≥70℃, L-Lys≥0.30%, L-Arg≥0.60%). L-His acted mildly, mainly increasing gel strength by 12% at 0.60% concentration via stabilizing
α-helix/
β-sheet coexistence. In concerning aspects, L-Lys and L-Arg reduced gel whiteness with increasing concentration; more critically, high concentrations (especially 0.60% L-Arg) intensified protein oxidation damage (peak carbonyl content: 0.92 nmol/mg) due to excessive unfolding and self-oxidation. In summary, L-Arg and L-Lys show advantages in optimizing solubility, inhibiting aggregation, and promoting crosslinking through charge interactions and structural transformation, serving as effective strategies for improving gels of high-myoglobin, low-fat yak meat MP, yet requiring concentration control to balance oxidation risks; L-His provides a milder alternative. Practical applications can select amino acid types based on product requirements, offering a theoretical basis for developing low-sodium, low-phosphorus yak meat products.