Effects of polysaccharides on the solubilization of myofibrillar protein in aqueous solution: A comparative study

Polysaccharide modification of myofibrillar protein (MP) is conceived as an effective solubilization strategy in low/free-salt media. This study investigated the effect of the non-covalent interactions of neutral (guar gum, konjac glucomannan), sulfated (κ-carrageenan, ι-carrageenan), and carboxylated (sodium alginate, carboxymethylcellulose) polysaccharides on the structure-solubility relationship of MP. The results showed that highly charged anionic polysaccharides were more effective in enhancing the solubility by the destruction of the electrostatic balance of the myosin rods, which impeded the formation of MP filaments, rather than manipulating system viscosity. In the presence of ι-carrageenan and carboxymethylcellulose, the highest solubility of MP was obtained, increasing from 15.23% to 44.16% and 45.36%, respectively. Meanwhile, anionic polysaccharides promoted the stable secondary conformation with a high α-helix content at the more folded state. FTIR suggested that electrostatic interaction and hydrogen bonds were the mainly non-covalent binding modes in the MP/anionic polysaccharide complexes. The electrostatic repulsion of anionic polysaccharides-coated MP molecules was significantly increased leading to high stability in the salt-free solution. The entanglement of polysaccharides induced the increase of protein surface hydrophilicity and shielded the sulfhydryl and hydrophobic groups reducing the protein self-aggregation, which might improve the affinity between the complexes and water molecules. The study gives important insights into the application of polysaccharides in novel low-salt meat products, which is conducive to driving the development of meat protein-based beverage/fluid food.