Interactions of water-soluble myofibrillar protein with chitosan: Phase behavior, microstructure and rheological properties

This study investigated the electrostatic interaction between water-soluble myofibrillar protein (MP) and chitosan (CH) for further developing muscle protein-based functional foods. Effects of pH (3.0–7.5), protein/polysaccharide mixing ratio (20:1–1:1), ionic strength (0.05–0.6 M KCl) and deacetylation degree (DD) of CH (70–95%) on the interactions were studied by turbidity analysis, phase behavior, zeta-potential, particle size, microstructure and rheological properties. Lower mixing ratios (5:1 and 1:1) improved the colloid stability of MP in mildly acidic environments (pH < 6.5). KCl (0.05–0.6 M) destroyed the colloidal stability and promoted phase separation. A high DD of CH (95%) promoted complexation by increasing the available cationic groups. Rheology displayed that the maximum viscoelasticity for each factor was occurred at a MP/CH ratio of 1:1, pH 6.5 and 95% DD of CH due to the enhanced intermolecular interactions. Fourier transform infrared spectroscopy (FTIR) confirmed that the electrostatic interactions contributed to complex formation, while hydrogen bonds also participated in. This research provided great insight for understanding the interaction of water-soluble MP with CH to further exploit low-salt meat protein-based foods.