Physicochemical and structural properties of composite gels prepared with myofibrillar protein and lecithin at various ionic strengths

Abstract

This study investigated the physicochemical and structural properties of composite gels prepared with porcine myofibrillar protein (MP) and lecithin at different NaCl concentrations. The results confirmed the existence of interactions between MP and lecithin, that the addition of lecithin may block the formation of disulfide bonds and that the main forces in composite gel systems were hydrophobic interactions and hydrogen bonds. The lecithin hydrophilic head might be partially bound to protein by hydrogen bonds, while the hydrophobic phospholipid fatty acid chain may be bound to the MP hydrophobic region by hydrophobic interactions during gelation. This aspect may contribute to the changes in the textural properties, water-holding capacity and whiteness of gels at different salt concentrations. In addition, analyses of the rheological properties and microstructures of the gels showed that the addition of lecithin could inhibit the “salting out effect” at high salt concentrations. Moreover, Raman spectroscopy analysis showed that the addition of lecithin contributed to the further unfolding of MP at high salt concentration, which could be caused by the intermolecular forces during competition for water between the lecithin-protein complexes and salt.