Dose-dependent effects of rosmarinic acid on formation of oxidatively stressed myofibrillar protein emulsion gel at different NaCl concentrations

The effects of rosmarinic acid (RA) (12, 60 and 300 μM/g protein) on the textural properties and stability of oxidized myofibrillar protein (MP) emulsion gels were investigated. A low dose (12 µM/g) of RA significantly prevented the loss of thiol and ε-NH2 groups and the unfolding of the oxidized MP. However, a high dose of RA (300 µM/g) covalently and non-covalently interacted with the MPs, which induced a significant loss of thiol and ε-NH2 groups and aggregation of the MPs, causing decreased solubility, resulting in a poor three-dimensional emulsion gel network, and hence, higher cooking loss and lower gel strength. Moreover, the emulsifying properties of the MP emulsion gel were jeopardized by 300 µM/g RA. A high concentration of NaCl (0.6 M) enhanced the interaction between RA and MPs, increasing deterioration of the internal structure and leading to extremely unstable emulsifying properties of the MP emulsion gel.