Effects of high intensity ultrasound modification on physicochemical property and water in myofibrillar protein gel

The effects of high intensity ultrasound (HIU) modification (power: 200, 400, 600, 800 and 1000W, corresponding to intensities of: 88, 117, 150, 173 and 193Wcm-2) on the physicochemical properties of myofibrillar protein (MP) and water in MP gel were studied. As the HIU power increased, the solubility, surface hydrophobicity and absolute value of the zeta potential increased, while turbidity and total sulfhydryl (SH) group content decreased. The G' and G″ of MP during thermal gelation decreased as ultrasound intensity increased due to greater protein denaturation. Low field NMR data showed that bound water (T2b) had lower water mobility and was more closely associated with proteins in HIU treated MP gel, while the proportions of immobilized water (PT21) and free water (PT22) had their maximum and minimum value, respectively, at 600W. Moderate HIU (≦600W) treatments had denser and uniform gel microstructure, which improved water holding capacity (WHC) of the gels, while stronger HIU (>600W) treatments had larger and irregular gel microstructures, accompanied by decreased WHC.