Interactions and gel strength of mixed myofibrillar with soy protein, 7S globulin and enzyme-hydrolyzed soy proteins

摘要

The mixed protein gels were prepared adding soy protein isolate (SPI), 7S globulin, enzyme-hydrolyzed soy proteins, 10- to 100-kDa ultrafiltration fraction and 0.5- to 10-kDa ultrafiltration fraction to myofibril protein isolate (MPI) gels, and five chemical interactions namely nonspecific associations, ionic bonds, hydrogen bonds, hydrophobic interactions and disulfide bonds in these gels were investigated by means of determining gel solubility within 20–75 °C. Furthermore, correlations between gel strength and different chemical interactions were evaluated statistically by Pearson’s correlation test. The gels with 0.5- to 10-kDa fraction presented the biggest gel strength below 60 °C, and the gels with SPI had better gel strength above 65 °C. At different endpoint temperatures, nonspecific associations decreased in order of MPI mixed with 0.5- to 10-kDa fraction, 10- to 100-kDa fraction, enzyme-hydrolyzed soy proteins, 7S globulin and SPI. Gels with ultrafiltration fractions had higher ionic bonds. Hydrogen bonds fluctuated in small scale below 55 °C and reduced at higher temperature. Hydrophobic interactions increased to maximum before decreasing slowly as the temperature went on. In short, both hydrophobic interactions and ionic bonds had significantly positive correlation with gel strength for mixed gels with enzyme-hydrolyzed soy proteins, whereas for the other four mixed gels, it was hydrophobic interactions and nonspecific associations.