Preparation of SP/Lysozyme Composite Gel and the Inhibition of <i>Staphylococcus aureus</i>

Soy glycinin (SG) and sugar beet pectin (SBP) were cross-linked using laccase to form a complex SG/SBP (SP) and then combined with lysozyme under the heating condition to form SP/lysozyme composite gels. The properties of SP/lysozyme composite gel and its inhibition on Staphylococcus aureus were investigated. Results revealed that the zeta potential changed from −32 to 8.2 mV upon adding lysozyme, its morphology was larger, and the particle size and turbidity increased. The Fourier transform infrared spectroscopy and X-ray diffraction results indicated that the interactions between SP and lysozyme were electrostatic interaction and hydrogen bonding. The mechanical properties showed that the SP/lysozyme composite gel could recover its original shape after 90% strain compression when SP/lysozyme was 10:4 and 10:5, and the storage modulus (G′) was higher at 10:5 about 105 Pa. Scanning electron microscopy results showed that the granular size increased, and the antibacterial property on S. aureus was enhanced.