Effect of a soy protein isolate/sodium alginate-stabilized diacylglycerol pre-emulsion prepared by ultrasound-assisted homogenization on properties and structure of pork myofibrillar protein composite gel

This study aimed to examine the rheological behavior, gel properties, and microstructure of composite gels prepared from pork myofibrillar protein (MP) and various diacylglycerol pre-emulsions. The results demonstrated that ultrasonic treatment prior to homogenization of pre-emulsions containing sodium alginate (SA), soy protein isolate (SPI), or both (SPI-SA) significantly enhanced the gel performance when compared to homogenization alone. The MP composite gel containing the ultrasonic SPI-SA pre-emulsion (U-SPI-SA) showed the highest gel strength (21.84 g), water-holding capacity (87.10 %), whiteness (94.20), thermal stability, shorter relaxation times, and reduced cooking loss (22.29 %). This gel also displayed greater hardness, springiness, and gumminess, as supported by the rheological measurements under various test modes. Raman spectroscopy revealed that the MP composite gel with U-SPI-SA pre-emulsion contained more β-sheet and fewer α-helix structures, resulting in a tighter and more uniform network structure and increased moisture proton density. Furthermore, intermolecular force analysis identified hydrogen bonding and disulfide bonding as the dominant interactions in the MP composite gels with different pre-emulsions. These findings support the potential of U-SPI-SA diacylglycerol pre-emulsion to improve the qualities of meat products.