Fabrication and characterisation of soy protein isolate-grafted dextran biopolymer: A novel ingredient in spray-dried soy beverage formulation.

Hybridization of macromolecules via the Maillard grafting reaction can punctuate specific forms of biopolymers, resulting in novel functionalities. The current study aimed at investigating and optimizing the conjugation of dextran-soy protein isolate (SPI), and to assess how Maillard modification can affect the properties of a spray-dried soy beverage. Analyses of SDS-PAGE, Glycation degree, SEM micrographs and FT-IR spectroscopy confirmed that the best condition for glycosylation operated on a pH value of 8.5 at 60°C for 8days. Results of differential scanning calorimetry (DSC) clearly show an increased denaturation temperature of proteins. Solubility, emulsifying properties, water holding capacity and DPPH radical scavenging activity of soy proteins were enhanced by conjugation. Spray-dried conjugated powders exhibited significantly higher values of reconstitution properties (solubility index, wettability and dispersibility), compared to un-conjugated ones, because of increased thermal stability and solubility of proteins via glycation. Altogether, the results suggest that dextran conjugation provides further functional attributes to the SPI and thus could improve the applicability of soy proteins in the food industries.