Formation of acid-precipitated soy protein-dextran conjugates by Maillard reaction in liquid systems

P>The conjugation reaction between soybean acid-precipitated protein (SAPP) and dextran in liquid systems via the initial stage of the Maillard reaction was studied. Functional SAPP-dextran conjugates were prepared in 80% ethanol-reacting system at 50 degrees C for 6 h, along with 95% ethanol-reacting system at 60 degrees C for 24 h. The covalent attachment of dextran to SAPP was confirmed by sodium dodecyl sulphate-polyacrylamide gel electrophoresis and gel filtration chromatography.Compared to the classical dry-heating, the reaction time of glycosylation in the two ethanol systems was largely shortened. Emulsifying activity of SAPP-dextran conjugates obtained by dry-heating incubation and in ethanol was similar at pH 7.0 and10.0, significantly higher than that of SAPP-dextran mixture or SAPP alone. In addition, SAPP-dextran conjugates obtained in 80% ethanol-reacting system for 6 h were completely soluble after heating at 90 degrees C for 20 min. The impact of various processing conditions on the formation of SAPP-dextran conjugates was investigated. This study provides important guidance to create protein-polysaccharide conjugates at mild temperatures in liquid systems.