Characteristics and functional properties of buckwheat protein–sugar Schiff base complexes

Maillard-type functional complexes were produced by reacting buckwheat protein (BWP) with five different saccharides (xylose, fructose, glucose, dextran, and maltodextrin) in aqueous solutions at 60 °C, pH 6.5. Xylose was the most reactive sugar with BWP as evidenced by losses of free amines (22.4% in 12 h) and strong difference UV absorption at 310 nm. The covalent attachments of different sugars/polysaccharides to BWP were confirmed by SDS–PAGE with both protein and carbohydrate staining. Conjugation did not significantly alter the solubility of BWP, but the BWP–dextran complex had superior emulsifying activity over control BWP (P < 0.05). Emulsions prepared with the complexes were substantially more stable (P < 0.05) than emulsion prepared with control BWP in the order of: dextran > maltodextrin > xylose > glucose > fructose > control. The conjugation also improved thermal stability of BWP.

► Functional buckwheat protein was produced via Maillard reaction. ► Buckwheat protein–dextran complex had superior emulsifying property. ► Buckwheat protein–polysaccharide conjugates were heat stable.