Oxidative polyaldehyde production: a novel approach to the conjugation of dextran with soy peptides for improved emulsifying properties

Dextran (polyol) was oxidized with 0, 0.5, 1, and 2 % sodium hypochlorite at pH 9.5 and 35 °C to produce polyaldehyde dextran (PD), which was subsequently conjugated with soy peptides (SP) to improve surface activity. SP–PD complexes were formed by heating 1 % SP and 10 % PD at 60 °C and pH 6.5 for 48 h. PD was more reactive than unmodified dextran with SP to produce conjugates based on the Schiff base with absorption at 294 nm. The formation of SP–PD complexes was confirmed by SDS–PAGE with glycoprotein staining. Turbidity and particle size measurements indicated the SP–PD conjugates had significantly improved emulsifying properties compared to non-conjugated SP and the SP/PD mixtures. The results indicate that controlled oxidation of polysaccharides can be a novel technique to efficiently synthesize amphiphilic functional biopolymers.