Effect of plant protein-polysaccharide complexes produced by mano-thermo-sonication and pH-shifting on the structure and stability of oil-in-water emulsions

This study was performed to develop a protein-polysaccharide complex system with protein nano-aggregates produced by a new MTS + pH shifting method to address the low solubility problem of the protein near pI, to examine the functional properties of the complexes, and to investigate the properties of emulsions produced by the protein-polysaccharide complexes. The physicochemical (e.g., solubility, surface hydrophobicity, free sulfhydryl, and disulfide bond (SS) content), interfacial (e.g., rheology), and emulsifying properties (e.g., droplet size, turbidity, emulsion stability, and emulsion activity indexes) of the protein-polysaccharide complexes were examined. The protein-polysaccharide complexes exhibited improved solubility around pI. Among all the treatments, the PPI & modified starch complexes showed better functional properties than the others. The emulsions from the protein-polysaccharide complex were shown to be stable during a 40-day storage. The emulsions also provided good protection of oil droplets against oxidation. The new protein-polysaccharide complex system and the microemulsions produced by the complexes may provide a good delivery system for the protection and delivery of hydrophobic bioactive compounds for the production of liquid food products, including acidic products, with enhanced nutritional values.