Complexation of β-lactoglobulin with gum arabic: Effect of heat treatment and enhanced encapsulation efficiency.

Heat treatment is widely used in food industry. Proteins and polysaccharides as important natural polymers in food, under heat treatment, the interactions between them could mediate the conformation and functional properties of proteins. Thermally induced β-lactoglobulin-gum arabic complexes (β-Lg-GA) were fabricated, and the effect of heat treatment on physicochemical properties of the complexes was systematically investigated. The average particle size of β-Lg-GA complexes decreased with temperature increased, at 85°C, a smaller size of 273 nm was obtained. A saturated adsorption of GA was found when mass ratio of β-Lg/GA was <1:2. At pH = 4.2-7.0, electrostatic attraction between β-Lg and GA was low and a fairly constant turbidity was observed, the formed composite particles had good stability to the pH value. Through UV, fluorescence, and FTIR spectroscopy, it was found that formation of the nanoparticles relied on thermal denaturation and aggregation of protein, the electrostatic, hydrophobic, and hydrogen bonding interactions between β-Lg and GA were also important. Scanning electron microscope further indicated β-Lg and GA had good compatibility, and the complexes had a spherical core-shell structure at molecular level. In addition, these prepared natural nanoparticles by heat treatment show significantly higher encapsulation efficiency for (-)-epigallocatechin-3-gallate (EGCG) than that of unheated, thus could be used as a promising carrier for biologically active substances.