Impact of Electrostatic Deposition of Anionic Polysaccharides on the Stability of Oil Droplets Coated by Lactoferrin

The purpose of this study was to investigate the effects of three anionic polysaccharides (low methoxyl pectin (LMP), high methoxyl pectin (HMP) and alginate) on the physicochemical properties and stability of lactoferrin (LF)-coated lipid droplets. LMP, HMP and alginate were shown to adsorb to the surfaces of LF-coated droplets at neutral pH, which was primarily attributed to electrostatic attraction between anionic groups on the polysaccharide molecules and cationic patches on the protein surfaces. In the absence of polysaccharide, the LF-coated droplets were highly unstable to aggregation when heated above about 60 degrees C at pH 7, presumably because thermal denaturation of the adsorbed proteins increased droplet attraction. The addition of either LMP or HMP prior to heating greatly improved the thermal stability of the emulsions, with no aggregation being observed from 30 to 90 degrees C. On the other hand, the presence of anionic polysaccharides had little effect on emulsion stability or even promoted emulsion instability when 0 to 200 mM NaCl or CaCl2 was added. This study shows that the stability of LF-coated lipid droplets can be improved by careful selection of an appropriate type and amount of anionic polysaccharide to incorporate.