Freeze-thaw stability of lecithin and modified starch-based nanoemulsions

The impact of freeze-thaw cycles on the physical stability of oil-in-water emulsions containing lecithin - coated and modified starch - coated droplets has been studied by combined dynamic light scattering (DLS) and differential scanning calorimetry (DSC) measurements. Emulsions prepared by high-pressure homogenization were within 200 nm size ranges. Lecithin-based emulsion systems were unstable to freeze-thaw cycles, which was attributed to extensive droplet aggregation induced by the ice formation during emulsion freezing process. Instead, modified starch systems were highly stable due to the formation of a thick layer of emulsifier which prevented the coalescence of nanoemulsions. The addition of ice nucleating protein lowered the freeze-thaw stability of lecithin-based emulsions, but had negligible effect on modified starch-based emulsions. In contrast, the addition of poly(ethylene glycol) improved the stability of lecithin-based emulsions but destabilized the modified starch-based emulsion systems.