Influence of environmental stresses on the physicochemical stability of orange oil bilayer emulsions coated by lactoferrin-soybean soluble polysaccharides and lactoferrin-beet pectin

Based on layer-by-layer electrostatic deposition, orange oil bilayer emulsions stabilized with lactoferrin (LF)-soybean soluble polysaccharides (SSPS) and lactoferrin (LF)-beet pectin (BP) were prepared. The effect of environmental stresses (ionic strength, pH, freeze-thaw and light) on the physicochemical stability of primary and secondary emulsions was investigated. In the absence of anionic polysaccharides, orange oil emulsion was highly unstable and aggregated at pH 7-9 and NaCl of 0.1-0.5 M. The droplets in LF-SSPS coated emulsion were stable against aggregation at pH range of 3-10 and NaCl concentration less than 0.3 M, while the droplets in LF-BP coated emulsion were stable against aggregation at pH 4-9 and NaCl concentrations of 0-0.5 M. All the primary and secondary emulsions showed the instability after the freeze-thaw treatment and the stability could be improved in the presence of maltodextrin. During the light exposure (0.35 W/m2, 45 °C) for 8 h, the bilayer emulsions could protect key volatile compounds (decanal, octanal and geranial) from the oxidation compared with the primary emulsions. These results suggested that the layer-by-layer electrostatic deposition could improve the stability of LF-coated emulsion to environmental stresses.