Interactions between lecithin and yolk granule and their influence on the emulsifying properties.

In this study, the interactions between egg yolk granule and soybean lecithin and their emulsion properties were investigated. For egg yolk granule, the increase of solubility and negative zeta-potential and decrease of hydrophobicity could be observed with the increase of lecithin concentrations, indicating the interactions between granule protein and lecithin. Results from the z-average particle size and the AFM image showed that the increase of solution pH and addition of lecithin could destroy the aggregated structure of the egg yolk granule. The disrupted granule exhibited better emulsion stability than that of native granule due to the higher surface charge and lower particle size. Notably, appropriate addition of lecithin (less than 0.25%) would be conducive to the formation of high stable emulsions by modestly reducing the contact angle, while extra lecithin (more than 0.50%) would induce excessive substitution of granule protein by competitive adsorption, leading to destabilization of the O/W emulsions via surfactant-induced depletion flocculation. Image 1 • The increase of solution pH and addition of lecithin could dissociate the egg yolk granule. • Dissociation of egg yolk granule was beneficial to emulsion stability. • Excessive displacement of interface granule proteins by lecithin resulted in stratification. [ABSTRACT FROM AUTHOR]