Study on external factors affecting egg yolk plasma by asymmetrical flow field-flow fractionation

In this work, the ability of asymmetrical flow field-flow fractionation (AF4) coupled with UV-vis, multiangle light scattering (MALS), and quasi-elastic light scattering (QELS) (AF4-UV-MALS-QELS) for monitoring aggregation of components of egg yolk plasma was evaluated. The effect of external factors (i.e., pH, storage conditions, freezing and heat treatments) on the egg yolk plasma was studied. The results reveal that the aggregation mechanism of components of egg yolk plasma during heat and freezing treatment is different. The results suggest that the low density lipoproteins (LDLs) in egg yolk plasma undergo a 'clusters-fusion-gel' process under heat treatment at pH10. The alkaline conditions promote the formation of LDL aggregates. Also, storage conditions play a role in the formation of LDL aggregates. It was found that the hen eggs stored for 7days at room temperature contain less aggregate than those stored at 4°C for the same period. The combination of AF4 with online MALS-QELS provided conformational information in terms of the shape and size distribution of LDL aggregates. AF4-UV-MALS-QELS was proved to be a rapid and gentle method for the separation and characterization of egg yolk plasma aggregates.