Scaling-up a process for the preparation of folate-enriched protein extracts from hen egg yolks

A simple separation process was used to fractionate egg yolk into plasma and granule fractions through the use of gravitational separation with laboratory- or pilot-scale centrifuges. The granule fractions at pilot-scale presented with higher protein concentrations (66-69%) and lower lipid contents (20-26%), on a dry basis, as compared to the plasma fraction. The recovery of protein, based on the raw material (egg yolk), was calculated to be 96% and 89% for the laboratory- and pilot-scale fractionation processes, respectively. Good agreement was achieved between the laboratory- and pilot-scale centrifugation processes, in terms of chemical composition and recovery of egg yolk components. The plasma fraction preserved 66-71% of the lipid with the laboratory-scale and 75-77% with the pilot-scale fractionation process. It was confirmed by SDS-PAGE and 2D-gel electrophoresis analysis that each egg yolk fraction incorporated different amount of LDL and HDL. SDS-PAGE and 2D-gel electrophoresis analysis revealed different profile patterns for the plasma and granule fractions. Folate content in plasma and granule fractions was measured using HPLC analysis. Folate analysis revealed that the plasma fraction of egg yolk was devoid of folate (5-CH3-H4folate), whereas the granule fraction was concentrated by a 3-fold factor in comparison to native egg yolk.