Identification of the Components Responsible for the Gelation of Egg Yolk during Freezing

The aggregates in gelled yolk were isolated by gel filtration with a Sepharose 4B column, after suspension in 1 m NaCl, and then they were identified by chemical analysis and sodium dodecyl sulfate polyacrylamide gel electrophoresis. No significant difference was found in lipid and protein composition between the aggregates and the low density lipoprotein in plasma (LDLP). It was concluded that the aggregates in gelled yolk were composed only of LDLP which suggested that the other yolk components (i.e. lipovitellins, livetins and phosvitin) might not directly participate in yolk gelation. However, the possibility that low deensity lipoprotein in granule (LDLG) might be partly responsible for gelation can not be excluded, because the lipid and protein composition of LDLG and LDLP were almost the same and LDLG also aggregated during the freezing as well as LDLP.