Studies on the Change of Egg Yolk Protein Components by Heat

Abstract

When the egg yolk solution was heated at various temperature from 55°C to 100°C for 1.5 min. or 5 min., the viscosity of egg yolk increased by heating. At 100°C for 1.5 min., the viscosity of heated yolk was finally 3 fold of the viscosity of unheated yolk. When separated fractions were heated, the viscosity of LDL(Low Density Lipoprotein)increased at above 80°C. On the contrary, the viscosity of Livetin did not almost increase. The viscosity of HDL(High Density Lipoprotein) rapidly increased at above 80°C, and HDL showed highest viscosity among separated fractions. In the disc gel electrophoresis, main bands of HDL almost disappered at above 90°C. When HDL and LDL were heated at 60°C for 5 min., particles of larger size was found in gel filtration. From the above findings, change of turbidity and viscosity of heated egg yolk was estimated to be mainly due to the coagulation of HDL and LDL.