Abstract: The effect of salt on properties of yolk protein during salting was investigated. The soluble protein content was 1.95 g/100 g in fresh egg yolk (on a wet basis) and increased to 4.30 g/100 g after salting for 15 weeks. The sulfhydryl content of fresh egg yolk was 0.057 mmol/g protein, and reached a peak level of 0.102 mmol/g protein after 3 weeks of salting. DSC results showed that salting promoted the heat tolerance of egg yolk protein. The thermal transition temperature of fresh yolk protein was 79.06 ℃, and increased to 80 ℃ after 15 weeks of salting. SDS-PAGE showed that salt did not affect the structure of peptide chains. Salt could result in a significant change in the secondary structure of yolk protein. The major secondary structures of fresh egg yolk protein were α-helix and β-sheet, accounting for 74.67% of all secondary structures. After salting, parts of α-helix and β-sheet turned into T turn.

Key words: egg yolk, protein, sulfhydryl, secondary structure