Abstract:

To prepare high-activity peptides with calcium absorption-promoting function, desalted duck egg white after
electro-dialysis was hydrolyzed by one of five enzymes (alcalase 2.4 L, neutrase 0.8 L, protamex, trypsin, and pepsin), and
then deamidation and amino acid composition analysis of the peptides were conducted. The results showed that protamex
was selected as the optimal enzyme when the amount of soluble calcium-binding peptide and the degree of hydrolysis (DH)
were measured. The optimal enzymatic hydrolysis conditions were as follows: Protamexdosage 20 000 U/g, substrate
concentration 30 g/L, temperature 50 ℃, pH 6.5, and hydrolysis time 3.5 h. Under these conditions, the DH reached 21.97%
and the amount of soluble calcium-binding peptide was 29.22 μg/mL. After deamidation, the amount of soluble calciumbinding
peptides was increased significantly (P ＜ 0.05). Amino acid analysis revealed that a lot of amino acids in the
peptides contributed to the calcium-binding capacity. Conclusion: Desalted duck egg white can be used to produce highactivity
peptides with calcium absorption-promoting functions and deamidation of duck egg white peptides can increase the
amount of soluble calcium-binding peptides significantly.

Key words: desalted duck egg white, enzymatic hydrolysis, peptides, amount of soluble calcium-binding peptide, deamidation