Abstract:

Casein peptide (CNH) was prepared by hydrolyzing NaCN with alcalase and extracted with water and isobutanol to obtain the bitterless peptide (CNH-H) and strong bitter taste peptide (CNH-A), respectively. Functional properties of casein peptide, CNH-H, and CNH-A were studied. Results showed that the three peptides all have a good solubility over the pH range of 2 to 11. However, their emulsifying activity, stability, foaming capacity and stability are quite lower than those NaCN (p ＜0.01), respectively. Among the three peptides, CNH-H exhibits the highest superoxide anion radical and hydroxyl radical -scavenging activity and strongest antibacterial effect against Pseudomonas, Staphylococcus aureus, Escherichia coli and Micrococcus luteus. However, CNH-A presents a higher DPPH radical scavenging activity as well as antioxidant activity in linoleic acid system and strong antibacterial effect against Bacillus subtilis. High ACE-inhibitory activity is also found on the three peptides and CNH-H shows the highest. Due to their high hydrophobicity, β-casomorphin-5 and β-casomorphin-7 are more likely contained in CNH-A instead of CNH-H.

Key words: casein peptide, bitter peptide, physicochemical property, biological activity