Contribution of amino acid composition and secondary structure to the antioxidant properties of tilapia skin peptides

• Published in: Journal of food measurement & characterization 2024-02, Vol.18 (2), p.1483-1498
• Main Authors: Ma, Yue-Yun, Mi, Chun-Xiao, Chen, Ju, Jiao, Rui-Wen, Li, Xiang, Wang, Qiu-Kuan, He, Yun-Hai, Ren, Dan-Dan, Wu, Long, Zhou, Hui
• Format: Article
• Language: English
• Subjects: Amino acid composition; Amino acids; Antioxidants; Chemistry; Chemistry and Materials Science; Chemistry/Food Science; Engineering; Enzymolysis; Food Science; Free radicals; Helices; Hydrophobicity; Hydroxyl radicals; Original Paper; Peptides; Protein structure; Response surface methodology; Scavenging; Secondary structure; Skin; Structural analysis; Technical services; Tilapia
• ISSN: 2193-4126; 2193-4134
• DOI: 10.1007/s11694-023-02265-0

Tilapia skin is a byproduct of tilapia processing and can be used as a potential resource to produce antioxidant peptides. In this study, the process conditions for the extraction of antioxidant peptides were optimized by response surface methodology, followed by amino acid and structural characterization of different antioxidant active fractions, and finally, the oxidative free radical scavenging mechanism was predicted. The enzymolysis process conditions are: enzyme dosage: 2.51% (w/w), temperature: 51 °C, solid‒liquid ratio: 1:50 (mg/mL), time: 9 h, and pH 10. Under these conditions, the IC 50 values of the DPPH, ABTS and hydroxyl radical scavenging capacity of peptides were 6.81 ± 0.06, 9.69 ± 0.04 and 14.35 ± 0.04 mg/mL, respectively. Six fractions with different antioxidant activities were obtained after separation and purification. Amino acid analysis indicated that high proportions of hydrophobic amino acids (Val, Leu and Pro) and aromatic amino acids (Phe and Tyr) played an important role in enhancing the free radical scavenging activity of the peptides. FTIR and CD spectroscopy analysis showed that the higher proportion of α-helices and lower proportion of random coils in the peptide structure were the main reasons for the excellent antioxidant activity. The analysis of the free radical scavenging mechanism suggested that the OH and SH groups contained in Pro, Tyr and Met play an important role in free radical scavenging. These findings not only provide theoretical basis for the study of the structure–activity relationship of antioxidant peptides, but also provide technical support for relevant processing enterprises to improve the production and utilization efficiency of tilapia skin peptides. Graphical abstract