Collagen peptide fractions from tilapia (Oreochromis aureus Steindachner, 1864) scales: Chemical characterization and biological activity

This research project was focused on the isolation of compounds from natural sources and their chemical characterization and biological activity were evaluated. Tilapia is a popular fish and large amounts of byproducts are generated from its industrialization. Considering the abundance of this waste and its low value-added uses, collagen can be recovered at low costs. Collagen has low toxicity, good compatibility, biodegradability, and functional properties in foods. Thus, industrial byproducts could be considered as a valuable source for the recovery of collagen and the isolation of collagen peptides. In this work, fish scales were used to isolate hydrolyzed collagen using papain. Two fractions of collagen peptides were separated: F1 (5–10 kDa peptides) and F2 (<5 kDa peptides) through molecular weight cut-offs to evaluate the biological activity improvement. Characteristic functional groups of native collagen were identified by Fourier transform infrared (FTIR) spectroscopy. The most abundant total amino acids were glycine, hydroxyproline, and proline, while the predominant free amino acids were glycine, tyrosine, and proline. In the evaluation of antioxidant activity and capacity, F1 presented the highest antioxidant content and required the least amount of sample to inhibit 50% of the ABTS and DPPH radicals (IC50). An antimicrobial effect against Escherichia coli of clinical origin was observed, although the fraction had no effect on Staphylococcus aureus. Therefore, hydrolyzed collagen is a valuable resource for the production of peptides with bioactive properties to be used in various applications.