Asian Journal of Fisheries and Aquatic Research

Marine-derived collagen represents a potential alternative to conventional mammalian collagen and offers opportunities for the utilisation of underused fish resources. This study investigated the extraction and physicochemical characterisation of acid-soluble collagen from whole Decapterus macarellus and its flesh, skin and other waste fractions. Collagen was extracted using alkaline pretreatment, demineralisation, acetic acid extraction and salt precipitation. The recovered materials were characterised using scanning electron microscopy (SEM), Fourier-transform infrared (FTIR) spectroscopy, ultraviolet–visible spectroscopy, X-ray diffraction (XRD), thermal analysis and humidity-regain measurements. Collagen yields from flesh, skin and waste fractions were 25.24 ± 5.21%, 8.51 ± 1.54% and 15.45 ± 2.95%, respectively, with flesh producing the highest yield among the separated tissues. SEM examination of whole-fish collagen revealed an entangled fibrous structure. FTIR spectra exhibited characteristic amide A, B, I, II and III bands, supporting the presence of collagen-associated functional groups. Ultraviolet–visible spectra showed characteristic absorption maxima and limited absorption in the 250–280 nm region. XRD analysis yielded d-spacing values of 0.2829, 0.2834 and 0.2799 nm for flesh, skin and waste collagen, respectively, consistent with structural features associated with the collagen helix. Thermal and humidity-regain analyses indicated variation among the extracted fractions. These findings demonstrate the feasibility of recovering collagen from different tissues of D. macarellus and provide preliminary physicochemical evidence supporting its further investigation as a source of collagen-based biomaterials.