Extraction and characterisation of collagen from the waste of grey mullet (Mugil cephalus)

Acid soluble collagen (ASC) from the skin (ASC-S) and bone (ASC-B) of grey mullet (Mugil cephalus) were isolated and characterized. Yields of ASC-S and ASC-B were 5.57 and 2.63 % respectively, on the basis dry weight. Proximate analysis showed both collagens had protein as a major constituent with trace amount of ash and fat. Both collagens contained glycine as the major amino acid with relatively high content of proline, alanine, hydroxyproline, arginine and glutamic acid. Nevertheless, they had the low content of tyrosine, methionine and leucine. Besides, fourier transform infrared spectroscopy (FTIR) proved that both collagens were integrated and native. SEM result depicted that both collagens were in the form of fiber sponge-like scaffolds. Thermal denaturation temperatures were determined to be 35.69 and 35.05C, respectively. The results of XRD proved that the two collagens retained their helical structures. These collagens had evident absorption at 230 nm by UV-Vis spectra. Extracted collagens were characterized as type I collagen basing on UV–Vis, FTIR spectrometer and amino acid composition. These findings suggested that grey mullet waste (skin and bone) collagen possess the potential to be an alternative collagen source for a variety of uses in many fields.