Isolation and properties of collagen extracted from mixed by-products obtained from different fish species

Abstract

Fish by-products consisting of skin, bones, or scales are collagen sources. Acid-soluble collagen (ASC) and pepsin-soluble collagen (PSC) mixed by-products derived from different fish species were extracted and evaluated. The properties evaluated for both collagens were chemical composition, amino acid- and SDS-PAGE- protein profiles, Fourier transform infrared spectroscopy (FTIR), denaturation temperature (Tmax), enthalpy (ΔH), and solubility. The ASC and PSC registered a protein content of 48.56 and 38.80 %, respectively. From the total amino acids detected, hydroxyproline accounted for 7 % and 6 % for ASC and PSC, respectively. The electrophoretic profile showed the presence of the type I collagen bands (α1, α2, β, and γ), whereas FTIR spectrum showed the presence of diverse collagen functional groups (Amide A, B, I, II, and III) for both extracted types, and demonstrated that the extraction process did not affect the collagen´s triple-helical structure. The Tmax of ASC and PSC were 38.27 and 38.07° C, respectively, whereas ΔH were 0.64 and 0.33 J g-1. The lowest solubility was registered at pH 5 for ASC and pH 9 for PSC. The caractheristics of the collagen extracted, indicated that a mixture of by-products from different species could be an alternative for their reutilization by the local markets.