Biochemical and thermo-mechanical analysis of collagen from the skin of Asian Sea bass (Lates calcarifer) and Australasian Snapper (Pagrus auratus), an alternative for mammalian collagen

Australasia has a large fish industry, and fish skin by-products from the processing industry could be used for the commercial production of fish collagen. The aim of this study was to characterize collagen extracted from the Asian sea bass (Australian barramundi) (Lates calcarifer) and snapper (Pagrus auratus) skin as an alternative to mammalian-derived collagen in gelatin products. The acid-soluble fractions of collagen from Asian sea bass and snapper skin were extracted and yielded about 8 and 7.5 % collagen (on a dry weight basis), respectively. The electrophoretic and chromatography patterns indicated that both collagens comprise of α1, α2, α3, and β chains, corresponding to the properties of calf skin collagen type I. Amino acid analysis and peptide mapping of digested collagen suggested differences in their amino acid sequences and collagen primary structure. Fourier transform infrared spectroscopy demonstrated that the helical structure of collagen was completely maintained in Asian sea bass and partially in snapper. Transition temperatures for the completion of the melting process in the two collagen networks were confirmed with differential scanning calorimetry and dynamic oscillatory rheology to be about 29 °C. Zeta potential analysis identified the isoelectric points (pI values) of collagen from Asian sea bass and snapper skin at pH 6.90 and 7.75, respectively. Thus, Asian sea bass and snapper skin could be an important alternative source of collagen to replace mammalian collagen for industrial applications.