Physicochemical properties of acid‐soluble collagens from different tissues of large yellow croaker ( Larimichthys crocea )

Acid-soluble collagens (ASCs) were extracted and characterised from different tissues of large yellow croaker (Larimichthys crocea). The yields of ASCs in bones, skins, scales and muscles were 3.22 ± 0.47%, 42.30 ± 1.15%, 2.82 ± 0.31% and 0.89 ± 0.12%, respectively. SDS-PAGE and ATR-FTIR analysis showed that all ASCs were type I collagen with intact triple helical structure and consisted of α1,3-chain, α2-chain, β-chain and γ-chain. Quantitative analysis of SDS-PAGE revealed that the ratio of β-chains in ASC from scales was lower than other tissues. The imino acid contents of ASC from bones, skins, scales and muscles were 169, 167, 162 and 173 residues/1000 residues, respectively. The maximum transition temperature (Tm) of ASC from scales was 30.15 °C, lower than the other three ASCs, indicated that the thermal stability of collagen was affected by both the content of imino acid and β-chains. The results also implied that thermal stability of ASC might exist the tissue specificity among different fish species.