Zhang, NingningGuo, ShaoliZheng, YutingLi, Weili2025-02-142025-02-142025-02-05Zhang, N., Guo, S., Zheng, Y., & Li, W. (2025). Isolation and characterisation of acid soluble collagens and pepsin soluble collagens from Eel (Anguilla japonica Temminck et Schlegel) skin and bone. Foods, 14(3), article-number 502. https://doi.org/10.3390/foods1403050210.3390/foods14030502http://hdl.handle.net/10034/629250© 2025 by the authors. Licensee MDPI, Basel, Switzerland.Eel (Anguilla japonica) is an important and valuable food fish in East Asia and its by-products have been reported to include bioactive and profitable components. This study aimed to extract, characterise, and compare the structure and properties of acid-soluble collagens (ASCs) and pepsin-soluble collagens (PSCs) from the skin and bone of eel (Anguilla japonica), providing insights into their composition, structure, and properties for various applications. The yields of ASC-S (from skin), PSC-S (from skin), ASC-B (from bone), and PSC-B (from bone) were 12.16%, 15.54%, 0.79%, and 1.34% on a dry weight basis, respectively. Glycine, the dominant amino acid, accounted for 16.66% to 22.67% of total amino acids in all samples. SDS-PAGE and FTIR analyses showed the typical triple-helical structure of type I collagen with slight variations in molecular order in extract and intermolecular cross-linking between skin and bone collagens. The denaturation temperature (Tmax1) measured by differential scanning calorimetry (DSC) is 81.39 °C and 74.34 °C, respectively, for ASC-B and ASC-S. Bone collagen has higher thermal resistance than skin collagen. Surface morphology imaged using a scanning electron microscope (SEM) showed that the bone collagen had a denser network structure, whilst the skin collagen was more fibrous and porous. The findings suggest that eel-derived collagens from skin and bone can serve as potential alternatives in the food, cosmetic, and healthcare industries.Licence for VoR version of this article starting on 2025-02-05: https://creativecommons.org/licenses/by/4.0/https://creativecommons.org/licenses/by/4.0/eel by-productsCollagenThermal stabilityAmino acid compositionArticle2304-8158Foods2025-02-14