Characterization of codfish gelatin: a comparative study of fresh and salted skins and different extraction methods

Third Achilles Workshop “Tendon Gene & Cell Therapy and clinical applications”, 25-27 October 2021, Porto, Portugal, and Final FoReCaST Conference “2D and 3D in vitro Tissue Models for Drug Screening: Strengths and Limitations of the Cancer Models”, 27-29 October 2021, Porto, PortugalGelatin is generally known as the product derived from thermal denaturation of collagen given origin to an unfolding and cleavage of the triple helix resulting in a polydisperse mixture of polymers [1]. Due to the similarities with collagen, it has been widely used in tissue engineering applications to produce new biomaterials or as cellular carrier [1,2]. The primary sources of gelatins are from mammal origin, yet by-products of the fishery industry have also been considered as raw materials for gelatin production [3]. Different extraction processes are described in literature to obtain gelatins from fish skins, however there is a lack of information about the preservation of those skins (fresh, frozen, salted, etc.) and how that affects the final yield and properties of gelatin. In this study we present a comparative analysis between gelatins produced from fresh and salted codfish (Gadus morhua) skins using different extraction protocols based on methodologies described in literature. The characterization of the materials was assessed based on yield of extraction, amino acid composition, molecular weight distribution, rheological properties, and gel strength, as well as the cell compatibility of the gelatins envisaging future biomedical application. Methodologies using sulphuric + citric acid during the washing processes and a thermal extraction in water demonstrated to produce gelatins rich in OH-proline + proline, enhanced gel strength and rheological behavior, and with higher melting points. Differences between fresh and salted skins were found, with gelatins derived from salted skins demonstrating lower viscoelastic properties, as well as gel strength, when compared with gelatins from fresh skins. Our research has highlighted the importance of choosing the right protocol according to the final application of the gelatins, as a tool on the quest for the sustainable valorization of fish by-products, included in a blue and circular bioeconomy frameworkWork partially funded by: European Regional Development Fund (ERDF) through the projects 0302_CVMAR_I_1_P (program INTERREG España-Portugal 2014/2020); 0245_IBEROS_1_E and the Structured Project NORTE-01-0145-FEDER-000021 (Norte2020); funding from Xunta de Galicia (Grupos de Potencial Crecimiento, IN607B 2018/19) and FCT Doctoral Program Do*Mar (ALA scholarship: PD/BD/127995/2016)N