Techno-functional characterization of gelatin extracted from the smooth-hound shark skins: Impact of pretreatments and drying methods

Ali Salem; Ola Abdelhedi; Haifa Sebii; Fadia Ben Taheur; Nahed Fakhfakh; Mourad Jridi; Nacim Zouari; Frederic Debeaufort

doi:10.1016/j.heliyon.2023.e19620

Techno-functional characterization of gelatin extracted from the smooth-hound shark skins: Impact of pretreatments and drying methods

Heliyon. 2023 Aug 29;9(9):e19620. doi: 10.1016/j.heliyon.2023.e19620. eCollection 2023 Sep.

Authors

Ali Salem¹, Ola Abdelhedi¹, Haifa Sebii², Fadia Ben Taheur³, Nahed Fakhfakh³, Mourad Jridi¹, Nacim Zouari³, Frederic Debeaufort^{4

5}

Affiliations

¹ Laboratory of Functional Physiology and Valorization of Bio-resources (LR17ES27), Higher Institute of Biotechnology of Beja (ISBB), University of Jendouba, 9000, Beja, Tunisia.
² Food Valuation and Safety Analysis Laboratory, Engineering National School of Sfax (ENIS), University of Sfax, Sfax, Tunisia.
³ High Institute of Applied Biology of Medenine, University of Gabes, Medenine, Tunisia.
⁴ Univ. Bourgogne Franche-Comté/Agrosup Dijon, UMR PAM A02.102, Physical-Chemistry of Food and Wine Lab, 1 Esplanade Erasme, 21000, Dijon, France.
⁵ IUT Dijon-Auxerre, BioEngineering Department, University of Burgundy, 7 Blvd Docteur Petit Jean, 21078, Dijon Cedex, France.

Abstract

Gelatin derived from marine by-products could be an interesting alternative to classic mammalian gelatin. The pretreatment and extraction conditions could influence the size of the resulting peptide chains and therefore their techno-functional properties. Thus, it is important to optimize the production process to get a gelatin for the appropriate applications. Skin pretreatment was done by microwaves or oven-drying and the extracted gelatin was dried by spray- or freeze-drying. Freeze-dried gelatin extracted from untreated skin (FGUS) had the highest gelatin yield (10.40%). Gelatin proximate composition showed that proteins were the major component (87.12-89.95%), while lipids showed the lowest contents (0.65-2.26%). Glycine showed the highest level (299-316/1000 residues) in the extracted gelatins. Proline and hydroxyproline residues of gelatins from untreated skin were significantly higher than those from pretreated skin-gelatin. FTIR spectra were characterized by peaks of the amide A (3430-3284 cm^-1), B (3000-2931 cm^-1), I (1636-1672 cm^-1), II (1539-1586 cm^-1) and III (1000-1107 cm^-1). Spray-drying decreased the gelling properties of gelatins, since it reduced gelling and melting temperatures compared to freeze-drying. Skin pretreatment significantly reduced the gel strength of gelatin by about 50-100 g depending on the gelatin drying method. The FGUS showed better surface properties compared to other gelatins. The highest emulsion activity index (39.42 ± 1.02 m²/g) and foaming expansion (172.33 ± 2.35%) were measured at 3% FGUS. Therefore, the promising properties of freeze-dried gelatin derived from untreated skin, gave it the opportunity to be successfully used as a techno-functional ingredient in many formulations.

Keywords: Drying; Emulsifying property; Foaming property; Gel strength; Gelatin; Smooth-hound shark (Mustelus mustelus) skin.