Gelatin from Solea aegyptiaca: physico-chemical, thermal, and interfacial properties

Solea aegyptiaca gelatin (GSA) is a promising alternative to conventional gelatin. With a yield of 9.64% after 9 h, it was produced by alkali pretreatment followed by acid extraction. GSA exhibited a positive surface charge (+ 2.88 mV), a pH of 4.96, and high protein and low lipid contents (79.6% and 0.2%, respectively). SDS-PAGE analysis confirmed its typical gelatin profile, showing β, α1, and α2 chains. The FTIR spectra displayed characteristic Amide A, I, II, and III bands. The gel demonstrated good textural properties, with a gel strength of 209.85 g and a hardness of 953.41 g. Thermal analysis indicated a gelation temperature of 6.5 °C and good thermal reversibility. GSA showed significant emulsifying capacity (25.97 m²/g) and moderate foaming properties, suggesting its potential application in confectionery products, dairy desserts, and aerated bakery formulations. Moreover, its marine origin makes it suitable for consumers with religious or dietary restrictions. The results support the development of alternative gelatin sources with industrial relevance by providing new information on adding value to fish processing residues. This study advances the United Nations Sustainable Development Goals, specifically SDG 12 (Responsible Consumption and Production) by valuing waste, SDG 9 (Industry, Innovation, and Infrastructure) by encouraging the development of sustainable biomaterials, and SDG 14 (Life Below Water) by promoting the responsible use of marine resources. Ultimately, the study promotes sustainable material development and circular bioeconomy strategies.