Recovery of Collagen/Gelatin from Fish Waste with Carbon Dioxide as a Green Solvent: An Optimization and Characterization

Fish processing produces large amounts of fish waste. Instead of disposing of it, it is wiser to recover the valuable resource for high‑value‑added products. Our study proposed a process using carbon dioxide‑acidified water as a green solvent under supercritical conditions to successfully re-cover collagen/gelatin from the skin and bone of striped catfish. The optimum extraction conditions were obtained at 75 bar, 37 ◦C, and 24 h. The yields from the dry skin and bone mass were around 37% and 8%, respectively. The extracted products were characterized by Fourier‑transformed in‑ frared spectroscopy to study the functional groups, scanning electron microscopy to evaluate the morphology, sodium dodecyl‑sulfate polyacrylamide gel electrophoresis to study the protein pattern, UV–vis analysis to measure the absorption peak, and thermal gravimetric analysis to determine the denaturation temperature. The results show the viability of the proposed method on an industrial scale. The characteristics of the extracted product show promising results and potential for be‑ ing developed further in many applications such as biomaterial engineering in healthcare or natural polymer‑based absorbent material for efficient removal of heavy metals from water and wastewater.