Extraction, optimization and characterization of collagen from sole fish skin

In this study, collagen was successfully extracted from marine waste i.e. Sole fish skin, which is available in the coastal area of Mangalore, India. The extraction process was optimized using One Variable at a Time (OVAT) and Response Surface Methodology (RSM) with Box-Behnken Design (BBD) was to achieve maximum yield and the extracted collagen was characterized. The optimal conditions to obtain highest collagen yield was determined to be, an acetic acid concentration of 0.54 M, NaCl concentration of 1.90 M, solvent/solid ratio of 8.97 ml/g and time of 32.32 h. The maximum collagen yield of 19.27 +/- 0.05 mg/g of fish skin was achieved under the optimal conditions. The analysis of variance and contour plots exhibited a significant interaction of all the selected variables over collagen extraction process. The SDS-PAGE (Sodium dodecyl sulfate -polyacrylamide gel electrophoresis) analysis suggested that the extracted collagen contained three alpha-chains i.e. (alpha 1)(2), alpha 2 (M.W. 118, 116 kDa) and one beta chain (M.W. 200 kDa) which was similar to commercially available calfskin Type I collagen. FT-IR (Fourier Transform Infrared Spectroscopy) analysis confirmed the existence of helical arrangements of collagen. SEM (Scanning electron microscopy) observation revealed that the extracted collagen was in the form of fibrils with irregular linkages.