Isolation and biochemical characterization of vital protein collagen: fish waste valorization of Arabian Sea fish Sardinella longiceps and its fluorescence quenching property

Abstract

Introduction and Aim: There has been a practice of dumping fish wastes or converting them into low market value products; the scope of this work relies on the fact that isolation of vital collagen in an efficient way from fish wastes by a valorization technique to convert it into a value-added product, hence decreasing environmental pollution load with increasing economic impact.

Materials and Methods: The acid-soluble type-I collagen (ASC) from fish bone, skin, fins and head of Indian oil sardine (Sardinella longiceps) was isolated and characterized. The protein content of isolated ASC was found to be 1.15 mg/g, 1.53 mg/g, 1.24 mg/g and 1.13 mg/g respectively. The ASC was isolated with a yield of 1.8%, 2.5%, 1.2% and 2.1% respectively.

Results: From the FTIR spectrum, it can be confirmed that ASC contains five amide bands with triple-helical nature of the polypeptide chain. The SEM analysis of the ASC surface exhibited densely packed fibers of collagen. The ASC exhibited the maximum absorption peak at 225 nm. The maximum solubility of ASC was observed at pH 4 and 4% of NaCl concentration. The study further extended to investigate the quenching property of collagen with Rhodamine B, which was confirmed by photoluminescence (PL) analysis. There is a decrease in absolute quantum yield ranging from 21 to 1.75%.

Conclusion: The quenching property of collagen was established by the PL assay of collagen mixed with Rhodamine B dye solution, which is a known fluorophore. So these materials might be used as biopolymer hybrid materials in the place of inorganic/organic quenching materials.

Keywords: Acid soluble collagen; Indian oil sardine; photoluminescence; Rhodamine B; quenching.