Rheological, Physico-chemical, and Surface-Active Properties of Gelatin Extracted from Bigeye Tuna (Thunnus obesus) Skin Waste

In the present investigation, bigeye tuna (Thunnus obesus) skin waste was utilized for the extraction of gelatin. Physico-chemical, rheological, and surface-active properties of the obtained gelatin were assessed. Proximate compositional analysis of tuna skin gelatin recorded high protein content of 88.6% and low levels of fat and ash contents. The isoelectric point (IEP) of tuna skin gelatin was around 6.24. Amino acid profiling recorded a glycine [31.7%] higher proportion, followed by imino acids (hydroxyproline + proline) [18.4%], and alanine [12.2%]. The electrophoretic pattern of purified gelatin exhibited three major bands (beta, alpha 1, and alpha 2) with wider molecular weight distribution in the range of 200-120 kDa. The Fourier Transform Infrared (FT-IR) spectra of gelatin also confirmed the bands corresponding to alpha helix, beta sheet, and random coil structures. The rheological studies of tuna skin gelatin revealed Newtonian and shear thickening properties. The method of extraction and assessment of its characteristic properties could be useful in the field of formulation of functional foods, nutraceutical, and biomedical applications.