Extraction and characterisation of gelatin from the skin of striped catfish (Pangasianodon hypophthalmus) and studies on its colour improvement

Abstract

Functional properties of gelatin from skin of striped catfish with and without bleaching for 48 h by 5% H₂O₂ (w/v)) were studied. Gelatin from skin bleached with 5% H₂O₂ for 48 h showed the highest yield (16.18 g). Bleaching not only improved the colour of gelatin gel by increasing the L* (lightness)-value and decreasing  a*(redness/greenness)-value, but also enhanced the bloom strength and the emulsifying and foaming properties of the resulting gelatin. Fourier transform infrared spectroscopic study showed higher intermolecular interactions and denaturation of gelatin from bleached skin than that of the control. These results indicated that hydrogen peroxide most likely induced the oxidation of gelatin, resulting in the formation of gelatin cross-links, hence improved functional properties.

Key words: Gelatin, catfish, color, bloom strength.