Characterization of gelatin obtained from unicorn leatherjacket (Aluterus monoceros) and reef cod (Epinephelus diacanthus) skins

Abstract

The properties of gelatin oven dried at three different temperatures from unicorn leatherjacket (L50, L60 and L70) and reef cod skin (R50, R60 and R70) were investigated. The gelatin yield was higher in unicorn leatherjacket skin (12.2%) than reef cod skin (9.8%). Unicorn leatherjacket skin gelatin had a higher protein content of 88.0–88.61%, lower moisture (9.51–9.91%), fat (0.18–0.29%) and ash (0.60–0.71%) compared to reef cod skin gelatin which had 87–87.73% protein, 10.29–11.03% moisture, 0.23–0.31% fat and 0.69–0.73% ash. SDS-PAGE revealed all the gelatin samples had α and β chains. Gelatin samples had a good proportion of imino acid, hydrophobic and essential amino acid. Fourier transform infrared (FTIR) spectra showed the presence of amide regions in all the samples. Differential scanning calorimetry (DSC) showed a higher melting temperature in unicorn leatherjacket skin gelatin (115.54–120.80 °C) than reef cod skin (106.25–118.92 °C). Foaming capacity and stability and emulsion stability were higher in unicorn leatherjacket skin gelatin. Emulsion activity index, fat binding and water holding capacities were higher in reef cod skin gelatin. Different oven drying temperatures has not affect the yield and quality of gelatin. This study could pave the way to utilize oven drying for the extraction of gelatin from fish skin.