Fourier transform infrared (FTIR) spectroscopic study of extracted gelatin from shaari (Lithrinus microdon) skin: effects of extraction conditions

Fourier Transform Infrared (FTIR) Analysis was used to characterize secondary structure of gelatins extracted from shaari skin and compared with bovine and porcine gelatin obtained from commercial source. The concentration and temperature of extracted solutions were varied from 0.01 to 1.0 N and 4 to 80°C, respectively. The intensity ratio of amide III and I as a measure of denaturation process showed that all samples had almost the same protein structure at 0.1 and 1.0 N concentration for all extraction temperatures. At low acid concentration (0.01 N) and low temperature (4°C) significant amount of triple helix remained intact (i.e. less denaturation). As the temperature increased from 20°C, the random coil structure increased as the protein became denatured and protein losses its triple structure. The cluster analysis showed that secondary structure of gelatin extracted using mild treatment (concentration: 0.01 N and temperature: 4°C) behaved completely different from other extracted gelatin.