Determination of Sulfuric Acid Effects on Degradation and Structural Changes of Gelatin Using Fourier-Transform Infrared Spectroscopy and Peak Deconvolution Analysis

The present research was aimed to investigate the effects of sulfuric acid on the structures of gelatin polypeptides. Gelatin samples were immersed in 0.5 M sulfuric acid solution for different periods of 15, 30, 60, 120, 240, 480, 960, and 1920 s, with possible structural changes analyzed by Fourier-transform infrared spectroscopy (FT-IR). Spectra at amide I and II regions were scrutinized using the Gaussian deconvolution method for the resulting changes in the protein secondary structure. The hydrolysis process initially led to a decrease in the α-helix chain and an increase in random coil and β-sheet structures. An equilibrium was formed in degradation and these structures were sequentially turned on each other. Results revealed a correlation between the peak intensity changes of these conformations, so that the degradation process could be observed in the conversion of α-helix to random coil and β-sheet structures and vice versa, indicating the oxidation and expansion of protein structure at the onset of the degradation process.