Thermal degradation behavior of collagen from sea cucumber (Stichopus japonicus) using TG-FTIR analysis

Collagen is the main protein of sea cucumber, and its structure and thermal properties were analyzed, which were related to the storage stability of sea cucumber. Collagen molecules (SCC) and collagen fiber from sea cucumber showed the similar amino acid composition. Fourier transform infrared (FTIR) spectra of SCC revealed amide A and I band shifted slightly when the temperature ranged from 20 degrees C to 100 degrees C, and X-ray diffraction indicated the distance between adjacent molecular chains decreased from 11.85 angstrom to 11.07 angstrom as the temperature increased from 20 degrees C to 100 degrees C. Thermal degradation behavior was analyzed by thermogravimetric analysis (TG) coupled with FTIR, and the degradation mechanism function of SCC could be described by G(alpha) = [-ln (1 - alpha)](2/3), and the thermal degradation activation energy was in the range of 163-173 kJ/mol. As the temperature increased, the amino acids in the SCC began to degrade. CO2, NH3, H2O, CH4, NO2 and HCN were released respectively along with various chemical reactions at different temperatures.