Kinetic Analysis Of The Thermal Denaturation Of Collagen From Jellyfish(Rhopilema Esculentum) Umbrella

Rhopilema esculentum is widely scattered in China’s coastlines. In China, production of farmed jellyfish reached 67532 tons in 2014, but the high-value utilization rate is still low. The umbrella of jellyfish is rich in collagen, which has highly economic value. Compared with other proteins, the particularity structure and composition of collagen, make it can be widely applied in biomedical materials, cosmetics and food, etc. In this thesis, the heating effect on crude collagen fibers(CCF) and pepsin-solubilized collagen(PSC) from jellyfish umbrella were studied, which can provide thetoratical basis for its high-value utilization.In this study, CCF and PSC were extracted from jellyfish umbrella, and their amino acid composition, swelling form, denaturation temperature and the thermal degradation, as well as the denaturation processes of PSC were analyzed by high performance liquid chromatography(HPLC), scanning electron microscope(SEM), differential scanning calorimetry(DSC), thermo gravimetric analyzer(TGA).CCF and PSC contain higher amout of glycine, 26.17±0.16% and 26.45±0.04%, respectively. The following is glutamic acid, proline, alanine, arginine and hydroxyproline. The amino acid compositons of CCF and PSC have no difference, and they are consistent with the composition of collagen. The PSC swelling effect is better than CCF. In relatively high concentrations, CCF can form dense film, while PSC failed to form and in aggregation state. The denaturation temperature of CCF and PSC were 47.14℃ and 35.22℃, respectively. The thermal stability of CCF is superior to PSC.The thermal degradation process of CCF and PSC from jellyfish umbrella can be divided into two stages: the first stage is mainly about moisture escape from room temperature to 130℃. The second one is from 130℃ to 500℃, in which peptide bonds were broken, and collagen degraded into peptides and amino acids by the effect of heating, then amino acid residues were destroyed eventually by deamination and dehydration. The initial and characteristics decomposition temperature of PSC were lower than CCF. The apparent activation energies of CCF and PSC from jellyfish umbrella in thermal degradation process were 63.10±2.17kJ/mol and 60.25±1.55kJ/mol, respectively, caculated by Horowitz-Metzger method. Compared with CCF, PSC has lower thermal stability, and is prone to thermal. In the process of thermal denaturation, with the decrease of the heating rate, the endothermic peak of PSC gradually moved towards the low temperature area, denaturation temperature decrease. Studies have shown that the regression equation which reaction order is 0.9 can better describe the PSC thermal denaturation process of change. The apparent activation energy of PSC is 481.90 kJ/mol. With the increase of heat treatment temperature, the thermal denaturation rate increased, in the temperature range of 34℃- 39℃.