Microstructural Change Of Collagenous Tissue Of Sea Cucumber Body Wall During Low-Temperature Heating

The body wall is the main edible part of the sea cucumber,containing abundant collagen,so the change of collagen tissue is closely related with the quality of sea cucumber.The body wall of the sea cucumber is the research object.Investigate the changes in the structure of wall tissues of sea cucumber in the low-temperature heating process,exploring the changing mechanism of sea cucumber collagen in the low temperature heating.Through the light microscope and electron microscope,it was found that with the extension of the heating time,the collagen fibers gradually bend and become thinner and the voids increase,and the final structure disorder and disorder.The content of the GAG in the body wall of the sea cucumber was determined by using DMMB.With the increase of heating temperature and heating time,the content of the GAG increases,showing structure of sea cucumber body wall degraded.Temperature effect on the collagen content of sea cucumber body wall showed that the content of RSF slowly increased by 303.5%,the content of ELF obviously increased by 406.1%,the content of TUF decreased gradually by 33.6%.Differential scanning calorimetry(DSC)analysis revealed the denaturation temperature of sea cucumber body wall was in the range of 45-55 ℃ with an endothermic peak at 51±0.3 ℃.The band change in amide I region of Fourier transform infrared(FTIR)spectra indicated the decrease in α-helix content and possible formation of other secondary structures.Rheological properties measurements indicated storage modulus(G’)changed after heated for 30 min with prolongation of heating time.With increase of heating temperature,the G’ and tanδ began to change slowly from 45 ℃.When the temperature reaches about 50 ℃,both the G’ and tanδ changed significantly,the temperature of the tanδ began to decrease,indicating the tissue of the sea cucumber body wall began to change from sol to gel.Results of NMR spin-spin relaxation time(T2)and MRI suggested that the population of immobile water of gel(A22)increased by 200.7 %,while that of free water(A23)decreased by 7.1%,and the intensity of the T2 weighted images decreased by 14.3% while T1 increased by 20.3% throughout the heating,as compared with unheated sea cucumber body wall.Overall,sea cucumber body wall showed a special thermal denaturation at 45 ℃ for around 30 min.This research provides the information of component and the structural changes in the sea cucumber body wall during the heating process,and offers the theoretic basis for sea cucumber low-temperature processing.