Effect Of Ultra-high Pressure Treatment On Quality And Structure Of Sheep Bone Collagen

Sheep bone as the test material,using ultra-high pressure assisted ethanol degreasing,ethanol degreasing as the control,to analyze the chemical composition and morphology of two kinds of sheep bone.Sheep bone collagen was extracted by enzymatic acid method and identified and analyzed.The effects of ultra-high pressure treatment on collagen extraction rate,thermal properties of collagen and pyridine crosslinking properties of sheep bone were studied.The test results are as follows:Through single factor and response surface experiments,the optimal degreasing process of sheep bone was determined,which was as follows: ultra-high pressure 300 MPa,holding time 8min,solid-liquid ratio 1:20g/m L.Under these conditions,the actual degreasing rate of sheep bone reached 95.58%(P<0.05).The composition and microstructure analysis showed that the fat content of ultra-high pressure skim sheep bone was significantly lower than that of ethanol-treated skim sheep bone,and the protein and collagen content of skim sheep bone were higher than that of ethanol-treated skim sheep bone.Infrared spectrum showed that the chemical structure of sheep bone did not change significantly under the two treatments,but the ultra-high pressure skim sheep bone had no obvious peak value at 2850 and 2919cm-1,indicating that its oil was completely removed.Through single factor and orthogonal experiments,the optimal extraction parameters of collagen from sheep bone were determined as follows: enzyme dosage 6%,extraction time 24 h,solid-liquid ratio 1:15g/m L,and the extraction rate of collagen was only 35.23%(P<0.05).Under the optimal basic technological conditions,the results showed that the maximum extraction rate of collagen reached 63.27%(P<0.05)when the ultra-high pressure was 300 MPa and the holding time was 8min.Ultra-high pressure extraction was28.04% higher than the basic extraction method.The collagen extracted from sheep bone was analyzed by SDS-PAGE gel electrophoresis,ultraviolet spectrum and infrared spectrum.The results showed that the sheep bone has three helical structure of collagen,accord with ? type collagen characteristics.The ultra-high pressure treated and untreated sheep bone collagens were analyzed by electron microscopy and thermal stability(DSC).The results showed that the structure of untreated sheep bone meal collagen was loose.Ultra-high treated collagen polymerizes briefly when the pressure is 100-300 MPa.When the pressure exceeds 400 MPa,collagen unfolds again,indicating that ultrahigh pressure destroys the tertiary structure of collagen.The denaturation temperature of collagen treated by ultra-high pressure was 31.7?,while that of untreated collagen was 44.9 ?.The results indicate that ultra-high pressure treatment can reduce the thermal denaturation temperature of collagen.The relationship between ultrahigh pressure and collagen pyridine cross-linking properties was studied by double antibody sandwich method.The results showed that HP and LP were negatively correlated with ultrahigh pressure and holding time.