为提高蛋清蛋白凝胶性,本研究以蛋清蛋白(Egg white protein,EWP)为研究对象,通过分析质构、持水率、分子作用力、傅里叶红外色谱、圆二色谱、粒径、电位、巯基含量、表面疏水力及扫描电镜的变化,探究超高压处理(Ultra-high pressure,U...为提高蛋清蛋白凝胶性,本研究以蛋清蛋白(Egg white protein,EWP)为研究对象,通过分析质构、持水率、分子作用力、傅里叶红外色谱、圆二色谱、粒径、电位、巯基含量、表面疏水力及扫描电镜的变化,探究超高压处理(Ultra-high pressure,UHP)、谷氨酰胺转胺酶处理(Transglutaminase,TG)及超高压协同TG酶处理(Ultra-high pressure synergistic Transglutaminase,UTG)的蛋清蛋白热诱导凝胶机理及结构的变化。结果表明:UHP-EWP、TG-EWP、UTG-EWP的硬度、弹性和持水性均有所提高,疏水相互作用力是维持凝胶的主要作用力;UHP-EWP、TG-EWP、UTG-EWP的α-螺旋含量均不同程度下降、β-折叠含量均上升;UHP-EWP的平均粒径值下降、电位绝对值下降,TG-EWP、UTG-EWP的变化与之相反;UHP-EWP、TG-EWP、UTG-EWP的游离巯基含量上升、总巯基含量下降、表面疏水性升高;凝胶结构更加致密光滑,平整度提高。本研究为蛋清蛋白热诱导凝胶改性提供了理论基础及研究思路。展开更多
Graphitized carbon foams(GFms)were prepared using mesophase pitch(MP)as a raw material by foaming(450℃),pre-oxidation(320℃),carbonization(1000℃)and graphitization(2800℃).The differences in structure and properties...Graphitized carbon foams(GFms)were prepared using mesophase pitch(MP)as a raw material by foaming(450℃),pre-oxidation(320℃),carbonization(1000℃)and graphitization(2800℃).The differences in structure and properties of GFms prepared from different MP precursors pretreated by ball milling or liquid phase extraction were investigated and compared,and semi-quantitative calculations were conducted on the Raman and FTIR spectra of samples at each preparation stage.Semi-quantitat-ive spectroscopic analysis provided detailed information on the structure and chemical composition changes of the MP and GFm de-rived from it.Combined with microscopic observations,the change from precursor to GFm was analyzed.The results showed that ball milling concentrated the distribution of aromatic molecules in the pitch,which contributed to uniform foaming to give a GFm with a uniform pore distribution and good properties.Liquid phase extraction helped remove light components while retaining large aromatics to form graphitic planes with the largest average size during post-treatment to produce a GFm with the highest degree of graphitization and the fewest open pores,giving the best compression resistance(2.47 MPa),the highest thermal conductivity(64.47 W/(m·K))and the lowest electrical resistance(13.02μΩ·m).Characterization combining semi-quantitative spectroscopic ana-lysis with microscopic observations allowed us to control the preparation of the MP-derived GFms.展开更多
文摘Graphitized carbon foams(GFms)were prepared using mesophase pitch(MP)as a raw material by foaming(450℃),pre-oxidation(320℃),carbonization(1000℃)and graphitization(2800℃).The differences in structure and properties of GFms prepared from different MP precursors pretreated by ball milling or liquid phase extraction were investigated and compared,and semi-quantitative calculations were conducted on the Raman and FTIR spectra of samples at each preparation stage.Semi-quantitat-ive spectroscopic analysis provided detailed information on the structure and chemical composition changes of the MP and GFm de-rived from it.Combined with microscopic observations,the change from precursor to GFm was analyzed.The results showed that ball milling concentrated the distribution of aromatic molecules in the pitch,which contributed to uniform foaming to give a GFm with a uniform pore distribution and good properties.Liquid phase extraction helped remove light components while retaining large aromatics to form graphitic planes with the largest average size during post-treatment to produce a GFm with the highest degree of graphitization and the fewest open pores,giving the best compression resistance(2.47 MPa),the highest thermal conductivity(64.47 W/(m·K))and the lowest electrical resistance(13.02μΩ·m).Characterization combining semi-quantitative spectroscopic ana-lysis with microscopic observations allowed us to control the preparation of the MP-derived GFms.
