【作者】 王辉；

【导师】 涂宗财；

【作者基本信息】 南昌大学 ， 农产品加工与贮藏工程， 2007， 硕士

【摘要】 动态超高压微射流均质技术是最近二十年刚刚发展起来的一种新型技术，其在食品加工与保藏技术中最具潜力和发展前景。物料在动态超高压微射流均质机的反应腔中受到强烈剪切、高速撞击、剧烈震荡、压力瞬间释放等动力作用，可能会导致生物大分子结构的变化，尤其是蛋白质。针对国内外用动态超高压微射流技术对蛋白质进行改性的研究少、功能性质变化研究深度不够的现状，本论文以蛋清蛋白为研究对象，研究动态超高压微射流技术对蛋清蛋白进行改性后功能性质的变化规律，初步探讨了蛋清蛋白动态超高压微射流技术改性的机理，并对蛋清蛋白经过动态超高压微射流改性后的产物进行了安全性评测。本论文为动态超高压微射流技术的应用提供了一个新领域，为动态超高压均质技术对蛋清蛋白大分子的作用效果提供了一个理论依据，同时为开发研究高功能性的蛋清蛋白提供一种新方法。本论文的实验和研究结果如下：1．蛋清蛋白经过动态超高压微射流不同均质压力处理后功能性质变化如下：随着压力的增大，动态超高压微射流处理对蛋清蛋白的溶解性影响不大，而凝胶性、成膜性、起泡性、流变性得到了改善。2．不同浓度的蛋清蛋白经过动态超高压微射流均质后功能性质变化如下：蛋清蛋白的溶解性随着浓度的增大而略有增大趋势，但是变化很小：2％、4％蛋清蛋白经过动态超高压均质后乳化性增大，6％、8％的蛋清蛋白溶液的乳化性会降低；6％、8％的起泡性优于4％的起泡性；不同浓度的蛋清蛋白经过动态超高压微射流均质后流变特性发生不同的变化。3．不同进料温度的蛋清蛋白经过动态超高压微射流均质后功能性质变化如下：温度会引起蛋清蛋白流变特性发生变化，对其他的功能性质影响不大。4．蛋清蛋白经过动态超高压微射流不同均质次数处理后功能性质变化如下：动态超高压微射流均质次数能使蛋清蛋白溶解性增强，乳化性和乳化稳定性降低，使起泡性略微改善，而蛋清蛋白的流变特性发生了变化。5．蛋清蛋白经过动态超高压微射流均质后粒度及功能性基团的变化如下：蛋清蛋白经过动态超高压微射流均质后平均颗粒尺寸显著减小，蛋清蛋白在160MPa达到最低为229.0nm；蛋清蛋白经过动态超高压微射流处理后，巯基含量随着压力的升高而降低，在160MPa时又有升高；蛋清蛋白表面疏水基团的含量在100MPa时最高；蛋清蛋白的紫外吸收在80MPa时最高：经过处理后蛋清蛋白的DSC曲线波峰均向右偏移。6．蛋清蛋白经过动态超高压微射流均质后二级结构的变化如下：圆二色谱的结果表明，动态超高压微射流处理对卵清蛋白有一定的影响，卵清蛋白的α-螺旋比例在经过普通均质后有了提高，β-折叠因所受处理压力的不同而不同。红外光谱的结果表明，经过动态超高压微射流处理的卵清蛋白在N-H和O-H的伸缩振动峰位发生红移，说明缔合成氢键，在酰胺I带发生蓝移，卵清蛋白的α-螺旋结构或无规则卷曲结构在总比例中得到提高，N-H的特征吸收峰的峰位因压力不同而发生不同的红移或蓝移。7．动态超高压微射流对蛋清蛋白功能性质的影响的机理：致密的蛋白质分子的舒展，致密结构的松弛，大凝聚体被打散成小粒子，亲水活性基团暴露，分子柔性提高，这些变化导致了蛋清蛋白在发挥功能作用时的有效作用力发生变化，从而影响了蛋清蛋白的功能性质。8．蛋清蛋白经过动态超高压微射流均质后产物的安全性评测如下：经过动态超高压微射流均质处理后的蛋清蛋白不影响小鼠的正常生长，没有毒副作用。更多还原

【Abstract】 Micro-fluidization technology is considered as the most potential and promising physical modification technology in the latest food processing and preservation activities. In the process of dynamic ultra-high pressure micro-fluidization, materials received strong shear, high-speed collision, acute shake, the instant release of pressure force and so on, which may lead to the changes in the structures of big molecules, especially in protein. In view of this fact that there are few researches on the application of ultra-high pressure micro-fluidization in the modification of protein, and according to the current situation that the studies on the functional property changes are not deep enough both at home and abroad, this paper focuses on the changes in the functional properties of egg white protein after treatment by ultra-high pressure micro-fluidization, tentatively discussing the mechanism of the modification technology of the micro-fluidization in protein and the safety estimation of the modified products. This paper offers a new approach to the protein modification as well as a new method on the application of dynamic ultra-high pressure micro-fluidization. The experimental results of this paper are hereby showed as follows:1. The changes in the functional properties of the protein after treatment by different pressures are indicated as follows: The solubility of egg white protein changes little with the pressure but the foaming capability, gel property and rheological property have been improved.2.The following is the changes of functional properties of the protein in different concentration after dynamic ultra-high pressure micro-fluidization: The solubility of egg white protein increases with the concentration, the emulsifying properties of 2% and 4% egg white protein increases, while those of 6% and 8% egg white protein decreases, the foaming capability of 6% and 8% egg white protein is better than that of 4% and the flow pattern of different concentration egg white protein is different.3. The changes in the functional properties of the protein in different temperatures after treatment are listed as follows: Temperature causes the changes in the flow pattern of the egg white protein, but leaves little changes in other functional properties.4. The changes in the functional properties of the protein after treatment by different micro-fluidization time are showed as follows: the solubility increases, emulsifying property and emulsifying stability decreases, its foaming capability is improved a little but its Theological property is changed and its flow pattern is also changed.5. Mean particle size and functional groups were changed by dynamic ultra-high pressure micro-fluidization: the mean particle size of egg white protein significantly decreases after the treatment by dynamic ultra-high pressure micro-fluidization. The mean particle size of egg white protein reaches the minimum of 229.0nm at 160MPa. Functional groups are changed by dynamic ultra-high pressure micro-fluidization with their results showed as follows: the -SH content of egg white protein decreases with the pressure at first, then increases at 120MPa and continuously rises up to 160Mpa. The content of surface hydrophobic group of egg white protein reaches the maximum at 100MPa; the UV absorbing intensity of egg white protein is the maximum at 80Mpa, and their DSC’s curve peak moves rightward.6. The changes in the secondary structure of ovalbumin by micro-fluidization are listed as follows: The results of CD spectroscopy show that dynamic ultra-high pressure micro-fluidization has a great influence, theα-helix ratio of ovalbumin increases by normal homogenization, whileβ-sheet ratio decreases. The results of infrared reflectance spectroscopy show that the peak of N-H stretching vibration moves to the low wave number, which confirms that dynamic ultra-high pressure micro-fluidization causes changes in the hydrogen bond of ovalbumin; and the absorption peak of amide group shows thatβ-sheet decreases. Different micro-fluidization pressures make different impacts on the secondary structure of protein.7. The following is the studies on the mechanism of the effect of the dynamic ultra-high pressure micro-fluidization on functional properties of egg white: The macro-aggregation was disrupted smaller particles by dynamic high pressure micro-fluidization. The protein structure was disrupted and co-aggregation which induced the change of the inter-reaction.8. The safety estimation results of proteins after homogenization by dynamic ultra-high pressure micro- fluidization are showed as follows: egg white protein have little influence on the regular growth of mouse and has no adverse effects.更多还原