Research On The Modification Of Egg White By Dynamic High Pressure Micro-fluidization And Tentative Studies On Its Mechanism

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.