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Effect Of Dynamic High Pressure Microfluidization On Properties And Structures Of Whey Protein

Posted on:2010-05-26Degree:MasterType:Thesis
Country:ChinaCandidate:J Z ZhongFull Text:PDF
GTID:2121360278970900Subject:Food Science
Abstract/Summary:PDF Full Text Request
The productions of whey protein are great in this world; the development and utilization of it has been abstracted by people all the time. The content of protein in whey is very high; how effective use of whey protein in the dairy industry has become urgent problems. Whey protein is the by-product in the production of cheese. Whey protein has been applying in many fields abroadly, just like food, medicine, feeding stuff, cosmetic and others. But, whey protein is one of sensitivity proteins; at some physical and chemical conditions, detrimental changes of their properties are prone to be happened in the processing application, which makes its scope of application to be limited. However, its physical and chemical properties are determined by the structure of whey protein as well as its particle size. Therefore, whey protein was modified by dynamic high pressure microfluidization in this paper. The effect of dynamic high pressure microfluidization on functional properties and its structure of whey protein were studied.The results of study in this paper were as follows:(1)Effect of dynamic high pressure microfluidization on the functional properties of whey protein: solubility, foaming capability and emulsifying stability property of 1%, 2% and 3% whey protein treated by dynamic high pressure microfluidization were improved to a certain extent. At the same pressure, 2% whey protein compared with others can be improved to a better degree. Meanwhile, the rheological model of whey protein was non-Newton fluid. After being dealed with dynamic high pressure microfluidization, the apparent viscosity was increased. DHPM didn't change the non-newtonian fluid property; only can the apparent viscosity of whey protein solution become obviously shear-thinning with shear rate increased after being treated by DHPM.(2) Effect of high pressure microfluidization on the microstructure of whey protein: dynamic high pressure microfluidization treatment was capable of leading the whey protein globle particles to pieces. As a result, the average particle size became smaller and the particle size distribution became narrower. When the pressure was reached 160MPa, the average particle can be the min, which of 2% concerntration WPC treated by DHPM was the minmum value. The average particle reduced to 196.3nm from 407.2nm. As the X-ray diffraction pattern showed, the microcrystal structure of whey protein was damaged, but the degree was not deep. In addition, the thermal analysis results showed that the thermal stability decreased, which illuminated DHPM treatment made the structure of whey protein to be loose.(3) Effect of dynamic high pressure microfluidization on molecular strcture of whey protein: Nearly no changes occurred in subunits and molecular weight of whey protein after being dealed with DHPM; SDS-PAGE showed the straps of whey protein treated by different pressue were not changed. The secondary structure of whey protein treated by DHPM was liitle change; as the infared spectrum showed, after being treated by dynamic high pressure microfluidization, nearly no changes occurred in the secondary structure of whey protein; just characteristic absorption peak showed litter blue shift or red shift after being treated by dynamic high pressure microfluidization technology. However, treated by DHPM, the three-dimensional structure of whey protein has been severely damaged; with the pressure increased, its free sulphydryl content was enhanced to be max at first and then reduced, but the surface hydrophobicity showed the opposite trend. When the pressure was 80MPa, the free sulphydryl content of whey protein can be improved to the max, but the surface hydrophobicity was reduced to the minmum value. In addition, the dynamic high pressure microfluidization technology damaged the surface molecule structure of whey protein; the UV spectrum showed that some conformational changes to the surface region of protein molecule were occurred.
Keywords/Search Tags:dynamic high pressure microfluidization (DHPM), whey protein, functional preperties, srtrcture
PDF Full Text Request
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