The Mechanochemical Effect Of The High Pressure Microfluidization To Rice Amylose

Rice starch as a renewable resource is utilized widely for its peculiar physico-chemical character, and is a good choice to replace traditional nonrenewable resources. But the qualitative of native starch is not very good in many aspects, such as insolubility, easy aging, poor shearing, easy retrogradation in low temperature and poor coating, which is not matching to new facilities and technological operation condition. Now more and more studies is focusing to modify the characteristic of rice starch with physical, chemical and enzymic method to increase some functionality or introduce new characteristics, to accord with industry requirement.Amylose was extracted from long-shaped rice by alkaline, then purified by crystallizing with n-butanol and isoamylol. The amylose was treated with high pressure microfluidization in different pressure (60 MPa,100 MPa,140 MPa and 180 MPa). The grain and molecular structure and their physico-chemical property were studied in this study. The main results in the paper were concluded as follows.1. The grain countenance, particle size distribution, specific surface area, polarized light cross and X-diffraction of amylose before and after treatment with different pressure were determined, which was measured with Scanning Electron Microscope, Laser Granularity, Specific Surface Machine and X-Diffraction Scanner. It showed that the structure of amylose was destroyed after the high pressure microfluidization treatment. Compared with un-treated amylose, the grain was smaller and the specific surface area was bigger. The rice amylose is uncrystallization which was not effected with the high pressure microfluidization treatment.2. The amylose contents molecular weight distribution and infrared spectrum of amylose before and after high pressure microfluidization treatment with different pressure were determined, which was measured with spectrophotometer, gel chromatography and Fourier infrared spectrum. The results showed that the amylose contents increased with the increasing pressure treatment especially with the pressure of 140 MPa. The molecular weight distribution determination was not good. The change from infrared spectrum was not obvious, every specific character functional group still there, and without the absorption peak of new functional groups appearing.3. Some physico-chemical property of amylose was analysed before and after high pressure microfluidization treatment, such as solubility, dilatation, hygroscopicity, retrogradation, clarity, freeze-thaw stability, iodine canister value and rheological characteristic. The results showed that the solubility, dilatation, clarity, hygroscopicity, iodine canister value, zymohydrolysis of amylose increased with the increasing treatment pressure. But the clarity increased first then decreased, the retrogradation decreased and the effect freeze-thaw stability was not obvious. The rheology determination results showed the amylose before treated was non-Newtonian fluids which also showed pseudoplastic fluid characteristic and the flow curve was fixed to the exponent law. The amylose paste had rheopexy at 25℃. The amylose turned to be newtonion fluids with the increasing pressure treatment. The rheopexy of amylose after treatment was weaken in low extent.4. From the above results, we can know influence of the high pressure microfluidization on the functional properties of rice amylase:the HPM treatment could change both the apparent structure and molecular structure, as the granules structure destroyed, granularity grown down, the specific surface area increasing, the amylase content increasing and so on, which lead the physico-chemical characters changed.