Study On The Properties Modification Of High Pressure Microfluidization On Starch

Starch is the main component of fruit,seed,earthnut and tuber of green plants. Itis complexed by CO₂ and water through photosynthesis and it is a crude resourcewhich can not be used up. Starch is wide distributed in plants and its content variedwith breed,weather,soil and other vegetal conditions. Starch is one of the importantnutriments. The energy people need mostly come from the starch in foodstuff.Research and empolder starch resource is one of the hotspots of worldwide research.Rice and corn starch were chosen as the experiments materials. The modificationof high pressure microfluidization (HPM) on starch is studied systematically; theoperating process of Microfluidizer to produce HPM is studied preliminary. Thegranule structure and properties of starch fore-and-aft HPM treatment weredetermined; the HPM treatment has modification effect on the properties of starch,which is drawn by comparing the results. The purpose of this research is to evaluatethe extent of HPM effect on starch and to relate those determined properties back tothe food industry. It also aims to draw a picture of future appliance of modificatedstarch as a new food additive and HPM as a new food processing method. The maincontents and results of this research are mentioned as the following:1. The granule shape,size and structure of starch fore-and-aft HPM treatment werestudied. The results showed that the HPM treatment could obviously effected thegranule structure of starch. Starch granules were fell to pieces after HPMtreatment, the granularity reduced and specific surface area increased as the HPMpressure increased. The polarimetric crosses of starch disappeared and the X-raydiffraction intensity of starch weakened after HPM treatment. The results showedthat the HPM treatment destroyed the crystal structure of starch.2. The properties of starch fore-and-aft HPM treatment was studied. The resultsshowed that the moisture absorption,solubility and dilatability of starch increasedfast at first and then slowed as the HPM pressure increased. The HPM treatmentmade the brabender viscosity,gelatinization temperature and gelatinizationenthalpy of starch reduced and effected the retrogradation of starch. After theHPM treatment, the diaphaneity of starch pastes increased,the sediment volumereduced and the freeze-thaw stability increased. And the results of gel textureanalyzer showed that proper HPM treatment could increase the intensity,viscidity and flexibility,but higher pressure HPM treatment destroyed the granule structureof starch which formed incompact gel structure after gelatinization resulted inreduced intensity,viscidity and flexibility. Thus it can be seen that the propertiesof starch changed after HPM treatment, the HPM treatment could modify theproperties of starch.3. The rheological properties of starch pastes fore-and-aft HPM treatment werestudied. The pastes of starch fore-and-aft HPM treatment were non-Newtonianflow with pseudoplastic flow characters, and their rheological curves could bedrawn up by power function. The HPM treatment made the starch pastes to beNewtonian flow and had good liquidity. With the same shear rate, the apparentviscosity of starch pastes decreased when the HPM treatment pressure increased.The pastes of starch fore-and-aft HPM treatment were shear thinning flow andthixo flow. The pastes of starch after 120MPa HPM treatment were not thixo flowalmost.