Study On The Aggregation Structure And Properties Of Non-crystallization Granular Rice Starch And It's High-efficient Preparation

The crystallinity and granular structure of starch is the base of the applications of starch gelatinization,retrogradation and plastification.Also it has become one of the research hot spots.It possesses both theoretical and practical significance to change the crystallinity of granular starch and turn its crystalline structure into non-crystalline structure through physical or chemical methods,so as to better its solubility,rheological property,biological application and reaction activity.In this research,with rice starch selected to be the experimental material,noncrystallized granular rice starch was prepared by high-frequency vibratory refrigerative ball milling.Polymer research methods and modern instrument analysis techniques(such as ESCA,SEM,DSC,IR,XRD) were used to do the research.Surface morphology and particle size distribution of the noncrystallized granular rice starch were characterized,the influence of mechanochemical effect on the aggregation structure of starch was researched,and how the change of the crystal structure affected the physical and chemical properties as well as the reaction activity of starch was examined.The main results and conclusions are as follows:1.High-efficient Preparation of the noncrystallized granular rice starch by refrigerative ball millingThe rice starch was treated in the high-frequency vibratory refrigerative ball mill for 5h,10h,20h and 40h,thus the samples of noncrystallized granular rice starch with different ball-milled treatment time were made.SEM was used to observe the samples' surface morphology and Laser Particle Size Analyzer was used to measure the particle size distribution.XRD was used to analyze the crystal structure and crystallinity.It showed that being treated in the high-frequency vibratory refrigerative ball mill,rice starch can be made into noncrystallized granular rice starch high-efficiently,the crystallinity of the rice starch decreased to 10.78%only after 20 h ball-milled treatment. After being treated by refrigerative ball milling,the rice starch granules cracked and the particle size increased remarkably—the particle size doubled after 20 h ball-milled treatment.The shape of the starch granule became irregular and the surface turned rough. As the ball-milled treatment time last,the particle size increased a step further,because it was easier for the tiny starch particles assembled. 2.The influence of mechanochemical effect on the primary structure and the thermal characteristics of the noncrystallized granular rice starchRefrigerative ball milling caused the intrinsic viscosity of rice starch and its component amylopectin and amylase decreased,and it showed that the amount of space occupied by the starch and its components reduced,the molecular weight dropped, especially the amylopectin.As the crystal structure mianly exists in amylopectin, therefore refrigerative ball milling destroyed the crystal structure heavily.FT-IR showed that there were almost not any changes in molecular structure and functional group for noncrystallized granular rice starch,compared with native rice starch.ESCA discovered that being treated by refrigerative ball milling,the atom composition,component and binding energies of the starch surface had not been changed.It showed that refrigerative ball milling had no effect on the molecular groups of the samples,but enhanced the degree of surface roughness.DSC analysis revealed that the starch-water crystal was damaged by refrigerative ball milling treatment and became less;the starch-starch crystal melting temperature and thermal decomposition temperature did not change in evidence, but the endothermic enthalpy went down remarkably.3.Structural explanation of physical and chemical properties and reaction activity of the noncrystallized granular rice starchThe adsorption ability and water-combining ability of the noncrystallized granular rice starch were strengthened,the hydroscopicity,solubility and dilatancy of the noncrystallized rice starch increased;the reaction activity was enhanced,and so did the enzymatic hydrolysis rate;the iodine-combining ability decreased,the blue value went down.These changes can be attributed to the noncrystallized treatment and drop in the molecular weight.Rice starch being treated by the way in this research is of great significance in manufacturing infant rice flour food.High-frequency vibratory refrigerative ball milling is an effective method for preparing noncrystallized starch and granular cold-water soluble starch.The innovation and significance of this research were that rice starch with rich sources was selected to be the experimental material,high-frequency vibratory refrigerative ball mill was used for the first time to prepare the noncrystallized granular rice starch at the temperature of -4℃.The study focused on the change of the aggregation structure of noncrystallized granular rice starch and how these changes affected the physical and chemical properties and reaction activity of the starch.The method used in this research was proved to be a simple,easy and high efficienct way to make noncrystallized starch;this research also provided a clue and new thinking for the application of rice starch.