Studies On Preparation And Properties Of Ultrafine Rice Starch

ultrafine powder was popularly paid attention to because of its unique property. Its preparation, characteristic and application were gradually put into research. ultrafine rice starch, nanometer starch, was obtained with rice by ball-mill. Molecular, crystal, thermodynamic and pasting characteristic and shape of prepared rice starch at the granularity of 50~5000nm were studied. The study has greatly academic and practical significance for making full use of rice, exploiting new nanometer material, accelerating nanometer technology and so on. Major conclusions are as follows:1. Ultrafine starch prepared by ball-mill was better than that by airflow grind and colloid mill. Optimum ball-mill technics was absolute ethanol as medium, the ratio of ball to material 5:4(w/w), the ratio of the number of big balls(Φ13mm) to small balls(Φ6mm) 7:3, and rotating speed 500r/min. Starch granularity less than 100nm.2. Starch granule firstly cracked, and then part of starch flaked away. The granularity of starch became smaller and smaller, and then the starch at small diameter aggregated gradually.3. During ball milling, degree of crystallinity decreased gradually. Crystal disappeared after ball-mill for 20h.The starch could gelatinize at room temperature after 75h. Molecule chain of starch was ruptured and small molecule was increased by ball-mill to some degree.4. With the granularity of starch decreasing,BV, hygroscopic moisture content, transmittance of starch, soluble protein, amylase susceptivity and stability of starch paste all increased, peak time, pasting temp of starch, and. peak paste, host paste, final paste, breakdown and setback of starch paste reduced . These parameters were stable after milling for 20~30h.5. Starch paste was pseudoplastic fluid. With the granularity decreasing, viscous coefficient decreased ,while rheologic index gradually increased and approached to the characteristic of Newtonian fluid. And the stability to temperature and concentration increased.6. With the granularity of starch decreasing, hardness and elasticity and stickiness ofstarch gel decreased. Stability of milled long time starch was bad when they were stored in low temperature.