The Influence Of Ultrasonic On Aggregation State Structure Of Cornstarch And Assist Of Chemical Modification

With the development of ultrasound in the food industry, the use in modified food ismore and more popular, in this paper, the influence of ultrasonic treatment on aggregationstate structures of starch granule was studied. The conclusion indicate that with the increase ofhydrolysis rate(under ultrasonic power of1000w and different ultrasonic time), the molecularweight of starches are reduced gradually, at the same time, the value of amylose/amylopectinincreased obviously. The reason may be as follows: the mechanical, ultrasonic cavitationeffect and oxidation of the ultrosound can damage the starch granular, which lead to pores orfissures on the surface and cut the amylose, the longer of the molecule line of amylose, theeasier to be cut off. α-1,6glycosidic bond of amylopectin was easily damaged by ultrasonic, andresult in the reduction of molecular weight of amylopectin and increasing of Amylose content.This is the first report that ultrasonic was applied in the esterification of normal cornstarch and OSA, the reaction condition has been reported that temperature controlled around35±1℃, pH controlled from8.0-8.5and OSA was added at a3%level(relative to the starchdry basis). Ultrasonic of50-1000w were chose in this research, stop the reaction when the pHdo not change in30min. the conclusion show that when the ultrasonic power come to500w,the degree of substitution went the peak of0.02145and reaction efficiency(RE) reach92.46%,compared with the condition that without ultrasonic, DS and RE was improvedapparently(without the assistant of ultrasonic, DS equals0.01758and RE equals75.78%) aswell as the reaction time was shorten from6.5h to1.5h. this is caused mainly by two sections:the OSA which is Hydrophobic dispersed by ultrasonic, as a result, accelerating the reaction.The next section is the starch structure become loose under the impact of ultrasonic, and theOSA droplet got more chance to act with the starch and may be have opportunity to thecrystalline region, so the DS and RE was improved.In this study, the distribution of OS groups in the starch granules was investigated usingCLSM after being stained MB+dye and confirmed the distribution of OS groups. The DS ofOS-Starch was measured after acidolysis, as well as Infrared spectrum to check the amount ofresidue of the OS group, then can confirm if the OS group enter into the crystalline region.