Study On Physicochemical And Digestive Properties Of Millet Starch By Enzymatic And Microwave Treatment

In this study,Dongfangliang No.1 millet was used as the raw material,and millet resistant starch was prepared by enzymatic and microwave treatment.The processing conditions were optimized.The physicochemical properties of millet starch and millet resistant starch were studied,and simulated digestion of the two starches in vitro was performed.,Measure the glycemic index(GI).The findings are as follows1.The physicochemical properties and structure of Dongfangliang millet starch were studied.Millet starch has low light transmittance,poor freeze-thaw stability,fast settling speed,and easy aging.As the temperature increases,the solubility and swelling of starch are increasing.The grain shape of millet starch is complete and the surface of the grain is relatively smooth,and most of them have an irregular oval shape.Granules are mainly composed of large particles and small particles.Starch particles show irregular polyhedrons,and the surface of some starch particles has a depressed pore-like structure to varying degrees.In the functional group region of millet starch,stretching vibration occurs at a specific absorption peak,which corresponds to different groups and chemical bonds of millet starch.Millet starch has strong diffraction peaks at 14.98 °,17.08 °,18.11 °,22.94 °,indicating that millet starch is a type A crystal.2.Based on the results of the single factor test,an orthogonal test was carried out,and the best process for preparing millet resistant starch was obtained: the pullulan enzyme addition amount was 120 U / g dry starch,starch milk mass fraction 15%,microwave The time is 120 s and the enzymolysis time is 12 h.Under these conditions,the average yield of millet resistant starch prepared by repeated experiments was about 8.39%,which was nearly 5.8times higher than the content of resistant starch in the original millet starch.3.Resistant starch has low light transmittance and poor freeze-thaw stability,and the settling property increases continuously with time.Compared with millet raw starch,when the temperature is in the range of 40-60 ° C,the swelling degree of resistant starch is greater than millet raw starch,and the solubility of millet resistant starch is slightly reduced.The integrity of millet resistant starch granules was destroyed,the surface of starch granules was slightly rough,and the new granules had stronger resistance to enzymatic hydrolysis.The strong diffraction peaks of millet resistant starch appeared at 17.0 °,19.4 °,and 22.9 °,indicating that the crystal type of millet resistant starch had changed from type A to type B at this time.The crystallinity is 34.62%,which is higher than that of rice starch 28.36%.There is no significant difference between the infrared spectrum of millet resistant starch and the infrared spectrum of millet starch,indicating that no new groups were formed during the preparation of millet resistant starch.4.The hydrolysis rate of millet starch is higher than that of millet resistant starch.The GI value of millet resistant starch is lower than that of millet starch,which meets the requirements of medium GI food.