Microwave-Annealing Of Potato Starch And Its Application In Extruded Rice

In order to promote the industrial structure of planting industry in China,ensure the security of national grain ration,and improve people's daily dietary structure.Under the background of national potato staple food strategy,in this study,potato starch was used as raw material,and the starch was modified by a physical method-microwave combined with annealing to prepare a green and safe modified potato starch with low peak viscosity,high gelatinization temperature,and easy to be extruded by extruder.By optimizing the technological parameters of potato starch modification,the changes of the structure,physical and chemical properties of potato starch before and after modification were studied,and the potato starch was application in extruded rice to explore the influence of different addition amounts on the quality of extruded rice,which laid a theoretical foundation for the development of potato staple food.The main research contents and results are as follows:1.Referring to the peak viscosity value of rice flour at 2726.00 c P,the effects of different starch emulsion concentration,microwave power,microwave time,annealing time and aging time were studied.The optimal preparation process of low viscosity modified potato starch by microwave-annealing was as follows: starch emulsion concentration was 30%,microwave power was 700 W,microwave time was6 min,toughening time was 18 h,and aging time was 6h.2.The structural changes of modified potato starch was characterized by Fourier transform infrared spectroscopy(FT-IR),differential scanning calorimetry(DSC)and X-ray diffraction(XRD).The results showed that the internal relative crystallinity of modified potato starch was increased by 2.16%,the crystal arrangement was more orderly,the enthalpy value was increased by 1.24J/g,and the structure was more stable.By optical microscope,scanning electron microscope(SEM),laser particle size instrument to observe the modified starch granule surface microstructure and the change of particle size,the gelatinization properties,solubility,swelling and digestibility were also measured,the results showed that the modified starch granule shape consistent with the original potato starch,part of the particle surface was appeared drape rift and particle size was decreased.After gelatinization,peak viscosity was significantly lower,the gelatinization temperature increased significantly,solubility and swelling were decreased,the content of slow digestion starch was increased.3.The extruded rice was prepared by using the optimum modification conditions of modified starch and mixed with crushed rice flour in the proportions of 30%,35%,40%,45% and 50%.The effects of the amount of modified potato starch on the sensory quality,cooking quality,color and texture quality of extruded rice were studied.The results found that,the overall sensory quality score decreased.The water absorption rate and volume expansion rate increased,and the solid dissolution rate of rice soup,namely the cooking loss rate decreased first and then increased.The brightness and whiteness of grains are reduce.In the experiment of the effect of rice cooking on texture quality,with the increase of soaking time,rice-water ratio and holding time,the hardness and chewiness of rice were decreased.Under the same conditions,with the increase of the amount of modified starch,the hardness and chewiness of rice decreased first and then increased.When the modified starch amount was 40%,the hardness and chewiness of the extruded rice were the lowest and combined with the sensory evaluation score,there was no significant difference in the overall sensory evaluation score between the 40% rice with the 30% and 35% rice.