Preparation And Studies Of Irradiated And Oxidized Starch

The preparation of potato starch irradiated with 0-25 kGy, oxidized potato starch and irradiated and oxidized starch were studied in this paper, then the SEM picture and structural properties of the modified starches were deeply researched, finally the effect of the compound of irradiation oxidized starch and hydrophilic colloid on steamed bread quality characteristics.Reduced whiteness and color were found in potato starch after the irradiation treatment, especially the 20 KGy irradiation treatment. The results of the rheological properties of potato were shown as follow. It was found that potato starch paste was pseudoplastic fluid characteristics after different irradiation treatment. The apparent viscosity and shear thinning of starch paste decreased gradually with increase of the irradiation. Compared to the native starch, peak viscosity, setback and retrogradation property of the irradiation starches decreased, transparency, fluidity and stability of starch paste increased. Besides, it was found that surface smoothness and particle integrity were not destroyed and the polarization cross of starch particle was still exist and the crystallinity of starch decreased by electron microscopic scanning, polarizing microscope and X-ray diffraction determination.The next research use the potato starch as raw material and sodium hypochlorite as oxidizing agent to prepare potato starch of various oxidized level, through single factor and orthogonal optimization. The results declared that the biggest effect of available chlorine content on reaction, next for PH, temp, time. The optimal conditions: pH=8, 35 ℃, 3hr, 5%. Reduced peak viscosity, pasting temperature and setback and increased fluidity were found in starch sample after oxidation treatment. It was found that surface smoothness and particle integrity were not destroyed and the polarization cross of starch particle was still exist and the crystallinity of starch decreased by electron microscopic scanning, polarizing microscope and X-ray diffraction determination after oxidation treatment, which was consistent with the results of irradiation treatment.The thirdly research use six different irradiation dose of potato starch as raw material to prepare potato starch of various oxidized and irradiation level, through optimal conditions 1(pH=7, 25℃, 2h, 3%) and 2(pH=8, 35 ℃, 3h, 5%). With the increase of irradiation dose, the starch viscosity decreased and the crystallinity increased under the same degree of oxidation. The results of static rheological properties were shown as follows: the apparent viscosity and the degree of shear thinning of irradiation oxidation starches decreased. Compared to the native starch, the enthalpy, freeze-thaw stability, pasting temperature and transparency of irradiation oxidation starches increased and peak viscosity decreased. X-ray diffraction pattern showed that irradiation oxidation starch and native starch were both B-type crystal, the effect of irradiation oxidation on crystalline structure was not big.Studied with irradiated and oxidized potato starch, konjac flour, carrageenan and sodium carboxymethyl cellulose starch of different mix proportion added to flour, to make steamed bread, to measure dough stickiness and hardness, and height to diameter ratio, volume, chroma, hardness and elasticity of steamed bread. The results showed that adding compound improvers can improve the viscosity and elasticity of the dough. At the same time, it can also improve height to diameter ratio, volume, color of steamed bread, and greatly improve the comprehensive quality of steamed bread. The results of this article is mainly for the production with high storage stability, and provides the theory basis for good quality modified potato starch. At the same time, there is important guiding significance in determination and application development of irradiated and oxidized starch.