| The physicochemical properties, gelatinization mechanism, retrogradation mechanism of lotus root starch were studied with X-diffraction, Dynamic Dheometer, revolving viscosity, Differential Scanning Calorimeter and Gel Permeation Chromatography.1. Starch from lotus root was separated by repeatedly water washing. With the method of complexing structure, Amylose and amylopectin had been successively separated and purified. The purity of lotus root starch and fractions were confirmed by Gel Permeation Chromatography and UV-Vis scans of their complex formed with iodine.2. Observed with optics microscope and SEM, Granules of Lotus root starch had two kinds of shapes: round and elliptic. Measured with optics microscope, round and elliptic granule size was 14.3um and 61.48μm, respectively starch granularity was 33.278μm (d(0.5))measured with Laser Light Granularity Analysis.3. Measured with Maltese cross disappearance, gelatinization temperature of lotus root starch was from 65.8℃ to 73.8℃. DSC spectrum of lotus starch showed that the gelatinization temperature was from 63.5℃ to 74.7℃. The dynamic rheology results revealed that the gelatinization temperature range was from 60.1℃ to 66.2 ℃.4. X-diffraction spectrum showed that the crystal structure of lotus root starch was B type, while amylase's was V type and amylopectin had no crystal structure. DSC spectrums of lotus root starch and fractions indicated that their crystal melt temperature and initiative vitrification temperature were relatively close to each other, but their crystal melt energy had great difference.5. The result of freeze-thaw stability experiments showed that lotus root starch paste had weak freeze-thaw stability. Glyceryl monostearate and CMC could reduce its freeze-thaw stability, cane sugar and salt could enhance its freeze-thaw stability, while phosphate and Xanthan Gum had no bad effect.6. The result of rheology showed that lotus root starch paste belonged to non-Newtonian fluid and had pseudoplastic characteristics. The paste had strong thixotropy and was easy to shear-thinning. Concentration and temperature could significantly influence the rheology of lotus root starch paste, but pH couldn't. Glyceryl monostearate, cane sugar and phosphate could weaken the rheology of lotus root starchpaste, but CMC, salt and Xanthan Gum would enhance the rheology.7. Through measuring the swelling properties, BV values, EH values and crystal properties of lotus root starch paste during gelatinization, Granule swelling, crystal melting and amylose divorcing were proved to be the essence of lotus root starch gelatinization. When lotus root starch was gelatinized in excessive water, the multiphase system was formed which included continuous phase of Am solution and disperse phase of Ap conglomeration.8. Through measuring the transparence ratio and the sedimentation ratio of lotus root starch paste, BV values, EH values and recrystal properties of lotus root starch paste and gel during storage, the retrogradation essence of lotus root starch was proved to be vitrification temperature ascending, molecular agglomerating and rigidity increasing and weak recrystal could accelerate retrogradation.
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