Study On Modifying Starch By Chemical Method And Applications Of The Modified Starch In Food Industry

Applications of natural potato starch and sweet potato starch are confinedto a certain extent because of heat-resisting instability , relative weakacid-resisting and freeze-thaw stability of their paste. On the basis ofcomparing all the making methods of modified starch, SMTP was chosen as across-linking agent to react with potato starch and sweet potato starch in water.Low cross-linked potato starch phosphate ester (PSPE) and sweet potato starchphosphate ester (SPSPE) were prepared by cross-linking reaction. The grainstructure, property of paste , chemical dynamics , LD50 and applications infood of PSPE and SPSPE had been studied systematically in this dissertation.By experiments and research, comprehensive knowledge of characters of PSPEand SPSPE and reaction mechanism of cross-linking reaction had attained. Theresults of this study are not only good for the expanding of application scope ofpotato starch and sweet potato starch, but good for the promotion of modifyingresearch of potato starch and sweet potato starch as well.Main researches are as follows:(1) By FTIR spectra, the molecules of PSPE and SPSPE with phosphatidyl had been proved. By using polarized light microscope and X-ray diffraction apparatus, the structure of the grains of PSPE and SPSPE had been studied. The changes on the surface of the grains of PSPE and SPSPE through cross-linking reaction with SMTP had been discovered.(2) Gelatinization property, transparency, retrogradation and freeze-thaw stability of PSPE and SPSPE were studied. Relations between gel strength of both PSPE and SPSPE and electrolyte as well as non-electrolyte, which are commonly used in food industry, were determined.(3) By studying the influences that pH and SMTP act on the cross- linking reactions of potato starch and sweet potato starch, the cross-linking reaction mechanisms of PSPE and SPSPE were proposed and the chemical reactive velocity equations were determined. The relations between cross-linking reactions and temperatures were studied, meanwhile the activation energy of chemical reactions and apparent frequency efficient of cross-linking reactions were calculated. Technical conditions of preparing PEPS and SPEPS were determined.(4)The proving of security of PEPS and SPEPS for using in food had been carried out. On the premise of security, the applications of PSPE and SPSPE in celery juice ice-cream, jelly and sausage had been studied.