| Because of hardly containing amylase, waxy starch can swell more than otherkinds of starch when it is dealt with alkaline, which help theGranular-cold-water-soluble (GCWS) starch preparation. And its physiochemicalproperty is excellent. So it is the raw materials of high quality that can be used for thepreparation of granular-cold-water-soluble starch.In the thesis, the granular-cold-water-soluble starch was prepared by waxy maizestarch and waxy rice starch as raw materials with the method of alcohol-alkaline, andfurthermore, its appearance morphologh and the starch paste's property were studied.On this base,, the effects of etherification reaction and esterification reaction on theproperty of GCWS starch paste were study, using hydroxypropylate and octenylsuccinic anhydride for representative.The main research results are as follows:(1) The effects of the starch suspension concentration, the alkali quantity andthe reaction time on the cold water solution(CWS) of GCWS starch had beenresearched though the single factor experiment. On the base of the single experiment,the regression equation for CWS of waxy maize starch had been gotten by responsesurface experiment. The order of the three factor's significance is: starch suspension＞the alkali quantity＞reaction time, all of their effects were prominence, and all ofthe interaction among the effect of any two on the starch cold water solubility had bepresented conspicuously. The best processing condition for GCWS waxy maize starchhad been attained: the starch suspension, the alkali quantity and reaction time were8.58%, 32.93mL and 17.57 rain respectively, and the cold water solubility of theGCWS waxy maize starch was 93.13%. In the same way, the regression equation forCWS of waxy rice starch had been gotten.The order of the three factor's significanceis: starch suspension＞the alkali quantity＞reaction time, both starch suspension andthe alkali quantity are prominence in the significance. What is more, the interactionamong the effect of starch suspension and reaction time, quantity of alkali andreaction time on the starch cold water solubility had be presented conspicuously. Thebest processing condition for GCWS waxy rice starch had been attained: starch suspension, the alkali quantity and reaction time were 8.08%, 29.87mLand 16.59minrespectively, the cold water solubility of GCWS waxy rice starch was 92.58%.(2) The surface morphology of GCWS was observed by scanning electronmicroscope (SEM). The result showed the granular structure of GCWS waxy maizeand waxy rice starch were still integrity and larger than their nature starch and therewere many pits on the particle surface. The whiteness of GCWS waxy maize and ricestarch was lower than their homologous nature starch, that was been measured by theauto differential colorimeter. The pasting profile of starch was been measured by RVAand it was found that the viscosity of GCWS was lower than the homologous naturestarch. At last, the properties of starch paste of GCWS waxy maize and rice starch hadbeen studied, and the result showed that the transparency, retrogradation stability andfreeze-thaw stability were improved obviously comparing with their nature starch.(3) The waxy maize and waxy rice starch were hydroxypropylated first, andthen be made to be Hydroxypropyl Granular-cold-water-soluble (HP-GCWS) starchby alcohol-alkaline method. The stach cold water solubility, transparency,retrogradation stability and freeze-thaw stability of HP-GCWS waxy maize and waxyrice starch had been measured, all of them were better than their homologous GCWSstarch. The dispersibility of HP-GCWS waxy maize and rice starch were still far frombest, but their viscosity were higher than their homologous GCWS starch.Octenyl succinic anhydride increased both the cold water solubility and viscosityof GCWS, and the emulsion stability of Octenyl Succinic AnhydrideGranular-cold-water-soluble (GCWS-OSA) starch was better than GCWS starchconspicuously. At the same time Octenyl succinic anhydride also increased thetransparency, retrogradation stability and freeze-thaw stability of GCWS waxy ricestarch. But it was reverse for its effect on GCWS waxy maize starch. Compared withGCWS waxy maize starch, the transparency, retrogradation stability and freeze-thawstability of GCWS-OSA waxy maize starch were lower.The surface morphology structure of two kinds of GCWS dual modified starcheswere observed by optical microscope, whose granular structure were integrity, andhad some rip on the particle surface. The study had been carried out by RVA on the rheological properties ofHP-GCWS starch, GCWS-OSA starch and their homologous GCWS starch and theeffect of temperature on their viscosity. The result showed that all of these starcheshad the shear-thinning phenomena, presenting the property of no-Newton typepseudoplastic fluid. Along with the increase of temperature, the viscosity of starchpaste showed a downward trend.
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