Modification Of The Preparation Of Pre-gelatinized Starch And Its Application For Frozen Noodles

In this work, the cassava starch was used to produce the hydroxypropylated cassavastarch with freeze-thaw stabilization. Then, hydroxypropyl starch, cassava starch, as rawmaterial， prepared pregelatinized hydroxypropyl starch, pre-gelatinized starchFreeze-thaw stabilization and molar substitution of hydroxypropylated as criterion，theconcentration of starch slurry, amount of propylene oxide, reaction temperature, reaction time,dosage of NaOH, dosage of Na2SO4which effected on cassava starch were studied. Thefollowing optimum conditions were obtained:40%of starch slurry,12%of propyleneoxide,1.3%of NaOH,14%of Na2SO4at45℃for20h. On this condition, freeze-thaw SWVof starch is35.1%, and molar substitution is3.4%. Freeze-thaw stability and gelatinizationdegree as indicators, pasting time, the mass fraction of the starch slurry, the starch slurry pHvalue, gelatinization time, gelatinization tempreture were researched for pre-gelatinized andpregelatinized hydroxypropyl starch. The optimum condition were determined for thepreparation of freeze-thaw stable starch: Gelatinization temperature of95°C,gelatinizationtime3h,the mass fraction of the starch slurry is5%, the starch slurry pH8. For pregelatinizedstarch, the SWVe is15.4%, the gelatinization degree to85.0%.For pregelatinizedhydroxypropyl starch, the SWVe is8.6%, the gelatinization degree to87.0%.Hydroxypropyl starch, pre-gelatinized hydroxypropyl starch, pre-gelatinized tapiocastarch structure have changed greatly. After pre-gelatinized and hydroxypropyl starch canreduced the viscosity of the starch RVA. Native starch had peak viscosity. Hydroxypropylstarch and the molecular structure were completely destroyed. After compared to the physical,chemical denatured starch thermal stability of the original cassava starch are better. Afterdenaturation of starch, the microscopic structure of the starch has undergone great changes.Starch, IR spectra and X-diffraction can be found, as compared with native starch,hydroxypropyl starch, crystalline structure becomes more stable, however, smaller crystallitesize, the crystal becomes less. Pregelatinized hydroxypropyl crystal structure is completelydestroyed.The cassava starch, hydroxypropyl starch, pregelatinized starch and pregelatinizedhydroxypropyl starch were added to flour to antifreeze better prepared frozen noodle.Determined by measuring the texture quality changes. First, the measured optimum amount of the various starch, best starch is then added to the frozen noodles, for a period of6monthsstorage experiments, and the determination of changes in the process of storage, the frozennoodle. The conclusion is as follows:Optimum adding amount of Starch was4g; optimal addition amount of hydroxypropylstarch, pregelatinized starch was8g; optimum amount of pregelatinized starch, pregelatinizedhydroxypropyl starch was6g. By comparison of TPA hardness, shear force, the change of theelastic strength, the two has good influence on the quality of frozen noodle starch ishydroxypropyl starch and pregelatinized hydroxypropyl starch.These two optimal starch, blank and potato starch (8g) were added to the frozen noodleNoodle texture quality determination of6months are as follows:TPA hardness, shear force and elastic strength of frozen noodle in the long-term storageconditions are worse. Wherein obvious change after1week. And hydroxypropyl starch,pre-gelatinized hydroxypropyl starch frozen noodle texture quality and blank frozen noodletrends, but flexible than the blank somewhat less.