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Preparation Of Oxidized Hydroxypropyl Tapioca Starch And Effects On Edible Quality Of Corn Steamed Bread

Posted on:2015-12-15Degree:MasterType:Thesis
Country:ChinaCandidate:L S CaoFull Text:PDF
GTID:2181330467976012Subject:Food Science and Engineering
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The tapioca starch was modified by wet process with the etherifying agent of propyleneoxide. The single factor experiments and orthogonal designs were conducted. The resultsshowed that the amount of propylene oxide, reaction time, alkali dosage and reactiontemperature were major influence factors. The optimal reaction process was conducted with12%of propylene oxide, reaction time16h, the amount of1%sodium hydroxide, reactiontemperature45℃,the results show a degree of hydroxypropyl substitution of0.125.The paste properties such as transparency, retrogradation, viscosity and rheologyproperties and paste properties of different starch products were analysed. Using laser particlesize instrument, polarizing microscope, infrared spectrometer, X-ray diffraction and electronscanning electron microscopy, the particle size, morphology and structure of starch productswere studied. The results showed that the transparency of hydroxypropyl starch were betterthan that of original starch which were enhanced with the increasing of MS. The particle size,polarization cross, and crystalline structure of the hydroxypropyl starches mainly stayed thesame with natively starch. However, introduction of new functional groups and particlemorphology changes happened in the amorphous region during denaturation process inconsideration of infrared spectrogram and scanning electron microscopy photographs.With hydroxypropyl starch as raw material and the sodium hypochlorite as the oxidant,oxidized starch was prepared by wet process. Firstly, the single factor experiments andorthogonal designs were studied, on the basis of the single factor experiments and orthogonaldesigns, The results showed that the optimal reaction process was conducted with the dosageof oxidant(available chlorine of starch quality percentage,%)5%, pH value8, reaction time2h,reaction temperature45℃, resulting Carboxyl group content of0.683%.The paste properties such as viscosity and rheology properties and paste properties ofdifferent starch products were analysed. Using laser particle size instrument, polarizingmicroscope, infrared spectrometer, X-ray diffraction and electron scanning electronmicroscopy, the particle size, morphology and structure of starch products were studied. Theresults showed that with the increase of carboxyl content, pasting peak viscosity and pastingtemperature reduction reduced.With increasing degree of substitution of hydroxypropyl,Increase in peak viscosity, pasting temperature reduced. With the increase in the carboxylgroup content and carboxyl content, products will produce better flow and exhibit lowerstorage modulus and better resistance to aging. The particle size, polarization cross, and crystalline structure of the oxidized hydroxypropyl starches mainly stayed the same withnatively starch. However, introduction of new functional groups and particle morphologychanges happened in the amorphous region during denaturation process in consideration ofinfrared spectrogram and scanning electron microscopy photographs.By analyzing the pasting properties and rheological properties of the mixture of oxidizedhydroxypropyl starch and cornmeal, Found that the viscosity of the mixture below the cornbatter and the storage modulus of the mixture was reduced that storage modulus of cornmeal.By adding oxidized hydroxypropyl starch to corn steamed bread, Found that the eatingquality of corn steamed bread has been improved, especially hardness decreased significantly,But there are still some problems should be solved, for example, the Increased of viscosity.
Keywords/Search Tags:hydroxypropyl starch, oxidized hydroxypropyl starch, corn steamed bread
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