Starch Properties Analysis Of Different Varieties Millet From Different Regions

In the millet includes the carbohydrate，the protein, the fatty acid, the mineral element, hisyellow pigment, the polyphenol and so on.The content of fresh millet per100g was10.60gwater，9.28g Protein，3.68g fat，74.62g starch，21.80mg Ca,0.57mg VB1，0.12mg VB2，268.00mg P.There were7kinds of amino acids in millet protein，of which contained7kinds of essentialamino acids. Millet grain which belongs to traditional material corp of health food has abundantnutrition，medicinal and edible function..In foreign countries，the millet as raw material tointensive processing product is widely used.In domestic，purifies millet,the millet cooked ricecrust are primarily used.Starch was the highest content of millet，Starch is used as a raw material for furtherprocessing and utilization.，its structure and characteristics were critical in the processing. Pastingproperty contributes greatly to applying forceps for contraceptive ring quality of corn starch andplays an important role in starch processing and application. In order to expand the application ofmillet starch, the laboratory-scale method isolating starch is studied, physicochemical properties ofmillet starch are studied. The results provide theoretical bases for the practical use of millet. Themain results are as follows:Former studies indicated that the type of solution、material-water ratio、temperature andrabbling time are the main influencing factors on the extraction rate of millet starch. Singlefactorial experiments were then performed to probe the effects of the concentration of solution、material-water ratio、temperature and rabbling time on the extraction rates of millet starch. At last,orthogonal experiments （L₉3⁴） were carried out based on the results of single factorial experiments.The extraction process of millet starch was optimized by a single factor and orthogonalexperiments，and the results showed that NaOH is0.2%, material-water ratio is1:4, rabbling timeis180min and temperature is35℃. Under this condition, the extraction rates were over70%, and0.1%SDS is better than before.Regular physico-chemical analysis of solubility, swelling power, light transmittance, freeze-thaw stability, Scanning electron microscopy （SEM）, X-ray diffraction（X-RD）, Brabenderviscosity and Differential scanning calorimetry （DSC） were used to research the characterizationof21kinds of millet starch, The main results were as follows:Proximate composition analysis indicated that millet starch contains11.55-15.60%water,73.40%starch，0.28-0.71%protein，0.21-0.55%fat,0.12-0.38%ash,90.90-93.40%whiteness andthe amylose content of millet starch was21.70-27.80%.Scaniing elcetron micrograph of millet starch revealed the most millet starch granules weresmall and round，average particle diameter of the twenty-one starches varied between5.03and11.64μm.The size, shape and distribution showed no significant distinctions between variousmillet starches. X-ray diffraction indicated that Millet starches exhibited strong diffraction peaksat2θwith values of around15.05°、17.23°、17.88°and22.95°.These results indicated that the crystalline pattern of arrowhead starch was A type and the crystallinity of different milletstarches ranged from28.20%to39.70%.Although there were only small differences between the starches in amylose content, theydisplayed significant variability in properties,including solubility，swelling power, pastingcharacteristics and Differeniial scanning calorimetry. The separating water rate of millet starchpaste freeze-thaw one time was obvious.Pasting properties of starches from different curves measured using Brabender showed that.Gelatinization onset temperature of millet starch was ranged68.9℃to72.3℃, Peak viscosityranged425BU to594BU, breakdown viscosity ranged230BU to399BU and setback viscosityranged116BU to469BU.The starch paste had higher peak viscosity and worse cold stabilitywhich was quite easy to retrogradation.Millet starch of the eigenvalue of Differeniial scanning calorimetry were T0（Starttemperature）58.59.49-71.49℃， TP（Peak temperature）69.50-78.43℃,TC（End temperature）79.69-87.34℃，△H（Enthalpy of gelationization）6.97-26.93（J/g）. The onset gelatinizationtemperature determined by DSC was lower than the pasting temperature determined byBrabender.The affection of starch and the pertinences of physical-chemical characters of starch wasanalyzed. The amylose content correlates significantly with freeze-thaw stability and pastingtemperature. The volume median diameter and light transmittance hasn’t significant correlationwith other properties. Crystalline and freeze-thaw stability correlates significantly with pastingtemperature. Solubility correlates significantly with swelling power and light transmittance. TheT0、TPand TCof the twenty-one millet starches relevanced a significant difference. However, nosignificant difference was observed in their enthalpy.