Application of Differential Scanning Calorimetry to Amaranth Starch Gelatinization – Influence of Water,Solutes and Annealing

Gelatinization phenomena of amaranth starch were investigated using differential scanning calorimetry. Slight variations in onset (To) and peak (Tpl) temperatures were observed at moisture contents over 0.48 g water/g total. However, completion temperature (Tc) increased significantly. The intermediate transition temperature (Tp2) appeared at 0.61 g water/g total and below. The degree of gelatinization decreased by decreasing the moisture content. The three transition temperatures (To. Tpl and Tc) were increased and gelatinization delayed as the concentration of sucrose was enhanced. The three latter transition temperatures tended to increase as the sodium chloride was raised to 0.066 g/g total, but further increases in salt reduced significantly these temperatures. The gelatinization was delayed by increasing the salt concentration. After annealing for 12 h at 25 to 65°C, starch samples exhibited higher To and Tpl values, and narrowed gelatinization ranges. The degree of gelatinization augmented up to the annealing temperature of 55ºC and significantly decreased thereafter.     

Prediction of Degradability of Starch by Gelatinization Enthalpy as Measured by Differential Scanning Calorimetry

It was investigated whether the degradability of starch could be predicted by differential scanning calorimetry (DSC). Degradation of potato starch with a varying degree of gelatinization. of isolated starch of different origins, and of raw materials differing in origin and technological treatment was determined with α-amylase and bovine ruminal fluid. Gelatinization enthalpy and the gelatinization temperature of starch were determined by DSC. There was a good correlation between gelatinization enthalpy measured by DSC and degradation with α-amylase and ruminal fluid for potato starches with varying degrees of gelatinization and for isolated starch granules of different origins. For raw materials of different origins there was a good correlation between gelatinization enthalpy and degradation with α-amylase, whereas the correlation between gelatinization enthalpy and degradation with ruminal fluid was poor. There was a good correlation between gelatinization enthalpy and degradation with both α-amylase and ruminal fluid for (technologically treated) raw materials of one and the same origin. There was no relation between starch degradation and gelatinization temperature.     

Application of Differential Scanning Calorimetry to Starch Gelatinization. III. Effect of Sucrose and Sodium Chloride

The influence of sucrose and salt on the gelatinization endotherm of wheat starch was examined using differential scanning calorimetry. Sucrose was found to decrease gelatinization energy (– ΔH_G) and to increase peak temperature (T_p) as its concentration was increased. Onset and conclusion temperatures (T₀ and T_c) were not affected by sucrose level. The effect of salt on the endotherm was more complex. A decrease in – ΔH_G occurred as the level of this solute in the aqueous phase was raised to 6% but further increases in salt caused it to rise again. Salt levels up to 9% caused increases in T₀ and T_p. With further rises in solute level, T₀ then decreased and T_p remained relatively constant. T_c rose slowly as salt concentration increased.     

Gelatinization Properties of Different Size Classes of Wheat Starch Granules Measured with Differential Scanning Calorimetry

The particle size distributions of wheat starch fractions, obtained after a sedimentation procedure, were characterized with a Coulter Counter. DSC-measurements of the starch samples showed that the small granules gelatinized within a broader temperature interval than the large granules. The gelatinization onset temperature of the small granules was lower, whereas the gelatinization peak temperature was higher compared to the large granules. The gelatinization enthalpy was independent of the particle size distribution. The enthalpy of the endothermic transition due to the amylose-lipid complex was found to be greatest for the small granules.     

Application of Differential Scanning Calorimetry to Starch Gelatinization. II. Effect of Heating Rate and Moisture Level

The influence of heating rate on the gelatinization of wheat starch and starch/water ratio on the gelatinization of wheat, maize, waxy maize and amylomaize starches was examined. More rapid heating resulted in a lowering of the onset temperature of gelatinization for wheat starch from 52 °C at 8°C/min to 46 °C at 32 °C/min. A linear relationship was observed between moisture content and gelatinization energy for starch/water ratios between 1 :2 and 2:1. This allowed calculation of the minimum level of water necessary to initiate gelatinization of each starch. These levels were in excess of the water binding capacity for each starch and were 0.45, 0.45, 0.47 and 0.52 g water/g of wheat, maize, waxy maize and amylomaize starches respectively.     

玉米淀粉的粒度效应对其糊化行为影响研究

研究和探讨了经过机械微细化处理的不同粒度玉米淀粉的糊化特性，结果表明，随着玉米淀粉粒度的降低，其糊化温度下降，糊化温度区间缩小，淀粉糊的粘度下降，但热糊稳定性增加。由于微细化处理后淀粉凝沉性增强，淀粉糊的透明度随淀粉粒度的下降而降低。     

Differential Scanning Calorimetry of Mung Bean Starch

Mung bean starch-water mixtures at water content between 13.6% and 90.2% (volume fraction of water V₁ 0.20 and 0.94) were studied by differential scanning calorimetry (DSC) and subjected to microscopic examinations afterwards. Only a monophasic endotherm appeared for water contents above 67% while for water contents between 67% and 37.3% a biphasic endotherm was found by DSC. No endothermic transition was observed for water levels below 37.3%. The melting temperature of the most perfect crystallites was correlated to the volumetric fraction of water, thus, enthalpy, entropy and extrapolated melting temperature of the transition were calculated.     

Application of Differential Scanning Calorimetry to Starch Gelatinization. I. Commercial Native and Modified Starches

Differential scanning calorimetry has been used to examine the gelatinization behaviour of native starches and modified wheat starches. The results indicated that the shape of the endotherms varied between native starches and also between modified wheat starches. Substitution appeared to decrease both the gelatinization energy and gelatinization peak temperature while the cross-linked starches also displayed lower gelatinization energies but slightly higher peak temperatures. Oxidation, dextrinisation and acid cut wheat starches all posses lower gelatinization energies but higher peak temperatures than unmodified wheat starch.     

Gelatinization of Low Water Content Wheat Starch — Water Mixtures. A Combined Study by Differential Scanning Calorimetry and Light Microscopy

The effect of heating starch-water mixtures of low water content (between 50% and 1.5% water) has been observed by the techniques of both birefringence measurement and differential scanning calorimetry. The temperature at which gelatinization was complete, i. e. at which complete loss of birefringence occurred, increased as the water content was reduced. Complete loss of birefringence occurred over the whole of this range of water content. A correlation was established between the loss of birefringence and passage through the M1 DSC endotherm, assigned to the melting of starch crystallites.     

Differential Scanning Calorimetry Studies on the Crystallinity of Ageing Wheat Starch Gels

The ageing of wheat starch gels stored at 4°C, 21°C and 30°C was examined by differential scanning calorimetry. Kinetics of the crystallisation process were studied using the Avrami model where it was found that the experimental data fitted the model more satisfactorily when the Avrami exponent was less than unity. At higher storage temperature the starch crystals appeared more symmetrically perfect. Addition of wheat flour pentosans to 50% starch gels did not significantly affect the kinetics of ageing. The extent of crystallisation during the ageing process depends on the moisture content of the starch gel. Crystallinity of the starch gel, measured in the temperature range 306–346°K does not occur if the solids content is below 10% or above 80% and a bell shaped curve is obtained. Reduction of the moisture content of the starch fraction of baked goods either directly or indirectly using materials competing for water, might therefore reduce the staling problem.     

高直链玉米淀粉的糊化特性研究

目的研究水浴加热、微波加热和高压加热方法对高直链玉米淀粉糊化性能的影响,为高直链淀粉的进一步开发和应用提供理论基础。方法以高直链玉米淀粉为原料,在过量水分存在条件下,分别采用水浴加热、微波加热和高压加热制备高直链玉米淀粉糊,分别研究不同温度和微波功率下,高直链玉米淀粉糊碘兰值和酶解力随糊化时间增加的变化规律。结果水浴加热、微波加热和高压加热糊化过程中高直链玉米淀粉的碘兰值和酶解力均随时间的延长呈上升趋势,微波加热高直链玉米淀粉糊的碘兰值和酶解力低于高压加热但高于水浴加热,微波加热淀粉的糊化速度大于水浴加热和高压加热。结论高压加热淀粉糊化效果好,淀粉的糊化程度高,是使高直链淀粉完全糊化的较好方法。     

Effect of Moisture on the Thermal Behavior of Strawberries Studied using Differential Scanning Calorimetry

Differential scanning calorimetry was used to determine the thermal transitions in fresh and freeze-dried strawberries and the moisture dependence of these transitions. The freeze-dried strawberry samples had a glass transition at 30–60°C, and the melting endotherm of the dried products was similar to that for freeze-dried sugars. The glass transition temperature of humidified samples was a linear function of the water activity; it decreased with increasing moisture content. Ice was found to melt at a moisture content of 21.4% or above. The melting of ice in strawberries was similar to that in sugar solutions and fruit juices.     

Screening Potato Starch for Novel Properties Using Differential Scanning Calorimetry

Thermal and other physicochemical properties of starch from 42 potato genotypes were studied to find those with unique properties for food use, and to analyze relationships between thermal and other physicochemical properties. Onset and peak transition temperatures and gelatinization enthalpy intercorrelated. Transition temperatures intercorrelated with pasting temperature using a Brabender Visco-amylograph. Gelatinization entbalpy correlated with Brabender pasting temperature and peak paste viscosity, and onset temperature correlated with phosphorus content. Genotype E55–3.5 with highest onset and peak transition temperatures also had highest phosphorus and peak Brabender viscosity. DSC might be useful for rapidly screening samples of <1g starch for such. Potato starch DSC characteristics did not correlate with amylose, intrinsic viscosity, or water-binding. For 10 genotypes from successive years, correlations were observed for pasting temperature (r = 0.83), phosphorus content (r = 0.80), and stability ratio (r = 0.66). Direct comparison between samples from consecutive years showed good reproducibility for amylose, but not for phosphorus or pasting.     

玉米淀粉退火处理及其性质变化

采用扫描电子显微镜(SEM)、激光粒度分析仪(LPA)、X射线粉末衍射仪(XRD)和差示扫描量热仪(DSC)研究退火处理对玉米淀粉颗粒形貌、粒径大小、晶体结构和热力学性质的影响。结果显示:退火处理会改变玉米淀粉颗粒的外貌,使其微孔增多,孔径增大;退火处理会增加玉米淀粉颗粒粒径;退火处理不涉及玉米淀粉晶体结构的变化;退火处理会使玉米淀粉糊化温度显著增高,糊化温度范围变窄;原玉米淀粉(NC)和退火处理玉米淀粉(AC)的溶解度和膨胀率都随着温度的升高而增大,在相同温度条件下,退火处理玉米淀粉(AC)溶解度和膨胀率均小于原玉米淀粉(NC)。     

Scanning Electron Microscopy Studies of Wheat,Potato and Corn Starch during Gelatinization

The gelatinization of a commercial wheat and potato starch and two types of corn starch (Amaizo Amylomaize VII and Amaizo Amioca Pearl starch) was examined by the scanning electron microscope. Concomitantly, the loss of birefringence in the wheat, potato and corn starch was followed with the light microscope. Swelling and deformation of the starch granules observed in the scanning electron microscope correlated with the loss of birefringence in the light microscope. The gelatinization range of the starches was detected with the scanning scope. Swelling of the wheat starch granules was first observed in the larger A-type granules. Amylomaize VII retained granular structure until approximately 95 °C even though birefringence changes were observed as low as 69°C. Some evidence of structural changes were evident at 83°C. Amioca Pearl underwent structural changes at approximately 68°C and abruptly lost granular structure at approximately 71 °C.     

Differential Scanning Calorimetry Properties and Paper-Strength Improvement of Cationic Wheat Starch

Cationic derivatives of normal corn and wheat starch were produced and investigated. Differential scanning calorimetry showed that substitution lowered the starch gelatinization temperature, the gelatinization endotherm, and the temperature of amylose-lipid V-complex dissociation. Substitution lowered the starch-iodine color and inhibited precipitation of the amylose-alcohol complex by standard fractionation techniques. Cationic derivatives of normal corn and wheat starch gave similar improvements in dry strength of paper when added at the wet-end.     

Effects of Annealing and Additives on the Gelatinization,Structure, and Textural Characteristics of Corn Starch

The effects of additives (sucrose, glucose, and sodium chloride) on textural properties of native and annealed corn starch gels were measured using differential scanning calorimetry, X-ray diffraction, scanning electron microscopy, and texture analyzer. Annealing temperature, additive concentration, and pH affected the corn starch gels. Firmness, consistency, cohesiveness, and viscosity values ranged from 20.55 to 43.70 g, 213.67 to 412.00 g/sec, –25.81 to –15.22 g, and –104.21 to –6.73 g/sec, respectively. The eigenvalue of the texture characteristics of annealed corn starch decreased without additives, and increased with additives. Annealing at 55°C had more effect than did annealing at 45°C.     

Subzero Glass Transition of Waxy Maize Starch Studied by Differential Scanning Calorimetry

A mixture of waxy maize starch and water (1:2, w/w) was heated in a differential scanning calorimeter (DSC) pan to different temperatures to obtain different degrees of gelatinization. Each pan was then quenched to ‐30°C and rescanned, and the subzero glass transition temperature (T_g′) of the content was determined. A three‐phase model of a starch granule—a mobile amorphous phase, a rigid amorphous phase, and a crystalline phase—was used to interpret results and explain the glass transitions in starch. Waxy maize starch had an onset gelatinization temperature (T_o) of 61.5°C, peak temperature (T_p) of 70.3°C, and completion temperature (T_c) of 81.7°C. The T_g′ was clearly noted after the starch and water mixture was heated to T_p and T_c, but was small and barely observable when the mixture was heated up to T_o and immediately cooled to ‐30°C. When the starch and water mixture was heated to 55°C, which was 6°C below the T_o, and held for 2 h, a T_g′ was observed. Moreover, T_g′ began to appear and was observable if the starch and water mixture was heated to 10°C below gelatinization onset temperature (51°C) and annealed for 2 h without any gelatinization. Further holding at ‐7°C showed a clear subzero glass transition of annealed native starch granules.     

利用差示扫描量热仪研究小米淀粉及小米粉的糊化特性

采用差示扫描量热仪（differential scanning calorimeter,DSC）研究NaCl添加量、蔗糖添加量及pH值对小米淀粉和小米粉糊化特性的影响,并用SPSS软件进行相关性及显著性分析,将小米淀粉和小米粉的糊化特性进行对比。结果表明：相同测试条件下,小米淀粉的糊化温度（包括糊化起始温度T0、峰值温度Tp、糊化终止温度Tc）比小米粉糊化温度低（2.65±0.87） ℃;糊化热焓值（ΔH）比小米粉高（2.51±0.32） J/g;添加NaCl的小米淀粉及小米粉的糊化温度比添加蔗糖的糊化温度高（4.30±1.24） ℃。酸性条件抑制小米淀粉的糊化作用,碱的存在则促进体系糊化。     

Gelatinization Transitions of Acid‐modified Tapioca Starches by Differential Scanning Calorimetry (DSC)

Tapioca starch was partially hydrolyzed by 6 % and 12 % hydrochloric acid (w/v) at room temperature for various length of time. The gelatinization transitions of the acid‐modified tapioca starches were studied using Differential Scanning Calorimetry. Starch suspensions (67 % moisture) were heated at 5 °C/min to follow melting transition of amylopectin. As the hydrolysis time increased, onset (T_o), peak (T_p) and conclusion (T_c) temperatures of gelatinization have been observed to increase, in the same order of relative crystallinity, until reaching some critical values, then decreased with the large broadening of the endotherms. The increasing of the transition temperatures corresponded to the retrogradation of the remaining partially hydrolyzed amylose followed by a decrease of these parameters corresponding to the reduction of the length of the chains of double helices amylopectin.