Viscosity and Gelatinization Characteristics of Hydroxyethyl Starch

Viscosity and gelatinization characteristics of corn and potato starches as well as their hydroxyethyl derivatives were investigated. The inherent viscosity increased from 164 in native corn starch to 209 in etherified one of DS 0.18. The etherified corn starch gelatinized at lower temperature than native corn starch due to their increase of DS. Maximum viscosity decreased from 93°C to 69°C for the modified corn starch. The retrogradation of starch was minimized by etherification as retrogradation ability of corn starch from its solution decrease from 22% to 6%. This is of great importance when starch is used as blood plasma volume expander. Variable results were obtained with etherified potato starch which might be due to its high contents of phosphorus.     

Chlorination of Cake Flour and Its Effect on Starch Gelatinization

The influence of a defined chlorination on the gelatinization behaviour of different cake flours in sucrose solutions (30–60% w/w) was investigated. Besides microscopic examinations, methods were developed for the estimation of hot paste viscosity and “amylose”

1 “Amylose” will throughout this paper mean linear polymers of glucose long enough to give a blue colour with iodine, but not necessarily native amylose as exists within the starch granule.

exudation from starch granules. The findings have shown that the amount of “amylose” which is exuded from starch granules during heating, as well as paste viscosity, increases with the chlorination of flour. High positive correlations were obtained between “amylose” exudation, hot paste viscosity and cake crumb firmness. It is proposed that this increased “amylose” exudation is, via an increase of gel strength, to a large extent responsible for the prevention of high ratio cake collapse. Besides reducing “amylose” exudation the high sucrose concentrations prevailing in cake batters were also found to inhibit greatly starch breakdown by malt and fungal amylase activity.     

Flow Behavior and Gelatinization of Cowpea Flour and Starch Dispersions

The flow behavior of a 25% cowpea slurry with 8% oil held at 70°C showed shear-thinning behavior and an Arrhenius temperature relationship. Cowpea flour (8%) and starch (2.5%) slurries heated for less than 1 min at 70–87°C exhibited shear-thickening while those heated longer times exhibited shear-thinning behavior. Maximum viscosities attained due to heat-induced gelatinization showed a power relationship with temperature of heating. Starch gelatinization kinetics followed a first-order equation and the temperature dependence of the rate constant followed the Arrhenius relationship with an activation energy of about 47.4 kcal/mol. Heating the slurries for >200 min above 80°C resulted in loss of viscosity.     

四种酯化交联木薯变性淀粉的粘度和糊化温度研究

分别选取国内外四种不同产地的木薯原淀粉,采用Brabender粘度仪和NDJ-79型粘度仪对这四种木薯淀粉原料及其乙酰化己二酸双淀粉酯的粘度及糊化温度等指标进行分析:广西产的木薯原淀粉具有的较高峰值粘度和较低的糊化温度。在同一工艺条件下,不同产地的木薯淀粉原料对变性淀粉的影响最大。     

莲藕淀粉糊化温度测定方法的比较

采用三种方法对莲藕糊化温度进行测定,实验显示:偏光十字消失法测得莲藕淀粉的糊化温度为63.8～71.8℃,该法操作简便,具有较好的重现性和一定的准确性;动态流变仪法测得糊化温度为60.1～66.2℃,准确性高,重现性好,测得的糊化温度范围较小,是相对精确的方法;差示扫描量热分析法(DSC)图谱法测得糊化温度为63.5～74.7℃,温度范围相对较大,并可以较全面地反映淀粉的糊化特性。     

淀粉类浆料的粘度测定

探讨了影响淀粉类浆料浆液粘度测定值的各因素,指出了提高测试数据准确性和可比怀应该注意的一些问题,从而使得测试方法进一步规范化     

部分糊化淀粉浆液黏度与浆液性能相关性分析

探讨部分糊化淀粉浆液黏度对浆液性能影响的规律。以玉米淀粉为原料,采用蒸汽升温方式分别在62℃~67℃制备了6种不同黏度的部分糊化淀粉浆液,对浆液的黏度、糊化度、结晶度、粒径和膨胀势进行测试,并应用SPSS统计软件的相关分析与线性回归分析功能对测试结果进行了相关性分析。结果表明:部分糊化淀粉浆液的黏度与结晶度呈负相关,结晶度随黏度的增大而降低;黏度与平均粒径、膨胀势呈极显著正相关,平均粒径和膨胀势值均随黏度的增加而明显增大;黏度与平均粒径、膨胀势呈明显的线性关系。认为通过相关性分析可以建立起部分糊化淀粉浆液的评价分析方法,运用此方法,可以直观、有效地对部分糊化淀粉浆液黏度性质进行评价分析。     

Production and Measurement of Starch Damage in Flour. Effect of Starch Damage on Hot Pasting Properties

Aqueous suspensions were made of wheat starches damaged, by different methods, to varying degrees. Apparent viscosities of the hot pastes declined as damage levels increased and the relationships between these factors were examined. Measured as “extractability”, starch damage had a linear relationship with apparent viscosity for starches damaged by both methods. Starch damage measured as “digestibility” had different relationships with apparent viscosity for each type of damage involved. Evidence was found for the association of amylolytic enzymes with the starches used in the experiments.     

不同糊化度马铃薯淀粉的黏度及凝胶特性分析

为探究不同糊化度马铃薯淀粉黏度及其凝胶特性的差异,本研究将马铃薯淀粉乳(料液比1:9)分别置于59℃和60℃条件下加热1、3、6、9、12、15、18 min,制备出糊化度为38.70%～91.13%的马铃薯淀粉样品。测定了不同糊化度马铃薯淀粉的黏度,微观结构,凝胶强度及弹力,并分析了马铃薯淀粉理化特性与其糊化度的相关性。结果表明,随水热处理温度升高和时间延长,马铃薯淀粉颗粒逐渐破裂,椭圆形特征形貌逐渐消失。马铃薯淀粉黏度,凝胶强度及弹力与其糊化度有显著的线性相关性(p0.01)。随糊化度的增大,预糊化马铃薯淀粉黏度由0.17m J增加至3.40m J。未经二次加热的不同糊化度马铃薯淀粉凝胶强度和弹力随初始糊化度的增大而显著增大,但经二次加热完全糊化的马铃薯淀粉凝胶的强度和弹力随初始糊化度的增大而显著降低。不同程度的预糊化处理显著改变了马铃薯淀粉的黏度及凝胶特性。     

The Effect of Barley β-Glucan Fiber Fractions on Starch Gelatinization and Pasting Characteristics

ABSTRACT: We evaluated the effects of extraction treatment on the yield and composition of β-glucan-rich fiber fractions from barley, and the subsequent influence of these fractions on the thermal properties and pasting behavior of starch pastes. Extraction treatment affected the yield of barley β-glucan (BBG) fiber fraction, and β-glucan recovery efficiency ( P < 0.05). The level of inclusion of these fractions in starch-water dispersions had a significant influence on the pasting characteristics such as peak viscosity (PV), breakdown (BD), and final viscosity (FV) development (as determined using a Rapid Visco Analyser). Substitution of 5% wheat starch with the fiber fractions decreased PV, BD, and FV in comparison to the control starch ( P < 0.05). Substitution of 5% wheat starch with BBG fiber fraction resulted in a decrease in enthalpy (J/g) values compared with the control ( P < 0.05). A reduction in pasting characteristics may be associated with a reduced enthalpy of starch gelatinization and retention of the integrity of the starch granule. The reduction in PV may also indicate a reduced degree of starch granule swelling.     

Effects of Organic Molecules on the Gelatinization Temperature of Starch

The effects of organic molecules on the gelatinization temperature of starch in water seem to stem from the electron polarizability of those organic molecules. The same fundamental characteristic is the basis of the explanation for the effects of anions on the gelatinization temperature. The proposed hypothesis is capable to explain the familiar phenomena which arise from the interactions between starch and electrolytes.     

Wet Method for Measuring Starch Gelatinization Temperature Using Electrical Conductivity

ABSTRACT:  The objective of the present study was to develop a method for obtaining the gelatinization temperature of starches by using electrical conductivity. Native starches from corn, rice, potato, and wheat were prepared with different proportions of water and heated from room temperature to 90 °C, in a device especially designed for monitoring the electrical conductivity as a function of temperature. The results showed a linear trend of the electrical conductivity with the temperature until it reaches the onset gelatinization temperature. After that point, the electrical conductivity presented an increment or decrement depending on the water content in the sample and it was related to starch swelling and gelatinization phenomena. At the end gelatinization temperature, the conductivity becomes stable and linear, indicating that there are no more changes of phase. The starch gelatinization parameter, which was evaluated in the 4 types of starches using the electrical conductivity, was compared with those obtained by using differential scanning calorimeter (DSC). The onset temperature at which the electrical conductivity increased or decreased was found to be similar to that obtained by DSC. Also, the final temperature at which the electrical conductivity returned to linearity matched the end gelatinization temperature of the DSC. Further, a wet method for measuring the onset, peak, and end gelatinization temperatures as a function of temperature using the electrical conductivity curves is presented for a starch–water suspension.     

Effects of Compositional and Granular Properties on the Pasting Viscosity of Rice Starch Blends

The changes in swelling power and pasting properties of suspensions of starch blends were studied in dependence on starch composition and at various isothermal temperatures (T_iso). Samples were prepared by mixing rice starches from Kaoshiung Sen 7 (KSS7, a high‐amylose‐content variety) and Taichung waxy 70 (TCW70, a waxy variety). Generally, mixing these starches at a comparable ratio caused significant decrements in overall swelling power, onset temperature of gelatinization or viscosity rise, and final viscosity of hot pastes after 30 min of isothermal stirring. Notable increases in the peak and conclusion temperatures of gelatinization and in the peak viscosity of the pastes were also observed. Generally, all viscosity parameters of the blends showed two linear dependencies on the starch composition, the graphs intersecting at a critical starch composition depending on the parameters concerned. The onset temperature of viscosity increase was related to the volume fraction of swollen granules when they were just closely packed in suspension. The volume fraction of KSS granules was smaller than that of TCW70. In addition, the rate of viscosity increase and the peak viscosity of the starch suspensions could be well described in terms of the swelling power (Q) when Q ≤ ∼27, and depending on the T_iso examined. From the photomicrographs of starch suspensions, the extensive shear‐induced disintegration of TCW70 granules in the co‐existence of rigid KSS7 granules was evident and in turn responsible for the reduced final viscosities of the hot pastes obtained from starch blends.     

Influence of Food Emulsifiers on Pasting Temperature and Viscosity of Various Starches

The influence of monoglycerides (DGMS), stearoyl-2-lactylates (CSL, SSL), and diacetylated tartaric acid esters of monoglycerides (DATE) on amylograph curves of various starches has been investigated. DGMS gave the greatest increase in pasting temperature of wheat and tapioca starch, followed by SSL, CSL and DATE. The pasting temperature of corn and potato starch was less affected by these emulsifiers. Peak viscosity of wheat starch in distilled water was increased by all emulsifiers, and was decreased in tapioca and potato starch. Both pasting temperature and peak viscosity were strongly influenced by variations in pH, and were to some extent also dependent on ion concentration. In hard tap water the peak viscosity was slightly decreased by the anionic emulsifiers (SSL > CSL > DATE), due to the presence of Ca⁺⁺ and Mg⁺⁺ ions, while DGMS gave a higher peak viscosity than in distilled water. DATE seems to be more sensitive to variations in pH or ion concentration than the other emulsifiers.     

Gelatinization of Starch and Modified Starch

Gelatinization temperatures of starch and hydroxyethyl starch was determined using Differential Scanning Calorimetry (DSC), hot stage microscopy and viscography. The gelatinization temperature based on peak temperature of DSC is incorrect. Viscograph overestimates the gelatinization temperature. Hot stage microscopy based on visual observation gives the correct gelatinization temperature. DSC gives the heat of gelatinization which is helpful in estimating heat requirement during cooking of starch. Hydroxyethylation of starch reduces gelatinization temperature and heat of gelatinization for starch.     

预糊化淀粉对糯米粉糊化、流变性能及微观结构的影响

将预糊化淀粉以不同的比例(0%～8%)分别添至糯米粉中,通过测定预糊化淀粉-糯米粉复合体系的糊化、流变特性并分析其微观结构,旨在改善糯米粉的加工及品质特性。结果表明:预糊化淀粉的添加能够显著提高糯米粉复合体系的峰值黏度、回生值、稠度系数(K)、触变回复率及弹性模量(G’),降低其损耗角正切值(tanδ),且随着添加量的增加,其凝胶结构特性变化更明显,从而证实了预糊化淀粉的添加有利于糯米粉形成稳定高的强凝胶结构。此外,预糊化淀粉的添加能够增强预糊化淀粉-糯米粉复合体系颗粒表面结构的致密性,提高其相对结晶度,从而有利于糯米粉糊形成三维网状凝胶结构,显著改善其凝胶性能。     

Starch Gelatinization in Cold Temperature Sweetening Resistant Potatoes

Differential scanning calorimetry was used to compare temperatures, enthalpies, and kinetic constants for starch gelatinization in tubers of Solarium tuberosum L, var Norchip and a cold sweetening resistant selection, ND 860-2, in an attempt to correlate cold sweetening susceptibility with starch granule stability. For corresponding heating rates, ND 860-2 onset and peak temperatures were higher (p0.05) while differences in enthalpies and activation energies were not (p>0.05) different. Activation energy for amorphous swelling was 281 kJ mol^?1 higher, and the minimum temperature to induce crystallite disruption was 3.5°C higher, for ND 860-2 granules. Results indicate greater stability in ND 860-2 granules and suggest granular stability contributes to cold sweetening resistance.     

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。     

响应面法分析球磨处理对玉米淀粉成糊温度和峰值黏度的影响

研究了经球磨处理后的玉米淀粉的成糊温度和峰值黏度。通过单因素试验和响应面法分析研究了球磨淀粉量,球磨转速和球磨时间对玉米淀粉成糊温度和峰值黏度的影响。结果表明:回归模型能很好地反映各因素水平与成糊温度和峰值黏度之间的关系;淀粉的成糊温度和峰值黏度随淀粉量的增加而升高,随球磨速度的增加和球磨时间的增长而下降;三因素对成糊温度的影响顺序为淀粉量>转速>球磨时间;三因素对峰值黏度的影响顺序为淀粉量>球磨时间>转速。结晶性研究和粒度分布结果表明,球磨后淀粉的结晶性下降,平均粒径上升,成糊温度和峰值黏度的变化是因为球磨改变了淀粉的结晶性及淀粉分子结构。     

Lipids and Rheological Properties of Starch Part I: The Effect of Fatty Acids,Monoglycerides and Monoglyceride Ethers on Pasting Temperature and Viscosity of Wheat Starch

By addition of saturated fatty acids (C₁₄-C₁₈) in concentrations of 0.34 and 0.57% gelatinization temperature (GT) of wheat starch is reduced from 82.5°C to 81°C. Oleic acid (C_18:1) increases GT. Palmitic and stearic acid (0.57%) cause a little increase of viscosity only, but during heating a slope of viscosity is observed. In contrast to saturated fatty acids monoglyderides increase GT with exception of glycerinmonooleate, which reduces GT. Glycerinmonomyristate and glycerinmonolinoleate increase the initial viscosity. Monoglyceride ethers, first time used for those studies, influence viscosity differently. Rac-1-O-octadecylglycerol reduces GT from 82.5 to 81°C and the final viscosity is lowered remarkable but rac-1-O-[(Z)-9-octadecenyl]glycerol causes an increase of GT from 82.5 to 85.5°C. Initial and end viscosity are raised also.