A Study of Annealing and Freeze‐Thaw Stability of Acid‐Modified Tapioca Starches by Differential Scanning Calorimetry (DSC)

Tapioca starch was partially hydrolyzed by 6% (w/v) hydrochloric acid at room temperature for various lengths of time. Annealing and freeze‐thaw stability of the acid‐modified starches were studied using Differential Scanning Calorimetry (DSC). In the annealing study, as the hydrolysis time increased, the effect of annealing on narrowing and shifting the endothermic peak to a higher temperature was decreased. The endothermic transition of annealed 48‐h acid‐modified tapioca starch showed a narrow peak and a broad shoulder, corresponding to the melting of the amylopectin double helices (crystalline regions) and the retrograded partially hydrolyzed amylose, respectively. This effect of annealing on the sharpening of the endotherm was less pronounced on acid‐modified tapioca starches annealed for 192 h and 768 h, respectively. These results indicated that annealing leads to more homogeneous crystallites and this effect is enhanced when the material contains more amorphous and homogeneous domains. In the case of the freeze‐thaw stability study, the melting endotherm of recrystallized amylopectin became larger with increasing hydrolysis time. The first detectable endotherm of native tapioca retrograded gel was observed after five cycles, while all acid‐modified retrograded gels showed the melting endotherm after only one cycle. Increasing hydrolysis time may increase the proportion of short chain amylose and amylopectin molecules, which are able to form double helices, resulting in an increase in the enthalpy and a higher retrogradation rate of the gel.     

Phase and State Transitions in Granular Starches Studied by Dynamic Differential Scanning Calorimetry

Phase and state transitions of granular starches heated in water are studied by dynamic differential scanning calorimetry (DDSC). The DDSC results of various granular starches show a stepwise heat capacity (C_p) change in the storage C_p curve, which starts at the beginning of melting or immediately preceding gelatinization and ends before the melting reaches its peak temperature. Annealing reduces the magnitude of this stepwise change in storage C_p. After the amorphous phase is selectively removed by acid, the stepwise storage C_p is greatly reduced. The stepwise storage C_p increase is not observed when recrystallized linear short chains from enzyme‐debranched waxy maize starch are heated in water. The results show that the stepwise change in C_p observed on the granular starch is a unique property associated with the phase transition of granular structure and reflects a glass transition of the rigid amorphous regions in starch granules. The glass transition of the mobile amorphous phase in granular starch is believed to extend over a broad range of temperatures before gelatinization. A small glass transition below 0°C is directly detected by DDSC and is attributed to part of the mobile amorphous fraction in granular starch.     

A Study of Some Physicochemical Properties of High‐Crystalline Tapioca Starch

Tapioca starch was partially hydrolyzed in hydrochloric acid solution at room temperature for various lengths of time to obtain high‐crystalline starches. RVA viscoamylograms of acid‐modified starches demonstrated a very low viscosity as compared to that of native tapioca starch. The relative crystallinity of native and acid‐modified tapioca starches were measured by X‐ray diffraction ranging from 39.53% to 57.75%. The native and acid‐modified tapioca starches were compressed into tablets using various compression forces. The % relative crystallinity of starch increased with the increase in hydrolysis time and the crushing strength of the tablet was also increased in line with the crystallinity while the amylose content decreased when the crystallinity increased. These results suggested that the erosion of amylose might cause the rearrangement of starch structure into a new more tightly packed form, which provided the higher crushing strength for the tablets.     

DSC法研究6种莲子淀粉糊化和老化特性

利用差示扫描量热仪(DSC)结合Avrami 方程研究在4℃、储存两周的条件下,6种莲子淀粉的糊化和老化特性,探讨直链淀粉以及贮存时间对其热力学行为产生的影响,并用SPSS软件计算其相关性。结果表明：6种莲子淀粉的糊化温度、ΔH、老化焓、老化度以及老化速率存在着一定的差异,老化速率的大小顺序为太空莲＞美人红＞大紫红＞武植2号＞鄂莲＞洪湖莲,太空莲淀粉的老化速率是洪湖莲淀粉的1.36 倍;6种莲子淀粉的成核方式均为瞬间成核;4℃条件下贮存两周的莲子淀粉的老化度随着贮存时间的增加而增大;直链淀粉含量与Avrami 指数n值呈负相关,与速率常数k值、ΔH、老化焓以及冰融溶焓呈正相关。     

Gelatinization and Retrogradation Properties of Native and Hydroxypropylated Crosslinked Tapioca Starches with Added Sucrose and Sodium Chloride

The effects of sucrose and sodium chloride on the gelatinization and retrogradation of native and hydroxypropylated crosslinked tapioca starches were investigated by using Differential Scanning Calorimetry (DSC). Hydroxypropylated crosslinked tapioca starches showed low gelatinization temperature and enthalpy compared to the native tapioca starch. Sucrose and sodium chloride increased the gelatinization temperatures of all starch samples. The enthalpy to melt retrograded amylopectin of hydroxypropylated crosslinked tapioca starches were low, compared to that of the native starch. Sucrose did not have much effect on retrogradation of the starch, while sodium chloride decreased retrogradation of all starch samples.     

Studies of Flavor Encapsulation by Agents Produced from Modified Sago and Tapioca Starches

The efficiency of sago and tapioca starch stearates for encapsulating lemon oil were studied and compared to the efficiency of gum arabic. The stearates were prepared by esterification of stearic acid with starch. To accomplish esterification, the stearic acid was first coated on the surface of the starch granules. Then the coated granules were heated at 150 °C for 2 h to obtain sago or tapioca starch stearate (SSS or TSS). SSS or TSS can be prepared as ready‐to‐use products in the form of pregelatinized‐hydrolyzed sago or tapioca starch stearate (PGHSSS or PGHTSS). The resulting modified starches were used for encapsulation of lemon oil. The lemon oil encapsulating efficiency for SSS with DS 0.009 and 0.014 were close to that of gum arabic, whereas the encapsulating efficiency for PGHSSS with DS 0.0052 and 0.016 were higher than that of the gum arabic. The TSS and PGHTSS provided encapsulating efficiencies lower than the gum arabic.     

Thermal and Pasting Properties of Acid‐treated Rice Starches

The physicochemical properties of acid‐treated rice starches were investigated. Rice starches were treated with hydrochloric acid at different acid concentrations and hydrolysis times. The pasting properties were tested using a Rapid Visco Analyser, and gelatinization and retrogradation properties using a differential scanning calorimeter. The results showed that acid concentration had a more pronounced effect on degree of polymerization (DP) and viscosity than hydrolysis time. The onset, peak and conclusion temperatures of gelatinization were increased significantly with hydrolysis time, while the gelatinization enthalpy (ΔH_G) was decreased. In addition, there was an increase in the gelatinization temperature range with longer hydrolysis time. After storing gelatinized starches at 4°C for 7 days, the transition temperature and enthalpy (ΔH_R) to melt retrograded amylopectin did not change significantly. Additionally, the temperature and enthalpy transition for melting amylose‐lipid complex of all gelatinized and retrograded starches were in the same range.     

用差示量热扫描方法研究米粉糊的老化

采用差示量热扫描方法研究米粉糊在低温贮存时的老化情况 ,比较了不同水分含量 (质量分数 )和添加剂对米粉糊抗老化能力的影响 .结果显示 :米粉糊在 4℃下贮存较在 2 5℃下贮存易于老化 .在米粉糊中添加 1 .0 %的蔗糖酯和 1 .0 %的CaCl2 能有效地提高米粉糊在贮存期间的抗老化性能 .     

Structures and Physicochemical Properties of Acid‐Thinned Corn,Potato and Rice Starches

The structures and physicochemical properties of acid‐thinned corn, potato, and rice starches were investigated. Corn, potato, and rice starches were hydrolyzed with 0.14 N hydrochloric acid at 50 °C until reaching a target pasting peak of 200—300 Brabender Units (BU) at 10% solids in the Brabender Visco Amylograph. After acid modification the amylose content decreased slightly and all starches retained their native crystallinity pattern. Acid primarily attacked the amorphous regions within the starch granule and both amylose and amylopectin were hydrolyzed simultaneously by acid. Acid modification decreased the longer chain fraction and increased the shorter chain fraction of corn and rice starches but increased the longer chain fraction and decreased the shorter chain fraction of potato starch, as measured by high‐performance size‐exclusion chromatography. Acid‐thinned potato starches produced much firmer gels than did acid‐thinned corn and rice starches, possibly due to potato starch's relatively higher percentage of long branch chains (degree of polymerization 13—24) in amylopectin. The short‐term development of gel structure by acid‐thinned starches was dependent on amylose content, whereas the long‐term gel strength appeared dependend on the long branch chains in amylopectin.     

Characterization and Utilization of Acid‐modified Rice Starches for Use in Pharmaceutical Tablet Compression

Acid modified, agglomerated starches offer specific advantages as fillers in production of pharmaceutical tablets. Spray drying can improve processing of tablet mixtures significantly. In order to investigate prerequisites in utilization of rice starch, non‐waxy and waxy types were partially hydrolyzed in 6% (w/v) HCl solution at room temperature for varied length of time to obtain rice starches with increased crystallinity (so‐called crystalline rice starches). Scanning electron micrographs of native and highly crystalline starches were used to study the morphological changes and to suggest the mode of acid attack during hydrolysis. Exo‐corrosion distributed over the surface of acid‐modified waxy rice starch (AWRS) was observed after 192 h of hydrolysis. In contrast, the surface of acid‐modified rice starch (ARS) remained unchanged at 192 h of acid hydrolysis. The amylose content and the median particle size (diameter) were reduced with increasing hydrolysis time. It was found by X‐ray diffraction that the relative crystallinity of acid‐modified starches at >95% relative humidity was clearly increased with prolonged hydrolysis time. For studying tablet properties spherical agglomerates of the native and acid modified starches were directly compressed at 4 kN to obtain tablets. Crushing strength and disintegration time of tablets increased with relative crystallinity. In contrast, tablet friability was reduced. Concerning tablet functionality, the crystalline starches were positioned in overlapping ranges between the common commercial tablet fillers (microcrystalline cellulose, pregelatinized starch and lactose, respectively).     

Amylose Chain Association Based On Differential Scanning Calorimetry

Amylose and lipid depleted starches from amylomaize, pea, maize, wheat, potato, and waxy maize were heated from 20°C to 180°C, cooled to 4°C, and then reheated to 180°C in a differential scanning calorimeter (DSC) in excess water. Cooling curves of the amylose and starch melts showed exothermic transitions (< 70°C) attributed to the mechanism of amylose chain association. Amylose/amylopectin mixtures covering the range 0–95% amylose were similarly heated and cooled. The association of linear amylose chains was restricted by amylopectin.     

Rheological,thermal properties,and gelatinization kinetics of tapioca starch–trehalose blends studied by non‐isothermal DSC technology

In this paper, we studied the effects of trehalose on the rheological and thermal properties of tapioca starch (TS). Temperature sweep experiments showed that trehalose shifted the peak gelatinization temperature (T_G′max) to higher value. Rheological features calculated from the power law model indicated that trehalose addition increased the consistency and decreased the thixotropy of TS gels. DSC experiments showed that trehalose retarded the gelatinization of TS–trehalose blends reflected in the increase of gelatinization temperature. The gelatinization kinetics was evaluated by a non‐isothermal technique based on the DSC endotherms. Kinetics analysis showed the addition of trehalose increased the activation energy and decreased the rate constants of TS–trehalose blends, indicating the same sugar effect as the rheological and DSC experiments. The work demonstrated that kinetics analysis could provide new evidences for the influence of trehalose on starch gelatinization.     

Effects of Na2CO3 and NaOH on Retrogradation of Selected Native Cereal Starches Studied by Differential Scanning Calorimetry and Nuclear Magnetic Resonance

ABSTRACT: Using differential scanning calorimetry and pulsed nuclear magnetic resonance (NMR), it was found that the presence of Na2CO3 and NaOH retarded retrogradation of aged starch (wheat, corn, waxy corn, rice, and waxy rice) gels during storage at 4°C. At the same level of addition (based on a fixed starch/water ratio), the effect of NaOH was observed to be more pronounced than that of Na2CO3. Kinetic studies using pulsed NMR showed a progressive reduction in rate of starch retrogradation with increasing concentration of alkali (up to a level of 1 g/100 starch).     

Determination of Amylose Content in Different Starches Using Modulated Differential Scanning Calorimetry

A simple calorimetric method for determination of amylose content in starch is reported. Starches were heated in the presence of two common surfactants, viz., sodium dodecyl sulphate (SDS) and cetyltrimethylammonium bromide (CTAB), and the enthalpies of melting of the amylose‐surfactant complexes were determined using Modulated Differential Scanning Calorimetry (MDSC). A large number of native starches including cereal, root and pea starches were examined. The results were compared with those obtained by iodimetry and gel permeation chromatography (GPC) for all the starches. There was a good correlation between the values from iodimetry and GPC with those obtained using the surfactants. Both surfactants seemed to work equally well, even for those starches with about 40% amylose content. However, in case of SDS higher standard deviations were usually obtained than for CTAB in the determination of transition enthalpies.     

Aging Effects on Sorbitol‐ and Non‐Crystallizing Sorbitol‐Plasticized Tapioca Starch Films

The effect of aging on the properties of tapioca starch films plasticized with either sorbitol (S) or non‐crystallizing sorbitol (NCS) was investigated in this study. Tapioca starch, plasticizer and deionized water were mixed, heated, cast on high‐density polyethylene plates and dried at ambient conditions. The results showed that S was more effective in plasticizing fresh starch film than NCS. However, sorbitol crystallization was observed in S‐plasticized starch film after one month of storage, while there was no crystallization observed in NCS‐plasticized starch film after two months of storage. Mechanical properties of both S‐ and NCS‐plasticized starch films changed significantly with time, but with less change in the NCS‐plasticized films. Tensile strength, elastic modulus and toughness increased over time; conversely, elongation decreased. Additionally, the water vapor transmission rate decreased as storage time increased. The fact that mechanical properties of both S‐ and NCS‐plasticized films changed is likely due to an increase in crystallinity of the starch in the films with time.     

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。     

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.     

Lintnerization of Two Amylose‐free Starches of A‐ and B‐Crystalline Types,Respectively

Waxy maize starch (WMS) and potato amylopectin starch (PAPS), representing amylose‐free A‐ and B‐crystalline granules, respectively, were subjected to hydrolysis in diluted hydrochloric acid (lintnerization). The solubilization rate of the granules was dependent on the temperature, but there were only small differences between the samples. The compositions of the lintners obtained at 29°C were also similar, though the sensitivity to enzymatic debranching was different. The degree of debranching increased significantly if pullulanase and isoamylase were used successively. Because some branches remained resistant to enzymatic attack, the degree of scattered branching was difficult to estimate. The amount and composition of β‐limit dextrins suggested, however, that both starches contained scattered branches. Long chains and the shortest chains in the amylopectin molecules were sensitive to lintnerization and therefore probably located outside the crystallites. The composition of the PAPS lintners was dependent on the temperature of the lintnerization, whereas that of WMS lintners was not. The composition of a lintner from normal potato starch was compared with PAPS, and it is concluded that the presence of amylose has a higher effect than the type of crystallinity on the lintnerization results.     

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.