Impacts of Hydrothermal Treatments on the Morphology,Structural Characteristics,and In Vitro Digestibility of Water Caltrop Starch

The influence of hydrothermal treatments on the structural properties and digestibility of water caltrop starch was investigated. Scanning electron microscopy (SEM) showed some small dents on the surface of starch granules for samples treated with heat moisture treatment (HMT), but not for samples treated with annealing (ANN) which generally showed smoother surfaces. The gelatinization temperature of starch was generally increased by hydrothermal treatments, accompanied by a trend of decreasing breakdown viscosity. These results implied the improvement of thermal and shearing stability, particularly for HMT in comparison to ANN. After being cooked, the native and ANN-modified water caltrop starch granules were essentially burst or destroyed. On the other hand, the margin of starch granules modified by HMT and dual hydrothermal treatments remained clear with some channels inside the starch granules. X-ray diffraction revealed that the crystalline pattern of water caltrop starch changed from the C_A-type to the A-type and the relative crystallinity reduced with increasing moisture levels of HMT. Results of ANN-modified water caltrop starch were mostly similar to those of the native one. Moreover, water caltrop starch modified with HMT20 and dual modification contained a pronouncedly higher resistant starch content. These results suggested that HMT, ANN, and dual modification effectively modified the functional properties of water caltrop starch.     

淀粉与木糖醇共混物的性能

淀粉与木糖醇共混物的性能于九皋，郑华武（天津大学化学系天津３０００７２）关键词淀粉，木糖醇，共混，热塑性研究具有环境条件下可降解的塑料已成为国内外专家学者广泛关注的研究课题。淀粉具有类似高聚物的分子结构，但由于分子量大，分子之间的亲合力强，很难加工成...     

Surface chemical modification of waxy maize starch nanocrystals

The surface of waxy maize starch nanocrystals obtained from sulfuric acid hydrolysis of native waxy maize starch granules was chemically modified using two different reagents, namely, alkenyl succinic anhydride and phenyl isocyanate. The occurrence of chemical modification was evaluated by FTIR and X-ray photoelectron spectroscopies. Contact angle measurements from which the surface energy of the materials under investigation was deduced showed that chemical modification led to more hydrophobic particles. Chemical modification altered the morphology of particles, as shown by observation by transmission electron microscopy, but not their crystallinity (X-ray diffraction analysis).     

Thermal behaviour of corn starch granules under action of fungal α-amylase

Corn starch, partially hydrolyzed by fungal α-amylase was investigated by using thermal analysis, microscopy and X-ray diffraction. After enzymatic treatment lower degradation onset temperatures were observed. DSC analysis showed almost similar range of gelatinization temperature, however, the enthalpies of gelatinization increased for the partially hydrolyzed starch granules. According to the X-ray diffraction analysis, stronger cereal pattern peaks were recognized after enzymatic digestion. The results suggested that the hydrolysis was more pronounced in the amorphous part of the starch granules.     

Evaluation of black tea polyphenol extract against the retrogradation of starches from various plant sources

The effects of black tea polyphenol extract (BTPE) on the retrogradation of starches from different plant sources were studied using differential scanning calorimetry (DSC) and X-ray diffraction (XRD). DSC analysis shows that the gelatinization temperature of maize starch and starches from different rice varieties increased with increasing BTPE level. After storage at 4 °C, BTPE at a concentration of 15% markedly retarded the retrogradation of maize starch and starches from different rice varieties. Native maize starch and starches from different rice varieties showed typical A-type X-ray diffraction patterns, while native potato starch showed a typical B-type X-ray diffraction pattern. Adding BTPE significantly affected the crystalline region and intensities of X-ray diffraction peaks of maize and rice starch granules. It is concluded that adding BTPE markedly inhibits the retrogradation of maize starch and starches from different rice varieties, but has no significant influence on the gelatinization and retrogradation characteristics of potato starch.     

Mn^3＋引发淀粉与丙烯腈接枝共聚物的研究

用过渡金属离子或其配合物引发淀粉的接枝共聚是一个饶有兴趣的课题。Ce~(4 )离子引发淀粉与烯类单体的接枝共聚已有广泛报道。Mehrotra等用稳定的[Mn(H_2P_2O_7)_3]~(3-)引发淀粉与烯类单体的接枝共聚取得了满意的结果。本文报道用电镜,x-射线衍射和热重分析等方法对这一接枝共聚物的形态、结构和热稳定性的研究结果。     

Effect of Different Moisture Contents on Crystallized State of Microwave Modified Tapioca Starch

1INTRODUCTION Microwave,as a sort of wave with high efficiency and strong penetrability,has been widely applied in food industry.There is always a keen interest in the application of microwave technology in starch physi-cal modification.Native starch granules are semi-crystalline structures characterized by alternating crystalline lamella and amorphous growth rings.These granules are predominantly composed of high branch,part crystal amylopectin and linetype amylo-se.Most amyloses dispers…     

大米淀粉糊化过程的光谱分析

采用衰减全反射傅立叶变换红外光谱仪跟踪测定了不同品种大米淀粉的糊化过程,同时与X-射线衍射仪测定的淀粉结晶度相对比,研究了淀粉颗粒内结晶结构在糊化过程中变化的详细情况.利用红外光谱仪计算出天然大米淀粉及其在糊化过程中各个阶段代表结晶区特征的1047cm-1和代表非晶区特征的1022cm-1两处红外吸收峰强度的比值.结果表明,天然淀粉的结晶区主要由支链淀粉侧链的双螺旋结构所形成;在加热过程中淀粉的结晶结构被破坏,并且直链淀粉含量越高,其结晶结构在糊化过程中破坏越慢,说明直链淀粉能抑制淀粉结晶结构的破坏.利用X-射线衍射仪测定了大米淀粉糊化过程各个阶段的结晶度,进一步验证了淀粉的结晶结构在糊化过程中的损失.虽然,两种测定方法对"结晶度"的定义不同,但对于淀粉结晶程度的测定具有相关性和可比性,能为研究淀粉的糊化行为提供有利的补充信息.     

非对称场流分离系统的构建及其在淀粉颗粒粒径表征中的应用

淀粉颗粒粒径与分子尺寸分别在1~100 μm和20~250 nm之间,是影响淀粉功能特性的重要因素之一。非对称场流分离(AF4)是一种基于样品与外力场相互作用机制的分离技术,已应用于表征淀粉分子尺寸分布。商品化的AF4系统的粒径检测范围为1 nm~10 μm,对于淀粉颗粒粒径表征具有一定的局限性。该文研制了AF4分离系统;考察了其在微米尺度下对红薯、莲子和大米淀粉颗粒粒径表征的性能;采用微米尺寸的聚苯乙烯乳化球(PS)标准样品验证了构建的AF4系统的分离性能。实验结果显示,构建的AF4系统对PS混合样品(粒径2、6、12、20 μm)实现了基线分离,同商品化AF4相比提高了检测上线,具有分离表征淀粉颗粒的潜力。此外,该文研究了载液组成对淀粉颗粒分离表征的影响;通过光学显微镜验证了构建的AF4系统在微米尺度上对淀粉颗粒粒径分布的表征能力。最后,采用商品化的AF4系统串联多角度激光光散射检测器和示差折光检测器对3种淀粉分子进行了分离表征,考察了淀粉的溶解温度对其表征结果的影响。在摩尔质量10 ⁶~10⁸ g/mol范围内,红薯和莲子淀粉的回转半径和水合半径的比值(R_g/R_h)在0.9~1.1之间,大米淀粉的R_g/R_h在1.2~1.4之间。实验结果证明构建的AF4系统是一种快速、准确的淀粉颗粒粒径表征方法,与商品化的AF4系统结合可为研究淀粉尺寸分布与其功能性质之间的关系提供技术支持。     

Effect of thermal treatment on potato starch evidenced by EPR,XRD and molecular weight distribution

Effect of heating of the potato starch on damages of its structure was investigated by quantitative electron paramagnetic resonance (EPR) spectroscopy, X‐ray diffraction and determination of the molecular weight distribution. The measurements were performed in the temperature range commonly used for starch modifications optimizing properties important for industrial applications. Upon thermal treatment, because of breaking of the polymer chains, diminishing of the average molecular weights occurred, which significantly influences generation of radicals, evidenced by EPR. For the relatively mild conditions, with heating parameters not exceeding temperature 230 °C and time of heating equal to 30 min a moderate changes of both the number of thermally generated radicals and the mean molecular weight of the starch were observed. After more drastic thermal treatment (e.g. 2 h at 230 °C), a rapid increase in the radical amount occurred, which was accompanied by significant reduction of the starch molecular size and crystallinity. Experimentally established threshold values of heating parameters should not be exceeded in order to avoid excessive damages of the starch structure accompanied by the formation of the redundant amount of radicals. This requirement is important for industrial applications, because significant destruction of the starch matrix might annihilate the positive influence of the previously performed intentional starch modification. Copyright © 2015 John Wiley & Sons, Ltd.     

Exposure of granular starches to low-pressure glow ethylene plasma

Polymerization of ethylene was initiated by low-pressure glow plasma generated in this gas. Depending on starch present in this plasma polymerization could be considered either as graft-polymerization of ethylene onto starch or homopolymerization. Result of the treatment of cassava, corn, potato, rice Indica, sweet potato, and waxy corn starches with ethylene plasma was analyzed by means of high-performance size exclusion chromatography, X-ray powder diffraction, thermogravimetry, digestion with β-amylase, and scanning electron microscopy. Analyses suggested that graft-polymerization occurred on sweet potato and rice starch. With other starches homopolymerization of ethylene on granules took place.     

Effects of NaOH treatment of cereal starch granules on the extent of granular starch hydrolysis

Effect of NaOH treatment on granular hydrolysis of cereal starches was studied and granular starch hydrolyzing enzyme is used to hydrolyze native and NaOH-treated starch for 24?h. The dextrose equivalent value of NaOH-treated starch increased significantly compared to native starch, i.e., 28–38?% for corn, 7–37?% for rice, but no significant increase for corn starch. Scanning electron microscopy micrographs showed that NaOH treatment caused an enlargement of pores and degrades the surface of starch granules. Hydrolyzed-treated starch exhibited rougher surface and more porous granules compared to native starch. The swelling power and pasting properties of NaOH-treated starches were markedly altered after hydrolysis. X-ray pattern of all starches showed no changes and the amylose content decrease significantly after hydrolysis, which could due to extensive degradation of amorphous region. Evidently, NaOH treatment below gelatinization temperature was effective in enhancing the degree of granular starch hydrolysis.     

Study on the morphology, crystalline structure and thermal properties of yam starch acetates with different degrees of substitution

This study was carried out to understand and establish the changes in physicochemical properties of starch extracted from Chinese yam (Dioscorea opposita Thunb.) after acetylation. Yam starch acetates with different degrees of substitution (DS) were prepared by the reaction of yam starch with glacial acetic acid/acetic anhydride using sulfuric acid as the catalyst. Their formation was confirmed by the presence of the carbonyl signal around 1750 cm-1 in the Fourier transform infrared (FT-IR) spectra. The thermal behavior of the native starch and starch acetate were investigated using thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The results reveal that the starch acetates are more thermally stable than the native starch. The starch esters showed 50% weight loss at tem- peratures from 328℃ to 372 ℃ , while the native starch underwent 50% weight loss at 325℃ . The glass transition temperature (Tg) of the starch decreased from 273℃ to 226℃. The X-ray diffraction (XRD) patterns could be classified as typical of the C-type for yam starch. X-ray diffraction also showed the loss of the ordered C-type starch crystalline structure and the degree of crystallinity of starch de- creased from 36.10% to 10.96% with the increasing DS. The scanning electron microscopy (SEM) sug- gested that the most of the starch granules disintegrated with many visible fragments with the in- creasing DS.     

Enzyme catalysis of insoluble cornstarch granules: Impact on surface morphology, properties and biodegradability

Granular cornstarch was treated with microbial glucoamylase (50 mM sodium acetate buffer at pH 5.5 at 30 °C, 150 rpm) for up to 8 h. Treated starch was recovered and evaluated for changes in granular morphology, chemical properties, thermal properties, crystallinity and impact on its biodegradability. As the enzyme treatment progressed, reducing sugars began to accumulate in the liquid culture media (total of 6% in 8 h) and the granule suffered roughly 6% weight loss within 8 h of incubation. While the granules appeared intact morphologically, numerous small pits developed throughout the surface of the granules as a result of the enzyme treatment. Even after 8 h of enzyme treatment, the pitted granules were not disrupted and remained intact. X-ray diffraction indicated no loss of crystallinity in the enzyme treated granules but rather an increase in relative crystallinity, suggesting that the enzyme preferentially catalyzed the anhydroglucose units in amorphous regions of the granule. These findings were further supported by FTIR data suggesting that granules become more resistant to enzyme attack as amorphous amylose is hydrolyzed faster than the crystalline amylopectin domains. These results also suggest that variations in the crystallinity of different types of starches have the potential to affect their rates of biodegradation. Enzyme treated starch granules exhibited resistance to biodegradation, and the degree of resistance was related to the length of enzyme treatment. Granules treated with enzyme for a total of 7 h and subjected to biodegradation in soil produced 40-50% less CO₂ in a closed circuit respirometer compared to the untreated samples. Differential scanning calorimetry (DSC) thermograms showed an endothermic reaction with little change in the onset and peak temperatures indicating that glucoamylase started by degrading the starch granules from the surface.     

Effects of chemical modification on the structure and mechanical properties of starch-based biofilms

Abstract  

In this work, chemically modified corn starch and plasticized corn starch biofilms were obtained and characterized in four steps: (1) preparation of corn starch microparticles, (2) preparation of malic acid-modified corn starch microparticles (MA–SM), (3) preparation of corn starch biofilms and MA–SM-plasticized corn starch biofilms, and (4) characterization of the biofilms. The effects of MA–SM concentration (4, 8, and 12% based on the amount of corn starch) on the structural characteristics and mechanical properties of the biofilms were investigated. Changes in the starch granules after chemical modification were studied by X-ray diffraction, FT-IR spectroscopy, and scanning electron microscopy. The presence of ester carbonyl group stretching vibration at 1,720 cm⁻¹ in FT-IR spectra was evidence of reaction of the starch microparticles with malic acid. The tensile yield strength and Young’s modulus of the films increased with increasing MA–SM content. Water uptake decreased from 69.8% for biofilm without MA–SM to 52.7% for biofilm with MA–SM. The improvement of these properties in the plasticized product could be attributed to the good interaction between the MA–SM filler and the corn starch.     

Fractionation and characterization of starch granules using field-flow fractionation (FFF) and differential scanning calorimetry (DSC)

Starch is one of the main carbohydrates in food; it is formed by two polysaccharides: amylose and amylopectin. The granule size of starch varies with different botanical origins and ranges from less than 1 μm to more than 100 μm. Some physicochemical and functional properties vary with the size of the granule, which makes it of great interest to find an efficient and accurate size-based separation method. In this study, the full-feed depletion mode of split-flow thin cell fractionation (FFD-SF) was employed for a size-based fractionation of two types of starch granules (corn and potato) on a large scale. The fractionation efficiency (FE) of fraction-a for corn and potato granules was 98.4 and 99.4%, respectively. The FFD-SF fractions were analyzed using optical microscopy (OM) and gravitational field-flow fractionation (GrFFF). The respective size distribution results were in close agreement for the corn starch fractions, while they were slightly different for the potato starch fractions. The thermal properties of FFD-SF fractions were analyzed, and the results for the potato starch showed that the peak temperature of gelatinization (T_p) slightly decreases as the size of the granules increases. Additionally, the enthalpy of gelatinization (ΔH) increases when the granule size increases and shows negative correlation with the gelatinization range (ΔT).

     

Starch Granule Size and Morphology of Arabidopsis thaliana Starch-Related Mutants Analyzed during Diurnal Rhythm and Development

Transitory starch plays a central role in the life cycle of plants. Many aspects of this important metabolism remain unknown; however, starch granules provide insight into this persistent metabolic process. Therefore, monitoring alterations in starch granules with high temporal resolution provides one significant avenue to improve understanding. Here, a previously established method that combines LCSM and safranin-O staining for in vivo imaging of transitory starch granules in leaves of Arabidopsis thaliana was employed to demonstrate, for the first time, the alterations in starch granule size and morphology that occur both throughout the day and during leaf aging. Several starch-related mutants were included, which revealed differences among the generated granules. In ptst2 and sex1-8, the starch granules in old leaves were much larger than those in young leaves; however, the typical flattened discoid morphology was maintained. In ss4 and dpe2/phs1/ss4, the morphology of starch granules in young leaves was altered, with a more rounded shape observed. With leaf development, the starch granules became spherical exclusively in dpe2/phs1/ss4. Thus, the presented data provide new insights to contribute to the understanding of starch granule morphogenesis.     

Copolymers of Starch and Polyacrylonitrile. Influence of Granule Swelling on Copolymer Composition under Various Reaction Conditions

Molecular weights and grafting frequencies of graft copolymers prepared with ferrous ammonium sulfate-hydrogen peroxide initiation showed a dependence on granule swelling similar to that found with ceric ammonium nitrate (increased swelling of starch granules decreased the number of grafted polyacrylonitrile chains and increased their average molecular weight). As with unswollen starch, the composition of the copolymer prepared from swollen starch was not influenced by granule size. Molecular weights of polyacrylonitrile branches grafted to swollen and unswollen starch were independent of reaction time; however, grafting frequencies with swollen and unswollen starch tended to converge toward a common value with increased reaction time and increased dilution. Data suggest that the influence of granule swelling on copolymer composition is due to a faster termination rate for growing polyacrylonitrile chains in unswollen starch.     

Study on the morphology, crystalline structure and thermal properties of yellow ginger starch acetates with different degrees of substitution

Yellow ginger starch acetates with different degrees of substitution (DS) were prepared by reacting native starch with glacial acetic acid/acetic anhydride using sulfuric acid as catalyst. X-ray diffraction (XRD) of acetylated starch revealed that the crystal structure of native starch was disappeared and new crystalline regions were formed. Their formation was confirmed by the presence of the carbonyl signal around 1750 cm⁻¹, as well as the reduced hydroxyl groups, in the Fourier transform infrared spectroscopy (FT-IR). The scanning electron microscopy (SEM) suggested most of the starch granules disintegrated with many visible fragments along with the increasing DS. The thermal behavior of the native starch and starch acetate were investigated using thermogravimetric analysis (TGA) and differential thermal analysis (DTA), it was observed that the thermal stability of acetylated starch depends on the degree of substitution. Thermal stability of high DS acetylated starch is much better than that of the original starch when DS reached to 2.67.     

Starch nanocrystals with large chain surface modifications

Nanoscale monocrystalline starch particles were successfully modified using stearic acid chloride and poly(ethylene glycol) methyl ether. Surface modification was confirmed using FTIR, XPS spectroscopy, and contact angle measurements. X-ray diffraction and DSC analysis confirmed that there was no alteration of the starch crystalline structure due to the surface modification. The grafts at the starch surface were also found to crystallize on the surface. TEM showed the individualization of nanoparticles as a result of the reduction of polar and hydrogen bonding forces. These results show our ability to modify the starch nanocrystal surface with plasticizing chains. Modified nanoparticles can find applications as compatibilized polymer additives, surface-active particles, and co-continuous nanocomposite precursors.