The Experts below are selected from a list of 309 Experts worldwide ranked by ideXlab platform
James N. Bemiller - One of the best experts on this subject based on the ideXlab platform.
-
Heterogeneity of Starch Granules and the effect of granule channelization on Starch modification
Cellulose, 2004Co-Authors: John E. Fannon, Kerry C. Huber, Jonathan A. Gray, Ninik Gunawan, James N. BemillerAbstract:This paper reviews the discovery of channels ID Starch Granules and progress of research on their effects on granule modification and digestibility, their nature, hypotheses on how they are formed and why they are present, and genetic control of their occurrence. Emphasized ID the relationship of channels to Starch derivatization. Channelization ID presented as additional evidence of the heterogenous nature of Starch Granules from source to source and within a single source. A new method of determining the location of anionic entities within Starch Granules that utilizes reflectance confocal laser scanning microscopy ID described.
-
location of sites of reaction within Starch Granules
Cereal Chemistry, 2001Co-Authors: Kerry C. Huber, James N. BemillerAbstract:ABSTRACT To observe granular reaction patterns within modified Starch Granules, Starch derivatives were converted to thallium(I) salts and viewed by scanning electron microscopy compositional backscattered electron imaging. Observation of phosphorylated potato and sorghum Starches and a hydroxypropyl analog of waxy maize Starch revealed that granular patterns of reaction were influenced by both Starch and reagent types. In waxy maize and sorghum Starches, flow of reagent into the granule matrix occurred from channels (laterally) and cavities (from the inside outward). In potato Starch Granules, which do not possess channels, reagent diffused inward through exterior granule surfaces. Phosphoryl chloride (highly reactive) reacted to a large extent at granule surfaces, while the propylene oxide analog (less reactive) appeared to diffuse into the granule matrix prior to reacting.
-
channels of maize and sorghum Starch Granules
Carbohydrate Polymers, 2000Co-Authors: Kerry C. Huber, James N. BemillerAbstract:The radial, tube-like channels of corn/maize and sorghum Starch Granules, which penetrate from the external surface inward toward a cavity at the hilum, were found to vary in depth of penetration from granule to granule. Most, but not all, channels spanned the entire granule matrix, from the outer surface to the central cavity. Under slight swelling conditions (water), cavities swelled somewhat closed, while channels appeared to remain open. Swelling also affected the permeability of the granule matrix to dye molecules. Penetration of an aqueous dye solution occurred primarily from the central cavity outward and laterally from channels. Even under the slight swelling conditions, colloidal gold particles filled channels and cavities, showing that they are voids.
-
Visualization of Channels and Cavities of Corn and Sorghum Starch Granules
Cereal Chemistry, 1997Co-Authors: Kerry C. Huber, James N. BemillerAbstract:ABSTRACT Evidence is presented that corn (maize) and sorghum Starch Granules have channels that connect a central cavity to the external environment. A mutant sorghum Starch with numerous, large surface pores was treated with a methanolic solution of merbromin and sectioned. Light, fluorescence, and compositional backscattering electron microscopy revealed channels connecting an internal cavity to the external surface in most Granules. Cavities and channels could also be seen in whole corn and sorghum Starch Granules treated with merbromin in methanol and viewed by fluorescence microscopy. Treatment of sorghum Starch Granules with an aqueous solution of merbromin revealed that the molecule penetrated the granule matrix under even slightly swelling conditions. Light microscopy showed cavities in unstained, whole, dry corn and sorghum Starch Granules mounted in immersion oil.
Kerry C. Huber - One of the best experts on this subject based on the ideXlab platform.
-
Heterogeneity of Starch Granules and the effect of granule channelization on Starch modification
Cellulose, 2004Co-Authors: John E. Fannon, Kerry C. Huber, Jonathan A. Gray, Ninik Gunawan, James N. BemillerAbstract:This paper reviews the discovery of channels ID Starch Granules and progress of research on their effects on granule modification and digestibility, their nature, hypotheses on how they are formed and why they are present, and genetic control of their occurrence. Emphasized ID the relationship of channels to Starch derivatization. Channelization ID presented as additional evidence of the heterogenous nature of Starch Granules from source to source and within a single source. A new method of determining the location of anionic entities within Starch Granules that utilizes reflectance confocal laser scanning microscopy ID described.
-
location of sites of reaction within Starch Granules
Cereal Chemistry, 2001Co-Authors: Kerry C. Huber, James N. BemillerAbstract:ABSTRACT To observe granular reaction patterns within modified Starch Granules, Starch derivatives were converted to thallium(I) salts and viewed by scanning electron microscopy compositional backscattered electron imaging. Observation of phosphorylated potato and sorghum Starches and a hydroxypropyl analog of waxy maize Starch revealed that granular patterns of reaction were influenced by both Starch and reagent types. In waxy maize and sorghum Starches, flow of reagent into the granule matrix occurred from channels (laterally) and cavities (from the inside outward). In potato Starch Granules, which do not possess channels, reagent diffused inward through exterior granule surfaces. Phosphoryl chloride (highly reactive) reacted to a large extent at granule surfaces, while the propylene oxide analog (less reactive) appeared to diffuse into the granule matrix prior to reacting.
-
channels of maize and sorghum Starch Granules
Carbohydrate Polymers, 2000Co-Authors: Kerry C. Huber, James N. BemillerAbstract:The radial, tube-like channels of corn/maize and sorghum Starch Granules, which penetrate from the external surface inward toward a cavity at the hilum, were found to vary in depth of penetration from granule to granule. Most, but not all, channels spanned the entire granule matrix, from the outer surface to the central cavity. Under slight swelling conditions (water), cavities swelled somewhat closed, while channels appeared to remain open. Swelling also affected the permeability of the granule matrix to dye molecules. Penetration of an aqueous dye solution occurred primarily from the central cavity outward and laterally from channels. Even under the slight swelling conditions, colloidal gold particles filled channels and cavities, showing that they are voids.
-
Visualization of Channels and Cavities of Corn and Sorghum Starch Granules
Cereal Chemistry, 1997Co-Authors: Kerry C. Huber, James N. BemillerAbstract:ABSTRACT Evidence is presented that corn (maize) and sorghum Starch Granules have channels that connect a central cavity to the external environment. A mutant sorghum Starch with numerous, large surface pores was treated with a methanolic solution of merbromin and sectioned. Light, fluorescence, and compositional backscattering electron microscopy revealed channels connecting an internal cavity to the external surface in most Granules. Cavities and channels could also be seen in whole corn and sorghum Starch Granules treated with merbromin in methanol and viewed by fluorescence microscopy. Treatment of sorghum Starch Granules with an aqueous solution of merbromin revealed that the molecule penetrated the granule matrix under even slightly swelling conditions. Light microscopy showed cavities in unstained, whole, dry corn and sorghum Starch Granules mounted in immersion oil.
Peter R Ellis - One of the best experts on this subject based on the ideXlab platform.
-
investigating the mechanisms of amylolysis of Starch Granules by solution state nmr
Biomacromolecules, 2015Co-Authors: Andrew J Baldwin, Danielle L Egan, Fredrick J Warren, Paul D Barker, Christopher M Dobson, Peter J Butterworth, Peter R EllisAbstract:Starch is a prominent component of the human diet and is hydrolyzed by α-amylase post-ingestion. Probing the mechanism of this process has proven challenging, due to the intrinsic heterogeneity of individual Starch Granules. By means of solution-state NMR, we demonstrate that flexible polysaccharide chains protruding from the solvent-exposed surfaces of waxy rice Starch Granules are highly mobile and that during hydrothermal treatment, when the Granules swell, the number of flexible residues on the exposed surfaces increases by a factor of 15. Moreover, we show that these flexible chains are the primary substrates for α-amylase, being cleaved in the initial stages of hydrolysis. These findings allow us to conclude that the quantity of flexible α-glucan chains protruding from the granule surface will greatly influence the rate of energy acquisition from digestion of Starch.
Ling Chen - One of the best experts on this subject based on the ideXlab platform.
-
study on supramolecular structural changes of ultrasonic treated potato Starch Granules
Food Hydrocolloids, 2012Co-Authors: Jie Zhu, Ling ChenAbstract:The supramolecular structural features of ultrasonic treated potato Starch Granules in excess water were investigated. Various ultrasonic treatments were used; an ultrasound probe set with different power (60, 105, 155 W) at a frequency of 20 kHz for 30 min. Scanning electron microscopy (SEM) images show that ultrasonic treatment induced notch and groove on Starch granule surface. The B-type crystal structure was scarcely affected according to polarized light microscopy (PLM) and X-ray diffraction (XRD) analysis. However, Small-angle X-ray scattering (SAXS) data manifest that fractal structures changed from surface fractal into mass fractal as the ultrasonic power increased, indicating that the compact Starch Granules swelled to a larger extent and loosed. The repeat cluster thickness was unchanged. The electron density contrast between the crystalline and the amorphous lamella decreased, while the electron density difference between the amorphous lamella and amylose background increased. Moreover, the molecular order in crystalline lamella was reduced. These results demonstrated that ultrasonic treatment affected cluster structure, especially the crystalline region, and amylose background was affected more compared to amylopectin amorphous lamella.
-
internal structures and phase transitions of Starch Granules during gelatinization
Carbohydrate Polymers, 2011Co-Authors: Pei Chen, George P Simon, Xingxun Liu, Katherine Dean, Ling ChenAbstract:The internal structures of corn Starch Granules with different amylose/amylopectin contents were studied using different microscopic techniques. The gelatinization phase transitions of the various Starches were investigated by hot-stage confocal laser scanning microscopy (CLSM) and scanning electron microscopy (SEM). The influence of the amylose/amylopectin ratio on the internal structures and morphologies could be revealed by these techniques. Sharp growth ring structures could be clearly identified for high-amylopectin Starches by CLSM and SEM following acid treatment. CLSM allowed the visualization of cross-sections of Starch Granules without the need for sectioning techniques that lead to destruction of the microstructure of sample, allowing exploration of the gelatinization mechanism. Three-dimensional images of Starch Granules during gelatinization could be constructed to further explore phase transition mechanisms. It was found that the Granules of waxy maize and normal maize Starch subsequently break through at their cavity and channels, when the Granules became swollen during gelatinization, whilst the Granules of G50 and G80 remain granular and break down to smaller pieces.
-
phase transition of Starch Granules observed by microscope under shearless and shear conditions
Carbohydrate Polymers, 2007Co-Authors: Pei Chen, Tim J Kealy, Ling ChenAbstract:Abstract The phase transitions of Starch Granules of cornStarches with different amylose/amylopectin contents (waxy: 0/100; maize: 23/77; Gelose 50: 50/50; Gelose 80: 80/20) were systematically studied under shearless and shear conditions. A microscope with a hot-stage was used to observe phase transition under shearless conditions during heating and isothermally at different temperatures. Phase transition under shear conditions was investigated using a rheoscope – a controlled rate/controlled stress rheometer with a built-in high-resolution video camera. An increase in Starch granule diameter, disappearance of birefringence and granule disappearing were used to describe the phase transition. The diameter growth rate and final accretion ratio sequence of Starch Granules during heating under shearless conditions was waxy > maize > G50 > G80, which correspond with amylose/amylopectin ratio. The growth rate of granular diameter under shear conditions was controlled by two factors: swelling and dissolving. Starch Granules were destroyed under shear conditions, but some could still be identified under shearless conditions up to about 100 °C. Granules totally disappeared in a very short time after gelatinization under shear stress conditions. Increased amylose content led to a lower granule diameter growth rate and accretion ratio, and a higher temperature before birefringence disappeared. It was found that the higher the melting temperature of the amylose–lipid complex, the higher the gelatinization temperature, and the amylose detected by differential scanning calorimetry in the high-amylose Starches is proposed as an explanation of the results observed by microscope.
Ravindra N. Chibbar - One of the best experts on this subject based on the ideXlab platform.
-
Starch-Branching Enzymes Preferentially Associated with A-Type Starch Granules in Wheat Endosperm
Plant physiology, 2000Co-Authors: Mingsheng Peng, Ming Gao, Monica Båga, Pierre Hucl, Ravindra N. ChibbarAbstract:Two Starch granule-bound proteins (SGP), SGP-140 and SGP-145, were preferentially associated with A-type Starch Granules (>10 μm) in developing and mature wheat (Triticum aestivum) kernels. Immunoblotting and N-terminal sequencing suggested that the two proteins were different variants of SBEIc, a 152-kD isoform of wheat Starch-branching enzyme. Both SGP-140 and SGP-145 were localized to the endosperm Starch Granules but were not found in the endosperm soluble fraction or pericarp Starch Granules younger than 15 d post anthesis (DPA). Small-size Starch Granules ( 10 μm). In contrast, small-size Starch Granules harvested after 15 DPA contained only low amounts of SGP-140 and SGP-145 and developed mainly into B-type Starch Granules (
-
Separation and Characterization of A- and B-Type Starch Granules in Wheat Endosperm
Cereal Chemistry Journal, 1999Co-Authors: Mingsheng Peng, Ming Gao, Pierre Hucl, E.-s. M. Abdel-aal, Ravindra N. ChibbarAbstract:ABSTRACT Mature wheat (Triticum aestivum L.) endosperm contains two types of Starch Granules: large A-type and small B-type. Two methods, microsieving or centrifugal sedimentation through aqueous solutions of sucrose, maltose, or Percoll were used to separate A- and B-type Starch Granules. Microsieving could not completely separate the two types of Starch Granules, while centrifuging through maltose and sucrose solutions gave a homogenous population for B-type Starch Granules only. Centrifuging through two Percoll solutions (70 and 100%, v/v) produced purified populations of both the A- and B-type Starch Granules. Analysis of Starch granule size distribution in the purified A- and B-type granule populations and in the whole-Starch granule population obtained directly from wheat endosperm confirmed that the purified A- and B-type Starch granule populations represented their counterparts in mature wheat endosperm. Centrifugations through two Percoll solutions were used to purify A- and B-type Starch granule...
