Molecular characteristics and physicochemical properties of very small granule starch isolated from Agriophyllum squarrosum seeds.

Novel starch resources isolated from accessible botanical origins are of special interest to food scientists in the context of food security. In this study, Agriophyllum squarrosum starches (AS-1, AS-2, and AS-3) were isolated from three ecotypes of A. squarrosum seeds and compared with quinoa starch (QS). The mean particle diameter of AS granules ranged from 1.12 to 1.15 µm, and AS amylopectin had a significantly higher Mw than QS (p < 0.05). Compared with QS, AS samples had more branching and substitution of amylopectin structures. The peak viscosity, breakdown viscosity, and swelling degree of the AS samples were significantly lower than those of QS (p < 0.05). AS showed a lower crystalline degree and higher gelatinization temperatures, and the freshly cooked AS showed a slower digestibility rate than QS. The physicochemical properties and chain profiles of AS facilitate the application of AS and the domestication of A. squarrosum crops.

Annealing treatment of amylose and amylopectin extracted from rice starch.

Annealing behavior of amylose and amylopectin was unclear. In this work, high purity amylose and amylopectin were extracted from rice starch, and structural properties of the retrograded rice starch, amylose, and amylopectin before and after annealing treatment were explored. It was found that the purity of the amylose and amylopectin was 95.64% ±â€¯2.69% and 94.98% ±â€¯0.97%, respectively. Their molecular weight was (2.93 ±â€¯0.21) × 106 Da and (5.90 ±â€¯0.13) × 107 Da, respectively. Besides, the relative crystallinities and ratios of 1047 cm-1/1022 cm-1 of the retrograded rice starch and amylose were significantly increased by annealing treatment, while that of retrograded amylopectin did not change. These results clarified that amylose was more sensitive to annealing treatment than amylopectin, and amylose was more responsible for annealing of starch than amylopectin. The findings contributed to a better understanding of the annealing behavior of starch.

Effect of degree of polymerization of amylopectin on the gelatinization properties of jackfruit seed starch.

Five gelatinized jackfruit starches (GJFSS: M1', M5', M6', M11', and BD') were prepared using amylose mixed with five types of amylopectin. M1' had the lowest degree of polymerization while BD' had the highest. The five GJFSS samples showed significant variations in microstructures, varying from a compact structure (M1') to a loose structure (BD'). The freeze-thaw stability was consistent with results of the microstructure. High syneresis formed compact structure (M1'), and low syneresis formed a loose structure (BD'). As the degree of polymerization of amylopectin increased, the gelatinization enthalpy, peak viscosity, breakdown, final viscosity, setback, and absorbance ratio decreased, while the transition temperature and pasting temperature increased. The thermal, pasting properties, and the short-range molecular order, were consistent with the results of the microstructure and syneresis. All the results indicated that the degree of polymerization of amylopectin is an important structural factor that can significantly affect the gelatinization properties of starch.

Three-dimensional porous graphene oxide-maize amylopectin composites with controllable pore-sizes and good adsorption-desorption properties: Facile fabrication and reutilization, and the adsorption mechanism.

Three-dimensional (3D) porous graphene oxide-maize amylopectin (GO-MA) composites with controllable pore-sizes composites in the range of 6-40 nm were prepared by facile hydrothermal-assisted assembly approaches. The morphologies, pore sizes, specific surface area (SSA) and compositions of GO-MAx:y composites with and different GO-to-MA mass ratios (x:y) were characterized by scanning electron microscopy (SEM), N2 adsorption-desorption isotherms, Fourier transform infrared spectroscopy (FT-IR) and X-ray photoelectron spectroscopy (XPS). To reveal the adsorption-desorption mechanism, effects of contact time, temperature, initial adsorbate concentration, pH value of the solution on the adsorption process were studied in detail. The adsorption capacities of 3D GO-MA20:1 composite for organic contaminants including tert-butyl hydroquinone (TBHQ), p-aminophenol (PAP), p-nitrophenol (PNP), o-nitrophenol (MNP), hydroquinone (HQ), alizarin red S (ARS) and neutral red (NR) were 22.17, 116.4, 44.78, 36.96, 16.10, 39.92 and 24.23 mg g-1, respectively. The adsorption capacities of GO-MA30:1 composite for inorganic substances including Pb2+, Mn2+, Cr2O72-, Cd2+, Cu2+, Nd3+, La3+, Y3+, Yb3+ and Er3+ were 84.76, 7.92, 13.6, 17.64, 30.56, 25.52, 12.48, 16.96, 23.32 and 30.32 mg g-1, respectively. In addition, GO-MAx:y composites also exhibited high mechanical properties and good reusability. Consequently, GO-MAx:y composites could be used as reusable adsorbents for removal/enrichment inorganic/organic substances in aqueous solutions.

The importance of amylopectin molecular size in determining the viscoelasticity of rice starch gels.

Amylose content as the key indicator in determining the viscoelasticity of starch gels has been widely accepted. In this study, 7 rice varieties are deliberately selected to investigate the structural basis of gel viscoelasticity of starches with similar amylose content. By quantifying starch molecular structure and rheological properties of starch gels, we find (i) starch with similar amylose content forms significantly different gel networks in terms of K*, n* and tan δ; (ii) molecular sizes of rice starches are significantly different between samples; (iii) the chain-length distributions (CLDs) of both amylopectin and amylose are parameterized by mathematic model fitting, and no large variations of these fitted parameters between samples are observed; (iv) amylopectin size are negatively correlated with K* (p < 0.01) while positively correlated with tan δ (p < 0.05). Molecular mechanisms are put forward to explain the role of amylopectin size in contributing to the strength of gel network.

Structure analysis and antioxidant activities of an amylopectin-type polysaccharide isolated from dried fruits of Terminalia chebula.

Dried fruits of Terminalia chebula (TF) are used as herbal medicine for diverse symptoms, and their bioactivities are known to involve antioxidant activities. The aim of this study was to elucidate the structure and antioxidant effects of an active TF polysaccharide (TFP). The neutral polysaccharide (named as TFP-a) isolated by ion-exchange chromatography was a homogenous α-Glc-rich polysaccharide (over 70% α-Glc, 534.9 kDa, PDI 1.36) with a porous and flake-like morphology. Linkage and NMR data comprehensively showed that TFP-a was an amylopectin-type polysaccharide with (1→4)-α-Glc(p) backbone branched at C6/C2. Side chains were composed of (1→4)-ß-Gal(p) substituted with α-Ara(f), ß-GalUA(p), ß-GalUA(p)-Me, and α-Rham(p). In antioxidant activity assays, TFP-a exhibited potent and concentration-dependent antioxidant effects, including DPPH and superoxide radical scavenging and reducing power. We concluded that TFP-a is an amylopectin-type polysaccharide that may be used as a potential natural antioxidant.

Characterization of amylose and amylopectin fractions separated from potato, banana, corn, and cassava starches.

Analytical techniques such HPSEC, DSC, and TGA have been employed for amylose determination in starch samples, though spectrophotometry by iodine binding is most commonly used. The vast majority of these techniques require an analytical curve, using amylose and amylopectin standards with physicochemical properties similar to those found in the original starch. The current study aimed to obtain the amylose and amylopectin fractions from potato, banana, corn, and cassava starches, characterize them, and evaluate their behavior via thermogravimetric curves. Blue amylose iodine complex and HPSEC-DRI methods have obtained high purity amylose and amylopectin fractions. All molecular weights of the obtained amylose and amylopectin fractions were similar to those presented in other reports. Different results were obtained by deconvolution of the amylopectin polymodal distribution. All amyloses presented as semi-crystalline V-type polymorphs, while all amylopectin fractions were amorphous. The Tg of all Vamyloses presented were directly proportional to their respective crystalline index. TGA evaluations have shown that selective precipitation of amylose with 1-butanol strongly changes its thermal behavior. Therefore, the separation procedure used was an ineffective pathway for obtaining standards for thermal studies.

On the molecular structure of the amylopectin fraction isolated from "high-amylose" ae maize starches.

The amylopectin fractions from starch of a series of amylose-extender (ae) maize samples (HYLON(®) V, VII and VIII starches) were isolated and analysed for their molecular composition and structure. The fractions from all samples contained both a high and a low molecular weight fraction (HMF and LMF), of which LMF increased with the amylose content of the starch and appeared to have substantially more of long chains than HMF. A normal amylose-containing maize starch (NMS), which served as a reference sample, contained very little LMF, which suggested that LMF was the inherent result of the effect of the loss of starch branching enzyme IIb activity in the ae mutants. Clusters were isolated from the amylopectin fractions using Bacillus amyloliquefaciens α-amylase, which effectively hydrolyses long internal chain segments between clusters. During the hydrolysis process, clearly more of small dextrins were released from the ae starches in comparison to NMS. It appeared that some of these small dextrins did not precipitate in methanol together with the majority of the clusters. Nevertheless, isolated clusters from the HYLON starch samples were smaller than in NMS and the clusters possessed a lower density of branches with longer chains. The composition of small, branched building blocks was also clearly different: HYLON starch samples possessed much more of single-branched blocks and less multiple-branched blocks than NMS.

Preparation of slowly digestible sweet potato Daeyumi starch by dual enzyme modification.

Sweet potato Daeyumi starch was dually modified using glycogen branching enzyme (BE) from Streptococcus mutans and amylosucrase (AS) from Neisseria polysaccharea to prepare slowly digestible starch (SDS). Dually modified starches had higher SDS and resistant starch (RS) contents than control starch. The branched chain length distributions of the BE-modified starches indicated an increase in short side-chains [degree of polymerization (DP)≤12] compared with native starch. AS treatment of the BE-modified starches decreased the proportion of short side-chains and increased the proportion of long side-chains (DP≥25) and molecular mass. It also resulted in a B-type X-ray diffraction pattern and an increased relative crystallinity. Regarding thermal properties, the BE-modified starches showed no endothermic peak, whereas the BEAS-modified starches had a broader melting temperature range and lower melting enthalpy compared to native starch. The combined enzymatic treatment resulted in novel glucan polymers with slow digestion properties.

In vitro digestibility and changes in physicochemical and structural properties of common buckwheat starch affected by high hydrostatic pressure.

High hydrostatic pressure (HHP), a non-thermal processing technology, was applied at 120, 240, 360, 480, and 600MPa to assess its effect on the in vitro digestibility, physicochemical, and structural properties of common buckwheat starch (CBS). HHP treatment resulted in CBS granules with more rough surfaces. With the increasing pressure level, amylose content, pasting temperature, and thermal stability substantially increased and relative crystallinity, hardness, swelling power, and viscosity decreased. At 120-480MPa, HHP did not affect the 'A'-type crystalline pattern of CBS. However, at 600MPa, HHP contributed to a similar 'B'-type pattern. Compared with native starch, HHP-modified CBS samples had lower in vitro hydrolysis, reduced content of rapidly digestible starch, and increased levels of slowly digestible starch and resistant starch. These results revealed that the in vitro digestibility, physicochemical, and structural properties of CBS are effectively modified by HHP.

Characterization of internal structure of maize starch without amylose and amylopectin separation.

Normal maize starch was used to characterize the internal structure of starch without separating amylose and amylopectin, and the result was compared with amylose-free waxy maize starch. The clusters in the whole starch were produced by partial hydrolysis using α-amylase of Bacillus amyloliquefaciens, and were subsequently treated with ß-amylase to remove the linear amylose and to produce ß-limit dextrins of clusters from amylopectin. The clusters were further hydrolyzed extensively with α-amylase to produce building blocks. The compositions of clusters in the form of ß-limit dextrins and their building blocks were analyzed by gel-permeation chromatography and high-performance anion-exchange chromatography. The results showed that the structures of clusters and building blocks from whole starch of normal and waxy starches were similar. By number, each cluster contained 9-10 chains and 5-6 building blocks. The inter-block chain length in the clusters of whole starch was around six glucosyl residues. This study explored an alternate procedure to characterize the composition of branches in whole starch without separating amylose and amylopectin components.

Crop-derived polysaccharides as binders for high-capacity silicon/graphite-based electrodes in lithium-ion batteries.

Rice to power: Amylopectin is a major component of agricultural products such as corn, potato, and rice. Silicon-graphite electrodes are prepared by using slurries of these polysaccharides as binders. Compared to the conventionally used binder PVdF, they exhibit drastically improved electrode performance in Li cells. The improved performance is coupled to the degree of branching.

Building block organisation of clusters in amylopectin from different structural types.

Clusters of chains consisting of tightly branched units of building blocks were isolated from 10 amylopectin samples possessing the 4 types of amylopectin with different internal unit chain profiles previously described. It was shown that clusters in types 1 and 2 amylopectins are larger than in types 3 and 4, but the average cluster size did not correspond to the ratio of short to long chains of the amylopectins. The size-distribution of the building blocks, having one or several branches, possessed generally only small differences between samples. However, the length of the interblock segments followed the type of amylopectin structure, so that type 1 amylopectins had shortest and type 4 the longest segments. The chains in the clusters were divided into characteristic groups probably being involved in the interconnection of two, three, and four - or more - building blocks. Long chains were typically found in high amounts in clusters from type 4 amylopectins, however, all cluster samples contained long chains. The results are discussed in terms of the building block structure of amylopectin, in which the blocks together with the interblock segments participate in a branched backbone building up the amorphous lamellae inside growth rings of the starch granules. In such a model, amylopectins with proportionally less long chains (types 1 and 2) possess a more extensively branched backbone compared to those with more long chains (types 3 and 4).

Effect of varying flow regimes upon elution behaviour, apparent molecular characteristics and hydrodynamic properties of amylopectin isolated from normal corn starch using asymmetrical flow field-flow fractionation.

A detailed study of the elution behaviour, apparent molecular characteristics and hydrodynamic properties of amylopectin-type fraction (isolated from normal corn starch) in aqueous media employing asymmetrical flow field-flow fractionation (AF4) was undertaken by systematically varying the channel flow (F(ch)), cross flow (F(cr)) and F(cr)/F(ch) ratios. Distributions of apparent molar masses and radii of gyration, mass recoveries and hydrodynamic radii decreased as a function of increasing F(cr) at a fixed F(ch), due to the increase in the retention of amylopectin-type fraction in the AF4 channel. Increased retention of the amylopectin-type fraction in the AF4 channel was also observed at low F(ch) and high F(cr)/F(ch) ratios. Large amylopectin-type molecules/particles (possibly aggregates) eluted at high F(ch), low F(cr) and low F(cr)/F(ch) ratios.

Structural and physicochemical characterisation of rye starch.

The gelatinisation, pasting and retrogradation properties of three rye starches isolated using a proteinase-based procedure were investigated and compared to those of wheat starch isolated in a comparable way. On an average, the rye starch granules were larger than those of wheat starch. The former had very comparable gelatinisation temperatures and enthalpies, but slightly lower gelatinisation temperatures than wheat starch. Under standardised conditions, they retrograded to a lesser extent than wheat starch. The lower gelatinisation temperatures and tendencies of the rye starches to retrograde originated probably from their higher levels of short amylopectin (AP) chains [degree of polymerisation (DP) 6-12] and their lower levels of longer chains (DP 13-24) than observed for wheat starch. The rapid visco analysis differences in peak and end viscosities between the rye starches as well as between rye and wheat starches were at least partly attributable to differences in the levels of AP short chains and in average amylose molecular weight. The AP average chain lengths and exterior chain lengths were slightly lower for rye starches, while the interior chain lengths were slightly higher than those for wheat starch.

Phosphate esters in amylopectin clusters of potato tuber starch.

Starch phosphate is important in starch metabolism and in order to deduce its location and structural effects in clusters and building blocks of amylopectin, these were isolated from a normal potato (WT) and two starches with antisense suppressed glucan water dikinase (asGWD) activity and starch branching enzyme (asSBE) activity possessing suppressed and increased phosphate contents, respectively. Neutral N-chains and phosphorylated P-chains of the amylopectin macromolecules were similar in WT and asGWD, whereas asSBE possessed considerably longer P-chains. Cluster ß-limit dextrins were isolated by α-amylase treatment and successive ß-amylolysis. Cluster sizes were generally smaller in asSBE. The building block composition of neutral N-clusters were very similar in WT and asGWD, while asSBE was different, containing less blocks with degree of polymerization (DP)>14. Phosphate content of the P-clusters of WT and asGWD was rather similar, while asSBE contained highly phosphorylated P-clusters with proportionally more P-chains and a low degree of branching. The average chain lengths of the P-clusters were, however, similar in all samples. Our data demonstrate only minor effect on the cluster structure in relation to phosphate deposition suggesting conserved reaction patterns of starch phosphorylation. Models are suggested to account for the principle structural and functional effects of starch phosphate esters.

The fine structure of cassava starch amylopectin. Part 2: building block structure of clusters.

The aim of this work was to analyse the organization of unit chains inside clusters of cassava amylopectin. beta-Limit dextrins of the clusters and partly fragmented clusters (sub-clusters) were isolated previously [Laohaphatanaleart et al., Int. J. Biol. Macromol. (2010) doi:10.1016/j.ijbiomac.2010.01.0049] and were now hydrolysed extensively with the alpha-amylase (liquefying type) of Bacillus subtilis into small, branched building blocks. The blocks were size-fractionated and characterized structurally. The smallest blocks predominated in the clusters. They were single branched and possessed a degree of polymerization (DP) of 5-9. Blocks with DP 10-15 were double branched and constituted the second largest group. The clusters of cassava amylopectin, which were of rather uniform size, possessed typically 7-9 building blocks, and all clusters contained similar size-distributions of the blocks. The inter-block chain length was 7-8 residues. The possible mode of attack by the enzyme between the building blocks is discussed. A model of the building block organization in the clusters is presented, in which the structural roles of different sub-groups of clustered chains are suggested. A three-dimensional model suggests a possible organization of the building blocks inside the amorphous lamellae in the granular starch.

Isolation and physicochemical characterization of Assam Bora rice starch for use as a plasma volume expander.

Water soluble polysaccharides are most effective oncotic agents which are used for treatment of intravascular volume deficiency. Nowadays, they are used as basic material for plasma volume expander. Plasma volume expander based on starch has lower tendency to remain in any major organ of body in comparison to other plasma volume expander. Branched component of starch amylopectin is very similar in structure to glycogen, the reserve polysaccharides of animal; for all this reason starch is compatible with body tissues. Physicochemical properties of raw starch and amylopectin, isolated from Assam Bora rice were characterized for use as plasma volume expander. Characterization involves the determination of ash value, weight average molecular mass, viscosity and resistance towards enzymatic (amylase) hydrolysis. Amylose content was almost negligible. The X-ray diffraction pattern of Assam Bora rice starch was typically A type. High degree of crystallinity of Assam Bora rice starch reflects its resistance towards enzymatic hydrolysis which is of therapeutic advantage for using it as a plasma volume expander.

The fine structure of cassava starch amylopectin. Part 1: Organization of clusters.

The enzyme alpha-amylase from Bacillussubtilis was applied to partly hydrolyze purified cassava amylopectin into groups of clusters, which were called domains. The domains were further size-fractionated by methanol precipitation and then subjected to a second stage of alpha-amylolysis until the rate of hydrolysis was slow in order to release the single clusters. All domain and cluster fractions were hydrolyzed with beta-amylase into beta-limit dextrins. The size distribution and chain composition of the beta-limit dextrins were analyzed by gel-permeation chromatography and high-performance anion-exchange chromatography with pulsed amperometric detection, respectively. The sizes of the clusters in the form of beta-limit dextrins were uniform with an average degree of polymerization of 67-78. The distribution profiles of B-chains were similar in all cluster fractions, which suggested that the internal structure of the cassava amylopectin clusters was homogenous. Long B-chains were involved in the interconnection of clusters in the domain fractions. These were cleaved and a new group of chains of intermediate length was produced by the alpha-amylase together with short chains. In the isolated clusters, however, some chains corresponding to long B-chains still remained, which is not predicted by the traditional cluster model of the amylopectin structure. Instead, the alternative two-directional backbone model could explain the mode of interconnection between the clusters.

Structural and thermodynamic properties of starches extracted from GBSS and GWD suppressed potato lines.

A combined DSC-SAXS approach was employed to study the effects of amylose and phosphate esters on the assembly structures of amylopectin in B-type polymorphic potato tuber starches. Amylose and phosphate levels in the starches were specifically engineered by antisense suppression of the granule bound starch synthase (GBSS) and the glucan water dikinase (GWD), respectively. Joint analysis of the SAXS and DSC data for the engineered starches revealed that the sizes of amylopectin clusters, thickness of crystalline lamellae and the polymorphous structure type remained unchanged. However, differences were found in the structural organization of amylopectin clusters reflected in localization of amylose within these supramolecular structures. Additionally, data for annealed starches shows that investigated potato starches possess different types of amylopectin defects. The relationship between structure of investigated potato starches and their thermodynamic properties was recognized.