Amylopectin Chain Length Distribution Research Articles

Elucidation of the low resistant starch phenotype in Phaseolus vulgaris exhibited in the yellow bean Cebo Cela.

Dry beans(Phaseolus vulgaris) are rich in complex carbohydrates including resistant starch (RS). RS, the starch fraction that escapes digestion, typically ranges from 35% in raw beans to 4% in cooked beans. A low RS bean genotype, Cebo Cela, was identified with 96% less RS (1.5% RS) than normal raw beans. The goal of this research was to elucidate the factors responsible for this low RS phenotype. The low RS phenotype was evaluated in whole bean flour and starch in Cebo Cela (yellow), Canario (yellow), Alpena (navy) and Samurai (otebo). α-Amylase activation was found to be a major contributor of the low RS content phenotype of the whole bean flour for Cebo Cela (-21.9% inhibition). Total starch (43.6%-40.2%), amylose (31.0%-31.5%), molecular weight and chain length distributions of amylose and amylopectin did not contribute to the low RS phenotype. Yellow bean starches were digested nearly 1.5 times (95%-94%) faster than starch granules from otebo and navy beans (65%-73%) due to lower proportions of amylopectin chains. PRACTICAL APPLICATION: This study is of value to the food industry because the yellow bean, Cebo Cela, is easily hydrolyzed by α-amylase and also has α-amylase promotion properties. Therefore, Cebo Cela can be used as an alternate starch source for ethanol fermentation and for the production of maltodextrins and fructose/glucose syrups which are used as food thickeners and sweeteners.

Relationships among molecular, physicochemical and digestibility characteristics of Andean tuber starches

This study aimed to determine and correlate the physicochemical, thermal, pasting, digestibility and molecular characteristics of native starches, such as mashua (Tropaeolum tuberosum R. and P.), oca (Oxalis tuberosa Mol.), and olluco (Ullucus tuberosus C.), which were extracted via successive washing and sedimentation. The morphology of native starches was determined by scanning electron microscopy, granule size distribution, thermal properties, pasting properties, X-ray diffraction (XRD), amylopectin chain-length distribution and amylose and amylopectin molecular weights. Mashua starch was smaller in size than oca and olluco starches. Moreover, the granules of mashua starch were round in shape, whereas those of oca and olluco starches were ellipsoidal in shape. The B XRD spectra showed similar profiles for the three Andean tuber starches. Mashua and olluco starches exhibited the lowest gelatinization temperatures and enthalpy values, and olluco amylopectin exhibited a longer chain length than mashua and oca starches. The resistant starch of gelatinized and ungelatinized samples exhibited a positive and strong correlation with the molecular properties of amylose and amylopectin, gelatinization enthalpy and molecular order.

Effect of molecular structure on phase transition behavior of rice starch with different amylose contents

Phase transition behaviors in starch-water system and molecular structures of rice starches isolated from four Korean cultivars with different amylose contents were investigated and the importance of structural features affecting starch phase transitions was also explored. The Dodam starch with the highest average chain length of amylopectin (26.1), the highest proportion (24.3 %) of long chains (DP ≥ 37), and the lowest proportion (17.5 %) of short chains (DP 6-12) displayed the highest gelatinization and retrogradation temperatures. Enthalpies of ice freezing and melting, and glass transition temperature (Tg′) of rice starches increased with increasing amylose content and decreasing proportion of short amylopectin chains because these structural features are related to a higher thermal stability of the starches. Ice melting temperature was also influenced by amylopectin chain structures. The results suggest that the phase transition behaviors of rice starches were highly influenced by their amylose content and amylopectin chain length distribution.

Water irrigation management affects starch structure and physicochemical properties of indica rice with different grain quality

The effects of water irrigation management including conventional irrigation (CK), constant flooding irrigation (CFI) and alternate wetting and drying (AWD) on starch structure and physicochemical properties of two indica rice cultivars with good- and poor-quality were evaluated in the field condition with two years. The results showed that AWD could significantly increase peak viscosity, breakdown and gelatinization temperature, decreased setback and gelatinization enthalpy in two indica rice cultivars. However, starch granule size and amylopectin chain length distribution were differed the trends in the rice cultivars and treatments. AWD reduced starch granules size and amylopectin short chain, especially for large starch granules, but increased medium and long chain, which might contribute to better thermal stability and pasting viscosity for good-quality cultivar. Our study indicated that water irrigation management affected starch structure and physicochemical properties of indica rice starch, and would provide favorable information for improvement of rice starch in food industry.

Functionality of cassava genotypes for waxy starch

Abstract: The objective of this work was to select cassava (Manihot esculenta) genotypes from the Brazilian germplasm bank with a functionality similar to that of waxy starch. A total of 881 genotypes were pre-selected using principal component analysis and hierarchical clustering, and their industrial potential was compared with that of the 7745-5WX waxy cassava and the WX-Maize waxy maize clones, both used as references. Two genotypes stood out: BGM0036 and BGM0083. Samples from these four genotypes were characterized by means of amylose content, scanning electron microscopy, X-ray diffraction, differential scanning calorimetry, paste viscosity, and chain-length distribution of amylopectin. The samples presented A-type crystallinity and no statistical differences (p > 0.05) regarding crystallinity degree (25.3 to 30.0), which shows similar proportions of the amylose/amylopectin fractions. No differences were observed in the microstructure of the cassava starches. Initial gelatinization temperature and amylopectin short chains presented a very strong negative correlation, indicating that a lower proportion of short chains of amylopectin results in a higher initial temperature of gelatinization. BGM0036 and BGM0083 show a low final viscosity, close to that of the waxy maize and cassava starches, being an alternative for use in different foods that require stability during freezing.

Interaction with longan seed polyphenols affects the structure and digestion properties of maize starch

This study investigated effects of longan seed polyphenols (LSPs) on the structure and digestion properties of starch, and discussed the interaction mechanism between starch and LSPs. The results showed cooking with 20 % LSPs did not change amylopectin chain length distribution of normal maize starch, however, the amylose content was reduced from 21.60 to 14.03 %. This suggests LSPs may interact with starch via non-covalent bond. Isothermal titration microcalorimetry and XRD results confirmed the existence of non-covalent interaction, and indicated that LSPs may enter the hydrophobic cavity of amylose, forming V-type inclusion complex. LSPs did not affect gelatinization temperatures of maize starch, whereas 20 % LSPs decreased the enthalpy change by about 26 %. The digestion results indicate significant inhibition effect of LSPs on the digestion of cooked starch, attributing to the interaction of LSPs with starch. These suggest potential applications of LSPs as functional ingredients in modulating postprandial glycemic response of starchy food.

Effects of BEIIb-Deficiency on the Cluster Structure of Amylopectin and the Internal Structure of Starch Granules in Endosperm and Culm of Japonica-Type Rice.

It is known that one of starch branching enzyme (BE) isoforms, BEIIb, plays a specific role not only in the synthesis of distinct amylopectin cluster structure, but also in the formation of the internal structure of starch granules in rice endosperm because in its absence the starch crystalline polymorph changes to the B-type from the typical A-type found in the wild-type (WT) cereal endosperm starch granules. In the present study, to examine the contribution of BEIIb to the amylopectin cluster structure, the chain-length distributions of amylopectin and its phosphorylase-limit dextrins (Φ-LD) from endosperm and culm of a null be2b mutant called amylose-extender (ae) mutant line, EM10, were compared with those of its WT cultivar, Kinmaze, of japonica rice. The results strongly suggest that BEIIb specifically formed new short chains whose branch points were localized in the basal part of the crystalline lamellae and presumably in the intermediate between the crystalline and amorphous lamellae of amylopectin clusters in the WT endosperm, whereas in its absence branch points which were mainly formed by BEI were only located in the amorphous lamellae of amylopectin. These differences in the cluster structure of amylopectin between Kinmaze and EM10 endosperm were considered to be responsible for the differences in the A-type and B-type crystalline structures of starch granules between Kinmaze and EM10, respectively. The changes in internal structure of starch granules caused by BEIIb were analyzed by wide angle X-ray diffraction, small-angle X-ray scattering, solid state 13C NMR, and optical sum frequency generation spectroscopy. It was noted that the size the amylopectin cluster in ae endosperm (approximately 8.24 nm) was significantly smaller than that in WT endosperm (approximately 8.81 nm). Based on the present results, we proposed a model for the cluster structure of amylopectin in WT and ae mutant of rice endosperm. We also hypothesized the role of BEIIa in amylopectin biosynthesis in culm where BEIIb was not expressed and instead BEIIa was the major BE component in WT of rice.

Structural basis of wheat starch determines the adhesiveness of cooked noodles by affecting the fine structure of leached starch

The relationship between the fine structure of original starch, leached starch during cooking, and the adhesiveness of noodles prepared by adding starches separated from different wheat cultivars was analyzed. The adhesiveness of noodles was primarily determined by the chain-length distributions of amylopectin rather than amylose. The adhesiveness of cooked noodles was positively correlated with the amount of short amylopectin chains with the degree of polymerization (DP) of 6–12, but negatively correlated with the amount of long chains with 25 < DP ≤ 36. The decrease of the proportion of short amylopectin chains and amylose chains and the increase of the amount of very long amylopectin chains with 37 < DP ≤ 100 in leachate led to decreased adhesiveness of cooked noodles. The reduction of the short-chain content in leached amylopectin caused by the increased proportion of long chains in original amylopectin is proposed to weaken the adhesiveness of cooked noodles.

Effects of amylose and amylopectin chain-length distribution on the kinetics of long-term rice starch retrogradation

Understanding the characteristics of long-term starch retrogradation is critical for developing functional foods with desirable textural attributes. The long-term retrogradation kinetics of 10 different rice starches with a wide range of amylose content were thus investigated in this study, focusing on their relations with the starch chain-length distributions (CLDs). Correlation analysis between the retrogradation parameters from differential scanning calorimetry (DSC) with starch CLDs showed for the first time that the amylose content had a parabolic relationship with the melting conclusion temperature and enthalpy of long-term retrograded starches, indicating that the amylose component has a bi-directional effect on the long-term amylopectin retrogradation property. Furthermore, the amount of amylose short-medium chains and amylopectin medium chains were negatively and positively correlated with the melting onset temperature of long-term retrograded starches, respectively. The information learnt from this study could be applied in the rice industry to improve the textural attributes of cooked rice.

Effects of Genetic Background and Environmental Conditions on Amylopectin Chain-Length Distribution in a Recombinant Inbred Line of an Inter-subspecies Rice Cross.

Amylopectin is an essential starch property, and the chain-length distribution of amylopectin (APCLD) is closely associated with the eating and cooking quality of rice. In this study, a series of recombinant inbred lines derived from an indica/japonica cross were planted in four areas with distinct ecological conditions (LN, SC, JS, and GD), and the relationship among APCLD, environmental factors, and genetic background was analyzed. The results showed that APCLD was strongly influenced by environmental factors, which dynamically changed from heading to the mature stage. The solar radiation, luminous flux, and light hours were positively correlated with Fa but negatively correlated with Fb1 and Fb2. The temperature was negatively correlated with Fa and Fb1 but positively correlated with Fb2 and Fb3. The temperature was the primary factor affecting APCLD, followed by humidity and light. There was no significant correlation between the indica pedigree percentage and APCLD. Furthermore, we detected six quantitative trait loci related to Fa, Fb1, Fb2, and Fb3 chains, several of which shared a similar region to previously reported loci, including DENSE AND ERECT PANICLE 1 (DEP1). The truncated dep1 allele increased Fa, Fb2, and Fb3 but decreased Fb1 in LN, whereas Fa was decreased but Fb1 and Fb2 were increased in JS. Elucidating the effects of climate factors and genetic background on APCLD could provide a theoretical basis and technical guidance for high-quality rice breeding.

On the role of the internal chain length distribution of amylopectins during retrogradation: Double helix lateral aggregation and slow digestibility

A structure-digestion model is proposed to explain the formation of α-amylase-slowly digestible structures during amylopectin retrogradation. Maize and potato (normal and waxy) and banana starch (normal and purified amylopectin through alcohol precipitation), were analyzed for amylose ratio and size (HPSEC) and amylopectin unit- and internal-chain length distribution (HPAEC). Banana amylopectin (BA), like waxy potato (WP), exhibited a larger number of B3-chains, fewer BS- and Bfp-chains and lower S:L and BS:BL ratios than maize, categorizing BA structurally as type-4. WP exhibited a significantly greater tendency to form double helices (DSC and 13C-NMR) than BA, which was attributed to its higher internal chain length (ICL) and fewer DP6−12-chains. However, retrograded BA was remarkably more resistant to digestion than WP. Lower number of phosphorylated B-chains, more S- and Bfp-chains and shorter ICL, were suggested to result in α-amylase-slowly digestible structures through further lateral packing of double helices (suggested by thermo-rheology) in type-4 amylopectins.

The texture of fresh rice noodles as affected by the physicochemical properties and starch fine structure of aged paddy

The physicochemical properties and starch fine structure change during paddy storage, which may be beneficial for the qualities of rice-based products such as fresh rice noodles (FRN). In this study, the textural properties of FRN prepared from polished rice of six indica paddy cultivars after different storage period at 36 ± 2 °C and 85% ± 5% relative humidity were investigated. The pasting properties, solubility (S), swelling power (SP) of rice flour and morphology of the starch granules, chain length distribution of amylopectin were analyzed to determine factors that impact the texture of FRN. The chewiness and springiness of FRN increased, and the adhesiveness decreased with increase in storage duration. The setback (SB) and pasting temperature (PT) increased while the S and SP decreased with extension of storage duration (0–90 days). Chain length distributions of amylopectin also changed. Pearson correlation analysis revealed that cool paste viscosity (CPV) of indica rice flour, short chain (DP 6–12) and long chain (DP 37–60) of amylopectin were the most correlated parameters with adhesiveness of FRN. Our results may provide insights for selecting raw materials for production of high-quality FRN.

Single nucleotide polymorphisms in GBBSI and SSIIa genes in relation to starch physicochemical properties in selected rice (Oryza sativa L.) varieties

Single nucleotide polymorphisms in GBBSI and SSIIa genes in relation to starch physicochemical properties in selected rice (Oryza sativa L.) varieties

Insights into chain-length distributions of amylopectin and amylose molecules on the gelatinization property of rice starches

Starch gelatinization is an endothermic transition arising during rice cooking, which significantly influences rice eating and cooking quality (ECQ). The nature of starch (especially amylose) fine molecular structures that gives rise to this endotherm is however currently unclear. A modified Gomperz model was developed in this study to fit the differential scanning calorimetry (DSC) thermograms, resulting complementary information to the traditional DSC parameters. Correlation analysis between DSC parameters with starch chain-length distributions (CLDs) from 14 different rice starches showed for the first time that although amylose CLDs didn't affect starch gelatinization temperatures, the relative length of amylose medium chains was negatively correlated with the gelatinization temperature range. Furthermore, gelatinization onset and peak temperature as well as maximum gelatinization rate were negatively correlated with the relative length of amylopectin short chains, while the conclusion temperature were related to the relative length of amylopectin medium chains. Based on these results, a model for the arrays of amylopectin and amylose molecules within semi-crystalline lamellas of rice starch granules was proposed. These results will enable plant breeders to produce rice with desirable ECQs based on better understandings of the importance of starch fine molecular structures in determining starch gelatinization property.

Microstructure, gelatinization and pasting properties of rice starch under acid and heat treatments

Microstructure of starch plays a vital role in the physicochemical properties. In this study, the microstructure, gelatinization and pasting properties of rice starches after acid, heat and acid-heat treatments were investigated. In our findings, molecular weight and size, amylopectin chain length distribution, degree of branching, amylose content, relative crystallinity, and hot water-solubility of rice starch were varied significantly after acid-heat treatment, showing a synergy between acid and heat. Correspondingly, acid-heat treatment markedly changed gelatinization and pasting properties of rice starch by sharply decreasing gelatinization and pasting temperatures as well as pasting viscosities. Pearson correlation analysis was performed, showing that molecular weight, size, amylopectin chain length distribution, and amylose content were significantly correlated to gelatinization temperatures, and crystallinity was remarkably correlated to gelatinization enthalpy. As for pasting properties, molecular weight and size as the major factors were substantially correlated to pasting viscosities and pasting temperature. This study provides a structure-property correlation for acid-heat treated rice starch, giving scientific basis for the application of starch in food industry.

The effects of the chain-length distributions of starch molecules on rheological and thermal properties of wheat flour paste

The rheological and thermal properties of wheat flour are important for eating and processing quality of flour-based foods. These properties are in part affected by the structure of the component starch, but the mechanisms underlying this are not well understood. In this study, the thermal and rheological properties of wheat-flour paste for 16 wheat varieties were measured and the results fitted with two standard models. Starch molecular structures were measured by fluorophore-assisted carbohydrate electrophoresis and size-exclusion chromatography. The resulting chain-length distributions of amylopectin and amylose were fitted using biosynthesis-based models, thereby representing the data in terms of biologically-meaningful parameters. Protein content was also measured. This gave quantitative relations between starch molecular fine structure and rheological and thermal properties of wheat flour paste. Long amylopectin chains were positively correlated with peak and conclusion temperatures, viscosity was positively, and elasticity negatively, correlated with the length of amylopectin short chains, while protein content showed no significant correlation with rheological and thermal properties. These results indicate that starch fine structure provides additional criteria for the selection of wheat varieties, complementary to the common use of protein composition and amylose content.

New insights into amylose and amylopectin biosynthesis in rice endosperm

How various isoforms of rice-starch biosynthesis enzymes interact during amylose and amylopectin synthesis is explored. The chain-length distributions of amylopectin and amylose from 95 varieties with different environmental and genetic backgrounds were obtained using size- exclusion chromatography, and fitted with biosynthesis-derived models based on isoforms of starch synthase (SSI-SSIV), starch branching enzyme (SBE, including SBEI and SBEII) and granule-bound starch synthase (GBSS) that are involved in amylose and amylopectin synthesis. It is usually thought that these are synthesized by separate enzymes. However, the amount of longer amylopectin chains correlated with that of shorter amylose chains, indicating that GBSS, SBE and SS affect both amylose and amylopectin synthesis. Further, the activity of GBSS in amylose correlated with that of SS in amylopectin. This new understanding of which enzymes are suggested by the statistics to be involved in both amylose and amylopectin synthesis could help rice breeders develop cereals with targeted properties.

Effects of pullulanase debranching on the properties of potato starch-lauric acid complex and potato starch-based film

The effects of different debranching time on the properties of potato starch and its films were evaluated. Potato starch granules were debranched with pullulanase for 0, 0.5, 1.0, 1.5 or 2.0 h. The effects of pullulanase debranching treatment on the chain-length distributions of amylopectin were analysed by high performance anion exchange chromatography (HPAEC), which proved that the shorter debranching treatment generated more linear chains with favourable lengths to facilitate the formation of potato starch-lauric acid complexes. The debranched starch-lipid complexes showed higher lauric acid content than that of the untreated sample. X-ray diffraction showed that the diffraction intensity of the debranched sample was stronger than that of the undebranched sample, and when the debranching time was >1.5 h, the diffraction intensity and relative crystallinity of the complexes decreased. The sample exhibited a high melting enthalpy (ΔH) under the pullulanase debranching treatment for 1.5 h. Scanning electron microscope data indicated that the surface of the composite film was flatter after the debranching treatment and that the films exhibited the lowest water vapour permeability and highest tensile strength after the treatment time for 1.5 h.

Study on crystalline, gelatinization and rheological properties of japonica rice flour as affected by starch fine structure

Although many researches have investigated the effects of starch characteristics on its functional properties to evaluate rice quality, few studies were carried out the correlations between starch molecular structure and rice processing properties. In this study, eight varieties of japonica rice with similar content of protein and lipid and less variant content of amylose (12.12–18.19%) were elaborately selected. The result showed that crystalline and pasting parameters were mainly reliant on the differences in chain length distribution of amylopectin. Amylose content and chain length distribution, especially for average exterior chain length (ECL) and interior chain length (ICL) and their entanglement, showed significant correlation on rheological parameters. Swelling power of rice flour showed negative correlation with amylose content. Furthermore, in temperature-reduction process when the temperature is lower gelatinization temperature of amylopectin, the variation of loss modulus was affected by amylopectin. In addition, the PCA plot clearly revealed the interrelationship of all parameters.

Insights into structure-function relationships of starch from foxtail millet cultivars grown in China

Structure-function relationships of starch isolated from eight cultivars of foxtail millets grown in China were investigated. The starch granules were polygonal with diameters between 5 μm and 10 μm. The amylose content ranged from 16.8% to 26.8%, and the relative crystallinity and the full width at half maximum (FWHM) of the Raman band at 480 cm−1 varying between 33.2% and 36.4% and 15.72 to 15.91, respectively. There were only small differences in amylopectin chain length distribution of the eight foxtail millet starches. Significant differences were noted in swelling power, gelatinization, pasting, gel textural properties of starches, but not in vitro enzymic digestibility. Correlation analysis results showed that amylose content and chain length distribution of amylopectin were more important determinants of functional properties of starch than the structural order of the starch granules.