Amylopectin Chain Length Distribution Research Articles

Effects of amylose and amylopectin fine structure on the thermal, mechanical and hydrophobic properties of starch films.

The fine structures of pumpkin, potato, wheat, cassava, and pea starches were determined, followed by an evaluation of how these structures affected the properties of starch films. The structures significantly influenced film properties. Starches with larger molecular weights exhibited greater thermal stability. The tensile strength of starch film was negatively associated with the amylose chain length (r = -0.88, p < 0.05). The chain length distributions of amylose and amylopectin affected the mechanical properties of starch films by influencing structure ordering, supported by the positive correlation between the double helix content and the tensile strength (r = 0.95, p < 0.05). The amylopectin B1, B2, and B3 chains increased film mechanical strength. Conversely, amylopectin A-chains reduced the mechanical strength. The water contact angle was negatively correlated with the B3 chain proportion (r = -0.93, p < 0.05). The pumpkin starch exhibited the highest tensile strength (14.29 MPa), while the wheat starch film showed the highest water contact angle (112°). This study offers valuable insights into the structure-function relationships of starch films, thereby facilitating the acquisition of starch films with enhanced strength and stability through screening or designing starch structures. Consequently, this will expand the application of starch films as packaging materials in various food products.

Molecular changes and interactions of wheat flour biopolymers during bread-making: Implications to upcycle bread waste into bioplastics

This study aims to understand the molecular and supramolecular transformations of wheat endosperm biopolymers during bread-making, and their implications to fabricate self-standing films from stale white bread. A reduction in the Mw of amylopectin (51.8 × 106 vs 425.1 × 106 g/mol) and water extractable arabinoxylans WEAX (1.79 × 105 vs 7.63 × 105 g/mol), and a decrease in amylose length (245 vs 748 glucose units) was observed after bread-baking. The chain length distribution of amylopectin and the arabinose-to-xylose (A/X) ratio of WEAX remained unaffected during bread-making, suggesting that heat- or/and shear-induced chain scission is the mechanism responsible for molecular fragmentation. Bread-making also resulted in more insoluble cell wall residue, featured by water unextractable arabinoxylan of lower A/X and Mw, along with the formation of a gluten network. Flexible and transparent films with good light-blocking performance (<30 % transmittance) and DPPH-radical scavenging capacity (~8.5 %) were successfully developed from bread and flour. Bread films exhibited lower hygroscopicity, tensile strength (2.7 vs 8.5 MPa) and elastic modulus (67 vs 501 MPa) than flour films, while having a 6-fold higher elongation at break (10.0 vs 61.2 %). This study provides insights into the changes in wheat biopolymers during bread-making and sets a precedent for using stale bread as composite polymeric materials.

Structure and functional properties of starches from Xiaozhan rice: Effects of varieties and growing regions

This study aimed to understand structure and functionality of starches from different Xiaozhan rice varieties grown in the same region and from the same variety grown in different regions. The amylose content varied from 15.6% to 23.2% among all rice starches, and the proportions of A, B1, B2, and B3 chains of amylopectin were in the range of 28.4%–38.1%, 46.2%–51.4%, 8.0%–13.4%, and 2.5%–12.0%, respectively. Significant differences were noted in swelling power, gelatinization, pasting, gel textural properties and in vitro enzymic digestibility of rice starches from different varieties grown at the same region and from the same variety grown in different regions. Correlation analysis results showed that amylose content and chain length distribution of amylopectin were the major determinants for the functional properties and amylolysis of starches, respectively. This study suggests that the quality of Xiaozhan rice related to starch properties was affected by the rice varieties and growing regions. The results obtained in this study are of importance for optimizing breeding strategies to produce better rice varieties.

Absolute Quantitative Lipidomics Reveals Different Granule-Associated Surface Lipid Roles in the Digestibility and Pasting of Waxy, Normal, and High-Amylose Rice Starches.

Granule-associated surface lipids (GASLs) and internal lipids showed different lipid-amylose relationships, contents, and distributions, suggesting their differing biological origins and functions, among waxy, normal, and high-amylose rice starch. The GASL content mainly depended on the pore size, while internal lipids regulated starch biosynthesis, as indicated by correlations of internal lipids with the chain length distribution of amylopectin and amylose content. Of the 1346 lipids detected, 628, 562, and 408 differentially expressed lipids were observed between normal-waxy, high-amylose-waxy, and normal-high-amylose starch, respectively. After the removal of GASLs, the higher lysophospholipid content induced greater decreases in the peak and breakdown viscosity and swelling power, while the highest digestibility increase was found with the highest triacylglycerol content. Thus, different GASL compositions led to different digestibility, swelling, and pasting outcomes. This study sheds new light on the mechanism of the role of GASLs in the structure and properties of starch, as well as in potential modifications and amyloplast membrane development.

Relationship between the physicochemical properties and amylose content of rice starch in rice varieties with the same genetic background

This study analyzed six mutant rice samples from uniform genetic and planting backgrounds with amylose contents ranging from 4.21% to 17.52%. The physicochemical, structural and functional properties of the extracted starches were investigated and their relationships were analyzed. No significant changes were observed in the morphology, granule size, amylopectin chain-length distribution, and crystalline type of rice starches. The average hydrodynamic radius (Rh), relative crystallinity (RC), the ratio of 1045 cm−1/1022 cm−1 (R1045/1022), and lamellar peak intensity (Imax) were significantly correlated with amylose content, impacting the digestion properties. A higher degree of order in starch structure was found to impede its digestion progress by affecting its physicochemical characteristics. The decreased onset temperature and increased gelatinization temperature range indicated increased crystalline structure instability, decreasing peak time and pasting temperature. Furthermore, there were notable reductions in starch digestion rate (k) and rapidly digestible starch content (RDS) as amylose content increased, despite no significant change in the final digestion percentage. The k exhibited a positive correlation with Rh, while there was a positive association between RC, R1045/1022, and Imax with RDS. These findings can provide valuable guidance for rice breeders in developing rice varieties with specific functional attributes.

Insights into multiscale structure and digestive characteristic of starch from two cultivars of chestnut during kernel development

Multiscale structure and digestive characteristic of starch during kernel development of Castanea henryi (‘Jinzhui’ (YS) and ‘Baiyan No.1’ (WS)) were investigated in this study. Structural analysis revealed that the surface of starch granules became smooth, the amylopectin content decreased (from 71.32 % to 70.47 %, from 71.44 % to 68.37 %, respectively), the chain length distribution of amylopectin reduced (the proportion of B1 chain decreased from 52.35 % to 50.60 %, from 52.22 % to 50.59 %, respectively) while the amorphous and semi-crystalline lamellae of starch increased during development, which was consistent with the decreasing relative crystallinity (from 28.79 % to 24.11 %, from 29.57 % to 23.66 %, respectively) and short-range ordering degree. The degradation of ordered structure further resulted in the increase of digestibility, especially in the late developmental stage, supported by a significant decrease of resistant starch content (from 70.21 % to 61.70 % and from 73.58 % to 58.86 %, respectively). Transcriptome analysis and RT-qPCR were performed to explore the possible molecular mechanisms affecting starch structure. The high expression of several key genes including AGPase, GBSS, SBE, SSS, ISA and PUL in late development stage might be the reason of structural changes during development. The results provided valuable information for starch accumulation during kernel development of Castanea henryi.

Effects of cooking methods on the physical properties and in vitro digestibility of starch isolated from Chinese yam

The objective of this study was to compare the structural and functional attributes of Chinese yam starches obtained via different domestic cooking methods. Cooking changed the crystalline type from the C type to the CB type, and disrupted the short- and long-range molecular order of Chinese yam starch. The average chain length of amylopectin in BOS (boiling starch) was the smallest at 22.78, while RWS had the longest average chain length, reaching 24.24. These alterations in molecular structure resulted in variations in functional properties such as solubility, swelling power (SP), pasting characteristics, and rheological properties. Among these alterations, boiling was the most effective method for increasing the water-binding capacity and SP of starch. Specifically, its water holding capacity was 2.12 times that of RWS. In vitro digestion experiments indicated that BOS has a higher digestion rate (k = 0.0272 min−1) and lower RDS (rapidly digestible starch), which may be related to its amylopectin chain length distribution. This study can guide us to utilize yam starch through suitable cooking methods, which is relevant for the processing and application of Chinese yam starch.

Amylopectin chain length distributions and amylose content are determinants of viscoelasticity and digestibility differences in mung bean starch and proso millet starch

This study aimed to reveal the underlying mechanisms of the differences in viscoelasticity and digestibility between mung bean starch (MBS) and proso millet starch (PMS) from the viewpoint of starch fine molecular structure. The contents of amylopectin B2 chains (14.94–15.09 %), amylopectin B3 chains (14.48–15.07 %) and amylose long chains (183.55–198.84) in MBS were significantly higher than PMS (10.45–10.76 %, 12.48–14.07 % and 70.59–88.03, respectively). MBS with higher amylose content (AC, 28.45–31.80 %) not only exhibited a lower weight-average molar mass (91,750.65–128,120.44 kDa) and R1047/1022 (1.1520–1.1904), but also was significantly lower than PMS in relative crystallinity (15.22–23.18 %, p < 0.05). MBS displayed a higher storage modulus (G′) and loss modulus (G′′) than PMS. Although only MBS-1 showed two distinct and discontinuous phases, MBS exhibited a higher resistant starch (RS) content than PMS (31.63–39.23 %), with MBS-3 having the highest RS content (56.15 %). Correlation analysis suggested that the amylopectin chain length distributions and AC played an important role in affecting the crystal structure, viscoelastic properties and in vitro starch digestibility of MBS and PMS. These results will provide a theoretical and scientific basis for the development of starch science and industrial production of low glycemic index starchy food.

Response of yield and quality of Japonica rice to different gradients of moisture deficit at grain-filling stage in cold regions

Abstract Water stress significantly affects on rice yield and quality. Eight Japonica varieties from the first and second accumulated temperature zones of Heilongjiang Province were used as materials and four moisture gradients (0, −10, −25 and −40 kPa) were conducted at the grain-filling stage to clarify the effect of water stress on the rice yield and quality in cold regions. The results showed that the rice yield was reduced due to the decrease in the seed setting rate. Rice chalkiness was significantly increased by drought stress, especially under −10 kPa. The protein content of most varieties was significantly reduced and taste quality was increased under −25 to −40 kPa. The effect on protein components increased with increasing drought stress. The gel consistency decreased and the average chain length of amylopectin was less affected by drought. With an increase in moisture deficit, the rapid viscosity analyzer characteristics and chain length distribution of amylopectin showed a trend of first increasing and then decreasing or decreasing and then increasing. The response of starch to mild and severe drought varied. Our study provides a theoretical basis for the efficient utilization of water and high quality and yield of Japonica rice.

Characterization of Starch Properties in Diverse Pea Accessions: Structural, Morphological, Thermal, Pasting, and Retrogradation Analysis

AbstractThe present work evaluates starch from 29 diverse pea accessions for structural (amylose content and amylopectin chain length distribution), granule size distribution, thermal, pasting, and retrogradation properties. Amylose content and the proportion of amylopectin chains with the degree of polymerization (DP) of 6–10, 11–20, and &gt;20 vary in the range from 21.4% to 57.0%, 17.9% to 25.8%, 64.0% to 66.5%, and 9.4% to 16.7%, respectively. Starches with a higher proportion of small granules (&lt;5 µm) have a greater proportion of amylopectin chains with DP &gt; 10 and exhibit higher transition temperatures/enthalpy and vice versa. Retrogradation in starch pastes relates negatively to the proportion of amylopectin chains with DP &lt; 10. Paste viscosities relate negatively with amylopectin chains with DP &gt; 10, amylose content, and retrogradation while positively with transition temperatures/enthalpy and the potential of granules to swell.

Retrogradation inhibition of starches in staple foods with maltotetraose-forming amylase

To effectively inhibit the retrogradation of staple foods, the effects of maltotetraose-forming amylase(G4-amylase) on the short and long-term retrogradation of different staple starches such as rice starch (RS), wheat starch (WS), potato starch (PS) were studied. The results indicated that G4-amylase decreased the content of amylose. Amylose contents (21.09%) of WSG4 were higher than that (14.82%) of RSG4 and (13.13%) of PSG4. WS had the most obvious change in the chain length distribution of amylopectin. A chains decreased by 18.99% and the B1 chains decreased by 12.08% after G4-amylase treatment. Compared to RS (662 cP) and WS (693 cP), the setback viscosity of RSG4 (338 cP) and WSG4 (385 cP) decreased. Compared to RS (0.41), WS (0.45), and PS (0.51), the long-term retrogradation rate of RSG4 (0.33), WSG4 (0.31), and PSG4 (0.38) significantly reduced. It indicated that G4-amylase significantly inhibited the long-term retrogradation of WS, followed by RS and PS.

Interaction between genetic regions responsible for the starch properties in non-glutinous rice varieties in Hokkaido, Japan.

Starch properties are the major determinants of grain quality and food characteristics in rice (Oryza sativa L.). Understanding the interactions between genetic regions responsible for starch properties will lead to the development of rice cultivars with desirable characteristics. This study investigated the genetic effect and interaction between qAC9.3, a low-amylose quantitative trait locus (QTL), and the genetic region around Starch branching enzyme IIb (SbeIIb). Both these factors are responsible for the starch properties of the Hokkaido breeding population. The amylose content, pasting temperature, and amylopectin chain-length distribution were compared using F5 lines derived from the cross between the lower amylose content and lower pasting temperature strain 'Hokkai332 (qAC9.3, SbeIIb)' and the higher amylose content and higher pasting temperature variety 'Kitagenki (-, SbeIIbsr )'. The qAC9.3 genotype exhibited low amylose content and reduced the hardness of boiled rice but increased the ratio of amylopectin long chains and did not alter the pasting temperature. In contrast, the SbeIIb genotype was associated with pasting temperature but did not affect the amylose content and hardness of boiled rice. It was suggested that appropriately selecting genotypes of these genetic regions and QTL would allow the fine-tuning of starch properties of cooked rice suitable for future demand.

Carbohydrate Profiling of Different Accessions of Three Underutilized Legumes: A Potential Source of Valuable Nutraceuticals and Pharmaceuticals

AbstractCarbohydrates are significant components of legumes, and their profiling can provide information about their nutritional value and potential health benefits. This study explores the proximate composition and carbohydrate profiles of accessions of three underutilized legumes, namely, Vigna radiata, Vigna mungo, and Macrotyloma uniflorum. The total starch and soluble sugar are determined. Starch granule morphology and diameter are determined using scanning electron microscopy and chain length distribution of amylopectin is analyzed using Capillary Electrophoresis. All accessions of the legumes vary both in their proximate composition and carbohydrate components. Accessions of M. uniflorum (PI‐658594‐01‐SD) have the highest carbohydrate component (7.6%) while V. radiata (TVR‐42) has the least (4.2%). Macrotyloma uniflorum accensions (PI‐658594‐01‐SD, and PI‐180437‐01‐SD) have the highest starch and sucrose contents, while V. mungo accensions (TVM‐13, and TVM‐11) have the lowest. The glucose and fructose contents are lower than sucrose in all the accessions of the legumes. Macrotyloma uniflorum accensions exhibit larger granules while accessions of Vigna species have the smallest granules. All species accessions exhibit similar amylopectin chain length distribution profiles although accessions of V. mungo slightly differ in their proportion of long and short glucan chains. The three species of underutilized legumes exhibit unique characteristics which make them suitable for consumption and may be exploited as a source of nutraceuticals and pharmaceuticals.

Impact of molecular structure of starch on the glutinous taste quality of cooked chestnut kernels

Chestnuts are a starchy food with a characteristic glutinous taste that is often used to assess their quality. In this study, our findings indicated that chestnuts with higher glutinous taste quality had lower amylose content and microcrystalline structures, as well as higher subcrystalline structures and relative crystallinity in both the raw and steamed starches. In the leached starch, chestnuts with higher glutinous taste quality had lower amylopectin B1 chains and microcrystalline structure, but higher amylopectin B2 chains, subcrystalline structure and relative crystallinity. These results suggest that amylose content, relative crystallinity, and amylopectin chain length distribution are important factors determining the glutinous taste quality of chestnuts. To further enhance our understanding of these factors, an sensory evaluation model was developed based on textural profile analysis parameters. This study provides valuable insights into the relationship between molecular structure of starch and the glutinous taste quality of starchy foods.

Relationships between starch molecular components and eating and cooking qualities of rice using single-segment substitution lines with different Wx loci

Waxy (Wx) gene in rice endosperm synthesizes amylose and amylopectin extra-long chain (ELC). Five rice lines with different Wx locus single-segment substitutions under the same genetic background were investigated for relationships of their starch molecular components and eating and cooking qualities (ECQs) including pasting, thermal, textural and sensory properties. Rice lines with different Wx loci exhibited different ECQs, and their starches had different apparent amylose contents (AACs), true amylose contents (TACs), ELC contents (ELCCs), and amylopectin chain length distributions. The AAC was correlated positively to hardness and cohesiveness of cooked rice, and negatively to adhesiveness and palatability of cooked rice and breakdown viscosity of rice flour. The TAC was correlated positively to gelatinization temperature range and negatively to gelatinization temperature and enthalpy. ELCC showed a positive relationship with pasting peak time of rice flour and chewiness of cooked rice, and could potentially be used as an important reference for rice ECQ evaluation. This study could help the applications of Wx loci in rice quality breeding.

Digestibility of indica rice and structural changes of rice starch during fermentation by Lactobacillus plantarum

Fermentation technology is a useful tool to modifying starch, and the relationship between starch structure and digestibility is a crucial parameter that affects fermentation technology. In this study, the changes in digestibility and starch structure of indica rice during fermentation by Lactobacillus plantarum were investigated. The relationship between digestibility and the changes in starch composition, amylose content, chain length distribution of amylopectin, short-range ordered structure, and relative crystallinity was analyzed. The results showed that during the fermentation of indica rice by L. plantarum, the glycemic index (GI) of the indica rice decreased, and after 60 h of fermentation, the GI of indica rice decreased from 82.88 to 74.53. Additionally, the contents of slowly digestible starch (SDS) and resistant starch (RS) increased. Furthermore, the proportion of short chain of amylopectin increased, which facilitated the intermolecular interaction of short chain to form a compact and orderly structure. This led to an increase in short-range ordered structure and relative crystallinity of indica rice starch. These structural changes promoted the stability of starch structure, resulting in a decrease in rice digestibility. This work has significant implications for the development of low-GI rice and rice-based foods.

The OsNAC24-OsNAP protein complex activates OsGBSSI and OsSBEI expression to fine-tune starch biosynthesis in rice endosperm.

Starch accounts for up to 90% of the dry weight of rice endosperm and is a key determinant of grain quality. Although starch biosynthesis enzymes have been comprehensively studied, transcriptional regulation of starch-synthesis enzyme-coding genes (SECGs) is largely unknown. In this study, we explored the role of a NAC transcription factor, OsNAC24, in regulating starch biosynthesis in rice. OsNAC24 is highly expressed in developing endosperm. The endosperm of osnac24 mutants is normal in appearance as is starch granule morphology, while total starch content, amylose content, chain length distribution of amylopectin and the physicochemical properties of the starch are changed. In addition, the expression of several SECGs was altered in osnac24 mutant plants. OsNAC24 is a transcriptional activator that targets the promoters of six SECGs; OsGBSSI, OsSBEI, OsAGPS2, OsSSI, OsSSIIIa and OsSSIVb. Since both the mRNA and protein abundances of OsGBSSI and OsSBEI were decreased in the mutants, OsNAC24 functions to regulate starch synthesis mainly through OsGBSSI and OsSBEI. Furthermore, OsNAC24 binds to the newly identified motifs TTGACAA, AGAAGA and ACAAGA as well as the core NAC-binding motif CACG. Another NAC family member, OsNAP, interacts with OsNAC24 and coactivates target gene expression. Loss-of-function of OsNAP led to altered expression in all tested SECGs and reduced the starch content. These results demonstrate that the OsNAC24-OsNAP complex plays key roles in fine-tuning starch synthesis in rice endosperm and further suggest that manipulating the OsNAC24-OsNAP complex regulatory network could be a potential strategy for breeding rice cultivars with improved cooking and eating quality.

Physicochemical Properties and Tissue Structure of High Kernel Elongation Rice (Oryza sativa L.) Varieties as Affected by Heat Treatment.

Heat treatment could affect the structure and properties of rice varieties. The present study was conducted in order to determine the effects of heat treatment on the physicochemical properties and tissue structure of Mahsuri Mutan, Basmati 370 and MR219 rice varieties. The three rice varieties were subjected to heat treatment (ageing) at 90 °C, using an oven, for 3 h. After the heat treatment, the samples were cooled at room temperature (25 °C) for 1 h. Physicochemical properties, such as alkali digestion value, water uptake ratio, solids in cooking water, high kernel elongation ratio and amylose contents, were determined. The procedure used in determining both apparent and absolute amylose involved measuring the iodine affinity of defatted whole starch. Ahigh-performance anion-exchange chromatograph was used to analyse branch chain length distribution of amylopectin quantitatively. The starch structure of the rice samples was observed under a scanning electron microscope. Data collected on physicochemical traits, heat treatment and control (ageing and non-ageing) were subjected to an analysis of variance using SAS software version 9.4. In this study, Mahsuri Mutan and Basmati 370 showed superior high kernel elongation as compared to their respective rice progenies. This study also found that heat treatment directly affected the increasingly high kernel elongation for both populations. The phenotypic correlation co-efficient indicated that there was a high positive correlation between high kernel elongation and water uptake ratio, implying that selection for water uptake ratio would increase the high kernel elongation characteristic. The heat treatment showed significant difference in all the physicochemical traits of the varieties studied. Heat treatment also affected the very long branch chains of starch, such as amylose. Observation under an electron microscope showed that the samples subjected to heat treatment had more cracks on the tissue structure compared to normal rice samples. The hexagon structure in Mahsuri Mutan produced a greater elongation effect on its kernel. The findings from this study could be useful to breeders in the selection and development of a new high kernel elongation rice variety.

Effect of frozen storage on the quality and amylopectin structure of Chinese steamed bread made from different wheat cultivars

The physicochemical properties of wheat flour and the chain-length distributions of amylopectin from eleven cultivars were studied. Chinese steamed bread (CSB) was made by a one-step fermentation procedure using these flours to explore the effects of frozen storage on the qualities of CSB and starch molecular structures. The results indicated that the protein and wet gluten had significant effects on the fermentation rheological properties of wheat dough and CSB qualities. The amylose content and amylopectin structure had important influences on the pasting properties of wheat flour and the firming of CSB. Water loss and migration in CSB during freezing, accompanied by the starch retrogradation, depended on the amylose content and amylopectin structure. After 60-day of frozen storage at −18 °C, the amylopectin extracted from CSB showed decreased fractions of B1 and B2 chains while the long B3 chain and average chain length increased. Moreover, short amylopectin chains were negatively correlated with the hardness of CSB (P < 0.01). These results confirmed that the structure-property relationships of wheat flour have crucial influences on the qualities of CSB, which would benefit our selection of wheat materials for the frozen food industry and provide a reference for wheat breeding.

Image mapping of biological changes and structure-function relationship during rice grain development via Synchrotron FTIR spectroscopy

The spatial distribution of compositional elements in milky, dough, and mature rice, together with the structure-function relationship was studied using synchrotron-FTIR. The dough stage aleurone and endosperm had high lipid, protein (amide I and II), and hemicellulose. The amylopectin chain length distribution of starch exhibited small differences among developmental stages. Dough starch featured a greater portion of A and B1 chains, implying a more crystalline and high in resistant starch. The protein in milky-to-dough stage aleurone and endosperm had higher contents of α-helixes than β-sheets, resulting in higher protein digestibility and availability. There were high intensities of the glycosidic peaks of hemicellulose and cellulose, pectin, carbohydrates, and β 1–6 glucans in milky-to-dough stages. They corresponded to higher total, insoluble, and soluble dietary fiber contents in milky-to-dough stage than in mature stage. Young-stage rice was found to be more nutritious and could thus be a functional food source.