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This study aims to explore the formation mechanism of starch structure and the relationships between the appearance quality and starch structure of soft rice under different nitrogen levels. We comprehensively investigated the physiological aspects, starch structure variations, and appearance quality of soft rice in response to different nitrogen applications. The results showed that under the moderate nitrogen application (270 N), the soft rice exhibited the highest AGPase activity, the highest large‐starch granule content, and the lowest chalkiness. Under the highest nitrogen application (360 N), the soft rice exhibited the highest GBSS and DBE activity and the lowest SBE activity, the highest content of long‐branched amylopectin, the lowest relative crystallinity, the fewest ordered structures, the most amorphous structures, the largest semi‐crystalline lamellar thicknesses, and the highest transparency of chalk‐free rice. In conclusion, moderate nitrogen fertilization (270 N) improved the AGPase activity, which leaded to fuller starch granules and more compact endosperm in soft rice. Thus, the grain chalkiness of soft rice decreased. Continuous nitrogen application (0‐360 N) constantly increased the GBSS and DBE activity and reduced the SBE activity in soft rice, leading a lower content of short‐branched amylopectin and a higher content of long‐branched amylopectin in soft rice. Thus, the relative crystallinity and ordered structures of soft rice were reduced. These structures improved the transparency phenotype of soft rice. [ABSTRACT FROM AUTHOR]

Studying diversity in local barley varieties can help advance novel uses for the grain. Therefore, starch was isolated from nine Ethiopian food barley varieties to determine starch structural, pasting, thermal, and digestibility characteristics, as well as their inter-relationships. The amylose content in the varieties significantly varied from 24.5 to 30.3%, with a coefficient of variation of 6.1%. The chain length distributions also varied significantly, and fa, fb1, fb2, and fb3 ranged from 26.3 to 29.0, 48.0 to 49.7, 15.0 to 15.9, and 7.5 to 9.5%, respectively. Significant variations were also exhibited in absorbance peak ratios, as well as thermal, pasting, and in vitro digestibility properties, with the latter two parameters showing the greatest diversity. Higher contents of amylose and long amylopectin fractions contributed to higher gelatinization temperatures and viscosities and lower digestibility. Structural characteristics showed strong relationships with viscosity, thermal, and in vitro digestibility properties. Cross 41/98 and Dimtu varieties are more suitable in functional food formulations and for bakery products. These results might inspire further studies to suggest target-based starch modifications and new product development. [ABSTRACT FROM AUTHOR]

In recent days, there has been a noticeable surge in demand for high-quality rice. However, the influences of salinity on the quality and starch properties of high-quality rice remain unclear. Three high-quality rice cultivars (Nanjing 9108, Nanjing 5055, and Nanjing 46) were studied to investigate the responses of grain quality to salt stress. There were three treatments, including a control zero salt level (0 g·kg−1, CK), and two salt levels of 0.1 g·kg−1 (0.1% salt stress, T1) and 0.2 g·kg−1 (0.2% salt stress, T2). The study involved the assessment of the appearance, milling, cooking, and eating qualities of rice. We also conducted an analysis of pasting properties, an evaluation of starch thermal properties, and an examination of the fine structure of amylopectin. The findings suggest that as the level of salt stress increases, the yield of rice gradually declines, which is primarily due to a significant reduction in the total spikelet number and the ratio of filled grains. Compared with CK treatment, the appearance and milling quality of rice were significantly improved within the T1 treatment. In addition, the protein concentration and amylose concentration were significantly decreased, the gel consistency was significantly increased, and the cooking and eating qualities were improved. In terms of starch properties, the peak viscosity, breakdown value, infrared ratio (1022/995), and short-chain-length amylopectin ratio increased significantly, while the setback value, pasting temperature, gelatinization enthalpy, relative crystallinity, and infrared ratio (1045/1022) decreased significantly. When comparing T2 with CK, the appearance quality and cooking and eating quality had deteriorated, and the milling quality was improved. The changes in the structural and physicochemical properties of starch were opposite to those in the comparison between the T1 treatment and the CK group. Accordingly, we propose that moderate salt stress has the potential to enhance rice quality, even though there may be a slight decrease in yield. This indicates that it is feasible to cultivate high-quality rice in saline–alkali beach areas. [ABSTRACT FROM AUTHOR]

Abstract This study aims to explore the formation mechanism of starch structure and the relationships between the appearance quality and starch structure of soft rice under different nitrogen levels. We comprehensively investigated the physiological aspects, starch structure variations, and appearance quality of soft rice in response to different nitrogen applications. The results showed that under the moderate nitrogen application (270 N), the soft rice exhibited the highest AGPase activity, the highest large‐starch granule content, and the lowest chalkiness. Under the highest nitrogen application (360 N), the soft rice exhibited the highest GBSS and DBE activity and the lowest SBE activity, the highest content of long‐branched amylopectin, the lowest relative crystallinity, the fewest ordered structures, the most amorphous structures, the largest semi‐crystalline lamellar thicknesses, and the highest transparency of chalk‐free rice. In conclusion, moderate nitrogen fertilization (270 N) improved the AGPase activity, which leaded to fuller starch granules and more compact endosperm in soft rice. Thus, the grain chalkiness of soft rice decreased. Continuous nitrogen application (0‐360 N) constantly increased the GBSS and DBE activity and reduced the SBE activity in soft rice, leading a lower content of short‐branched amylopectin and a higher content of long‐branched amylopectin in soft rice. Thus, the relative crystallinity and ordered structures of soft rice were reduced. These structures improved the transparency phenotype of soft rice.

Polymer network is a crucial component of hydrogels, and network imperfection is a prominent feature of polymer networks, significantly influencing the performance of hydrogels. Two essential features of network imperfection are unequal chain lengths and dangling chains, both of which have a significant impact on the mechanical properties of single-network (SN) hydrogels. However, a theoretical framework considering network imperfection in SN hydrogels is still lacking. Here, we propose a theoretical model for SN hydrogels with network imperfection to study the damage behavior during deformation, in which we adopt different chain length distributions to accurately depict the real physical characteristics of the polymer network and incorporate the normalized critical chain force for a more precise measurement of network damage. To verify our theory, we discuss the effects of model parameters on the stress-stretch responses of SN hydrogels and predict the results of uniaxial loading-unloading tests of SN hydrogels, which agree well with experimentally measured stress-stretch behaviors. Finally, we implement the constitutive model into ABAQUS as a user subroutine to study the inhomogeneous deformation of hydrogels.

The objective of this study was to characterize the endosperm starch in rice that ectopically overexpressed the α-amylase. Transgenic rice plants, transformed with cauliflower mosaic virus 35S promoter driven AmyI-1 (35S::AmyI-1) and AmyII-4 (35S::AmyII-4), and 10 kDa prolamin promoter driven AmyI-1 (P10::AmyI-1), were cultivated under standard conditions (23 °C, 12 h in the dark/ 26 °C, 12 h in the light), and brown grains were subsequently harvested. Each grain displayed characteristic chalkiness, while electron microanalyzer (EPMA)-SEM images disclosed numerous small pits on the surface of the starch granules, attributable to α-amylase activity. Fluorescence labeling and capillary electrophoresis analysis of starch chain length distribution revealed no significant alterations in the starches of 35S::AmyI-1 and 35S::AmyII-4 transgenic rice compared to the wild-type. Conversely, the extremely short α-glucan chains (DP 2-8) exhibited a dramatic increase in the P10::AmyI-1 starch. Rapid visco-analyzer analysis also identified variations in the chain length distribution of P10::AmyI-1 starch, manifesting as changes in viscosity. Moreover, ¹H-NMR analysis uncovered dynamic modifications in the molecular structure of starch in rice grain transformed with P10::AmyI-1, which was found to possess unprecedented structural characteristics. [ABSTRACT FROM AUTHOR]

Studying diversity in local barley varieties can help advance novel uses for the grain. Therefore, starch was isolated from nine Ethiopian food barley varieties to determine starch structural, pasting, thermal, and digestibility characteristics, as well as their inter-relationships. The amylose content in the varieties significantly varied from 24.5 to 30.3%, with a coefficient of variation of 6.1%. The chain length distributions also varied significantly, and fa, fb1, fb2, and fb3 ranged from 26.3 to 29.0, 48.0 to 49.7, 15.0 to 15.9, and 7.5 to 9.5%, respectively. Significant variations were also exhibited in absorbance peak ratios, as well as thermal, pasting, and in vitro digestibility properties, with the latter two parameters showing the greatest diversity. Higher contents of amylose and long amylopectin fractions contributed to higher gelatinization temperatures and viscosities and lower digestibility. Structural characteristics showed strong relationships with viscosity, thermal, and in vitro digestibility properties. Cross 41/98 and Dimtu varieties are more suitable in functional food formulations and for bakery products. These results might inspire further studies to suggest target-based starch modifications and new product development.

The main element influencing the quality of potato starch is the environment. To investigate the effects of different altitude cultivation locations on the molecular structure and physicochemical properties of starch, two potato varieties, Jiusen No.1 B1 and Qingshu No.9 B2, were planted in three different altitude zones: A1 at low altitude (Chongzhou 450m), A2 at middle altitude (Xichang 2800 m), and A3 at high altitude (Litang 3650 m). The results showed that the average volume, number, surface area diameter, average branched polymerization degree, crystallinity, and gelatinization temperature of two potato granules in high altitude areas were significantly lower than those in middle and low altitude areas were, and the gelatinization performance of potato starch was affected according to the correlation of starch structure characteristics. Potato starch with more shortbranched chains and less long branched chains resulted in a lower gelatinization temperature in high altitude areas. The results showed that Jiusen No. 1 and Qingshu No. 9 were mainly affected by accumulated radiation and accumulated rainfall in Litang, a high altitude area, and by effective accumulated temperature in Xichang, a middle altitude area. This study quantified the influence of meteorological factors on themain starch quality of potato tubers. The results can be used as a theoretical basis for the scientific planting of high-quality potatoes. [ABSTRACT FROM AUTHOR]

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Rice flour is produced by various methods for use in the food industry, but little is known about how the structure of starch is affected during rice flour production. In this study, the crystallinity, thermal properties, and structure of starch in rice flour were investigated after treatment with a shearing and heat milling machine (SHMM) at different temperatures (10–150 °C). Both the crystallinity and gelatinization enthalpy of starch showed an inverse relationship with the treatment temperature; rice flour treated with the SHMM at higher temperatures showed lower crystallinity and gelatinization enthalpy than that treated at lower temperatures. Next, the structure of undegraded starch in the SHMM-treated rice flour was analyzed by gel permeation chromatography. A significant reduction in the molecular weight of amylopectin was observed at high treatment temperatures. Chain length distribution analysis showed that the proportion of long chains (degree of polymerization (DP) > 30) in rice flour decreased at temperatures ≥ 30 °C. By contrast, the molecular weight of amylose did not decrease. In summary, the SHMM treatment of rice flour at high temperatures resulted in starch gelatinization, and the amylopectin molecular weight decreased independently, due to the cleavage of amorphous regions connecting the amylopectin clusters. [ABSTRACT FROM AUTHOR]

In recent days, there has been a noticeable surge in demand for high-quality rice. However, the influences of salinity on the quality and starch properties of high-quality rice remain unclear. Three high-quality rice cultivars (Nanjing 9108, Nanjing 5055, and Nanjing 46) were studied to investigate the responses of grain quality to salt stress. There were three treatments, including a control zero salt level (0 g·kg−1, CK), and two salt levels of 0.1 g·kg−1 (0.1% salt stress, T1) and 0.2 g·kg−1 (0.2% salt stress, T2). The study involved the assessment of the appearance, milling, cooking, and eating qualities of rice. We also conducted an analysis of pasting properties, an evaluation of starch thermal properties, and an examination of the fine structure of amylopectin. The findings suggest that as the level of salt stress increases, the yield of rice gradually declines, which is primarily due to a significant reduction in the total spikelet number and the ratio of filled grains. Compared with CK treatment, the appearance and milling quality of rice were significantly improved within the T1 treatment. In addition, the protein concentration and amylose concentration were significantly decreased, the gel consistency was significantly increased, and the cooking and eating qualities were improved. In terms of starch properties, the peak viscosity, breakdown value, infrared ratio (1022/995), and short-chain-length amylopectin ratio increased significantly, while the setback value, pasting temperature, gelatinization enthalpy, relative crystallinity, and infrared ratio (1045/1022) decreased significantly. When comparing T2 with CK, the appearance quality and cooking and eating quality had deteriorated, and the milling quality was improved. The changes in the structural and physicochemical properties of starch were opposite to those in the comparison between the T1 treatment and the CK group. Accordingly, we propose that moderate salt stress has the potential to enhance rice quality, even though there may be a slight decrease in yield. This indicates that it is feasible to cultivate high-quality rice in saline–alkali beach areas.

A major challenge in modern rice production is to achieve the dual goals of high yield and good quality with low environmental costs. This study was designed to determine whether optimized nitrogen (N) fertilization could fulfill these multiple goals. In two-year experiments, two high yielding ‘super’ rice cultivars were grown with different N fertilization management regimes, including zero N input, local farmers’ practice (LFP) with heavy N inputs, and optimized N fertilization (ONF). In ONF, by reducing N input, increasing planting density, and optimizing the ratio of urea application at different stages, N use efficiency and the physicochemical and textural properties of milled rice were improved at higher yield levels. Compared with LFP, yield and partial factor productivity of applied N (PFP) under ONF were increased (on average) by 1.70 and 13.06%, respectively. ONF increased starch and amylose content, and significantly decreased protein content. The contents of the short chains of A chain (degree of polymerization (DP) 6–12) and B1 chain (DP 13–25) of amylopectin were significantly increased under ONF, which resulted in a decrease in the stability of rice starch crystals. ONF increased viscosity values and improved the thermodynamic properties of starch, which resulted in better eating and cooking quality of the rice. Thus, ONF could substantially compensate the negative effects caused by N fertilizer and achieve the multiple goals of higher grain quality and nitrogen use efficiency (NUE) at high yield levels. These results will be useful for applications of high quality rice production at high yield levels.

Climate warming affects rice growth at different phenological stages, thereby increasing rice chalkiness and protein content and reducing eating and cooking quality (ECQ). The structural and physicochemical properties of rice starch played important roles in determining rice quality. However, differences in their response to high temperature during the reproductive stage have been rarely studied. In the present study, they were evaluated and compared between two contrasting natural temperature field conditions, namely, high seasonal temperature (HST) and low seasonal temperature (LST), during the reproductive stage of rice in 2017 and 2018. Compared with LST, HST significantly deteriorated rice quality, including increased grain chalkiness, setback, consistence, and pasting temperature and reduced taste values. HST considerably reduced the total starch and increased the protein content. Likewise, HST significantly reduced the short amylopectin chains [degree of polymerization (DP) <12] and increased the long amylopectin chains (DP > 12) and relative crystallinity. The starch structure, total starch content, and protein content explained 91.4%, 90.4%, and 89.2% of the total variations in pasting properties, taste value, and grain chalkiness degree, respectively. In conclusion, we suggested that rice quality variations were closely associated with the changes in chemical composition content (total starch and protein content) and starch structure in response to HST. These results indicated that we should improve the resistance of rice to high temperature during the reproductive stage to improve the fine structure of rice starch in further breeding and practice. [ABSTRACT FROM AUTHOR]

Depolymerization by chain‐end scission enables ideally full recovery of monomers, which is considered as a promising route for polymer recycling. Despite attractive experimental achievements, insightful depolymerization kinetic modeling study is capable of providing information for better understanding polymer degradation process and reactor design in polymer industry. Herein, an improved analytical solution for depolymerization by chain‐end scission is derived and validated by numerical exact solution. The strength of the as‐derived analytical solution lies on its capability of capturing depolymerization kinetics of polymers with large degrees of polymerization and different initial distributions (e.g., Gamma, monodisperse, Poisson, Flory‐Schulz, exponential, and log‐normal distributions). Additionally, the changes in average properties of polymer are accessed by using a hybrid method based on the method of moment (MoM) and the improved analytical solution considering dimers in chain‐end scission process for the first time. Finally, kinetic insights into depolymerization of self‐immolative polymers are also gained by the MoM‐based model in parallel with two sets of experimental data. This work offers simulation protocols for a profound understanding of depolymerization kinetics and inspecting molecular properties during depolymerization. [ABSTRACT FROM AUTHOR]

Starch is comprised of very large α-glucan molecules composed primarily of linear amylose and highly branched amylopectin. Most methods for analyses of starch structure use hydrolytic enzymes to cleave starch. When undegraded, whole starch structures can be analyzed by gel-permeation chromatography (GPC), but this typically yields a single peak each for amylopectin and amylose. The objective of this study was to stably separate amylopectins in whole starch based on their molecular weight using GPC, and to determine the structure of each peak. When alkali-gelatinized whole starch was applied to GPC columns (Toyopearl HW75S x 2, HW65S, and HW55S), it was separated into three peaks. Iodine staining and chain length distribution analyses of debranched samples showed that peaks were mainly composed of high-molecular weight (MW) amylopectin consisting of many clusters, low-MW amylopectin consisting of a small number of clusters, and amylose. [ABSTRACT FROM AUTHOR]

Starch is a primary source of food energy for human beings. Its chain-length distribution (CLD) is a major structural feature influencing physiologically-important properties, such as digestibility and palatability, of starch-containing foods. Diabetes, which is of epidemic proportions in many countries, is related to the rate of starch digestion in foods. Isoforms of three biosynthesis enzymes, starch synthase, starch branching enzymes and debranching enzymes, control the CLDs of starch, which can be measured by methods such as size-exclusion chromatography and fluorophore-assisted carbohydrate electrophoresis. Fitting observed CLDs to biosynthesis-based models based on the ratios of the activities of those isoforms yields biosynthesis-related parameters describing CLD features. This review examines CLD measurement, fitting CLDs to models, relations between CLDs, the occurrence and management of diabetes, and how plant breeders can develop varieties to optimize digestibility and palatability together, to develop starch-based foods with both a lower risk of diabetes and acceptable taste. [Display omitted] [ABSTRACT FROM AUTHOR]

High amylose starch shows wide applications in food and non-food-based industries. Traditional complex-precipitation approach for the amylose fractionation required a large volume of organic reagents and was possibly risky for food safety. The object of this work was to establish a novel method to obtain starch fractions rich in amylose from debranch starch through repeated short-term retrogradation and centrifugation. Four starch fractions were obtained with the amylose content of 52.08% (C1), 62.28% (C2), 63.58% (C3), and 64.74% (C4). The thermograms of samples displayed that multiple endothermic peaks were detected in C1 and C2 and only one endothermic peak with melting temperature over 120 °C were observed in C3 and C4, indicating their differences in retrogradation behavior. The chain length distribution results of sample exhibited that C1 and C2 contained more short chains (DP ≤ 24), while C3 and C4 consisted of mainly long chains (DP ≥ 25). Accordingly, the differences in fine structures could provide more choices for these fractionated high amylose starch to utilize in practical applications.

High temperature (HT) during grain filling had adverse influences on starch synthesis. In this study, the influences of HT on resistant starch (RS) formation in rice were investigated. Most genes in ssIIIa mutants especially in RS4 were upregulated under Normal Temperature (NT) while downregulated under HT when compared with those of wild parent R7954. ssIIIa mutants had higher RS content, more lipid accumulation, higher proportion of short chains of DP 9-15, and less long chains of DP ≥37. ssIIIa mutation exacerbated the influences of HT on starch metabolite and caused larger declines in the expression of BEI, BEIIa, BEIIb, and SSIVb when exposed to HT. HT reduced the contents of total starch and apparent amylose significantly in wild type but not in mutants. Meanwhile, lipids were enriched in all varieties, but the amounts of starch-lipid complexes and the RS content were only heightened in mutants under HT. HT led to greatest declines in the amount of DP 9-15 and increases in the proportion of fb3 (DP ≥37); the declines and increases were all larger in mutants, which resulted in varied starch crystallinity. The increased longchain amylopectin and lipids may be the major contributor for the elevated RS content in mutants under HT through forming more starch-lipid complexes (RSV). [ABSTRACT FROM AUTHOR]

Long-term retrogradation of amylopectin always leads to the quality deterioration of starch-based food. In this paper, the purified maize amylopectin was co-crystallized with NaCl to obtain anti-retrograded amylopectin. The results showed that the retrogradation rate of maize amylopectin dropped directly from 27.92 % to 19.05 % at the conditions of amylopectin: 5 % NaCl (m/v) = 1.7:10, eutectic times 24 h at 4 °C. The co-crystals with a dendritic shape consisted of a center and several large branches and the length of the largest branch reached up to 10,000 μ m. The results of the maximum absorbance of iodine-attached amylopectin, molecular weight and chain length distributions showed that hydrolysis and graft of amylopectin happened in the eutectic process. Residues produced by acid hydrolysis linked to the main chains via α-1,6 glycosidic linkage at the late stage of eutectic reaction. The marked signs for single helix of maize amylopectin with M w >20 × 105 g/mol were the enhancement of weak resonance at 100.0 ppm (104.1, 100.0, 94.6, 82.9 ppm). Single-helix maize amylopectin was more likely to form sharp X-ray diffraction during being dried without gelatinization. The possible mechanism for anti-retrogradation of maize amylopectin by co-crystal treatment was deduced. Co-crystallization with NaCl to produce single-helix amylopectin was a promising strategy to prepare anti-retrogradation amylopectin. [ABSTRACT FROM AUTHOR]

The computational fluid dynamics (CFD) and kinetic‐based moment methods coupled approach is adopted to simulate the bulk copolymerization of styrene–acrylonitrile (SAN) in a stirred tank reactor. Numerical simulations are carried out to investigate the impacts of impeller speed, monomer ratio, initiator ratio, and initial reaction temperature on the copolymerization process and product properties. Particularly, the Chaos theory is selected as a criterion for evaluating the occurrence of the thermal runaway. The Flory's and Stockmayer's distributions are employed to calculate chain length distribution and copolymer composition distribution of copolymer. The simulation results highlight that the appearance of thermal runaway can be postponed by properly increasing the rotation speed, decreasing the initiator loadings, initial acrylonitrile contents and initial reactor temperature. Furthermore, significant differences exist in the product properties that predicted by the ideal and non‐ideal models, which demonstrates that the temperature heterogeneity plays a crucial role in SAN copolymerization. This study could offer references for the safe operation and design of polymerization processes. [ABSTRACT FROM AUTHOR]

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.

In this study, the in vitro digestibility of corn starch with different amylose content was determined. The results showed that waxy corn starch (WCS) and corn starch (CS) have the highest digestibility, while high amylose corn starch (HACS) has a higher content of resistant starch (RS). Besides being related to amylose content, RS content is also closely related to particle shape, debranched fine structure, molecular structure, and semi-crystalline structure. HACS can maintain a complete particle structure after gelatinization and enzymolysis; differential scanning calorimetry showed a positive correlation between gelatinization enthalpy and RS content. As the amylose content increased, the content of fa (DP 6–12) decreased, while the content of fb2 (DP 25–36) and fb3 (DP ≥ 37) increased, which in-turn decreased the cluster polymer formed by short branch chains, and the formation of more hydrogen bonds between long chain branches improved starch stability. D, which characterizes the compactness of starch semi-crystalline structure, increased with the increase of RS content. HACS 60 with the highest RS content had a unique surface fractal structure between 7.41 < d (2π/q) < 10.58 nm, indicating that the dense structure is effective in maintaining the RS content.

The large thixotropy of the starch-thickened foods is often unfavorable in many applications. This study examined the contribution of the proportion of amylopectin chain length to time-dependence of starch gels. The α-amylase (AM) from Bacillus stearothermophilus and maltogenic α-amylase (MA) from Bacillus subtilis were used to trim amylopectin in different reaction patterns. HPLC, HPAEC and IBC data suggested AM attacked B-chains (DP 12–36), causing an increment in number of the chains with DP 6–12, whereas MA primarily trimmed the short B-chains (DP 12–18) and partial A-chains (DP 9–12) to generate short chains with DP 6–9. Interestingly, the recovery of AM-gels was faster than MA-gels at the same degree of hydrolysis when subjected to shear according to the linear correlation analysis. When releasing the same mass of sugar, shortening of the long internal chains played an important role in reducing time dependence of starch gel rather than the external side chains. Possible models were proposed to illustrate the differences in the mechanism of rapid-recovery caused by different side-chain distributions. The outcome provided a new perspective to regulate the thixotropy behavior of starch through enzyme strategies in the granular state. • Shortening of the internal long chains is the key factor for enhancing anti-thixotropy. • The hysteresis loop area of AM samples was smaller than MA at the same DH. • The iodine binding capacity of MA samples was higher than that of AM samples. • AM and MA hydrolysis produced amylopectin with different chain length proportion. [ABSTRACT FROM AUTHOR]

Potato starch with mutations in starch branching enzyme genes (SBEI, SBEII) and granule-bound starch synthase gene (GBSS) was characterized for molecular and thermal properties. Mutations in GBSS were here stacked to a previously developed SBEI and SBEII mutation line. Additionally, mutations in the GBSS gene alone were induced in the wild-type variety for comparison. The parental line with mutations in the SBE genes showed a ∼ 40 % increase in amylose content compared with the wild-type. Mutations in GBSS-SBEI-SBEII produced non-waxy, low-amylose lines compared with the wild-type. An exception was a line with one remaining GBSS wild-type allele, which displayed ∼80 % higher amylose content than wild-type. Stacked mutations in GBSS in the SBEI-SBEII parental line caused alterations in amylopectin chain length distribution and building block size categories of whole starch. Correlations between size categories of building blocks and unit chains of amylopectin were observed. Starch in GBSS-SBEI-SBEII mutational lines had elevated peak temperature of gelatinization, which was positively correlated with large building blocks., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Authors. Published by Elsevier Ltd.. All rights reserved.)

The objective of this study was to characterize the endosperm starch in rice that ectopically overexpressed the α-amylase. Transgenic rice plants, transformed with cauliflower mosaic virus 35S promoter driven AmyI-1 (35S::AmyI-1) and AmyII-4 (35S::AmyII-4), and 10 kDa prolamin promoter driven AmyI-1 (P10::AmyI-1), were cultivated under standard conditions (23 °C, 12 h in the dark/ 26 °C, 12 h in the light), and brown grains were subsequently harvested. Each grain displayed characteristic chalkiness, while electron microanalyzer (EPMA)-SEM images disclosed numerous small pits on the surface of the starch granules, attributable to α-amylase activity. Fluorescence labeling and capillary electrophoresis analysis of starch chain length distribution revealed no significant alterations in the starches of 35S::AmyI-1 and 35S::AmyII-4 transgenic rice compared to the wild-type. Conversely, the extremely short α-glucan chains (DP 2-8) exhibited a dramatic increase in the P10::AmyI-1 starch. Rapid visco-analyzer analysis also identified variations in the chain length distribution of P10::AmyI-1 starch, manifesting as changes in viscosity. Moreover, 1 H-NMR analysis uncovered dynamic modifications in the molecular structure of starch in rice grain transformed with P10::AmyI-1, which was found to possess unprecedented structural characteristics., Competing Interests: The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (2024 by The Japanese Society of Applied Glycoscience.)

Honeycomb-like granules, with 2–4 μm pores on the surface, were prepared by heating potato starch suspensions in water at the pasting temperature. These granules with a yield of 84% were most amorphous (relative crystallinity 1.9%). Their total pore area was 0.668 m2/g, porosity was 73.4%, and mean particle size (D 50) was 154.3 μm. The molecular weights (M W) of honeycomb-like granules were: amylopectin, 8.7 × 107 g/mol; amylose, 3.1 × 105 g/mol, close to those of native starch. The chain length distribution profiles of honeycomb-like granules were similar to those of native starch, while the proportions of B2 and B3 chains were higher. The water and oil adsorption of honeycomb-like granules were about 1.5 and 2.4 times those of native starch, respectively; and the cold water solubility of honeycomb-like granules was 88.5%, while native starch showed no solubility in cold water. Thus honeycomb-like starch granules have the potential to be applied as adsorbents, thickeners and adhesives for their dispersibility, adsorption capacity and cold water solubility. [ 1–54 ] Unlabelled Image • A method to prepare honeycomb-like starch granules was established. • The pore size of the honeycomb-like potato starch granules was about 2–4 μm. • The honeycomb-like potato starch granules had better adsorption capacities. • The cold water solubility of honeycomb-like potato starch granules was 88.5%. [ABSTRACT FROM AUTHOR]

The distribution of chain lengths in elastomer networks occurs naturally during polymerization, and has a critical role in the mechanical behavior of these materials, including the damage and fracture response. A common underlying assumption for the majority of constitutive models for rubber elasticity is that all the chains admit the same length. Moreover, in the classical statistical mechanical model for elastomer networks, the changes in internal energy are generally assumed to be negligible in comparison to the changes in configurational entropy. In contrast, the fracture process in a elastomer network, as already demonstrated in the well-known Lake-Thomas model, is essentially internal energy dominated. In this paper, we formulate a phase-field model for brittle fracture in polydisperse elastomer networks extending and merging recent advances in the fields of (a) homogenization of elastomer networks and (b) the variational approach to brittle fracture, allowing for predictions of crack nucleation, initiation and propagation. The free energy of the continuum is obtained employing an eight chain network model, accounting for (a) internal energy contributions from the extension of molecular bonds and (b) arbitrary chain length distribution. The representative chain in the eight chain network model takes into account the distribution of chain lengths, following the recently developed equal force model. We employ a mixed displacement-pressure formulation for the discretization of the incompressible large deformation elastic problem that arises. The analytical solution for the crack nucleation problem of an incompressible hyperelastic bar under uniaxial loading is compared with the three-dimensional simulation result. Finally, we demonstrate through a representative numerical simulation the capability of the gradient damage model to simulate crack propagation in an incompressible elastomer network. [ABSTRACT FROM AUTHOR]

• Elevated temperatures affect structural parameters of starch chain length distribution. • Nitrogen decreased the height of fifth amylopectin peak that increased at elevated temperature. • Nitrogen increased the height of second amylose peak at elevated temperature. • Nitrogen changed pasting properties and decreased relative crystallinity under warming. Nitrogen fertilization can mitigate the negative effects of high temperatures on rice. In this study, we simulated dynamic field temperature increases using a free-air temperature enhancement system. Changes in the physicochemical properties of starch were investigated under increasing nitrogen fertilization during the grain-filling stage. We observed that the application of nitrogen at elevated temperatures (ETN) did not change the chain length distribution compared with elevated temperatures (ET) alone; however, it did significantly increase the heights of the first and second amylose peaks. Specifically, ETN significantly decreased the height of fifth amylopectin and relative crystallinity, and the changes it introduced in the physicochemical properties of starch were greater than those of ET. Overall, these changes in starch properties may be associated with the ability of nitrogen to facilitate the maintenance of rice quality at high temperatures. [ABSTRACT FROM AUTHOR]

Characterization of local varietal barley quality diversity can help boost further development of novel value-added utilization of the grain. Therefore, in this study starch was isolated from 11 Ethiopian malting barley varieties to determine starch structural, pasting, thermal and digestibility characteristics, and their inter-relationships. The varieties showed significant differences in all amylopectin chain length fractions, and the A, B1, B2 and B3 chains ranged from 25.4 to 30.1, 47.4–50.1, 14.3–16.0 and 7.8–9.0 %, respectively. The varieties also exhibited significant variation in amylose content, relative crystallinity, absorbance peak ratios, pasting and thermal properties. Moreover, on average about 83 % raw starch of the varieties was classified as slowly digestible and resistant, whereas after gelatinization this was reduced to 9 %. Molecular and crystalline structures were strongly related to pasting properties, thermal characteristics and in vitro digestibility of the starches. The study provides information on some starch quality characteristics and the inter-relationships among the parameters, and might inspire further studies to suggest possible target-based starch modifications, and future novel utilization of barley. More studies are required to investigate the association of starch quality parameters with malting quality attributes. • Starches from 11 Ethiopian malt barley varieties had distinct physical properties. • All the barley starches exhibited A-type crystalline packing arrangements. • Starch with higher proportions of long amylopectin chains had lower digestibility. • Traveller and Planet varieties are selected as most suitable for functional foods. [ABSTRACT FROM AUTHOR]

Enzymatically modified starch granules are useful in the food industry by endowing improved thermal properties, resistance to digestion and complexation capacity. However, it is of interest to correlate structural features on the granular surface with functional characteristics relevant to given applications. To meet this requirement, a method was developed to quantify the density of α-1,6 branch points on differently structured starch granules as based on interfacial enzyme catalysis. The branch points are attacked by pullulanase, a debranching enzyme, and the branch point density, as calculated from the kinetic attack site density (kinΓ max), was linked to the chain length distribution (CLD) of the released segments. The procedure involved a combination of conventional and inverse Michaelis–Menten (MM) kinetics for pullulanase degradation of native, branching enzyme- or 4-α-glucanotransferase-modified granular waxy and normal maize starch (WMS and NMS). The treatment by branching enzyme increased the branch point density for WMS from 1.7 to 3.3 nmol/g starch granules. CLD analysis indicated that 4-α-glucanotransferase catalyzed hydrolysis and/or cyclization on the surface of the granules, rather than disproportionation. The CLD data reflected the different spatial organization of amylopectin chains within WMS and NMS granules related to their different amylose contents of 0.7 and 20.7%, respectively. Scanning electron microscopy confirmed that the starch granules retained the morphology without prominent cracks or pores after pullulanase hydrolysis for the analysis of interfacial kinetics. Comparison with the corresponding gelatinized starches gave new insights into the connection between substrate structure and specificity of the two glucotransferases acting on the different starches. [Display omitted] • Branching points on starch surface (kinΓ max) was determined using interfacial kinetic. • Branching enzyme (BE) and 4-α-glucanotransferase (4αGT) verified accuracy of kinΓ max. • BE catalyze transglycosylation on both gelatinized and ungelatinized starch. • 4αGT showed transglycosylation on gelatinized starch but not on ungelatinized starch. [ABSTRACT FROM AUTHOR]

Abstract Background Although starch consists of large macromolecules composed of glucose units linked by α-1,4-glycosidic linkages with α-1,6-glycosidic branchpoints, variation in starch structural and functional properties is found both within and between species. Interest in starch genetics is based on the importance of starch in food and industrial processes, with the potential of genetics to provide novel starches. The starch metabolic pathway is complex but has been characterized in diverse plant species, including pea. Results To understand how allelic variation in the pea starch metabolic pathway affects starch structure and percent amylose, partial sequences of 25 candidate genes were characterized for polymorphisms using a panel of 92 diverse pea lines. Variation in the percent amylose composition of extracted seed starch and (amylopectin) chain length distribution, one measure of starch structure, were characterized for these lines. Association mapping was undertaken to identify polymorphisms associated with the variation in starch chain length distribution and percent amylose, using a mixed linear model that incorporated population structure and kinship. Associations were found for polymorphisms in seven candidate genes plus Mendel’s r locus (which conditions the round versus wrinkled seed phenotype). The genes with associated polymorphisms are involved in the substrate supply, chain elongation and branching stages of the pea carbohydrate and starch metabolic pathways. Conclusions The association of polymorphisms in carbohydrate and starch metabolic genes with variation in amylopectin chain length distribution and percent amylose may help to guide manipulation of pea seed starch structural and functional properties through plant breeding.

• An increment in substitution with pretreatments was noticed in all samples. • Pre-treatment by citric acid favorably increase the resistant starch. • Pre-treated by sonication showed a higher cholesterol and bile salts binding ability. • A higher reduction in molecular weight was seen in acid treated succinylated starch. Influence of different pre-treatments (Ultra-sonication, heat-moisture treatment (HMT) and acid hydrolysis) on the functional properties, in vitro binding capacity and structural properties of succinylated foxtail millet starch were investigated. The degree of substitution was found to be higher in the succinylated starch pretreated by sonication (USFS-0.39). Pre-treatment of succinylated starch by citric acid (ASFS) had markedly increased the resistant starch content. In vitro studies have confirmed that USFS exhibited the highest cholesterol binding capacity at both pH 2.0 (1.86 mg/g) and pH 7.0 (3.12 mg/g) owing to the chemical bonding and entrapment of cholesterol molecules in the starch matrix. FT-IR had confirmed the cross-linking of succinic anhydride as indicated by the presence of a new peak at 1724 cm−1. This study concludes that prior treatment of succinylated starch by ultra-sonication is an efficient way to improve the resistant starch content and principally in vitro cholesterol and bile acid/salts binding ability. [ABSTRACT FROM AUTHOR]

• HPLC-CAD developed for direct chain length characterization of polySia. • HPLC-CAD was shown to provide the actual chain length of polySia. • CAD as an alternative for time consuming DMB-derivatization. • Application of HPLC-CAD for polySia quantification in a broad concentration range. Polysialic acid (polySia) is widely investigated in various biopharmaceutical applications (e.g. treatment of inflammatory neurodegenerative diseases), whereby a certain polySia chain length with an average degree of polymerization 20 (polySia avDP20) shows most promising effects. In this study, a rapid analytical method using a HPLC and charged aerosol detector (CAD) for the direct chain length characterization of biopharmaceutically relevant polySia was developed. It was evaluated as a fast alternative to the commonly used 1,2-diamino-4,5-methylenedioxybenzene (DMB) HPLC application. In contrast to HPLC-FLD, the CAD-application provides the actual chain length of polySia within ∼3 h. The reliability of the HPLC-CAD was evaluated with a commercial reference sample of known chain length and biotechnologically produced LC polySia (long chain polySia with a DP ∼130). Moreover, HPLC-CAD was successfully applied in the direct detection of oligo- and polySia until DP ∼65 and can be used to monitor the thermal hydrolysis and subsequent chromatographic isolation of polySia avDP20 (average degree of polymerization 20) without DMB sample derivatization. In addition, CAD was successfully applied for polySia quantification using a modified elution gradient. It was tested as a fast alternative to commonly used thiobarbituric acid (TBA) assay. A differentiation between LC polySia and smaller, hydrolysed polySia chains was intended and possible. For LC polySia and polySia avDP20, a quadratic relation between polySia mass-concentration and CAD signal was observed. In case of LC polySia, a quadratic dependency with a determination coefficient of R2 = 0.99 in a broad concentration range between 0.025 and 15 mg mL−1 was determined. Quantification of polySia avDP20 was found to have quadratic dependency with a determination coefficient of R2 = 0.99 in a concentration range between 0.02 and 0.25 mg mL−1. The HPLC-CAD was tested for quantification with polySia references of known concentration and showed high accordance with a concentration deviation ≤6.7%. The CAD quantification method was also applied in the polySia avDP20 production process and was compared to the TBA assay. Results of a correlation plot showed a high determination coefficient of R2 = 0.98. Overall, HPLC-CAD analysis was successfully tested as a suitable characterization and quantification application in the biopharmaceutical production of polySia. [ABSTRACT FROM AUTHOR]

Cuticular waxes cover the plant surface and serve as hydrophobic layer, exhibiting various wax profiles between plant species and plant organs. This paper reports comprehensive analysis of the waxes on organs exposed to air, including leaf, stem, pod pericarp, and petals (banner, wing and keel), and on seed coat enwrapped in pod pericarp of faba bean (Vicia faba). In total 7 classes of wax compounds were identified, including fatty acids, primary alcohols, alkyl esters, aldehydes, alkanes, cinnamyl alcohol esters, and alkylresorcinols. Overall, primary alcohols dominated the waxes on leaves and the seed coat enwrapped in pod pericarp, alkanes accumulated largely in stem and petals, whereas alkylresorcinols were observed in leaf, stem and pod pericarp. Organs exposed to air had higher coverage (>1.2 μg/cm2) than those on seed coat (<0.8 μg/cm2), and keel having the highest wax coverage. Meanwhile, the wax coverage on seed coat reduced during the seed development. The variations of wax coverages, compound class distributions and chain length profiles among organs suggested that wax depositions were associated with their ecophysiological functions, and the enzymes involved in wax biosynthesis also showed organ-specific. Image 1 • Wax coverage varied between faba bean organs and even between different petals. • Alkyl ester and cinnamyl alcohol ester were only observed on banner and wing petals. • Organs exposed to air had higher wax coverage than those on seed coat. • Alkane and alcohol and polyketide biosynthesis pathways were involved in faba bean. [ABSTRACT FROM AUTHOR]

Highlights • n -Alkanes were characterised across both temporal and spatial variations in climate. • Characteristics show little correlation with climate through time at a site. • Characteristics correlate significantly with climate across a large spatial transect. • Correlations are consistent with the functional role of n -alkanes. • Sub-fossil leaf wax records are likely to reflect large climatological shifts. Abstract In higher plants, leaf waxes provide a barrier to non-stomatal water loss, and their composition varies both between and within species. Characteristics of n -alkanes, a suite of ubiquitous compounds in these waxes, are thought to be influenced by the availability of water and the temperature in a plant's growing environment. Longer n -alkane distributions with less variability in chain length are hypothesised to confer greater resistance to non-stomatal water loss and thus are expected in higher abundance in desiccating environments. Relationships between the distribution of n -alkanes and both precipitation and temperature have previously been observed. Despite this, it is unclear whether n -alkane chain length distributions vary plastically in response to climate, or whether they are fixed within populations in different climate settings. To better understand this, we examine the relationship between n -alkane characteristics of Melaleuca quinquenervia and both spatial and temporal climate variation. Across eastern Australia, we find that n -alkane homolog concentrations and distributions in leaves of M. quinquenervia do not vary with climate where samples are proximate, even when climate shows significant variability. However, the concentration and distribution of n -alkane homologs do differ considerably between geographically separated populations in very different climate regimes. These results suggest n -alkane characteristics are not a plastic response to climate variability, and instead are likely fixed and could be driven by genetic differences between populations. This has important implications for the use of n -alkane characteristics as palaeoenvironmental proxies. [ABSTRACT FROM AUTHOR]

Highlights • Native waxy corn starch was treated by ultrasound treatment. • The molecular structure and physical properties of ultrasonicated waxy corn starch were characterized. • Higher population of A chain, lower proportion of B1,B2 and B3 chains were observed in ultrasonicated waxy corn starch. • α-(1,6) glycosidic linkages were destroyed easily than α-(1,4) glycosidic linkages. • The molecular structure of amylopectin is a critical factor in determining physicochemical properties of waxy corn starch. Abstract As a simple and effective physical method, ultrasound irradiation has been used to modify starch. Native waxy corn starch was treated by ultrasound irradiation at 100 and 400 W in this study. Compared with native waxy corn starch, lower proportion of B 1 , B 2 , and B 3 , higher proportion of A chain were observed in ultrasonicated waxy corn starch. 1H NMR combined with HPSEC-MALLS-RI data showed that lower degree of branching was observed in ultrasonicated waxy corn starch, and α-1,4 glycosidic linkages were more stable than α-1,6 glycosidic linkages in waxy corn starches. 13C NMR data indicated that the content of double helices was decreased, and single helix and amorphous components were increased after ultrasound irradiation. The A-type crystal structure was scarcely affected according to X-ray diffraction (XRD) analysis. The granule surface of ultrasonicated waxy corn starch became notch and rough fragment, and lower particle diameter was observed in ultrasonicated waxy corn starch. These results demonstrated that ultrasound irradiation affected chain length distribution, double helices, single helices and amorphous state, especially α-1,4 glycosidic linkages and α-1,6 glycosidic linkages, of waxy corn starch. [ABSTRACT FROM AUTHOR]

The objective of this study was to investigate the effects of rice variety, water content, and preparation temperature on the textural properties of gels processed from cooked rice grains via high‐speed shear homogenization. Rice gels were prepared from seven high‐amylose rice varieties. The results demonstrated the significant differences in rice gel hardness and hardening rates during storage based on the rice variety used. The proportion of short chains of amylopectin was negatively correlated with the hardness of the rice gel. The sample temperature before shear treatment also influenced the rice gel hardness. Rice gels prepared from cooked rice maintained at 75°C prior to homogenization showed a higher breaking force than those from cooked rice at 25°C. Observation using scanning electron microscopy demonstrated the tendency of the cooked rice sample maintained at 75°C to form a finer gel network after homogenization than those at 25°C from the same rice variety. The objective of this study was to investigate the effects of rice variety, water content, and preparation temperature on the textural properties of gels processed from cooked rice grains via high‐speed shear homogenization. The starch characteristics of each rice variety were reflected in the differences in rice gel hardness. In addition, the gel network formed in the process of high‐speed shear homogenization had a considerable impact on gel hardness. [ABSTRACT FROM AUTHOR]

Abstract Cuticular wax is the main transpiration barrier against uncontrolled water loss for all aerial plant organs. This study presents water permeability and chemical composition of the cuticle on the petals and leaves of two cultivars of Rosa chinensis ('Movie star' and 'Tineke'). Numerous cultivar- and organ-specific differences, such as the water permeability and total cuticular wax, were detected among rose petals and leaves. Overall, the permeability to water is higher in petals than in leaves, varying between 1.8 × 10−5 m s−1 ('Tineke' leaves) and 1.0 × 10−4 m s−1 ('Tineke' petals). The cuticular wax coverage ranges from 4.9 μg cm−2 ('Tineke' petals) to 13.2 μg cm−2 ('Movie star' petals). The most prominent components of the waxes are n -alkanes with the odd-numbered chain lengths C 27 and C 29 in petals, and C 31 and C 33 in leaves. The lower water permeability of leaves is deduced to be associated with the higher weighted average chain length of their acyclic cuticular waxes. This study on transpiration via the cuticular wax barrier of the leaf and petal of rose provides further insight to link the chemical composition to the cuticular transpiration barrier properties. Highlights • Cuticular wax is the main transpiration barrier against uncontrolled water loss. • Petals have a higher water permeability than leaves. • The cuticular wax coverage varies intraspecifically. • Chain lengths of n -alkanes in the waxes are longer in leaves than in petals. [ABSTRACT FROM AUTHOR]

Highlights • Foxtail millet starch was modified by annealing and ultra-sonication treatments. • Resistant starch was significantly enhanced up to 45% in the dual modified starch. • Sonicating starch after annealing had presented a greater acid and shear stability. • Sonication, when used as the second treatment elevated the final viscosity. Abstract Foxtail millet starch was modified by annealing (AS), ultra-sonication (US) and a combination of the two treatments (annealing and ultra-sonication (AUS) or ultra-sonication and annealing (UAS)) and they were characterized. Compared to the native starch (NS), modified starches particularly UAS contained the highest amylose (27.96%). Ultra-sonication prior to annealing had a predominant effect on resistant starch (RS) level (UAS-45.59%). Among the modified starches, UAS had exhibited superior resistance to acidic (0.94) and shear (0.68) stability. Sonication, when used as the second treatment (AUS) elevated the final viscosity compared to its counter ones possibly due to the effects of cavitation promoted by sonication treatment. UAS had showed an A-type diffraction pattern and dominant peaks in FT-IR spectra. It can be inferred that dual modification of starch by ultra-sonication followed by annealing had exhibited the most desirable properties such as high acid and shear resistance, high freeze–thaw stability and improved gel texture. [ABSTRACT FROM AUTHOR]

To examine the roles of starch phosphatases in potatoes, transgenic lines were produced where orthologs of SEX4 and LIKE SEX FOUR2 (LSF2) were repressed using RNAi constructs. Although repression of either SEX4 or LSF2 inhibited leaf starch degradation, it had no effect on cold-induced sweetening in tubers. Starch amounts were unchanged in the tubers, but the amount of phosphate bound to the starch was significantly increased in all the lines, with phosphate bound at the C6 position of the glucosyl units increased in lines repressed in StSEX4 and in the C3 position in lines repressed in StLSF2 expression. This was accompanied by a reduction in starch granule size and an alteration in the constituent glucan chain lengths within the starch molecule, although no obvious alteration in granule morphology was observed. Starch from the transgenic lines contained fewer chains with a degree of polymerization (DP) of less than 17 and more with a DP between 17 and 38. There were also changes in the physical properties of the starches. Rapid viscoanalysis demonstrated that both the holding strength and the final viscosity of the high phosphate starches were increased indicating that the starches have increased swelling power due to an enhanced capacity for hydration.

High amylose starch shows wide applications in food and non-food-based industries. Traditional complex-precipitation approach for the amylose fractionation required a large volume of organic reagents and was possibly risky for food safety. The object of this work was to establish a novel method to obtain starch fractions rich in amylose from debranch starch through repeated short-term retrogradation and centrifugation. Four starch fractions were obtained with the amylose content of 52.08% (C1), 62.28% (C2), 63.58% (C3), and 64.74% (C4). The thermograms of samples displayed that multiple endothermic peaks were detected in C1 and C2 and only one endothermic peak with melting temperature over 120 °C were observed in C3 and C4, indicating their differences in retrogradation behavior. The chain length distribution results of sample exhibited that C1 and C2 contained more short chains (DP ≤ 24), while C3 and C4 consisted of mainly long chains (DP ≥ 25). Accordingly, the differences in fine structures could provide more choices for these fractionated high amylose starch to utilize in practical applications., Competing Interests: The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (© 2023 The Authors.)

Summary: Composition, structure and physicochemical properties of starch from red‐ and purple‐fleshed potatoes were investigated and compared to those of typical yellow‐fleshed potatoes. The starch from yellow has highest amylose (25.23%) content, following by purple (23.30%) and red (20.26%). The growth ring of the three starches differed, but granule morphology was largely similar. Each potato starch exhibited B‐type crystalline patterns, with crystallinity ranging from 20.33% to 22.25%. The molecular weights and z‐average radius of gyration exhibited significant difference among the three starch samples. The branch chain length distribution showed that purple potato starch had highest population of A chains and lowest population of B1 chains. Moreover, the pasting properties of the three samples differed remarkably. The purple (90.92%) and red (86.41%) potato starches presented extremely good light transmittance compared with the yellow potato starch (34.03%). Dynamic rheological analysis showed that all samples possessed a weak elastic gel‐like structure. [ABSTRACT FROM AUTHOR]

Chain length distribution (CLD) is one of fine structural parameters of starch, playing significant roles in determining starch physicochemical properties. In this study, six pigmented potato cultivars were used to explore the relationship between starch structural properties and starch functional properties. It was found that the amylose content, the peak height of amylose ( h AM ) and the first peak height of amylopectin ( h AP1 ) significantly differed, whereas the other structure parameters had small variations among the potato starches. The average length of amylopectin side chains varied from 24.8 to 26.4 degree of polymerization (DP), and fractions fa, fb 1 , fb 2 and fb 3 of amylopectin showed no significant difference. A wide variation in the starch pasting and thermal properties was observed. Correlation analysis indicated that the pasting properties were affected by the fine structures of both amylose and amylopectin, while the thermal properties were only affected by the amylopectin fine structure. These results contribute to our understanding the structure-function relationships among potato starches. [ABSTRACT FROM AUTHOR]

The objective of this study was to obtain structure-digestion relationships of fully gelatinized starch. Twelve starch samples with marked fine structural differences (HPLC-SEC) were studied for their retrogradation behavior (thermal and rheological properties of starch gels) and in vitro digestibility. A reduction in the digestion rate during storage for 7 days was observed in all samples and, interestingly, this reduction was particularly evident in sago (64.7%), potato (57.3%), pea (55.1%) and acid-converted maize (ACM, 51.6–51.8 %) starches. Results indicated two potential interactions that may result in slowly digestible supramolecular structures: 1) double helices between external A and B1 chains of DP at peak maximum ≥ 15.5 Glucose Units (perhaps involving internal long chains) that also are prone to forming intermolecular associations [high relative drop in the storage modulus (G’) during heating of 7 days-stored gels] and; 2) interactions of small molecular size acid-hydrolyzed starch molecules that may be more mobile and easily aligned. [ABSTRACT FROM AUTHOR]

To elucidate the influence of chain distributions on enzymatic digestibility of lotus rhizome and kudzu amylopectins, the correlation between the chain length distribution and enzymatic hydrolysis of amylopectins was studied. The results indicated that lotus rhizome amylopectin was more susceptible to amylase hydrolysis than kudzu amylopectin since lotus rhizome amylopectin contained a higher proportion of short chains. Using α-amylase and glucoamylase, individually or in combination, the values of digestion rate constant k of kudzu amylopectin were lower than that of lotus rhizome amylopectin. A small amount of glucose was released from kudzu and lotus rhizome amylopectins with α-amylase alone, whereas the release of glucose remarkably increased with α-amylase and glucoamylase. It confirmed that the synergism existed between α-amylase and glucoamylase in glucose released from kudzu and lotus rhizome amylopectins. The chain length distribution of amylopectins significantly affected the hydrolysis of amylases and they were highly correlated with the digestibility properties of lotus rhizome and kudzu starches. [ABSTRACT FROM AUTHOR]