B-type Granules Research Articles

Penalties in Granule Size Distribution and Viscosity Parameters of Starch Caused by Lodging in Winter Wheat

Granule size distribution of wheat starch is an important characteristic that could affect the functionality of wheat (Triticum aestivum L.) products. Lodging is a major limiting factor for wheat production. Few studies have been conducted to clarify how lodging influences the granule size distribution and viscosity parameters of starch in wheat grains. Two growing seasons, two high-yield winter wheat cultivars, and five artificial lodging treatments were imposed. The results indicated that lodging significantly reduced the content of starch and increased that of protein. Additionally, lodging caused a marked drop in both starch and protein yields. The relative loss of grain yield, starch yield, harvest index, and protein yield all differed remarkably among lodging treatments with a ranking of L2 > L1 > L4 > L3. Lodging also led to a reduction in the proportion (both by volume and by surface area) of B-type granules and a corresponding increase in that of A-type granules, and the more serious the lodging degree, the greater effect on the changes in these proportions. The smaller starch granules predominated in number, even though their collective contribution to the overall volume is was relatively minor. Meanwhile, it was found that the peak viscosity, hold viscosity, final viscosity, breakdown viscosity, and rebound value of wheat starch were significantly decreased by lodging. Correlation analysis showed that the peak and final viscosities were negatively correlated with volume percentages of A-type starch granules, but were positively correlated with B-type granules. This indicates that B-type granules have higher peak and final viscosities compared with A-type granules in wheat kernels. Lodging can reduce the proportion of B-type starch granules, and thus reduce the peak and the final viscosity in wheat grain.

Effects of wheat starch content on its flour and frozen dough bread

The refined wheat flour was mixed with different types of wheat starch in different addition levels, their microstructure, chemical bonds in the dough and baking characteristics of 0–8 weeks frozen dough bread were studied. With the increase of A-Type starch granules and whole wheat starch, the pores of gluten network first decreased and then increased. Conversely, an increase in B-Type starch granules consistently reduced gluten network porosity. With the increase of whole wheat starch, the content of free sulfhydryl group and hydrophobic interaction decreased gradually. Minimal additions of B-Type granules were found to enhance the specific volume of fresh bread, whereas increased quantities improved the specific volume of frozen dough bread. The addition of a small quantity of A- or B-Type granules enhances the freezing stability of bread. This study provides effective information for elucidating the effects of wheat starch on the frozen dough and bread properties in protein-starch matrix.

Starch phosphorylation regulates starch granule morphological homogeneity in Arabidopsis thaliana.

Starch granule morphological homogeneity presents a gap in starch research. Transitory starch granules in wild-type plants are discoid, regardless of species. Notably, while the shape of starch granules can differ among mutants, it typically remains homogeneous within a genotype. We found an Arabidopsis thaliana mutant, dpe2sex4, lacking both the cytosolic disproportionating enzyme 2 (DPE2) and glucan phosphatase SEX4, showing an unprecedented bimodal starch granule diameter distribution when grown under a light/dark rhythm. dpe2sex4 contained 2 types of starch granules: large granules and small granules. In contrast to the double starch initiation in wheat (Triticum aestivum) endosperm, where A-type granules are initiated first and B-type granules are initiated later, dpe2sex4 small and large granules developed simultaneously in the same chloroplast. Compared with the large granules, the small granules had more branched amylopectin and less surface starch-phosphate, thus having a more compact structure that may hinder starch synthesis. During plant aging, the small granules barely grew. In in vitro experiments, fewer glucosyl residues were incorporated in small granules. Under continuous light, dpe2sex4 starch granules were morphologically homogeneous. Omitting the dark phase after a 2-wk light/dark cycle by moving plants into continuous light also reduced morphological variance between these 2 types of granules. These data shed light on the impact of starch phosphorylation on starch granule morphology homogeneity.

Initiation of B-type starch granules in wheat endosperm requires the plastidial α-glucan phosphorylase PHS1.

The plastidial α-glucan phosphorylase (PHS1) can elongate and degrade maltooligosaccharides (MOSs), but its exact physiological role in plants is poorly understood. Here, we discover a specialized role of PHS1 in establishing the unique bimodal characteristic of starch granules in wheat (Triticum spp.) endosperm. Wheat endosperm contains large A-type granules that initiate at early grain development and small B-type granules that initiate in later grain development. We demonstrate that PHS1 interacts with B-GRANULE CONTENT1 (BGC1), a carbohydrate-binding protein essential for normal B-type granule initiation. Mutants of tetraploid durum wheat (Triticum turgidum) deficient in all homoeologs of PHS1 had normal A-type granules but fewer and larger B-type granules. Grain size and starch content were not affected by the mutations. Further, by assessing granule numbers during grain development in the phs1 mutant and using a double mutant defective in both PHS1 and BGC1, we demonstrate that PHS1 is exclusively involved in B-type granule initiation. The total starch content and number of starch granules per chloroplast in leaves were not affected by loss of PHS1, suggesting that its role in granule initiation in wheat is limited to the endosperm. We therefore propose that the initiation of A- and B-type granules occurs via distinct biochemical mechanisms, where PHS1 plays an exclusive role in B-type granule initiation.

Increasing amyloplast size in wheat endosperm through mutation of PARC6 affects starch granule morphology.

The determination of starch granule morphology in plants is poorly understood. The amyloplasts of wheat endosperm contain large discoid A-type granules and small spherical B-type granules. To study the influence of amyloplast structure on these distinct morphological types, we isolated a mutant in durum wheat (Triticum turgidum) defective in the plastid division protein PARC6, which had giant plastids in both leaves and endosperm. Endosperm amyloplasts of the mutant contained more A- and B-type granules than those of the wild-type. The mutant had increased A- and B-type granule size in mature grains, and its A-type granules had a highly aberrant, lobed surface. This morphological defect was already evident at early stages of grain development and occurred without alterations in polymer structure and composition. Plant growth and grain size, number and starch content were not affected in the mutants despite the large plastid size. Interestingly, mutation of the PARC6 paralog, ARC6, did not increase plastid or starch granule size. We suggest TtPARC6 can complement disrupted TtARC6 function by interacting with PDV2, the outer plastid envelope protein that typically interacts with ARC6 to promote plastid division. We therefore reveal an important role of amyloplast structure in starch granule morphogenesis in wheat.

Starch Chemical Composition and Molecular Structure in Relation to Physicochemical Characteristics and Resistant Starch Content of Four Thai Commercial Rice Cultivars Differing in Pasting Properties.

Variations in starch pasting properties, considered an alternative potential quality classification parameter for rice starches, are directly controlled by the diverse starch molecular composition and structural features. Here, the starch characteristics of four rice cultivars (i.e., RD57, RD29, KDML105, and RD6) differing in pasting properties were assessed, and their relationship was determined. The results revealed that protein and moisture contents and their crystalline type were similar among the four rice starches. However, their molecular compositions and structures (i.e., reducing sugar and amylose contents, amylopectin branch chain-length distributions, granule size and size distribution, and degree of crystallinity) significantly varied among different genotypes, which resulted in distinct swelling, solubility, gelatinization, retrogradation, and hydrolytic resistance properties. The swelling power and gelatinization enthalpy (∆H) were positively correlated with C-type granule and relative crystallinity, but were negatively correlated with amylose content, B-type granule and median particle size (d(0.5)). Conversely, the water solubility and resistant starch content negatively correlated with C-type granule, but positively correlated with amylose content, B-type granule, and d(0.5). The gelatinization onset temperature (To(g)), and retrogradation concluding temperatures (Tc(r)), enthalpy (∆H(r)), and percentage (R%) were positively impacted by the amount of protein, amylose, and B1 chains (DP 13-24), while they were negatively correlated with short A chains (DP 6-12). Collectively, the starch physicochemical and functional properties of these Thai rice starches are attributed to an interplay between compositional and structural features. These results provide decisive and crucial information on rice cultivars' suitability for consumption as cooked rice and for specific industrial applications.

Impact of wheat starch granule size on viscoelastic behaviors of noodle dough sheet and the underlying mechanism

The contribution of starch to dough behaviors has been largely overshadowed by the role of gluten, receiving much less attention in comparison. The impact of wheat starch granule size on the viscoelastic behaviors of low-moisture noodle dough and its underlying mechanism were investigated. Dough with a high ratio of B-type starch granules (BS) had higher viscoelastic moduli (G″ and G′), percent stress relaxation (SR%), and smaller creep compliance (J max ), indicating higher viscoelasticity and strength. This might be related to the higher filling ability and water-binding capacity of B-type starch. Compared to large A-type starch granules (AS), small B-type granules would easily embed to form a more closely packed and uniform network structure. In addition, the differences in water distribution and hydration properties could affect the hydrophobicity of starch and the surface environments of the protein, thus influencing the polymer interactions in the doughs. The hydrogen bonds were the main con-covalent bonds in the low-moisture noodle dough. With increasing B-/A-type starch ratios, β-sheet and hydrogen bond contents significantly increased, while the GMP content showed a decrease, suggesting the enhanced hydrogen bond interaction in a high ratio of B-type starch dough could cooperate with intermolecular disulfide bonds to stabilize the network structure of gluten, improving the dough strength. These results demonstrated that the viscoelastic behaviors of dough sheets were related to the granule size distribution of wheat starch. Finally, a schematic model describing the mechanism of the influence of starch granule size on dough behaviors was built. • B-type wheat starch granules promoted uniform and compact gluten network formation. • Small B-type granules led to stronger hydrogen bond interaction in the noodle dough. • The enhanced interaction by hydrogen bonding could improve the dough strength. • Viscoelasticity of dough sheet increased with increasing B- to A-type starch ratios.

Physicochemical properties of A- and B-type granules isolated from waxy and normal hull-less barley starch

Large A-type and small B-type starch granules separated from waxy and normal hull-less barley starches were investigated for their physicochemical properties. Hull-less barley starch granules were covered by a membrane composed mainly of phospholipids. Channels of waxy A- and B-type granules were rich in proteins and phospholipids. Compared with A-type starch, B-type starch exhibited higher specific surface area, volume and average diameter of mesopores. Waxy A-type granules exhibited the higher peak, breakdown, final and setback viscosity than did B-type granules, while normal A-type granules showed the lower peak, breakdown, final viscosity and the higher setback viscosity than did B-type granules. B-type starch gels with lower storage modulus exhibited a less elastic gel network structure and retrograded more slowly. Moreover, in vitro hydrolysis of starch showed that the B-type granules exhibited a higher hydrolysis extent and rate than the A-type granules in the first stage, which was consistent with higher initial α-amylase binding ability of B-type granules. The study showed that the A-type and B-type starch separated from waxy and normal hull-less barley exhibited very different physicochemical properties.

Rheological, microstructure and mixing behaviors of frozen dough reconstituted by wheat starch and gluten

The effects of starch and gluten on the physicochemical properties of frozen dough were studied using reconstituted flour. The profiles of frozen dough were studied by Mixolab, rheometer, scanning electron microscopy (SEM), confocal laser scanning microscopy (CLSM), differential scanning calorimetry (DSC) and Fourier transform infrared spectroscopy (FTIR). Results revealed that starch, rather than gluten, played a decisive role in mixing properties. The breakdown and aggregation of the gluten network structure as well as the formation of β-turns and β-sheets in the frozen dough would be aggravated by the freezing of wheat starch. Smaller wheat starch granules (B-Type granules) affected the secondary structure of gluten network more than larger granules (A-Type granules), resulting in greater rheological property changes. The viscoelastic properties and freezable water content of frozen dough were more influenced by the freezing of gluten.

Analysis of starch structure and functional properties of tetraploid wheat (Triticum turgidum L.) with differing waxy protein composition.

An increased demand for food has mirrored the increasing global population. Obesity and diabetes are two disorders induced by poor eating choices. Consequently, there is an urgent need to develop modified foods that can ameliorate such illnesses. The objective of this study was to explore the effect of Waxy genes on the structural and functional properties of starch, with the aim of improving food quality. Wild-type tetraploid wheat was compared with three mutants with different Waxy gene combinations. The proportion of B-type granules was higher in the mutants than in the wild-type (Wx-AB), and there were significant changes in the starch granule size, number, and phenotype in the Wx free mutant (Wx-ab). The lowest branch chain length was observed in Wx-ab, whereas Wx-AB had the highest branch chain length of DP ≥ 37. Wx-ab had the highest degree of crystallinity. The crystallinity trend followed the order Wx-ab>Wx-Ab>Wx-aB>Wx-AB. The amount of slowly digestible starch (SDS) was higher in native, gelatinized, and retrograded starch in the mutant. The amount of retrograded starch was closer to gelatinized starch than to native starch. Waxy proteins make a substantial contribution to starch structure. A lack of waxy proteins reduced the unit chains markedly compared with the control. Waxy proteins significantly affected the smaller and longer chains of starch. The lines with differing waxy composition had different effects on food digestion. The Wx-AB in native starch and Wx-Ab in gelatinized starch can control obesity and diabetes by slow-digesting carbohydrates and high resistance to digestion. © 2022 Society of Chemical Industry.

New insight into the contribution of wheat starch and gluten to frozen dough bread quality

The contribution of starch granules to the baking properties of frozen dough bread has been investigated using reconstituted dough method. The baking and aging characteristics of frozen dough bread were studied by texture analyzer, colorimeter, DSC, FTIR and LF-NMR. Results showed that starch had more impact on bread than gluten in specific volume of frozen dough bread, while gluten contributed more in color and cell density of frozen dough bread crumb during 8-weeks frozen storage. The changes of hardness mainly contributed to starch deterioration in first 4 weeks, then it was dominated by gluten in the later 4–8 weeks. A-Type granules have more effect on texture properties, number of cells and enthalpy of frozen dough bread during storage. B-Type granules contributed more on the size of cells in bread. The main aging change of wheat starch in profiles of bread was provided by A-Type granules during frozen storage.

Multi-scale structure of A- and B-type granules of normal and waxy hull-less barley starch

The multi-scale structure of combined (A- and B- type granules), A-type, and B-type granules from normal (NHB) and waxy hull-less barley (WHB) starch was studied, including crystalline structure, molecular branching, nanostructural and fractal characteristics. Particle size distribution was applied to determine the separation purity (>95%), and micrography was used to distinguish between the A-type and B-type granules. Lacking amylose, WHB had higher relative crystallinity, gelatinization temperature, enthalpy, level of scattering intensity and uniformity of orientation of double helices than NHB starch. Generally, B-type granules had higher gelatinization temperature, lower enthalpy, greater relative crystallinity, higher ratio of crystalline to amorphous region, more fa chains in amylopectin, and thicker semi-crystalline lamellae than A-type and combined granules. The results showed that the multi-scale structure of A-type and B-type granules differed greatly, and the characteristics of combined granules were not the same as those of its two constituent granule fractions.

Effects of irrigation schemes on the components and physicochemical properties of starch in waxy wheat lines

The waxy wheat shows special starch quality due to low amylose content. However, less information is available concerning the physicochemical properties of starch in different waxy wheat under different irrigation. In this study, two wheat near-isogenic lines (NILs) and a normal wheat cultivar were used to investigate the contents, size distribution and crystallinity of starch by biochemical methods, laser-diffraction and X-ray diffraction analysis. The amylose content in wheat grains was the lowest in waxy wheat lines, SJZ8-N, followed by the partly waxy wheat lines, SJZ8-P, and the highest in the normal wheat, SJZ8, with significant differences among wheat lines. Waxy wheat starch had more B-type granules and a higher degree of crystallinity than normal wheat starch, with the order as SJZ8-N > SJZ8-P > SJZ8. When compared with the conventional and water-saving irrigation, the rainfed treatment showed the lowest starch content, amylose content (except SJZ8-N), amylopectin content and relative crystallinity in the three wheat lines indicating that water deficiency was not benefited starch accumulation and crystal formation in wheat grains. It was concluded that (1) wheat lines not only differed in amylose content but also in size distribution and crystallinity of starch; (2) irrigation markedly influenced the physicochemical characteristics of wheat starch; therefore, the irrigation schemes could be adjusted to achieve high-quality wheat production.

Gelatinization or Pasting? The Impact of Different Temperature Levels on the Saccharification Efficiency of Barley Malt Starch.

Efficient enzymatic hydrolysis of cereal starches requires a proper hydrothermal pre-treatment. For malted barley, however, the exact initial temperature is presently unknown. Therefore, samples were micro-mashed according to accurately determined gelatinization and pasting temperatures. The impact on starch morphology, mash viscometry and sugar yields was recorded in the presence and absence of an amylase inhibitor to differentiate between morphological and enzymatic effects. Mashing at gelatinization onset temperatures (54.5–57.1 °C) led to negligible morphological and viscometric changes, whereas mashing at pasting onset temperatures (57.5–59.8 °C) induced significant starch granule swelling and degradation resulting in increased sugar yields (61.7% of upper reference limit). Complete hydrolysis of A-type and partial hydrolysis of B-type granules was achieved within only 10 min of mashing at higher temperatures (61.4–64.5 °C), resulting in a sugar yield of 97.5% as compared to the reference laboratory method mashing procedure (65 °C for 60 min). The results indicate that the beginning of starch pasting was correctly identified and point out the potential of an adapted process temperature control.

Effects of supplemental irrigation on winter wheat starch structure and properties under ridge-furrow tillage and flat tillage

Supplemental irrigation (SI) is an important strategy to improve the water-use efficiency (WUE) of crops without compromising the yield. However, such strategy can influence the starch and grain quality. Hence, the effects of SI on winter wheat starch structure and functionality were studied on ridge-furrow (RF) and flat tillage (FT) treated fields. Flat irrigation was set as control. RF + SI significantly increased the grain yield throughout the study period (2016–2018). SI decreased the amylose content and the content of amylopectin chains with DP 13–24 but increased the proportions of amylopectin chains with DP 6–12 and 25–36. The starch granule relative crystallinity decreased, and more B-type granules were produced by SI treatment. SI significantly increased the resistant starch content in both raw and cooked starch systems. Flat tillage enhanced the effect of SI on granule specific surface area (SSA) and viscosity, which increased starch paste viscosity, while SI + RF showed the opposite effects. Our study demonstrates important combined effects of SI and tillage on wheat starch quality.

Physicochemical and digestive properties of A- and B-type granules isolated from wheat starch as affected by microwave-ultrasound and toughening treatment

In this study, the effect of microwave-ultrasound or/and toughening treatment on the physicochemical, structural properties, and in vitro digestibility of A- and B-type granules isolated from wheat starch were investigated. From the SEM, microwave-ultrasound and toughening treatment (MU-T) led to the appearance of irregular and disrupted structure significantly and an increment in the resistant starch content of A- and B-type granule. Furthermore, the MU-T starch possessed the lowest swelling power, light transmittance, and gelatinization temperature range (Tc –To) and the highest ΔH. After MU-T, the relative crystallinity (RC) of X-ray pattern, Fourier transform infrared ratio of 1047/1022 cm−1, and the content of double helix and single helix of 13C CP/MAS NMR had increased significantly. In particular, there was a difference in the content of RS and SDS between A-starch granules and B-starch granules as well as their changes after modification (from 69.305% to 82.93 for A-starch and form 74.97% to 88.17 for B-starch, respectively), which was a similar trend with RC and helix content. This study indicated that, for both A-type granule and B-type granule starches, microwave-ultrasound and toughening treated samples had unique properties compared to singly modified starches.

Effects of low temperature at stem elongation stage on the development, morphology, and physicochemical properties of wheat starch

The low temperature in spring is a meteorological problem in wheat production because it leads to yield reduction and alteration of wheat quality. In this study, an artificial low-temperature treatment (LTT) at the stem elongation stage was implemented to investigate the starch granule development and physical and chemical properties of wheat starch. Results showed that the agronomic traits of spike, such as spike length, spikelet number per spike, and grain number per spikelet, decreased after LTT. LTT promoted the development of starch granules in developing grains at 15 days post-anthesis, resulting in increased B-type granules and reduced C-type granules with an irregular shape in mature grains. The swelling power of the starch granules was reduced, but their solubility was enhanced by LTT. The proportion of the amorphous structure within the granules increased, but the crystalline component decreased after LTT, leading to a significant reduction in the relative degree of crystallinity and double- and single-helix structures. Three types of hydrolysis showed that starch in LTT was easy to hydrolyze, resulting in a high degree of hydrolysis. The findings suggest that low temperature at the stem elongation stage can not only reduce the yield parameters of spike but also alter starch accumulation, thereby affecting the processability and structure characteristics of starch in wheat grains.

Impact of ultrasonication on functional and structural properties of Indian wheat (Triticum aestivum L.) cultivar starches

In the present study, functional and structural properties of wheat starches treated with ultrasonication for 15 and 30 min (US-15 and US-30, respectively) were studied. Functional properties such as swelling power, amylose content and oil absorption capacity increased significantly (P ≤ 0.05) upon ultrasonication. A-type crystalline nature of wheat starches remained unaffected with ultrasound treatment, whereas relative crystallinity increased after US-15 and US-30, but the percentage increase was less in case of US-30 (30.82–34.06%) as compared to US-15 (33.70–37.36%). FTIR spectral patterns showed that no new bond was formed or broken by ultrasonication in starch molecule, whereas the absorbance ratios 1022/995 cm−1 decreased significantly (P ≤ 0.05) and ranged between 0.976 and 1.056 and 1.003–1.055, for US-15 and US-30, respectively. Scraps and deformities made on granule surfaces by ultrasonic waves were clearly observed in SEM images, which were more prominent in case of large sized starch granules. Particle size analysis revealed that the percent volume of A-type granules increased with both US-15 (68.85–79.72%) and US-30 (70.96–79.89%), whereas that of B-type granules decreased after US-30 treatment.

Physiological and histopathological responses of Porcellio laevis (Isopoda, Crustacea) as indicators of metal trace element contamination

This study was designed to assess the impact of the mixture of cadmium (Cd) and zinc (Zn) on the bioaccumulation and the ultrastructural changes in the hepatopancreas of Porcellio laevis (Latreille, 1804) after 4 weeks of exposure to contaminated Quercus leaves under laboratory conditions. For each metal, four concentrations were used with four replicates for each concentration. Metal concentrations in the hepatopancreas and the rest of the body were determined using atomic absorption spectrometry. From the first week until the end of the experiment, a weight gain in P. laevis was observed particularly between the first and the end of exposure from 93.3 ± 18.22 mg fw to 105.22 ± 16.16 mg fw and from 106.4 ± 22.67 mg fw to 125.9 ± 23.9 mg fw for Mix1 and Mix4, respectively. Additionally, the determined metal trace elements (MTE) concentrations in the hepatopancreas were considerably higher compared to those in the rest of the body and seem to be dose-dependent. Using transmission electron microscopy (TEM), some alterations were highlighted in the hepatopancreas. The main observed alterations were (a) the destruction of the microvilli border in a considerable portion of cells, (b) the increase of the lipid droplets with different shapes and sizes, (c) the increase in the number of the mitochondria, and (d) the appearance of TE in the form of B-type granules. The obtained results confirmed the ability of P. laevis to deal with high amounts of MTE, suggesting its possible use in future soil's biomonitoring programs.

Effect of A- and B-granules of wheat starch on Chinese noodle quality

To investigate the effect of A- and B-type granules of wheat starch on noodle quality, the fractionation and reconstitution method was used to prepare noodles with five different ratios of A-to B-granules (100A-0B, 75A-25B, 50A-50B, 25A-75B, 0A-100B). The pasting and swelling properties of reconstituted flours and the microstructure of noodles observed under a confocal laser scanning microscope (CLSM) indicated that there were at least two aspects were responsible for the changes in noodle quality. First, the water distribution, texture and cooking quality of noodles were influenced by the different physicochemical properties of A- and B-granules; and second, the gluten structure in noodles was altered by the granule size distribution, which further led to a difference in noodle quality. In general, with increasing number of B-granules, the A22 (the proportion of less immobilized water) of raw noodles and the hardness, resilience and chewiness of cooked noodles increased first and then decreased, while the cooking loss, water absorption and protein loss showed the reverse trend. Raw noodle samples containing 50A-50B had the minimum T22 (less immobilized water) but the maximum A22 and, when cooked, had the greatest hardness, chewiness and resilience and the least cooking loss (6.6%) and water absorption (166.1%). These results have important implications for illustrating the mechanism by which A- and B-granules affect noodle quality and guide efforts to improve noodle quality and wheat breeding.