Large Starch Granules Research Articles

Post-silking carbon partitioning under nitrogen deficiency revealed sink limitation of grain yield in maize.

Maize (Zea mays) plants exhibit altered carbon partitioning under nitrogen (N) deficiency, but the mechanisms by which N availability affects sugar export out of leaves and transport into developing ears remain unclear. Maize was grown under field conditions with different N supply. Plant growth, sugar movement, and starch turnover in source or sink tissues were investigated at silking and 20 or 21 days after silking. Nitrogen deficiency stunted plant growth and grain yield compared with N-sufficient plants, and resulted in greater starch concentrations in leaves due to more as well as larger starch granules in bundle sheath cells. Transmission electron microscopy revealed an open symplastic pathway for sucrose movement in N-deficient leaves, while the expression levels of transporters responsible for sucrose efflux and phloem loading were lower than in N-sufficient leaves. Nonetheless, greater starch concentrations in the apical cob portion of N-deficient plants implied sufficient carbon supply relative to the diminished sink strength (decreased kernel number and weight). Together with the high sugar concentrations in the developing kernels, the results indicated that reduced sink capacity and sugar utilization during grain filling may limit the yield in N-deficient plants, which in turn imposes a feedback inhibition on sugar export from leaves.

Comparison of Structural and Functional Properties of Wheat Starch Under Different Soil Drought Conditions

Drought influences cereal crop yield and quality. However, little is known about changes in the structural and functional properties of wheat starch under soil drought conditions. In this study, two wheat cultivars were subjected to well-watered (WW), moderate soil-drought (MD), and severe soil-drought (SD) from 7 tillers in the main stem to maturity. The structural and functional properties of the resultant endosperm starch were investigated. In comparison with WW soil, the MD increased starch accumulation in grains, the proportion of large starch granules, amylose and amylopectin long branch chain contents, and average amylopectin branch chain length, which were accompanied by the increase in activities of granule bound starch synthase and soluble starch synthase. MD treated-starch had a lower gelatinization enthalpy, and swelling power, but a higher gelatinization temperature, retrogradation enthalpy, and retrogradation percentage when compared to WW conditions. The MD also increased starch resistance to acid hydrolysis, amylase hydrolysis, and in vitro digestion. The SD had the opposite effects to the MD in all cases. The results suggest that soil drought more severely affects amylose synthesis than amylopectin synthesis in wheat grains, and moderate soil-drought improves molecular structure and functional properties of the starch.

Influence of environmental temperature during grain filling period on granule size distribution of rice starch and its relation to gelatinization properties

High temperature (HT) is the major environmental factor affecting grain starch properties of cooking rice cultivars. However, little information has been available on the effect of environmental temperature on the starch granule size distribution of rice grains. In this paper, five indica rice genotypes, including the wild type (9311) and its four mutants differing in amylose content (AC), were used to investigate the effect of environmental temperature on the starch granule size distribution, as well as its relation to AC and gelatinization properties of rice starch. Two temperature treatments (HT and NT) at filling stage were imposed to rice plants under the controlled temperature chambers. The result showed that HT increased the average diameter of starch granules and enhanced the proportion of large starch granules (LSG, D > 2.6 μm) by number, volume and surface area, respectively. However, influence of HT on GT and starch granule size distribution was relatively independent of their alteration in AC level for different rice genotypes. Therefore, HT-induced increase in the average diameter of starch granules and LSG percentage was strongly responsible for the higher starch gelatinization temperature and inferior cooked palatability of HT-ripening rice grains, which be not inherently associated with their varying AC level.

Effects of CO2 enrichment and spikelet removal on rice quality under open-air field conditions

The increase of atmospheric carbon dioxide (CO2) concentration adversely affect several quality traits of rice grains, but the biochemical mechanism remains unclear. The objectives of this study were to determine how changes in the source-sink relationship affected rice quality. Source-sink manipulation was achieved by free-air CO2 enrichment from tillering to maturity and partial removal of spikelet at anthesis using a japonica rice cultivar Wuyunjing 23. Enrichment with CO2 decreased the head rice percentage and protein concentration of milled rice, but increased the grain chalkiness. In contrast, spikelet removal resulted in a dramatic increase in the head rice percentage and protein concentration, and much less grain chalkiness. Neither CO2 enrichment nor spikelet removal affected the starch content, but the distribution of starch granule size showed distinct treatment effects. On average, spikelet removal decreased the percentage of starch granules of diameter >10 and 5–10 µm by 23.6 and 5.6%, respectively, and increased those with a diameter of 2–5 and <2 µm by 4.6 and 3.3%, respectively. In contrast, CO2 elevation showed an opposite response: increasing the proportion of large starch granules (>5 µm) and decreasing that of <5 µm. The starch pasting properties were affected by spikelet removal much more than by CO2 elevation. These results indicated that the protein concentration and starch granule size played a role in chalkiness formation under these experimental conditions.

Newly released oat varieties of himalayan region -Techno-functional, rheological, and nutraceutical properties of flour

Physico-chemical, functional, rheological and antioxidant properties of three varieties of oat flour (Sabzaar, SKO20, & SKO90) were investigated. Flour analysis revealed β-glucan, resistant starch, and total starch contents in an appreciable quantity. Scanning electron microscopy showed the presence of small and large starch granules, oval or irregular shape with varying dimensions, embedded in the network of proteins. Rheological analysis suggested that oat flour consisted of interchain aggregations and showed shear thinning behavior as revealed from Herschel-Bulkely model and frequency sweep. The phenolic content varied significantly within varieties and ranged from 752.27 to 795.37 μg GAE/g and 693.29 to 724.77 μg FAE/g. The total flavonoids content ranged from 201.58 to 244.92 μg rutin equivalent/g. Further antioxidant activity was evaluated by three complementary assays: DPPH radical scavenging activity, reducing power, and metal chelating activity.

Geometrical, functional, thermal, and structural properties of oat varieties from temperate region of India.

Geometrical, functional, thermal properties and FTIR analysis of three varieties of oat flour (Sabzaar, SKO20, & SKO90) were investigated. Sabzaar showed highest thickness, geometric mean diameter, arthimetic mean diameter, sphericity and grain volume. The density of oat grains varied from 0.393 to 0.37g/mL (bulk) and 1.2 to 1.8g/mL (true). WAC showed significant (P < 0.05) difference among the cultivars with Sabzaar flour showing the highest value (2.36g/g) and SKO20 (1.98g/g) the lowest. Peak viscosity of oat flours was in the range of 460.33-489.33cP. Flour samples showed the presence of small as well as large starch granules, oval or irregular shape with a smooth surface having some dents or fissures and some damaged starch and with varying dimensions. Average granule size of oat starch samples was within the range of 1.5-6.6μm in Sabzaar, 1.1-5.2μm in SKO20, and 1.7-6.8μm in SKO90. The gelatinization transition temperatures onset temperature (To), peak temperature (Tp), and conclusion temperature (Tc) varied significantly (p < 0.05) among three varieties.

Preparation and Characterization of Starch Particles for Use in Pickering Emulsions

Particle‐stabilized emulsions, called Pickering emulsions, can be produced by using starch particles. In this work we studied how the properties of the starch particles affect the droplet size and creaming of such emulsions. In the study, various sizes of starch particles were generated by two different methods and used to stabilize Pickering emulsions. Sedimentation according to Stokes’ law was used to separate small and large starch granules. Acid hydrolysis was another method used to obtain smaller particles. All samples were modified with octenyl succinic anhydride (OSA) to increase their hydrophobicity with a level of OSA substitution between 1.8 and 3.1%. The size of starch particles was the main factor influencing emulsion droplet sizes. Furthermore, the droplet size decreased as the starch concentration increased. Using small starch particles with sizes &lt;10 μm produced stable emulsions with smaller droplet size compared with larger sizes of starch particles, &gt;10 μm. When subjected to acid hydrolysis, smaller starch particles were generally obtained, which could subsequently create smaller emulsion droplets. The emulsion index increased for the acid‐hydrolyzed starch owing to the size reduction of starch particles. The shape of the starch seemed to have a minor impact on the droplet size and the creaming of Pickering emulsions.

Case Study: Commercialization of Sweet Sorghum Juice Clarification for Large-Scale Syrup Manufacture

The precipitation and burning of insoluble starch granules from sweet sorghum juice on heating coils prevented the large-scale manufacture of syrup at a new industrial plant in Missouri, USA. To remove insoluble starch granules, a series of small and large-scale experiments were conducted at the plant on raw juice extracted by roller milling from two commercial sweet sorghum cultivars Honey Drip and M81E. Both starch concentration and granule size contributed to processing problems. Leaving de-aerated raw juice in settling tanks before clarification settled out a considerable amount of small to medium sized starch granules, but did not remove enough starch. Hot clarification of juice performed better than cold clarification in removing starch and turbid particles. During the USDA hot clarification process (heat to 80 °C; lime to pH 6.5 with milk of lime [360 g/L]; 5 ppm polyanionic flocculant) in the plant, some starch was solubilized. Small to large size starch granules were removed in the clarification mud which improved as settling time progressed. At least 1 h of settling is recommended in the plant. Late in the processing season, scum formed on the surface of the juice that did not contain any starch granules, but did contain microscopic bubbles making the scum less dense than juice and unprecipitable. This highlights sweet sorghum quality differences across the processing season that still need to be addressed along with cultivar differences. Overall, the introduction of juice de-aeration, settling, and clarification steps enabled the large-scale manufacture of syrup and helped to mitigate quality and processing differences due to cultivar and environmental effects and thus assured continual supply to customers.

Structural and chemical analysis of native and malted barley kernels by polarized Raman spectroscopy (PRS)

In this work, barley kernel sections embedded in resin were mapped using polarized Raman spectroscopy (PRS) for evaluation of both chemical and structural changes in endosperm upon malting. A multivariate analysis that includes Band-Target Entropy Minimization (BTEM) was used to resolve the individual spectrum of components present on sections and to reconstruct images based on their relative signal. BTEM-resolved spectra matched with several individual model compound spectra that allowed the identification of protein, starch, non-starch carbohydrates, esterified ferulic acid and embedding media. Raman images also revealed chemical changes in the cell walls within starchy endosperm and inside cells due to enzymatic reactions in malting. The anisotropic response of the C–O–C Raman band associated with the orientation of ordered structures inside starch granules remains despite a notorious shape distortion of large starch granules.

Structural changes in plastids of developing Splachnumampullaceum sporophytes and relationship to odour production.

Many mosses of the family Splachnaceae are entomophilous and rely on flies for spore dispersal. Splachnum ampullaceum produces a yellow- or pink-coloured hypophysis that releases volatile compounds, attracting flies to the mature moss. The biosynthetic sources of the visual and aromatic cues within the hypophysis have not been identified, and may be either symbiotic cyanobacteria or chromoplasts that break down lipids into volatile compounds. Here, we used transmission electron microscopy and gas chromatography-mass spectrometry (GC-MS) to investigate the sources of these attractants, focusing on different tissues and stages of maturation. Microscopy revealed an abundance of plastids within the hypophysis, while no symbiotic bacteria were observed. During plant maturation, plastids differentiated from amyloplasts with large starch granules to photosynthetic chloroplasts and finally to chromoplasts with lipid accumulations. We used GC-MS to identify over 50 volatile organic compounds from mature sporophytes including short-chain oxygenated compounds, unsaturated irregular terpenoids, fatty acid-derived 6- and 8-carbon alcohols and ketones, and the aromatic compounds acetophenone and p-cresol. The hypophysis showed localised production of pungent volatiles, mainly short-chain fermentation compounds and p-cresol. Some of these volatiles have been shown to be produced from lipid oxidase degradation of linolenic acid within chromoplasts. However, other compounds (such as cyclohexanecarboxylic acid esters) may have a microbial origin. Further investigation is necessary to identify the origin of fly attractants in these mosses.

Expression of an amylosucrase gene in potato results in larger starch granules with novel properties.

Expression of amylosucrase in potato resulted in larger starch granules with rough surfaces and novel physico-chemical properties, including improved freeze-thaw stability, higher end viscosity, and better enzymatic digestibility. Starch is a very important carbohydrate in many food and non-food applications. In planta modification of starch by genetic engineering has significant economic and environmental benefits as it makes the chemical or physical post-harvest modification obsolete. An amylosucrase from Neisseria polysaccharea fused to a starch-binding domain (SBD) was introduced in two potato genetic backgrounds to synthesize starch granules with altered composition, and thereby to broaden starch applications. Expression of SBD-amylosucrase fusion protein in the amylose-containing potato resulted in starch granules with a rough surface, a twofold increase in median granule size, and altered physico-chemical properties including improved freeze-thaw stability, higher end viscosity, and better enzymatic digestibility. These effects are possibly a result of the physical interaction between amylosucrase and starch granules. The modified larger starches not only have great benefit to the potato starch industry by reducing losses during starch isolation, but also have an advantage in many food applications such as frozen food due to its extremely high freeze-thaw stability.

Effect of different mineral fertilization technologies on the size of starch granules in potato

The objective of the study was to assess the effect of soil fertilization with 280 and 420 kg NPK ha−1 as well as foliar application of the fertilizers Basfoliar 12-4-6, ADOB Mn and Solubor DF on quality parameters of potato which belonged to three classes of earliness: medium-early (cultivar Adam), medium-late (cv. Pasja Pomorska) and late one (cv. Ślęza). The scope of the research encompassed determinations of the content of starch and starch granulation, which were closely correlated with the potato cultivar and doses of mineral fertilizers applied to soil. An increase in the dose of the soil-applied fertilizer by 140 kg NPK ha−1, including 40 kg more of N ha−1, caused a decrease in the content of starch concurrently with a higher share of starch granules smaller than 20 µm in diameter. The analysed plant material contained mostly large starch granules of the diameter >40 µm. The foliar fertilizers did not have any significant effect on the examined parameters.

Effect of nitrogen fertilizer on distribution of starch granules in different regions of wheat endosperm

This study provided visual evidence of a nitrogen effect on starch granules (SGs) in wheat endosperm. Winter wheat (Titicum aestivum L.) cultivar Xumai 30 was cultured under no nitrogen (control) and 240kgha−1 of nitrogen applied at the booting stage. The number, morphology, and size of A- and B-type SGs in subaleurone of dorsal endosperm (SDE), center of dorsal endosperm (CDE), modified aleurone (MA), subaleurone of ventral endosperm (SVE), and center of ventral endosperm (CVE) were observed under light and electron microscopes. (1) The distribution of SGs in SDE was similar to that in SVE, the distributions of SGs in CDE and CVE were similar, but the distribution of SGs in MA was different from those in the other four endosperm regions. The number of SGs in the five endosperm regions was in the order SDE>CDE>SVE>CVE>MA. (2) Nitrogen increased the number of A- and B-type SGs in SDE and SVE. Nitrogen also increased the number of B-type SGs but decreased the number of A-type SGs in CDE and CVE. Nitrogen decreased the numbers of A-type and B-type SGs in MA. The results suggest that increased N fertilizer application mainly increased the numbers of small SGs and decreased the numbers of large SGs, but that the results varied in different regions of the wheat endosperm.

Effect of Shading During Grain Filling on the Physicochemical Properties of Fresh Waxy Maize

Grain physicochemical properties determine the table quality of fresh waxy maize. Two waxy maize varieties, Suyunuo 5 (shading tolerant) and FHN003 (shading sensitive), were used to estimate the effect of shading (plants received 30% less radiation than control) during grain filling (from 0 d to 23 d after pollination) on physicochemical properties of fresh waxy maize grain. Shading decreased the grain fresh weight of Suyunuo 5 and FHN003 by 8.4 and 19.1%, respectively. Shading increased the grain water content of FHN003, whereas that of Suyunuo 5 was not affected. In both varieties for shading treatment, soluble sugar, starch and protein contents were decreased, whereas zein content was increased. The changes in globulin, albumin and glutenin contents under shading were variety dependent. In both varieties, shading decreased λmax, iodine binding capacity and the percentage of large starch granules (diameter >17 μm) but increased crystallinity. The results of rapid visco analysis showed that the viscosity characteristics (except for pasting temperature) of both varieties were decreased by shading; however, FHN003 was more severely affected than Suyunuo 5. Under shading, ΔHret and %R were decreased in both varieties, whereas the changes in ΔHgel and transition temperatures were variety dependent. Hardness, cohesiveness and chewiness were decreased in both varieties. Significant differences in physicochemical characteristics were observed between the two varieties.

Physicochemical and functional characterization of yam starch for potential industrial applications

Yam is a significant and highly prized starchy crop in West and Central Africa, but largely underutilized industrially. Functional and physicochemical properties of starches extracted from forty‐three varieties of Dioscorea rotundata, Dioscorea alata, Dioscorea dumetorum, Dioscorea cayenensis, and Dioscorea bulbifera were investigated for their potential industrial utilization. Water binding, swelling, gelation capacity, granule size, amylose/amylopectin, pasting characteristics, paste clarity, and syneresis were determined. Results showed that starches from D. rotundata, D. alata, D. cayenensis, and D. bulbifera had large starch granules (25–50 µm) while D. dumetorum had small granules (7–12 µm). There was variability in the starch granule shapes, which were mostly oval, round, and triangular. The least gelation concentration of the starches was between 4 and 16%. Paste clarity of the starches decreased as storage days increased and all the starches exhibited high syneresis indicating tendencies to retrograde on low storage temperature. There were differences in the pasting characteristics of the yam starches with D. rotundata and D. bulbifera having high peak viscosities compared to others. These differences in functional and physico‐chemical properties of the yam starches are discussed as indicators of the various products for which they can be utilized in both food and non‐food applications.

Differences of Starch Granules in Grains from Different Spikelet Positions and Their Correlation with Grain Weight in Winter Wheat

The purpose of this study was to reveal the differences in development and size-distribution of starch granules in endosperm of wheat grains in different grain positions and spikelet positions. The endosperm cell size, and the number, volume and surface area distribution of starch granules in mature caryopsis, as well as the changes of starch granule number during endosperm development, were studied using wheat cultivar Jimai 20 grown in the field. The results showed that the development of starch granule was closely related with grain position and spikelet position. In the same spikelet position, starch grains formed 4–5 d earlier in superior grains (the first and the second grains) than in inferior grains (the third and the fourth grains).At the same grain position, starch granules developed first in the grains of the middle spikelets, and then in grains of upper and lower spikelets. The amount of starch granules was the highest in the middle spikelet grains all the time. The lower spikelet grains had the least starch granules at the beginning of grain filling, however, the number of starch granules increased gradually and surpassed that of the upper spikelet grains as caryopsis matured. Correlation coefficients between grain weight and starch granule amount became more significant with grain filling, which reached 0.88 ** (large starch granule) and 0.78 ** (small starch granule) at mature stage. Correlation coefficients between grain weight and large starch granule amount were higher than 0.96 ** , and had no difference among different spikelet positions. Correlation coefficients between grain weight and small starch granule amount were higher than 0.93 ** , and had a trend of upperlowermiddle in different spikelet positions. The trend of size distribution was BL-typeBS-typeA-type. There were more BS-type granules in superior grains than in inferior grains. The number of BS-type granules increased with the spikelet position rising, whereas the number of BL-type granules showed a reverse trend. The size distribution of starch granules had similar changes to volume and surface area. The formation and size distribution of starch granules were affectedsignificantly by grain position and spikelet position, and inferior grains had the potential of increasing grain weight through increasing the quantity of starch granules.

Effect of hydrothermal treatment on physicochemical and digestibility properties of oat starch

The oat grain is often subjected to different hydrothermal treatments to inactivate hydrolytic enzymes that can have undesirable effects on the end-product quality. Hydrothermal treatments may affect the functional properties of oat starch. The objective of this work was to evaluate the effect of eight different hydrothermal treatments on the physicochemical and digestibility properties of oat starch. Hydrothermal treatments were selected based on heat treatment applications in oat industry and listed as HT-1) Ethanol boil HT-2) Ethanol boil and toasted HT-3) Steamed at 106°C HT-4) Steamed at 106°C and toasted HT-5) Covered autoclaved at 120°C HT-6) Uncovered autoclaved at 120°C HT-7) Covered autoclaved at 130°C and HT-8) Uncovered autoclaved at 130°C. The morphology of the oat starch was altered as a result of various heat treatments. HT-5 and HT-7 treatments had more large starch granules than the other samples, however the apparent molecular weight of the starch from these samples was unaffected by the treatment. HT-6 and HT-8 resulted in the most significant changes to the gelatinization properties of the oat starch. HT-6 oat sample had significantly (P<0.05) lower paste viscosity than starches from the oat samples with other treatments. The in vitro starch digestibility increased significantly (P<0.05) for the HT-6 and HT-8 oat samples. This study demonstrated that thermal treatments can cause reorganization of the amylose and amylopectin chains that can result in changes in their physicochemical and digestibility properties.

Leaf anatomy, ultrastructure and plasticity of Coffea arabica L. in response to light and nitrogen availability

Phenotypic plasticity in response to environmental variation occurs at all organizational levels and across temporal scales within plants. However, the magnitude and functional significance of this plasticity is little explored in perennial species. We examined the influence of different light regimes and nitrogen (N) availability on the morphological and physiological plasticity of coffee seedlings (Coffea arabica L.). Potted plants were grown under 100% and 50% of full sunlight and were fertilized with Hoagland’s solutions containing 0, 16 or 23mM N. Most leaf traits responded to light with a classic 100% vs. 50% dichotomy [e.g., compared with those grown under 100% of full sunlight, 50% leaves had a thinner palisade mesophyll and a lower leaf mass per area (LMA) for improved light capture]. The outer periclinal cell walls in both epidermises exhibited thick epicuticular wax and three distinct layers. Chloroplasts of the mesophyll cells were densely occupied by thylakoids and starch grains. These characteristics were observed most clearly in plants supplemented by nitrogen or in those grown in shade conditions. Large starch granules were observed, but no membrane injuries were observed in either treatment. The plasticity index was high for the physiological traits that are associated with photoprotection and the maintenance of a positive carbon balance under 50% of full sunlight but was low for most morpho-anatomical features.

Discovery, characterization, and structural analyses of glucan phosphatases from plants to humans

We initially demonstrated that the human phosphatase laforin and plant phosphatase Starch EXcess4 (SEX4) are glucan phosphatases. Mutations in the gene encoding laforin cause glycogen to become hyperphosphorylated, resulting in starch‐like glucans called Lafora bodies (LBs) and the fatal neurodegenerative disorder Lafora's disease. Plant starch contains covalently bound phosphate at the C6‐ and C3‐position of glucosyl residues. Reversible phosphorylation of starch outer glucans renders these glucans accessible to hydrolyzing enzymes. In the absence of starch phosphorylation or dephosphorylation, plants accumulate excessively large starch granules that they are unable to breakdown. SEX4 activity is a necessary step in the starch degradation cycle of glucan phosphorylation, hydrolysis, and dephosphorylation. We utilized X‐ray crystallography to determine the structure of SEX4 and this structure assisted in the identification of Like Sex Four2 (LSF2). Unlike SEX4, LSF2 lacks a carbohydrate‐binding module yet LSF2 binds starch. We found that SEX4 releases phosphate from the C3‐ and C6‐position, but prefers C6. Alternatively, LSF2 hydrolyzes phosphate from the C3‐position and plants lacking LSF2 have elevated C3‐bound phosphate. Lastly, we determined the crystal structure of LSF2 and utilize site‐directed mutagenesis with in vitro assays to define the structural elements of glucan phosphatases.

Effect of Temperature during Grain Filling Stage on Endosperm Structure and Apperance Quality of Aromatic Rice

Based on the experiment of two inbred aromatic rice varieties and one hybrid aromatic rice line treated under four different temperatures( daymean temperature 21°C, 23°C, 26°C and 30°C respectively) during grain filling stage in phytotrons, the shape and arrangement of endosperm starch granules in rice grain transection were observed by scanning electron microscope and the related characteristics of rice grain qualities of chalky percent and chalkiness were analyzed at the same time. The results showed that under the lower temperature( daymean temperature21°C and 23°C), many large compound starch granules with clear angulars packed together regularly without significant natural gaps bewteen starch granules in the tansectional endosperm. However, with the increase of temperature, starch granules in the transectional endosperm were changed from regularly shaped and closely and orderly arranged to various shaped and chaoticly arranged with obvious natural gaps between starch granules, which was closely consistent with the poorer appearance quality under the higher temperature, which indicated that the endosperm structure is closely related with appearance quality of aromatic rice.