Amylose-rich Starch Research Articles

Characterization of starches isolated from Mexican pulse crops: Structural, physicochemical, and rheological properties

This work aimed to characterize and compare the physicochemical properties of four pulse starches: bean, chickpea, lentil, and pea. Chemical proximate analysis, elemental composition, morphological grain characterization, crystalline structure, thermal analysis, FTIR analysis, and pasting properties were conducted. The proximate analysis shows that these starches have low fat, mineral, and protein content but high amylose values ranging from 29 to 36 % determined by colorimetry. Despite the high amylose content, the starches did not exhibit the typical behavior of an amylose-rich starch, with high peak viscosity and low breakdown and setback. It was found that this behavior was likely due to the large granule size of the ellipsoidal, spherical, and kidney-shaped granules and the high content of some minerals such as Na, Mg, K, Fe, Mn, P, and Si. The study also found that all pulse starches simultaneously contain monoclinic and hexagonal crystals, making them C-type starches. The findings were verified through the Rietveld analyses of X-ray diffraction patterns and differential scanning calorimetry, in which bimodal endothermic peaks evidenced both types of crystals being gelatinized.

Extraction and characterization of polysaccharides from tamarind seeds, rice mill residue, okra waste and sugarcane bagasse for its Bio-thermoplastic properties

The aim of the present study is to extract potential thermoplastic polysaccharides from agricultural industrial wastes. Polysaccharides were extracted from renewable agro industrial wastes such as tamarind seeds [rich in starch (TSS)], okra head waste [rich in mucilage polysaccharide (OMP)], sugarcane bagasse [rich in cellulose (SBC)] and residual rice mill wastes [rich in starch and fiber (RS)]. Urigam variety of tamarind seed starch found to be an amylose rich starch. Different polysaccharides extracted from agro wastes were found to be having high thermal stability, except okra polysaccharide (comparatively low). X-ray diffraction pattern of tamarind seed starch proved its high crystallinity index. Crystallinity index of investigated polysaccharides were found to be in the order of SBC > TSS > RS > OMP. Chemical nature of extracted polysaccharides was confirmed by Fourier transform infrared spectroscopic analysis. Residual rice bran starch granules and tamarind seed starch globules were found to be having comparatively reduced particle size than sugarcane bagasse cellulose and okra mucilage. Scanning electron microscopic analysis revealed the cluster formations of RS granules and TSS globules. Residual rice bran starch found to be associated with other fibers (present in outer coat of rice). Okra mucilage and SBC were examined to be having linear sheets and linear bundles structures, respectively.

Thermal and Mechanical Properties of Natural Rubber and Starch Nanobiocomposites

Large-scale starch nanoparticles of about 10–50 nm were obtained by acidic hydrolysis of amylopectin-rich cornstarch (waxy starch). They were used to prepare nanobiocomposites with natural rubber by mastication technique. Up to 30 phr (parts per hundred of rubber) of the filler was successfully incorporated leading, to an enhancement in thermo-mechanical properties. Tensile and elongation were even higher than those of conventional composites of untreated waxy starch and amylose-rich starch as well as carbon black at all loadings. SEM revealed single-phase morphology of nanocomposites, indicating extremely uniform mixing. It was observed that starch could be a potential substitute for carbon black as filler.

Amylolysis of wheat starches. II. Degradation patterns of native starch granules with varying functional properties

Scanning electron microscopy (SEM) and X-ray diffraction (XRD) were employed to investigate degradation patterns of native starch granules from wheat ( Triticum aestivum L.) by different starch-degrading enzymes. The starches examined were from a waxy wheat and four varieties with slightly elevated amylose content, but with different functional properties. Differences in the digestion patterns after partial α-amylolysis of starch granules were noted between the starches. The waxy starch seemed to be degraded by endocorrosion, whereas the amylose-rich starches followed a slower mode of hydrolysis starting from the granular surface. X-ray diffractograms of the amylose-rich starches were not significantly altered by 2 h of α-amylolysis, whereas partial hydrolysis of the waxy starch decreased scattering intensity at higher 2 θ angles, consistent with a different mode of attack by α-amylase in the initial digestion stages of granules of waxy and amylose-rich starches. We propose these differences are due to the combined effects of the change in packing density and partial preference for hydrolysis of amorphous material. The native starch granules were also attacked by beta-amylase, isoamylase and amyloglucosidase, which indicates that α-amylase is not the only starch-degrading enzyme that is able to initiate starch hydrolysis of native granules.

Modified Polysaccharides as New Commodity Materials and for Light-Converting Systems: Syntheses, Characterization and Processing

Potato starch (PS), also one amylose-rich starch (high amylose maize starch, HAMS) and one amlyopectin-rich starch (waxymaize starch, WMS) were used for the syntheses as raw materials. Starch acetates were synthesized by reaction with acetic acid anhydride and potassium carbonate as activator. Tests of thermoplastic processability of the starch acetates were performed by extrusion followed by injection molding to specimens. Glycerine triacetate (triacetin, TAc) was attached as plasticizer to starch acetate. For this system a processing procedure was acquired under variation of different parameters. Starch- and cellulose-based films containing inorganic luminescent quantum dots, namely europium doped yttrium vanadate (YVO4:Eu) and cerium and terbium doped lanthanum phosphate (LaPO4:Ce,Tb) as well as an organic laser dye (naphthaldiimide, LV 570) were prepared by tape casting and air brush technique. Under UV-light exposure, they show a bright fluorescence radiation depending on the incorporate dye or quantum dot.

Resistant Starches (RS2 and RS3) have Variable Effects on Bone Mineral Status in Rats

Nondigestible oligosaccharides may increase mineral absorption by changing the intestinal environment. The effect of feeding a diet containing 5% resistant starch, RS2 (uncooked native) or RS3, (cooked and retrograded) on cal- cium absorption and bone mineral status was studied in growing male rats for 4 weeks. Almost 100g more feed was con- sumed with resistant starch compared to control in four weeks. Mineral status improved as determined by femur concen- tration, but not through absorption. Mineral content of femurs increased 12, 10 and 9% for Ca, Mg and Zn respectively, while Fe decreased 23% after feeding RS3, but not RS2, compared with the control group. There was no increase in the percent retention for any of the tested minerals. 45 Ca absorption capacity was not affected by either resistant starch. We conclude that resistant starches improve mineral status possibly through increased food consumption, but not through in- creased absorption efficiency. potato and high amylose starch, were compared at the same level and fed to rats for 7 days (12), no differences were found in calcium and magnesium absorption. Cecal concen- trations of calcium, potassium, and phosphate, but not of magnesium, were significantly increased in rats fed either 25% or 50% amylose-rich starch, 10% lactulose or 10% pec- tin compared to the control (13). The cecal pool of all these minerals was increased in a dose-dependent manner with the 25% and 50% amylose. All of the studies cited above used high levels of resistant starch (15 to 50%) and some (9,10) used higher levels of dietary calcium (up to 0.75%). The calcium requirement for rats is 0.5%. It is likely that any effect of calcium-absorption enhancers would be dampened above this level. The present study was designed to investigate the effect of two resistant starches, high amylose resistant cornstarch containing 60% resistant starch (RS2) and a high amylomaize retrograded resistant cornstarch containing 55% resistant starch (RS3), at 5% by weight on calcium absorption, mineral balance and bone mineral concentration in rats fed a 0.5% calcium diet.

B→A Allomorphic Transition in Native Starch and Amylose Spherocrystals Monitored by In Situ Synchrotron X-ray Diffraction

The B-->A phase transition in native starch granules and spherocrystals prepared from DP 20-40 synthetic amylose chains was investigated in situ at intermediate moisture content (20-30%) by wide-angle synchrotron X-ray scattering, using a temperature-controlled pressure cell. The transition in native starch was monitored at hydrostatic pressures of 1.6-11.0 MPa and occurred in a temperature range of 90-110 degrees C. The transition temperature increased with increasing amylose content and the transition was incomplete in amylose-rich starch. The B-->A transition in highly crystalline amylose spherocrystals was monitored at pressures between 2.0 and 28.5 MPa. The transition temperature was higher than in native starch, ranging from 125 to 135 degrees C. At 2.0 MPa, after conversion, the hydrated spherocrystals melted at 185 degrees C. Surprisingly, at the same pressure, in excess water, the spherocrystals did not solubilize but converted to allomorph A at 100 degrees C and melted at 160 degrees C. For all samples, the transition occurred in a matter of minutes and a higher pressure decreased the transition temperature. For the first time, thermal expansion coefficients were estimated for A- and B-amylose at intermediate moisture. A strong thermal anisotropy was observed for A-amylose, the expansion being higher along the b-axis than along the a-axis of the monoclinic unit cell. This anisotropy was attributed to the fact that, in the b-direction, amylose double helices lie at the same height along the chain axis while, in the a-direction, they are more closely packed in a zigzag fashion.

Effects of annealing on gelatinization and microstructures of corn starches with different amylose/amylopectin ratios

Corn starches with different amylose/amylopectin ratios (waxy 0/100, normal corn 23/77, Gelose 50 50/50, Gelose 80 80/20) were annealed at below their gelatinization temperatures in excess water. The effects of annealing on the gelatinization and microstructures of the starches were studied using DSC, XRD and a microscope equipped with both normal and polarized light. In addition, a high-pressure DSC pan was used to study the effects of high-temperature annealing on the multiphase transitions of starches with different water contents. The granular size of the starches increased after the annealing process, but the size variation rates were different, with higher amylopectin contents resulting in a higher diameter growth rates and final accretion ratios. DSC results showed that annealing increased the gelatinization enthalpy of the amylose-rich starches. The increased enthalpy was mainly attributed to endotherm G – there were no significant changes to endotherms M1, M2 or Z – indicating that annealing mainly affected the helical length of shorter or sub-optional amylopectins, in particular the amylopectin in amylose-rich starches. The XRD traces of all starches after annealing remained unchanged.

Rheological properties of starches with different amylose/amylopectin ratios

The rheological properties of corn starches with different amylose/amylopectin ratios (80/20, 50/50, 23/77, and 0/100) were systematically studied by Haake rheometry. The starches were initially pre-compounded with water to designated moisture content levels using a twin-screw extruder. A single-screw extruder with a slit capillary die was then used to characterize the shear stress and melt viscosity characteristics of sample pellets, as a function of both moisture content (19–27%) and extrusion temperature (110–140 °C). The melts exhibited shear thinning behavior under all conditions, with the power law index (0 < n < 1) increasing with increasing temperature and moisture content in the majority of cases. The higher the amylose content, the higher is the viscosity (for example, η increases from 277 Pa s to 1254 Pa s when amylose content increases from 0% to 80% under a certain condition), which is opposite to the sequence of molecular weight; amylopectin-rich starches exhibited increased Newtonian behavior. These rheological behaviors are attributed to the higher gelatinization temperature of amylose-rich starches, and in particular the multiphase transitions that occur in these starches at higher temperatures, and the gel-ball structure of gelatinized amylopectin.

Effect of annealing and pressure on microstructure of cornstarches with different amylose/amylopectin ratios

This work focuses on the effect of annealing and pressure on microstructures of starch, in particular the crystal structure and crystallinity to further explore the mechanisms of annealing and pressure treatment. Cornstarches with different amylose/amylopectin ratios were used as model materials. Since the samples covered both A-type (high amylopectin starch: waxy and maize) and B-type (high amylose starch: G50 and G80) crystals, the results can be used to clarify some previous confusion. The effect of annealing and pressure on the crystallinity and double helices were investigated by X-ray diffraction (XRD) and 13C CP/MAS NMR spectroscopy. The crystal form of various starches remained unchanged after annealing and pressure treatment. XRD detection showed that the relative crystallinity (RC) of high amylopectin starches was increased slightly after annealing, while the RC of high amylose-rich starches remained unchanged. NMR measurement supported the XRD results. The increase can be explained by the chain relaxation. XRD results also indicated that some of the fixed region in crystallinity was susceptible to outside forces. The effect of annealing and pressure on starch gelatinization temperature and enthalpy are used to explore the mechanisms.

Comparison of conventional and ultrasound-assisted extraction of phenolics-rich heteroxylans from wheat bran

Various two-step extraction procedures with and without a short application of ultrasound in the first step at various reaction conditions (extracting agent, temperature and time), and constant conditions in the second step (5% NaOH, room temperature, 60 min) were used to isolate the hemicellulose component of industrial wheat bran. The polysaccharides recovered from the extracts were characterised by yield, chemical composition and radical scavenging activity. Similar total yields of polysaccharides were achieved by a short ultrasound-assisted extraction (up to 10 min) in the first step using 0.5% or 2% NaOH, when compared to the classical extraction lasting 60 min, what represents a shortening of the process by about 60% and lower consumption of the NaOH. The extracted polysaccharides comprised a complex of phenolics-rich heteroxylans contaminated to various extents with co-extracted amylose-rich starch as well as protein, which can be in part governed by the extraction conditions. The water-soluble fractions from both the classical and ultrasonics experiments were shown to exhibit significant radical scavenging activity in vitro, indicating their potential application as polysaccharide-based antioxidants.

Studies of the retrogradation process for various starch gels using Raman spectroscopy

The retrogradation of untreated wild-type starches (potato, maize, and wheat), waxy maize starches, and one pregelatinized, modified amylose-rich starch was investigated continuously using Raman spectroscopy. The method detects conformational changes due to the multi-stage retrogradation, the rate of which differs between the starches. The pregelatinized, modified amylose-rich starch shows all stages of retrogradation in the course of its Raman spectra. In comparison to amylose, the retrogradation of amylopectin is faster at the beginning of the measurements and slower in the later stages. The untreated starches can be ranked in the order of their rate of retrogradation as follows: potato > maize > wheat.

Development and characterization of aqueous amylose-rich maize starch dispersion for film formation

Development and characterization of amylose-rich starch dispersion for film forming was performed. The influence of dispersion preparation temperature on amylose-rich maize starch (Hylon VII) film formation, and the physical properties of the films were investigated. The film-forming ability of the dispersions was evaluated with free films plasticized with glycerol and sorbitol, and the films were prepared at an elevated temperature (70°C) by a casting technique. The solid-state and particle properties of dispersions were investigated by means of X-ray diffraction (XRD), Fourier transform near infrared (FT-NIR) spectroscopy and laser diffraction particle size analysis. Free films were characterized with respect to their appearance, by FT-NIR spectroscopy, and by XRD. Mechanical stress–strain properties were also studied. Increasing the temperature of dispersion preparation results in higher crystallinity, thus affecting the film forming ability. Mechanically strong and elastic films can be formed from amylose-rich starch dispersion formed at 40°C. The more crystalline precipitate complex (obtained at 80°C) and the entirely amorphous gel (obtained at 10°C) formed non-continuous and cloudy films. The better film-forming properties of the dispersion formed at 40°C are probably due to the highly amorphous structure and smaller particle size. The study shows the possibility of using ambient tempered amylose–starch dispersion for film forming.

Ultrasonic extraction of plant materials––investigation of hemicellulose release from buckwheat hulls

Various one- and two-step extraction procedures with and without a short application of ultrasound at the beginning of the extraction were used to examine the effect of sonication on the extractibility of the hemicellulose components of buckwheat hulls. The polysaccharides recovered from the extracts were characterised by yield as well as composition determined by chemical methods and spectroscopic techniques. They comprised a complex of glucuronoxylan and co-extracted amylose-rich starch in various proportions contaminated with other cell wall components (protein, pectic polysaccharides). The hemicellulose fractions obtained by classical and ultrasound-assisted extraction exhibited significant immunomodulatory activities. The increased yield of ultrasonically extracted hemicelluloses, which have preserved their structural and molecular properties as well as immunological activity, confirmed the importance and great potential of ultrasound-assisted extraction of industrially important polysaccharides from different tissues of plant materials.

A Novel Amylose Corn-Starch Dispersion as an Aqueous Film Coating for Tablets

A novel aqueous coating dispersion of amylose-rich corn starch (Hylon VII) was evaluated in an aqueous film-coating process of tablets using an instrumented laboratory-scale pan-coating apparatus. The influence of two independent process variables, the coating temperature and the atomizing air pressure, on the properties of the coated tablets were investigated. The pre-use stability of aqueous coating dispersion (i.e., amylose corn-starch precipitate) was studied using a powder X-ray diffraction (XRD) technique. The crystallinity of amylose starch in the coating dispersion was found to increase slightly during 9 months of storage (in a refrigerator 6±2°C). The film coatings of an aqueous amylose-rich starch dispersion were successfully applied onto tablets without any significant drawbacks, such as nozzle blockage or related problems. It was found that the temperature in the coating pan had a significant influence on the film surface roughness, mechanical strength, and drug release in vitro. When the lowest coating temperature (30°C) was used, rougher film coatings were obtained due to overwetting. At higher temperatures (up to 50–60°C), lower surface roughness and higher mechanical strength values for the coated tablets were obtained. With the present amylose starch dispersion, the atomizing air pressure had a minor influence on the quality of the coating. Under appropriate coating conditions, a smooth tablet film coating was produced with this new, natural, and inexpensive amylose starch dispersion.

Physical properties of acetylated starch-based materials: Relation with their molecular characteristics

Abstract In order to obtain thermoplastic starch-based materials with a reinforced hydrophobicity, amylose and amylopectin were acetylated following the pyridine-acetic anhydride procedure. An amylose-rich starch triacetate was saponified under controlled conditions to obtain products with different acetyl contents. The adsorption of water by these polymers equilibrated in a 98% r.h. atmosphere was studied using thermogravimetric analysis and differential scanning calorimetry. A slight increase of non-freezing water content is observed when the acetyl content increases up to DS ≈ 1.3–1.4. For higher acetyl contents, the hydrophobicity of the material is efficiently enhanced and no more freezing water is adsorbed. Tensile strength measurements were performed on films with different amylose acetate-amylopectin acetate ratios: no variation of the tensile modulus (2.5 ± 0.5 GPa) was observed when composition changed, but the elongation at break was strongly decreased when the amylopectin acetate content increased. The influence of acetyl content on thermal properties was also studied. The position of glass transition (∼150°C in the dried state) was unchanged when DS ranged from 1.7 to 3, and moved towards higher temperatures when the acetyl content decreased. This thermal characteristic when DS > 1.7 will allow easy processing of these materials.

The Cell Wall Material of the Wood Parasite Cistanche deserticola Y. C. Ma.

The polymeric components of the cell wall material (AIR) of the holoparasite Cistanche deserticola Y.C.Ma., known as a tonic in traditional oriental medicine. were characterised by chemical and spectroscopic methods. The parasite grows on the roots of Haloxylon ammodendron, a dicotyledonous plant used in reforestation of deserts and steppes. AIR accounting for 16.1% of the original dry drug mass represents a complex of protein, lignin and polysaccharides. In contrast to woody tissues, an amylose-rich starch as well as pectic-like polysaccharides were the major polysaccharide components of AIR. Xylan represents the main hemicellulosic component and resembles in primary structure the 4-O-methyl-D-glucurono-D-xylan type present in angiosperms, to whom the host plant belongs.

Effect of Amylomaize Starch on Plasma Lipoproteins of Lean and Obese Zucker Rats.

Male Zucker rats either genetically obese (fa/fa) or lean (Fa/-) were fed a semi-purified diet containing either cornstarch or amylomaize starch (Eurylon 7R) rich in amylose (70%). Obese rats were hyperlipidemic (cholesterol, 3.27±0.18; triglycerides, 2.11±0.12g/liter), when compared with lean rats (cholesterol, 1.13±0.03; triglycerides, 0.75±0.05g/liter). The amylomaize diet did not reduce the body weight of the Zucker rats. However, it decreased weight, esterified cholesterol, and triglyceride content of the liver in both lean and obese rats. The amylomaize diet decreased plasma cholesterol levels of obese rats (-42%) and lean rats (-30%), while plasma triglyceride levels were significantly decreased only in the lean rats (-43%). The cholesterol content of chylomicrons, VLDL, LDL1 (1.006-1.040), and LDL2 (1.040-1.063, which contains apo E-rich HDL) was reduced by 40 to 50%, while that of HDL was reduced by only 20% (lean) or 23% (obese). Diet containing amylose-rich starch therefore constitutes a promising new way of nutritional control of hyperlipidemias.

Effects of Feeding Fermentable Carbohydrates on the Cecal Concentrations of Minerals and Their Fluxes between the Cecum and Blood Plasma in the Rat

This study was conducted to determine in rats to what extent fermentable carbohydrates alter the mineral composition of cecal contents and the absorption of the major cations. The carbohydrates studied were as follows: an oligosaccharide (lactulose, 10%); a soluble fiber (pectin, 10%); and an amylose-rich starch, incompletely broken down in the small intestine (amylomaize starch, 25 or 50%). All of these carbohydrates elicited a marked enlargement of the cecum, a drop of cecal pH and an increase in the volatile fatty acids (VFA) pool. With the lactulose diet, the VFA concentration was the lowest, whereas VFA absorption was similar to that observed with the 10% pectin or 25% amylomaize diets. From comparisons between germfree and conventional rats adapted to a fiber-free diet, it appears that VFA are required as counter anions to maintain high concentrations of cations, especially sodium. In conventional rats fed fermentable carbohydrates, sodium concentration in the cecal fluid was approximately 80 mM, except with the lactulose diet (49.5 mM), due to osmotic effects of lactulose. There was, compared to the fiber-free diet, an increase in the cecal concentrations of potassium, calcium and phosphate, but not of magnesium; nevertheless, the cecal pool of all of these minerals was considerably increased. Potassium absorption was increased by fermentable carbohydrates in the cecum, which also appears to be a major site of magnesium and calcium absorption. Thus, fermentable carbohydrates shift aborally the absorption of the major cations, and this point is especially interesting in regard to calcium, since an enhanced supply of calcium in the large bowel has been invoked for fiber effects on colonic carcinogenesis.

The development of specific sieve-element plastids in wound phloem ofColeus blumei (S-type) andPisum sativum (P-type), regenerated from amyloplast-containing parenchyma cells

In experimentally-induced wound phloem, sieve-element plastids express their genetically determined type in depositing amylopectinrich sieve-tube starch (Coleus, S-type) and polygonal protein crystals (Pisum, P-type). Sieve-element plastids budd off from preexisting amyloplasts, pass through a short amoeboid state and develop into spherical plastids with translucent matrix. During early phases of differentiation wound sieve-elements contain two populations of plastids: typical sieve-element plastids and residual parenchyma plastids with large amylose-rich starch grains. The retardation in the break down of the latter is discussed. Sieve-tube and amyloplast starches are likewise digested by α-1,4- and α-1,6-bond cleaving glucosidases.