Percentage Of Amylose Research Articles

A novel triple‐wavelength colorimetric method for measuring amylose and amylopectin contents

AbstractA novel triple‐wavelength colorimetry based on the principle of iodine binding was developed to determine amylose and amylopectin contents. Detection wavelengths of different starch material were different for each method. Comparative trials were carried out by both single‐ and dual‐wavelength colorimetry. We found that single‐wavelength colorimetry could only be used to evaluate amylose content. Correlation coefficient of standard curves for amylopectin content determination was improved by increase of detection wavelength numbers. The precision and recovery coefficient was also improved by triple‐wavelength colorimetry compared to single‐ and dual‐wavelength colorimetry. Percent amylose of cassava, potato, and high‐amylose maize determined by triple‐wavelength were 19.3, 21.8, and 42.3%, respectively, and percent amylopectin were 78.9, 76.9, and 54.5%, respectively. This developed triple‐wavelength colorimetry could provide accurate data for evaluating amylose content and have potential for amylopectin content detection.

Macromolecular Changes in Extruded Starch‐Films Plasticized with Glycerol, Water and Stearic Acid

AbstractNative corn starch, plasticized with water, glycerol and stearic acid, was extruded in a conical twin‐screw extruder and sheeted into 0.4–0.6 mm thick films. The effects of extrusion and plasticizers on gelatinization, as well as the molecular and structural changes, in thermoplastic starch were analyzed. The onset and peak gelatinization temperatures of extruded starch varied from 42–46°C and 52.9–56.9°C, respectively, depending on the glycerol content. The enthalpy of gelatinization of extruded thermoplastic starch in excess water varied from 3.6–7.6 J/g, which also increased with plasticizer content. Amylose‐lipid complexes were formed during extrusion, and their enthalpies depended on the initial stearic acid and moisture contents. High‐performance size‐exclusion chromatography (HPSEC) data revealed that the starch underwent fragmentation during extrusion even under highly plasticized conditions, but the degradation was not severe as compared to previous findings. The relative percentages of amylopectin and amylose in native starch were 76.9 and 23.1%, respectively, which were changed to 71.3–76.6% and 23.4–28.7% in the extrudates. The average molecular weights of amylopectin and amylose in the extrudates ranged from 1.55×107–2.07×107 and 4.35×105–7.39×105, respectively. On the other hand, the molecular weights of amylopectin and amylose in native corn starch were observed as 2.27×107 and 4.68×105, respectively. Cross‐polarization magical angle spinning (CP/MAS) and high‐power decoupling (HP‐DEC) nuclear magnetic resonance (NMR) spectra of thermoplastic starch revealed the characteristics of amylomaize starch, confirming HPSEC results that the amylopectin macromolecules underwent fragmentation into amylose‐like fractions. In the extrudates, glycerol was found to be less mobile and entrained within the starch network.

Structure and Function of Starch and Resistant Starch from Corn with Different Doses of Mutant Amylose-Extender and Floury-1 Alleles

Four corn types with different doses of mutant amylose-extender (ae) and floury-1 (fl1) alleles, in the endosperm, including no. 1, aeaeae; no. 2, fl1fl1fl1; no. 3, aeaefl1; and no. 4, fl1fl1ae, were developed for use in making Hispanic food products with high resistant starch (RS) content. The RS percentages in the native starch (NS) of 1-4 were 55.2, 1.1, 5.7, and 1.1%, respectively. All NS were evaluated for pasting properties with a rapid viscoanalyzer (RVA) and for thermal properties with a differential scanning calorimeter (DSC). NS 1 had a low peak viscosity (PV) caused by incomplete gelatinization, whereas NS 3 had the greatest PV and breakdown of all four starch types. On the DSC, NS 2 had the lowest onset temperature and greatest enthalpy. NS 1 and 3 had similar onset and peak temperatures, both higher than those of NS 2 and 4. The gel strength of NS heated with a RVA was evaluated by using a texture analyzer immediately after RVA heating (fresh, RVA-F) and after the gel had been stored at 4 degrees C for 10 days (retrograded, RVA-R). NS 1 gel was watery and had the lowest strength (30 g) among starch gel types. NS 3 gel, although exhibiting syneresis, had greater gel strength than NS 2 and 4. The structures of the NS, the RS isolated from the NS (RS-NS), the RS isolated from RVA-F (RS-RVA-F), and the RS isolated from RVA-R (RS-RVA-R) were evaluated by using size exclusion chromatography. NS 1 had a greater percentage of amylose (AM) (58.3%) than the other NS (20.4-26.8%). The RS from all NS types (RS-NS) had a lower percentage of amylopectin (AP) and a greater percentage of low molecular weight (MW) AM than was present in the original NS materials. The RS-RVA-R from all starches had no AP or high MW AM. The percentages of longer chain lengths (DP 35-60) of NS were greater in 1 and 3 than in 2 and 4, and the percentages of smaller chain lengths (DP 10-20) were greater in 2 and 4 than in 1 and 3. In general, NS 3 seemed to have inherited some pasting, thermal, and structural characteristics from both NS 1 and 2, but was distinctly different from 4.

Genetic analysis of high amylose content in maize (Zea mays L.) using a triploid endosperm model

Traditionally, high amylose starch (HAS) from maize (Zeamays L.) has been mainly used as an ingredient in gum candies and as an adhesive for corrugated cardboard. Two recent advances have increased interest in the use of HAS. The first one has been the development of starch-based biodegradable thermo plastics. Second, high amylose maize is a source of resistant starch (RS), a type of starch that resists digestion. As a food additive, consumers can benefit from added RS since it will lower the glycemic index and the risk of colon cancer in accordance with recent research in food science. Normal maize has about 25% amylose starch. A maize inbred line, GEMS-0067 (Reg. no GP-550, PI 643420) possesses high amylose modifier gene(s) that, together with the recessive amylose extender (ae) gene, raises the starch amylose percentage to at least 70%. The objective of this study was to determine the gene effects, non-allelic interactions and heritability of high amylose content in maize using Bogyo’s triploid model. Nine populations were derived from a cross between H99ae, a maize inbred line with 55% amylose starch, and GEMS-0067. Data were collected from two locations in Missouri (MO) and South Dakota (SD) over 2 years (2005 and 2006). Incomplete dominance explained some of the inheritance of HAS. Maternal effects were also detected. The triploid models for MO and SD were separately established based on the corresponding data in 2005 and 2006. The additive and type 1 dominance effects in MO, and the additive, type 1 dominance, type 2 dominance, and additive × additive in SD were significantly different from zero meaning that those effects played an important role in amylose synthesis. Both broad-sense and narrow-sense heritabilities were high indicating that high amylose content could be effectively selected for in a segregating population.

The effect of drying temperatures on morphological and chemical properties of dried chestnuts flours

The effect of drying conditions on morphological and chemical properties of two Portuguese Castanea sativa varieties (Longal and Martainha) was evaluated. All chestnut drying curves were found to be different according to drying temperatures (40 °C, 50 °C, 60 °C and 70 °C). Those conditions also affected both chemical composition of flours and morphological properties of starch. Colour parameters of the flours ( L∗ c∗ h°) generally decreased with increasing drying temperature, total colour difference (TCD∗) also significantly changed for samples dried at different tested conditions. The drying temperature seems to affect starch morphology, with Longal starch granules always somewhat smaller. The results showed that the higher the drying temperature, the higher the reducing sugars content and the lower the starch content. In what concerns differences among the studied varieties, it can be stated that Longal presents whiter flours, higher reducing sugars content, lower starch and sucrose contents. In opposition, Martainha flours presented lower percentage of amylose and damaged starch. From the results it can be concluded that the marked effects that drying temperature exerted on the characteristics and properties of chestnut flours are different in both varieties studied.

Effect of Variation in Amylose Content and Puroindoline Composition on Bread Quality in a Hard Spring Wheat Population

ABSTRACTMilling and breadbaking quality of hard‐textured wheat may be influenced by alternative alleles at the Wx loci controlling percent amylose in the endosperm, and the puroindoline (pin) loci controlling grain hardness. For this experiment, we developed recombinant inbred lines (RIL) from a cross between Choteau spring wheat cultivar and experimental line MTHW9904. Choteau has the PinB‐D1b mutation conferring grain hardness and the Wx‐B1a allele at the Wx‐B1 locus conferring wild‐type amylose content. MTHW9904 has the PinA‐D1b allele conferring grain hardness and the Wx‐B1b allele conferring lower amylose content, causing a partial waxy phenotype. RIL with the PinB‐D1b mutation (n = 49) had significantly softer kernels, higher break flour yield, and higher loaf volume than lines with the PinA‐D1b mutation (n = 38). Lines with partial waxy phenotype due to Wx‐B1b (n = 43) had significantly lower kernel weight, lower amylose content, and higher flour swelling power than lines with wild‐type starch due to Wx‐B1a (n = 51). These results provide additional evidence for the positive effect of PinB‐D1b on bread quality in hard wheats, while genotype at Wx‐B1 was generally neutral for bread quality in this population. Interactions between the Pin and Wx loci were minimal.

Effects of Milling Ratio on Properties of Endosperm Starches and Rice Flours from Milled Japanese Rice Grains

Flour and endosperm starch prepared from rice grains of three Japanese rice cultivars milled from 90 to 30% of their original weight were subjected to physicochemical/structural analysis in order to examine the relationship between milling ratio and physicochemical/starch structural properties. The peak viscosity of the rice flours was found to increase with decreasing milling ratio, while that of the purified starches did not change significantly. The gelatinization peak temperature of the rice flours was found to decrease while enthalpy changes increased with decreasing milling ratio. The gelatinization peak temperature of the purified starches was not found to change significantly with different milling ratios. Differences in structural properties of purified starches were examined by gel-filtration chromatography of isoamylase debranched starch. The FI (percentage of amylose) and FIIb/FIIa (ratio of short-to-long chain amylopectin) were found to be constant for all three cultivars for milling ratios ranging from brown rice to 30%.

Functional properties of starch from normal and mutant corn genotypes

The thermal and functional properties of starches from a wild-type corn, and amylose extender25, dull39, sugary2 ( su2), and sugary1( su1) corn mutants, all in the same (ExSeed68) genetic background were evaluated and related to their structural features obtained in a previous study. The onset temperature of gelatinization values of starches from all mutant lines ranged from 52.0 to 62.9 °C, temperatures that were all lower than that of the wild-type starch. The viscosity of the su2 starch was relatively stable over the cooking process, showing only a small breakdown of the peak viscosity, suggesting high stability of starch granules against mechanical shear. The su1 mutant starch formed the strongest gel among all starch-gel samples during measurements of both fresh and stored gel. Correlations were established between amylose percentage, chain-length distributions and pasting properties; Rapid Visco Analyser (RVA) and Differential Scanning Calorimeter (DSC) parameters; and DSC and texture analysis data.

Material Properties and Glass Transition Temperatures of Different Thermoplastic Starches After Extrusion Processing

AbstractFour different starch sources, namely waxy maize, wheat, potato and pea starch were extruded with the plasticizer glycerol, the latter in concentrations of 15, 20 and 25% (w/w). The glass transition temperatures of the resulting thermoplastic products were measured by Dynamic Mechanical Thermal Analysis (DMTA). Beside mechanical and structural properties also the transition temperatures of the materials were evaluated during tensile and impact tests. Above certain glycerol contents, dependent on the starch source, a lower glass transition temperatureTgresulted in decreased modulus and tensile strengths and increased elongations. Lowering theTgat different glycerol contents did not influence the impact strength. When the amylose/amylopectin ratio increased a decrease inTgwas found. For pea, wheat, potato and waxy maize starch theTgwas 75 °C, 143 °C, 152 °C and 158 °C, respectively. Therefore products with higher percentages of amylose are more flexible. The shrinkage of the specimens made by injection molding was considerable compared to the specimens made by pressing.

Nutritional value of potato tubers from field grown plants treated with deltamethrin

Tubers showed changes in their nutritional value caused by the treatment of the plants with the insecticide deltamethrin. The level of starch was increased in comparison with control tubers; but the amylose percentage was not affected. In contrast, the total protein content decreased in tubers from treated plants, whereas free amino acids level and ascorbic acid content increased. The results showed that the changes in the tubers caused by the treatment of potato plants with deltamethrin did not adversely affect the nutritional value of the progeny tubers.

Physico-chemical characterisation of sago starch

The physico-chemical characteristics of various sago starch samples from South East Asia were determined and compared to starches from other sources. X-ray diffraction studies showed that all the sago starches exhibited a C-type diffraction pattern. Scanning electron microscopy showed that they consist of oval granules with an average diameter around 30 μm. Proximate composition studies showed that the moisture content in the sago samples varied between 10.6% and 20.0%, ash between 0.06% and 0.43%, crude fat between 0.10% and 0.13%, fiber between 0.26% and 0.32% and crude protein between 0.19% and 0.25%. The amylose content varied between 24% and 31%. The percentage of amylose obtained by colourimetric determination agreed well with the values obtained by fractionation procedures and potentiometric titration. Intrinsic viscosities and weight average molecular weight were determined in 1M KOH. Intrinsic viscosity for amylose from sago starches varied between 310 and 460 ml/g while for amylopectin the values varied between 210 and 250 ml/g. The molecular weight for amylose was found to be in the range of 1.41×10 6 to 2.23×10 6 while for amylopectin it was in the range of 6.70×10 6 to 9.23×10 6. The gelatinisation temperature for the sago starches studied varied between 69.4°C and 70.1°C. The exponent ‘ a’ in the Mark–Houwink equation and the exponent ‘ α’ in the equation R g= kM α was found to be 0.80 and 0.58, respectively for amylose separated from sago starch and these are indicative of a random coil conformation. Two types of pasting properties were observed. The first was characterised by a maximum consistency immediately followed by sharp decrease in consistency while the second type was characterised by a plateau when the maximum consistency was reached.

Conversion of cyclodextrin into high-amylose starch of low molecular mass by means of cyclodextrin glucanotransferase.

alpha-Cyclodextrin (CD) was converted by Bacillus macerans cyclodextrin glucanotransferase into highly insoluble high-amylose starch with a low average degree of polymerization (56-73), in yields as high as 78% over a wide range of temperatures (25-70 degreesC). Ability to undergo this conversion was highly concentration-dependent. gamma-CD was also convertible in good yield; however, beta-CD was relatively resistant to conversion. Degrees of polymerization and the percentages of amylose in the high-amylose products were estimated from spectrophotometric measurements on their iodine complexes. A plausible mechanism for conversion of CD into starch is proposed.

A Study of Maize Endosperm Hardness in Relation to Amylose Content and Susceptibility to Damage

ABSTRACTThe relative amounts of amylose and amylopectin in maize starch were determined in samples representing hard and soft endosperm. Although differences were small, amylose content differed significantly (P < 0.001 and P < 0.05) between the two types of endosperm, with hard endosperm containing a higher percentage of amylose. Scanning electron microscopy was used to determine that the surface appearance of starch granules from hard and soft endosperm differed. Starch granules from soft endosperm had randomly distributed pores on their surfaces, which had a rough appearance. Few pores were observed on granules from hard endosperm. A fairly common occurrence with starch granules from soft endosperm was the development of wrinkles or fissures upon prolonged exposure to the beam of the electron microscope. Thus, a correlation existed between endosperm hardness, amylose content, and susceptibility to wrinkling and fissures. The granules of the soft endosperm of maize, presumably less mature than the granules of the hard endosperm, have a lower amylose content (20.5 ± 1.9% vs. 23.0 ± 1.0%), exhibit more surface pores, and are more susceptible to wrinkling in an electron beam, compared with granules of the hard endosperm. Results suggested that the composition and internal architecture of the starch granule differ depending on the hardness of the endosperm from which it was obtained.

Changes in Amylose and Total Starch Content in `Fuji' Apples during Maturation

Total starch and amylose (AM) concentration and a starch index (SI) were determined in `Fuji' apple (Malus domestica Borkh.) fruit from weekly harvests in 1990 and 1991. As apples matured, SI scores increased and total starch and amylose content decreased. The percentage of AM in the total starch decreased as the apples matured. Because KI solutions interact efficiently only with AM, the SI is less reliable in representing total starch during later stages of `Fuji' apple maturation.

Regulatory mechanisms involved in the biosynthesis of starch

Abstract

Solubility Behavior of Granular Corn Starches in Methyl Sulfoxide (DMSO) as Measured by High Performance Size Exclusion Chromatography

AbstractThe extent of corn starch dispersibility and the relative molecular solubility of amylose and amylopectin in methyl sulfoxide (DMSO) were determined. Granular corn starches with <l, 25, 53, and 70% amylose were dispersed in 0–100% DMSO (in water) solutions at 30°C for 30 min. Maximum dispersibility for all starches (98%) was obtained when 90% DMSO/10% water was used; regular (normal) dent corn starch was equally dispersed in solutions with 88–94% DMSO. Molecular solubility, the presence of individual molecules of amylose and amylopectin, of starches was also measured (after centrifugation and filtration) by high performance size‐exclusion chromatography (HPSEC). Starches were dispersed in 90% DMSO and heated for 10 min at temperatures of 35–120ºC. At low temperatures, high coefficients of variation resulted from additional DMSO solubilization after treatment. At 120ºC, 70% amylose starch was >90% solubilized, while waxy starch was only 47% solubilized. When starches were treated for 18–89 h in 90ºC DMSO, solubility stopped increasing after 67 h. High amylose starch (70%) was mostly solubilized, but 53% amylose, waxy and regular starches could only be fully solubilized after exposure to shear. Amylopectin molecules appeared more susceptible to shear induced depolymerization than amylose. The percent amylopectin in the high amylose starches reflected that as determined by iodine binding analysis and the manufacturer; while the percent amylopectin in regular starch was too low (manufacturers: 75%, HPSEC: 65%). Undispersed components were mostly amylopectin. Since amylose is fully solubilized, however, the HPSEC can be used to quickly determine percent amylose in starch.

Some Properties of Starches of Sugary‐1; Brittle‐1 Maize (Zea mays L.)

AbstractStarch granules were prepared from mature kernels of sugary‐1 (su1) [sweet corn hybrid P39–5XP51—B] and its brittle‐1 (bt1), sugary‐1; brittle‐1 (su1; bt1), and normal counterparts. Amylose percentage and the distribution of linear chains of amylopectin were determined by gel filtration after debranching of the starches with Pseudomonas isoamylase. Pasting characteristics by differential scanning calorimetry (DSC) and starch‐granule susceptibility to amylase were also investigated. Starch granules of su1; bt1 maize are of a high‐amylose type, easily digestible, and have lower gelatinization temperature and smaller heat of gelatinization than those of the other three genotypes. Results obtained suggested that bt1 is epistatic to su1 for pasting characteristics of starch by DSC. However, su1 is epistatic to bt1 for the ratio of fraction III to fraction II of amylopectin, and amylose content and starch‐granule susceptibility to amylase are affected by both su1 and bt1 genes.

Starch characteristics in cultures of normal and mutant maize endosperm

Vigorously growing suspension cultures of 'normal', amylose-extender (ae) and waxy (wx) maize endosperm were established from near isogenic lines of maize inbred A636. The recovery of the ability to produce vigorous cultures of ae and wx endosperm by backcrossing demonstrate the genetic control of endosperm growth in vitro. Phenotypic expression of the endosperm mutants in culture was studied by examining the properties of starch accumulated in endosperm cultures and starch from developing and mature kernels of the same genotype. After 9 months in culture, the amylose contents of the starch in normal callus tissue and normal endosperm tissue were not significantly different, 28.2% and 31.7%, respectively. Starch granules from normal cultures and endosperm stained blue-black with iodine and were round to polygonal in shape. The starches of wx endosperm and callus cultures contained no amylose, and wx starch granules stained brown-orange with iodine. Although, wx starch granules were primarily round, a few granules with "jagged edges" were observed in starch samples isolated from cultures and kernels. The percent amylose in starch from ae callus was significantly lower than the amylose content of starch from ae endosperm tissue, 39.9% and 67.7%, respectively. Starch granules from ae endosperm and cultures were smaller than normal and wx starch granules. Irregular starch granules which are typical of ae endosperm were present in ae callus tissue, but were less frequently observed. We conclude that specific endosperm mutant phenotypes are expressed in vitro.

Título en español

Se midieron los azúcares reductores y no reductores de siete cultivares de batatas que variaron en dulzura. Al cocinar estas batatas las cantidades de azúcares reductores aumentaron en seis de las siete cultivares y las de azúcares no reductores se quedaron igual o disminuyeron un poco. La inspección del tamaño de las partículas de almidón o contenido de amilosa no ayudó a explicar la variedad no dulce, "Ninety-nine". Sin embargo, al medir el poder reductivo del almidón mismo y su viscosidad intrínseca se encontró la sugerencia de que tal cultivar tenga una molécula grande y poco ramificada. Este cultivar sirve como prototipo de una clase nueva de batatas gue se está desarrollando, baja en dulzura y apropiada para comer todos los días.

Developmental Changes in the Structure of Endosperm Starch of Rice (Oryza sativaL.)

The developmental changes in the structure and properties of endosperm starches were investigated using the near-isogenic lines for wx alleles of rice. The amylose content in nonwaxy starch was increased during the development of rice grains. Because the accumulation of amylose in endosperm stopped earlier than that of amylopectin during development, the percentages of amylose reached a maximum at the 17th day after flowering in nonwaxy endosperm. Since the distributions of the unit-chain length of amylopectin in waxy and nonwaxy starches were unchanged with the development of the grains, these amylopectins would be synthesized in a similar manner through development. The structure and properties of endosperm starches were reconfirmed to be conspicuously affected by the temperature at the early developmental stages of the grain-filling period, namely, they appeared to be characterized by the temperature at which the starch was accumulated in the endosperm.