Amylopectin Chain Length Distribution Research Articles

Starch Characteristics of the Rice Mutant du2‐2 Taichung 65 Highly Affected by Environmental Temperatures During Seed Development

ABSTRACTThe effects of environmental temperature (21 vs. 28°C) during rice seed development on the starch characteristics (apparent amylose content, amylopectin chain length distribution, and gelatinization properties) of nonwaxy Taichung 65 (T65), waxy Taichung (T65wx), du2‐2 mutated low‐amylose strain Taichung (76‐3/T65), and Koshihikari were studied. Amylose contents increased with decreasing environmental temperatures. Analysis of the amylopectin chain length distribution showed that the relative amounts of long chains with degree of polymerization (DP) > 25 in all starches decreased if maturation occurred at 21°C. Gelatinization onset, peak, and conclusion temperatures and enthalpies decreased with decreasing environmental temperatures. Of all starches studied, the du2‐2 mutated low‐amylose Taichung (76‐3/T65) was most affected by maturation temperatures. These results indicate that the du2‐2 mutated low‐amylose Taichung (76‐3/T65) may be a useful strain in understanding biochemical and genetic starch biosynthesis response to slight changes in temperature.

Relationchip among Starches from Different Origins Classified according to Their Physicochemical Properties

The physicochemical properties of starch from arrowroot, cassava, corn, edible canna, indian lotus root, katakuri, kuzu, potato, sago and sweet potato were measured. Potato exhibited a remarkably high value for swelling power of 88.0 at 95°C, next being cassava with 45.3. The swelling power of indian lotus root was 30.5, while the values for the other starches were in the range of 16.2-28.0. Cassava was the most soluble of the starch samples, corn being the lowest in solubility. Amylography represented the features of starch samples well, the temperature for increasing viscosity being in the 52.2-81.0°C range. The 6-12 chain length distribution of amylopectin was characteristic to each sample, the proportion of 6-9 chain length in particular being different. Data for the swelling power, solubility, amylograph and some physicochemical properties that had previously been measured in our laboratory were studied by principal component analysis. The component scores for the first three principal components, which related to characteristics under large deformation, those of negligible deformation, and those of starch granules, were plotted in a three-dimensional space. It was showed that the starches examined were classified into four groups by the plotted position.

Characterization of Residues from Partially Hydrolyzed Potato and High Amylose Corn Starches by Pancreatic α-Amylase

High amylose corn starch (HACS) and potato starch were hydrolyzed by pancreatic α-amylase in vitro. Residues after hydrolysis were collected and characterized for their physicochemical properties and molecular structure. Compared with raw starches, residues had lower apparent amylose contents and higher resistant starch contents. The gelatinization enthalpy of residues from HACS increased while enthalpy of residues from potato starch decreased from 15.4 to 11.3 J/g. Peak viscosity and breakdown values of the residues from potato starch were markedly decreased but final viscosity values did not show much change. Chain length distribution of debranched amylopectin from the residues indicated that the relative portion of short chain in the residue decreased for both starches. More molecules with intermediate chain length (DP 16—31) were found in residue after 48-h hydrolysis of potato starch.

Structure-retrogradation relationship of rice starch in purified starches and cooked rice grains: a statistical investigation.

Amylose content and amylopectin chain length distribution, the two most commonly used structural parameters of starch, have significant effects on starch retrogradation. In the present work, starches were separated and purified from 18 rice cultivars. The amylopectin was purified from each starch. Amylopectin chain length distribution was analyzed by high-performance size-exclusion chromatography after debranched using isoamylase. The blue value was used to measure the amylose content before and after the defatting of starch. The amount of amylose associated with lipid was calculated. Pulsed nuclear magnetic resonance was used to follow the retrogradation of starch both in cooked rice grains and in the purified form. The Avrami equation was employed to describe the retrogradation kinetics of rice starch. To look into the relationship between the starch structure and retrogradation behavior, the structural parameters were correlated with retrogradation kinetics parameters using both Pearson and partial correlations. The results indicated the following: first, the retrogradation behavior of rice starch remains similar in both the purified form and cooked rice grains; second, the peak value of amylopectin short-chain length has a significant positive relationship with the amylopectin crystallization rate constant k; third, the amylose content after defatting has a significant positive relationship with the parameter k and a negative relationship with the Avrami exponent n; and fourth, the amount of amylose associated with lipid has a negative relationship with the parameter k.

Structures and physicochemical properties of six wild rice starches.

Starches from six wild rice cultivars were studied for their chemical structures and physicochemical properties and compared with a long-grain rice starch. The six wild rice starches were similar in morphological appearance, X-ray diffraction patterns, swelling power, and water solubility index but different in amylose content, beta-amylolysis limit, branch chain length distribution, thermal properties, and pasting properties. The structure of the wild rice amylopectins was close to that of waxy rice amylopectin with more branching and a larger proportion of short branch chains of degree of polymerization 6-12 as compared with that of amylopectin from rice starch with a similar amylose content. The differences in branch chain length distribution of amylopectin and amylose content were assumed to contribute to the differences in physicochemical properties among the six wild rice starches as well as to the differences between the wild rice starches and the rice starch.

Physico-chemical Characterization of Floridean Starch of Red Algae

The current work reports on isolation and physico-chemical characterization of floridean starch from three species of agarophytic macro red algae. As determined by 1H-NMR spectroscopy, the average chain length and degree of branching frequency of this starch were 18 and 4.8, respectively. According to its amylopectin chain length distribution obtained by Dionex analysis, the crystalline polymorph of floridean starch from the red alga Gracilariopsis lemaneiformis was deduced to be C-type and this was further supported from its X-ray crystallographic pattern. Enzymatic analysis of its glucose 6-phosphate content showed that floridean starch had a low level of covalently linked phosphate (1 nmol per milligram starch) and this was further confirmed by 31P-NMR. The absorbance peak of floridean starch with iodine occurred at 527—530 nm and the blue value was low (0.1), indicating the absence of amylose, which was confirmed by differential scanning calorimetry (DSC). Floridean starch exhibited low gelatinization temperature, low viscosity, high clarity and little or no retrogradation upon repetitive freeze-thaw cycles, as studied by DSC and rapid viscosity analysis (RVA). These results are discussed in light of the functional properties and the structure of floridean starch.

Order in maize mutant starches revealed by mild acid hydrolysis

Maize mutants starches cover a broad range of features with respect to apparent amylose content (1–63%), fine structure of amylopectin (short- to long-chain ratios), crystallinity level (19–48%) and polymorphic type (various proportions of A-, B- and V allomorphs). This study subjected starches from single and double maize mutants to mild acid hydrolysis (35 days) with 2.2 N HCl. The crystallinity of these starches before and after 12 days of mild hydrolysis was studied by X-ray diffractometry. The linear chain length distribution of amylopectin and residues was studied after debranching, followed by high-performance anion-exchange chromatography with pulsed amperometric detection. Regardless of amylose content or crystallinity level, starches with a predominant B-crystalline type were less susceptible to acid degradation than others, and initial rates of hydrolysis were lower for B-type than A-type starches. Changes in initial hydrolysis rate may have been due to defective crystallites and/or dangling chains. Branch points were more frequent in residual fractions of A-type starches (normal, wxdu) than in predominant B-type starch ( aewx). Conversely, residual fractions of a pure B-type starch ( ae) appeared to have no branch points, suggesting the involvement of apparent amylose in crystallites.

Structural Differences in Amylopectin Affect Waxy Rice Processing

We studied the varietal differences in the rice cake hardening rate, which is one of the important characters in waxy rice processing. Waxy upland rice cv. Kanto-mochil72 had fewer short chains (dp 7 to 10) of amylopectin and more intermediate-length chains (dp 12 to 21) than cv. Tsukuba-hatamochi and cv. Mangetsu-mochi, which harden much more slowly when made into rice cakes, mochi, than does Kanto-mochil72. Based on zymogram analysis of the soluble fraction from the developing endosperm, the activity of starch synthase 2 (SS2), a candidate enzyme responsible for the difference in the amylopectin chain length was detected with Kanto-mochil72. SS2 activity was absent, however, in Tsukuba-hatamochi and Mangetsu-mochi. Using the progeny derived from a cross between Kanto-mochil72 and Mangetsu-mochi, we showed that differences in amylopectin chain length corresponded to the gelatinisation temperatures of the rice flours and rice cake hardening rates. The progeny of those rich in short amylopectin chains showed lower gelatinisation temperature and slower rice cake hardening rate than the progeny of those having amylopectin with fewer short chains. These results indicate that the differences in chain length distribution of amylopectin, polymorphisms in starch synthase activity, differences in rice flour gelatinisation temperature, and differences in rice cake hardening rate are not merely correlated with each other but are intimately linked since they are related to amylopectin properties.

Composition, molecular structure, and physicochemical properties of starches from four field pea (Pisum sativum L.) cultivars

Abstract Starch from four cultivars (Carneval, Carrera, Grande and Keoma) of field pea ( Pisum sativum L.) was isolated and its physicochemical properties were compared with those of other legume starches. The yield of starch was in the range 32.7–33.5% on a whole seed basis. The starch granules were round to elliptical with smooth surfaces. The free lipid was 0.05% in all starches. However, bound and total lipids ranged from 0.24 to 0.29% and from 0.28 to 0.34%, respectively. The total amylose content ranged from 48.8–49.6%, of which 10.9–12.3% was complexed by native lipid. The degree of polymerization (DP) of amyloses ranged from 1300 to 1350. The chain length distributions of debranched amylopectins of the starches were analyzed using high performance anion-exchange chromatography equipped with a post-column amyloglucosidase reactor and a pulsed amperometric detector. The proportion of short branch chains, of chain length DP 6-12, ranged from 16.2 to 18.6%. Keoma displayed a larger portion (19.4%) of long branch chains (DP>37) than the other three starches (16.2–16.9%). The average amylopectin branch chain length ranged from 22.9 to 24.2. The maximum detectable DP was higher in Keoma (71) than in the other three starches (64–65). The X-ray pattern was of the ‘C’ type. The relative crystallinity was in the range 20.8–25.1%. The proportion of ‘B’ polymorphic form was higher in Keoma (25.6%) than in the other three starches (22.1–24.1%). There were no significant differences in swelling factor. The extent of amylose leaching at 95°C ranged from 25.20 to 26.85. All four starches exhibited nearly identical gelatinization transition temperatures and enthalpies. However, the gelatinization temperature range ( T c – T o ) followed the order: Grande∼Keoma>Carneval∼Carrera. The four starches showed identical pasting temperatures and exhibited only marginal differences with respect to 95°C viscosity and to the increase in consistency during the holding period at 95°C. However, the set-back viscosity for Carneval was lower than that of the other starches. There were no significant differences in the extent of acid hydrolysis. However, susceptibility towards hydrolysis by α-amylase followed the order: Carneval∼Carrera∼Grande>Keoma. The extent of retrogradation (monitored by changes in enthalpy) during storage at 40°C/24 h followed the order: Carneval>Carrera>Grande>Keoma. However, differences in the extent of retrogradation among starches were not discernable by freeze-thaw stability measurements.

Relationship Between Physicochemical Properties of Starches and White Salted Noodle Quality in Japanese Wheat Flours

ABSTRACTThis study describes the effect of starch properties of Japanese wheat flours on the quality of white salted noodles (WSN). Starch was isolated from 24 flours of 17 Japanese cultivars and amylose content was determined along with pasting properties by Rapid Visco Analyser (RVA), thermal properties by differential scanning calorimetry (DSC), and the distribution of amylopectin chain length by high‐performance anion exchange chromatography (HPAEC). Twenty flours were used to prepare WSN. As expected, 5–6% lower amylose content was associated with good WSN quality (higher scores in softness, elasticity, and smoothness). RVA analysis indicated that the pasting temperature had the greatest influence on WSN quality, while breakdown and setback showed slight effects on WSN quality. DSC results showed that lower endothermal enthalpy (ΔH) in the amylose‐lipid complex was associated with good WSN quality. Chainlength distribution of amylopectin by HPAEC was not an important factor in relation to WSN quality.

Structural, physicochemical, and pasting properties of starches from potato plants with repressed r1-gene.

The aim of this work was to investigate the effect on starch molecular and physicochemical properties of down regulation of the R1 protein in potato (Solanum tuberosum L. cv. "Dianella") tubers. Most prominent is a 90% suppression of the phosphate content in the isolated potato tuber starch. The amylopectin chain length distribution profile as determined by HPAEC/PAD was not affected, but the amylose content was increased in the most down-regulated plants. The pasting properties of the transgenic starch revealed a pronounced decrease in peak viscosity and increased setback viscosity as measured using a rapid Visco analyzer. The starch gels displayed an increased hardness and stickiness with a maximum at 1.7 nmol of Glc-6P mg-1 of starch compared to the control lines. At very low phosphate levels (1.4 nmol of Glc-6P mg-1 of starch), the gel hardness was decreased as a result of increased gel brittleness. The increase in gel brittleness is believed to be an effect of an increased proportion of free amylopectin blocklets in the starch as determined by SEC/RI. The possible links between the structural and physicochemical parameters are discussed.

The isolation and characterization of a waxy mutant of diploid wheat ( Triticum monococcum L.)

A waxy mutant of diploid wheat ( Triticum monococcum L.) was isolated by screening M 3 seeds derived from 1% ethyl methanesulfonate (EMS) mutagenized materials with KI-I 2 staining of endosperm starch. This mutant was controlled by a single waxy gene that completely lacked amylose, the 59-kDa waxy protein and the granule-bound starch synthase I (GBSS I) activity in the endosperm. Moreover, the T. monococcum exhibited the gene dosage effects in terms of amylose content, the amount of waxy protein and the GBSS activity. The chain length distribution of amylopectin of the waxy mutant endosperm starch slightly differed from that of the wild type; the long chains of DP≧19 were more enriched in the waxy amylopectin than those in the wild type. The mutant can be an important material for studies on starch metabolism and breeding in Triticum species.

Molecular structure of three mutations at the maize sugary1 locus and their allele-specific phenotypic effects.

Starch production in all plants examined is altered by mutations of isoamylase-type starch-debranching enzymes (DBE), although how these proteins affect glucan polymer assembly is not understood. Various allelic mutations in the maize (Zea mays) gene sugary1 (su1), which codes for an isoamylase-type DBE, condition distinct kernel phenotypes. This study characterized the recessive mutations su1-Ref, su1-R4582::Mu1, and su1-st, regarding their molecular basis, chemical phenotypes, and effects on starch metabolizing enzymes. The su1-Ref allele results in two specific amino acid substitutions without affecting the Su1 mRNA level. The su1-R4582::Mu1 mutation is a null allele that abolishes transcript accumulation. The su1-st mutation results from insertion of a novel transposon-like sequence, designated Toad, which causes alternative pre-mRNA splicing. Three su1-st mutant transcripts are produced, one that is nonfunctional and two that code for modified SU1 polypeptides. The su1-st mutation is dominant to the null allele su1-R4582::Mu1, but recessive to su1-Ref, suggestive of complex effects involving quaternary structure of the SU1 enzyme. All three su1- alleles severely reduce or eliminate isoamylase-type DBE activity, although su1-st kernels accumulate less phytoglycogen and Suc than su1-Ref or su1-R4582::Mu1 mutants. The chain length distribution of residual amylopectin is significantly altered by su1-Ref and su1-R4582::Mu1, whereas su1-st has modest effects. These results, together with su1 allele-specific effects on other starch- metabolizing enzymes detected in zymograms, suggest that total DBE catalytic activity is the not the sole determinant of Su1 function and that specific interactions between SU1 and other components of the starch biosynthetic system are required.

A comparison between MALDI-TOF mass spectrometry and HPAEC-PAD analysis of debranched starch

Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry, MALDI-TOF MS, was used in this study to determine chain length distribution of amylopectin, the main constituent of starch. The technique was compared with high-performance anion-exchange chromatography with pulsed amperometric detection, HPAEC-PAD, an established technique for this purpose. Starch from potato, wheat, and waxy maize was debranched with isoamylase and analysed using both techniques. MALDI-TOF MS is a faster and more sensitive technique and provides more detailed information on the molecular mass of the unit chains. A difference between chain length distribution for amylopectin from different sources was observed with both methods. In addition, removal of amylose was not necessary for MALDI-TOF analysis. However, the technique was less reproducible than HPAEC-PAD and overestimated the amount of longer chains.

The distribution of covalently bound phosphate in the starch granule in relation to starch crystallinity

Five selected starches with a 60-fold span in their content of monoesterified starch phosphate were investigated with respect to distribution of glucose 6-phosphate and glucose 3-phosphate residues, amylopectin chain length distributions and gelatinisation properties. The distribution of starch phosphate in the starch granules was determined by preparation of Nägeli dextrins followed by quantitative 31P-nuclear magnetic resonance spectroscopy. Total starch phosphate content was positively correlated to the unit chain lengths of the amylopectin as well as to the chain lengths of the corresponding Nägeli dextrins. The major part (68–92%) of the total starch phosphate content was partitioned to the hydrolysed (amorphous) parts. Starch-bound glucose 6-phosphate per milligram of starch was 2-fold enriched in the amorphous parts, whereas phosphate groups bound at the 3-position were more evenly distributed. The gelatinisation temperatures of the native starches as determined by differential scanning calorimetry were positively correlated ( R 2=0.75) to starch phosphate content, while crystallinity (gelatinisation enthalpy) and crystal heterogeneity (endotherm peak width) showed no correlations to starch phosphate content. The relations between starch molecular structure, architecture and functional properties are discussed.

Chemical and physical properties of ginkgo ( Ginkgo biloba) starch

Starch isolated from mature Ginkgo biloba seeds and commercial normal maize starches were subjected to α-amylolysis and acid hydrolysis. Ginkgo starch was more resistant to pancreatic α-amylase hydrolysis than the normal maize starch. The chain length distribution of debranched amylopectin of the starches was analyzed by using high performance anion-exchange chromatography equipped with an amyloglucosidase reactor and a pulsed amperometric detector. The chain length distribution of ginkgo amylopectin showed higher amounts of both short and long chains compared to maize starch. Naegeli dextrins of the starches prepared by extensive acid hydrolysis over 12 days demonstrated that ginkgo starch was more susceptible than normal maize to acid hydrolysis. Ginkgo dextrins also demonstrate a lower concentration of singly branched chains than maize dextrins, and unlike maize dextrin, debranched ginkgo shows no multiple branched chains. The ginkgo starch displayed a C-type X-ray diffraction pattern, compared to an A-type pattern for maize. Ginkgo starch and maize starch contained 24.0 and 17.6% absolute amylose contents, respectively.

Characterisation of Starch from Inner and Peripheral Parts of Normal and Waxy Barley Kernels

A previous microscopical examination of barley kernels indicated an uneven distribution of amylose in the waxy cultivar SW7142-92, where the subaleurone layer was strongly stained by iodine. To explain these results, starch was isolated from fractions of inner and peripheral parts of kernels of the waxy cultivar and a cultivar with normal starch. Analyses of amylose content showed a higher concentration of amylose in starch from the outer part of the waxy barley kernel, where the amylose, determined by a colorimetric method, made up 8·6% of the starch compared with 5·9% in the middle and 2·2% in the innermost part of the waxy kernel. This difference in amylose distribution was not observed in the normal starch kernel. The results were confirmed by gel permeation chromatography. No differences in amylopectin chain length distribution were detected by size exclusion HPLC and HPAEC-PAD of amylopectins from different parts of the barley kernels.

Differences in Amylopectin Structure Between Two Rice Varieties in Relation to the Effects of Temperature During Grain-Filling

The structure of endosperm amylopectin was compared between two rice varieties, Kinmaze (subspecies japonica) and IR36 (subspecies indica), as well as their waxy mutants, all grown under controlled temperature. The distinct varietal difference in chain length distribution of amylopectin was confirmed by high performance anion-exchange chromatography equipped with pulsed amperometric detection. Amylopectin from Kinmaze contains more very short chains with degree of polymerization (DP) between 6 and 10 and less chains with DP from 13 to 22 than amylopectin from IR36, while there is little difference in the distribution of longer chains with DP > 24 between the two varieties. Waxy mutation had little effect on chain length distribution of endosperm amylopectin. The temperature during grain-filling affected the chain length distribution of amylopectin in both varieties in a similar way; grain-filling at lower temperatures lead to an increased proportion of chains of DP 6—13 and decreased the percentage of chains with DP 20—27 and DP 44—54. However, the temperature-dependent changes in chain length distribution of amylopectin were within the range of varietal difference between Kinmaze and IR36. These results strongly suggest that factors regulating the varietal difference in patterns of chain length of amylopectin are dissimilar to those causing the temperature effects on amylopectin fine structure in rice endosperm.

Molecular Characterization of Wheat Amylopectins by Multiangle Laser Light Scattering Analysis

ABSTRACTWeight‐average molecular weight (Mw) and chain length of eight amylopectins isolated from one Australian, two United States, and five Korean wheats were measured using multiangle laser light scattering (MALLS) and refractive index (RI) detectors operated in a microbatch mode, and in a high‐performance size‐exclusion chromatography (HPSEC) mode. The Mw of amylopectins measured in the microbatch mode ranged from 29 × 106 to 349 × 106. Three amylopectins (Geuru, Tapdong and WW) showed significantly high Mw values over 200 × 106. The Mw measured by HPSEC mode with MALLS‐RI detectors (42 × 106 to 73 × 106) were significantly less than those obtained in the microbatch mode with exception of dark northern spring hard wheat (DNS) amylopectin, indicating the possible variation of Mw by the analysis mode. Root‐mean square of the radius of gyration (Rg) also was greater when the microbatch mode was used (122–340 vs. 95–116 nm). Chain length distributions of debranched amylopectins of different cultivars, measured by the HPSEC‐MALLS‐RI system, were similar. Weight average degrees of polymerization (DPw) of A, B1, and larger B chains (B≥2) had ranges of 13–22, 26–46, and 58–73, respectively, and mass ratios of A and B chains ranged from 0.7 to 1.1.

Relationships between chain length distribution of amylopectin and gelatinization properties within the same botanical origin for sweet potato and buckwheat

Starch samples from 51 sweet potatoes and 27 buckwheats with large variations in onset ( T o), peak ( T p) and heat (Δ H) for gelatinization determined by differential scanning calorimetry (DSC) were studied. Amylose content was found to be independent of all the DSC parameters. The quantitative molar distributions of the amylopectin chain length (DP 6–17) analyzed by high performance anion-exchange chromatography had a large influence on all the DSC parameters. It is concluded that, within the same botanical origin, an increase in short outer chains in amylopectin molecules reduces the efficiency of packing within the crystalline region of starch granules, resulting in lower T o, T p and Δ H.