Method for determining the amylose content, molecular weights, and weight- and molar-based distributions of degree of polymerization of amylose and fine-structure of amylopectin
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Keywords:
Degree of polymerization
Molar mass
Molar mass distribution
Multiangle light scattering
Degree of polymerization
Branching (polymer chemistry)
Potato starch
Enzymatic Hydrolysis
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Chemically modified starches are commonly used for various purposes. Depending on the type of derivatization, a chemical degradation of the original polymeric structure may occur, resulting in a change of molar mass. It is therefore always of interest to know the molar mass and possibly the conformation of the derivative. Four commercially available hydroxypropyl and hydroxyethyl modified starches were examined by asymmetrical flow field-flow fractionation combined with multiangle laser light scattering. The weight-average molar mass and the molar mass distribution were determined, with emphasis put on the rapid analysis and studies of the suitable experimental conditions regarding flow rates so that accurate data were obtained. The molar mass distribution determinations showed good reproducibility and repeatability and were fast. Efforts to obtain conformational information are described.
Molar mass
Multiangle light scattering
Molar mass distribution
Repeatability
Field-Flow Fractionation
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Degree of polymerization
Molar mass
Molar mass distribution
Multiangle light scattering
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A high amylose rice mutant Goamy2 and its wild type Ilpumbyeo were used to analyze starch pasting properties and structure. There were considerable differences in physico-chemical characters and pasting properties between the high amylose mutant Goamy2 and its wild type Ilpumbyeo,as well as their water soluble and insoluble starch structure according to the results of Size Exclusion Chromatography(SEC). The cold water soluble components of rice flour of the mutant Goamy2 were mainly smaller molecules with the degree of polymerization(DP) of DP141 to DP2. The cold water soluble components of the wild type Ilpumbyeo were bigger molecules and the proportion of branched chains with the degree of polymerization of DP4100 to DP64 was high(33.3%). The hot water soluble starch of Goamy2 were mainly amylose,and the ratio of amylose to amylopectin was 4∶1 approximately,whereas for the hot water soluble starch of Ilpumbyeo,amylose and amylopection were both nearly a half. The ratios of long chains to short chains in hot water soluble amylopectin of the mutant and the wild type varied,being 0.67 and 0.32,respectively. The hot water insoluble starch of both two varieties were mostly amylopectin,and the proportion of amylose were less than 5%. The chain of the hot water insoluble amylopectin in the wild type was mainly short chains,with a proportion of short chains of 72.5%,whereas for the mutant,the proportion of long chains was close to the proportion of short chains.
Degree of polymerization
Wild type
Water soluble
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The mean polymerization degree of amylose and amylopectin of the control and fermented corn starch was determined using gel filtration chromatogram,and then the fine structure characteristics of the amylopectin separated were analyzed.The results indicated that the mean polymerization degree of the amylose and amylopectin decreased,the mean chain length and the mean external chain length increased,and the mean number of chains and the chain density decreased after spontaneous fermentation.
Degree of polymerization
Corn starch
Maize starch
Molar mass distribution
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【Objective】 Providing a theoretical and practical basis for breeding and germplasm enhancement by means of genetic analysis on resistant starch content in japonica rice. 【Method】 Using japonica rice lines with significant differences in resistant starch content , this paper analyses differences and correlation of amylopectin chain length distribution, RVA spectral properties value, dietary fiber and amylose content and other quality characteristics between them. 【Result】 The chain length distribution of amylopectin shows significant differences between high and low resistant starch content strains . For the high resistant starch content strains, the relative percentage of the degree of short chain polymerization 5 to 12 about amylopectin content, which is obviously lower than low resistant starch content strains. However, the degree of polymerization in long chain (particularly above 13 proportions) is obviously higher than the low ones. Dietary fiber and amylose content of high resistant starch content is higher than that of low ones. And the peak viscosity, cool paste value, hot paste viscosity and breakdown value of high resistant starch content is significantly or very significantly lower than that of the low ones. The polymerization degree (DP≤12) of short chain amylopectin shows very significantly negative correlation to resistant starch content. On the contrary, the very significantly positive correlation between resistant starch content and the proportion of polymerization degree (12DP≤36) of long chain amylopectin, and the amylose content and the dietary fiber content was observed. 【Conclusion】 The resistant starch content is closely related to amylopectin chain length distribution, amylose content, RVA spectral properties value. Therefore, it could be used as a breeding index.
Degree of polymerization
Resistant Starch
Japonica rice
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Molar mass and molar mass distribution of polymers are parameters of fundamental importance as they influence the performance of the polymer in applications. Polysaccharide derivatives are a class of polymers that have attracted significant scientific and commercial interest as they can be manufactured from a wide range of abundant sources in nature and thereby often are both cheap and biocompatible. However, the molar mass analysis of such derivatives is not always easy with commonly used analytical techniques mainly due to their large size. One technique that has shown its applicability to molar mass analysis of very large polymers, among them polysaccharide derivatives, is the combination of field-flow fractionation (FFF) with multiangle light scattering (MALS). This thesis describes the further evaluation and development of FFF-MALS for molar mass analysis of polymers, especially polysaccharide derivatives. The methodology has been successfully applied to different industrially important derivatives of starch and cellulose. Among the results the separation enabled the detection of ultra-high molar mass components in cellulose derivatives and facilitated further investigations on its chemical structure. The investigations include discussions on suitable experimental conditions, such as polymer concentration, flow rate and choice of programmed field function, for the separation of polysaccharide derivatives with FFF. The MALS technique, especially the extrapolation procedure involved, was investigated with respect to the accuracy of the determined molar masses for very large polymers.
Molar mass
Multiangle light scattering
Field-Flow Fractionation
Molar mass distribution
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Asymmetrical flow field-flow fractionation coupled to multiangle laser light scattering has been shown to be an effective method to determine the molar mass distribution of polysaccharides. Two polymer standards, dextran and pullulan, were analyzed in the temperature range 30-60 degrees at intervals of 10 degrees C. The weight average molar mass and molar mass distribution obtained at each temperature agreed well with quoted values. The diffusion coefficient, hydrodynamic radius, radius of gyration, and activation energy of diffusion were calculated and all agreed well with literature data obtained by dynamic and static light scattering. The asymmetry factor Rg/Rh suggests a flexible random coil conformation for both polymers, which was supported by the molar mass dependence of both the radius of gyration and the hydrodynamic radius. The results show the potential of asymmetric flow field fractionation coupled to multiangle laser light scattering in undertaking measurements of molar mass distribution as a function of temperature.
Multiangle light scattering
Molar mass
Radius of gyration
Field-Flow Fractionation
Molar mass distribution
Hydrodynamic radius
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ABSTRACT The wide molar mass distribution of native starch creates obstacles in investigating the physicochemical characteristics of starch, such as retrogradation, because samples thought to be the same are actually compounds containing many chains with different molar masses. In this paper, the sweet potato amylose and amylopectin isolated from retrograded starch were treated with the retrogradation–hydrolysis method three times, and their physicochemical changes in this process were determined by absorbance of the starch–iodine complex, light microscopy, and molar mass and chain length distributions. The results showed that repeated retrogradation and hydrolysis caused the molar mass distribution of sweet potato amylose and amylopectin to reduce from 4.2 × 10 7 –205 and 7971–223 to 6.0 × 10 4 –730 and 4533–211 g mol −1 , respectively. This retrogradation–hydrolysis cut the chain length distribution of sweet potato amylose from DP 9–35 to DP 3–13, but that of amylopectin remained unchanged. The double helix in sweet potato amylopectin will not form if the percentage of chain length with DP ≥ 4 is less than 25%. Repeated retrogradation and hydrolysis was an appropriate method to obtain amylose or amylopectin with a narrower molar mass distribution. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133 , 43849.
Retrogradation (starch)
Molar mass
Molar mass distribution
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ABSTRACT Structural characteristics of starches have been important to determine their physicochemical and functional properties. Solubilization procedures were tested to find a higher solubilization percentage and thereafter to study the structural characteristics of amylose and amylopectin. Size‐exclusion chromatography with refractive index (SEC‐RI) system using a pullulan standard curve was tested to study the amylose molar mass. Also, a microbatch system using a MALLS detector was used to determine the molar mass and gyration radius of starch and amylopectin. Microwave heating produced higher solubility percentages than autoclaving, and there was a difference between both starches. The sample solubilized with microwave heating presented higher molar mass and gyration radius values than autoclave samples, showing that this process for structural studies provided information representative of the initial starch sample. When starch components were separated, amylose showed lower purity than amylopectin. Lower purity was obtained for amylose separated from barley starch, but no difference was obtained for purity of amylopectin separated from both starches. Barley amylopectin had a higher solubility percentage than maize amylopectin. Molar mass of barley amylose was 1.03 × 10 5 g/mol and for maize of 2.25 × 10 5 g/mol. Molar mass values of amylopectin separated from both starches were lower than the starch counterparts, although the same solubilization procedure (microwave heating) was used. The difference might be due to depolymerization during separation of starch components.
Molar mass
Isoamylase
Radius of gyration
Depolymerization
Maize starch
Retrogradation (starch)
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