Molecular Weight Of Konjac Glucomannan Research Articles

Properties of plant-derived soluble dietary fibers for fiber-enriched foods: A comparative evaluation

Plant-derived soluble dietary fibers (SDF) have many important physiological functions and the applications of SDF vary based on their properties, which are worth further investigating for fiber-enriched food production. In this study, SDF derived from konjac, apple, chicory, flaxseed, orange, psyllium seed, soybean and oat were purified, and their structural, physicochemical and functional properties were systematically evaluated. Monosaccharide composition analysis showed that these SDF belonged to heteropolysaccharides, of which konjac, psyllium seed, apple, soybean and oat SDF were glucomannan, arabinoxylan, pectin, arabinogalactan and glucan, respectively. The molecular weight of konjac glucomannan (KGM, 5.22 × 106 Da) was the highest, and inulin, soybean arabinogalactan (SA) and oat glucan (OG) had higher water solubility. Moreover, KGM, apple pectin (AP), flaxseed SDF (FS) and psyllium seed arabinoxylan (PA) exhibited better water-holding capacity, swelling capacity, emulsifying activity and stability. Rheological studies and texture profile analysis suggested that KGM had the best viscosity and gelation ability. In addition, AP and orange SDF (OS) showed better α-amylase inhibitory activity, while OS and KGM had higher pancreatic lipase inhibitory activity. Also, KGM and FS displayed fine cholesterol absorption capacity. To summary, these functional properties illustrated the feasibility of SDF to regulate blood sugar and blood lipid levels.

Application of Glucomannan

Glucomannan (GM) a water-soluble polysaccharide possesses mannose residues which are extracted from tubers, bulbs, softwoods and roots of many plants. Glucomannan is considered to be a dietary fibre which is actually present in some plant species in the form of hemicelluloses component in the cell wall. Its structure consists of linear chain of mixed residues of α-1,4 linked D-mannose and D-glucose monomers arranged in blocks. The molecular weight of native GM lies between 1×104– 2×106. Low molecular weight GM could be obtained by de-polymerization technique. The average molecular weight of Konjac Glucomannan (KGM) is 500,000 – 2,000,000 and varies with species, growing area, storage time and processing methods. The glucomannan from different sources vary in its mannose to glucose ratio. Konjac tuber glucomannan has a molar ratio of 1.6:1 or 1.4:1 (ratio differs with konjac breeds), Orchid tubers and Scotch pine have molar ratios of 3.6:1 and 2.1:1 respectively. Diversity of glucomannan also depends on degree of acetylation in GM chain. Values of degree of acetylation are 5to10% or every 19th sugar residue (attached randomly at C-6 position in KGM), is actually responsible to facilitate dispersion and solubility by inhibiting the intra-molecular hydrogen bonds. This solubility function is attractive for multiple pharmaceutical applications. However increase in acetylation degree in GM slows the gelation process. The intrinsic viscosity of KGM solution is highest among the polysaccharides that facilitate swelling behaviour and hence gel formation that finds application in food industry. Gels have good stability, films, hydrogel, beads, micro and nanoparticles of Glucomannan may have potential usage in therapeutic drug delivery systems without causing toxicity. It may also be useful in treatment of chronic constipation, decreasing serum cholesterol, and increasing insulin sensitivity. As a food supplement it could play a significant role in weight loss. Carboxymethylated glucomannan improves the properties of paper, such as burst index, dry tensile index, and wet tensile index. These diverse applications make Glucomannan a most sought after biomolecule. Keywords: Biomolecule, Glucomannan, Diverse application

Interaction between konjac glucomannan and tannic acid: Effect of molecular weight, pH and temperature

The objective of this study was to investigate the interaction between tannic acid (TA) and konjac glucomannan (KGM) with different molecular weight at different pHs,temperatures and urea concentration. The different molecular weight of KGM without change in primary structure were obtained by ultrasonic treatment. Turbidity titration showed that TA/KGM complexes could form at lower pH. The dynamic light scattering (DLS) and transmission electron microscopy (TEM) results indicated that the TA/KGM complexes assembled into large and uniform colloidal particles and would lead to precipitate with the increase of TA/KGM weight ratio. Isothermal titration calorimetry (ITC) results further revealed two-step binding behavior: the first stage corresponded to soluble complex formation, while the second stage represented aggregation between complexes. When the molecular increased, the transition of TA/KGM mass ratio between stage 1 and stage 2 changed from 3.5 to 3.0. KGM of higher molecular weight needed to bind more TA to move to the next stage. When the pH was 7 at 25 °C, the pH was 3.8 at 40 °C or urea addition, the ITC signal was completely abolished, the formation of complexes between KGM and TA was shown to be highly dependent on pH, temperature, urea concentration, suggesting the main driving force of TA-KGM complexes formation was hydrogen bond.

Comparative Study on Molecular Weight of Konjac Glucomannan by Gel Permeation Chromatography-Laser Light Scattering-Refractive Index and Laser Light-Scattering Methods

The gel permeation chromatography, combined with laser light scattering and refractive index (GPC-LLS-RI) online method and laser light scattering (LLS) single method, researched the weight-average molecular weight (Mw) of konjac glucomannan (KGM) in this paper. The results show that the determination results of molecular weight of KGM are similar by two method, the molecular weight of KGM is2.476×105 g/mol by online method measured, and it is2.508×105 g/mol by single method measured, compared with only 1.3% difference between the two methods. At the same time, the molecular weight distributions of KGM and conformation index were analyzed by online method, while the second virial coefficient (A2) that characterizes the interaction between KGM molecules and solvent molecules was acquired by single method, which can provide reliable foundation for the molecular chain morphology research of KGM.

Characterization of glucomannan from some Amorphophallus species in Vietnam

In this work, konjac glucomannans (KGM) have been isolated from Amorphophallus tubers (used three Amorphophallus species: Amorphophallus panomensis, Amorphophallus paeoniifolius and Amorphophallus tonkinensis) by a simple method without using toxic chemicals. The konjac glucomannan content was about 5–9% (w/w) of original Amorphophallus tubers. The structure, moisture uptake, molecular weight of konjac glucomannan were investigated by nuclear magnetic resonance spectroscopy (NMR), differential scanning calorimetry (DSC) and viscosimetry. The results indicated that the main component of konjac flour was glucomannan. The mannose/glucose molar ratio and molecular weight ( M w ) of glucomannan isolated from Amorphophallus paeoniifolius, Amorphophallus panomensis and Amorphophallus tonkinensis were 1/0.13; ( M w = 1.115 × 10 6) , 1/0.10; ( M w = 1.023 × 10 6) and 1/0.25; ( M w = 1.043 × 10 6), respectively. The moisture uptake of konjac glucomannans was about 7.5–9.2%.

Study on Stabilizing Mechanism of Konjac Glucomannan in Tea Infusions

ABSTRACT: The stabilizing mechanism of konjac glucomannan (KGM) in tea infusions was studied using a conventional transmission electron microscope (TEM), scanning electron microscope (SEM), ethanol sedimentation, and other methods. As a result, many water‐soluble complexes among the KGM molecules and tea components such as thearubigins (TRs), theaflavins (TFs), total catechins (TC), and tea polyphenols (TPP) were obviously formed in tea infusions with addition of KGM. The aggregations of tea components, which caused tea cream down, were decreased because of KGM addition and the stability of suspended particles in tea‐KGM infusions was enhanced. These findings suggested that the strong adsorption happened among KGM and tea components and particles through strong hydrogen bonding functions. Molecular weight of KGM in tea infusions was smaller than that in water solution. In water solution, it was 4.83 × 105, but in black tea infusions 3.41 × 105, and in oolong tea infusions 3.51 × 105. The experiments also revealed that the tea‐KGM infusions had stronger antielectrolyte coagulation capacity and the static electrification action exists among the molecules of tea infusions. These findings indicated that KGM could be a useful stabilizer for stability of the tea infusions.

Lipase‐catalyzed modification of konjac glucomannan

AbstractRegioselective acylation of konjac glucomannan (KGM) with vinyl acetate in a solvent‐free system was successfully performed using Novozym 435 as a biocatalyst. The degree of substitution (DS) of the modified KGM was used to evaluate the extent of acylation. The influence of various factors, such as water activity (aw), reaction temperature, shaking rate, enzyme dosage, and the molecular weight of KGM, on the reaction was examined. The water activity of the reaction system played a key role in the acylation of KGM. The optimum water activity, reaction temperature, shaking rate, and enzyme dosage were 0.84, 50°C, 200 rpm and 400 U/mL, respectively. It has also been found that the DS of modified KGM sample decreases with increase in KGM molecular weight. Additionally, the acylation of KGM was shown to be regioselective, with acylation occurring at the C6OH. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 1335–1340, 2006

Molecular weight and intrinsic viscosity of konjac gluco-mannan.

For the purpose of making clear the macromolecular chemical properties of konjac gluco-mannan, the light scattering and viscosity measurements were carried out for the aqueous solutions of the partially methylated derivatives, and following results were obtained: 1) The weight-average molecular weight, Mw, and the root mean square of radius of gyration, <S2>1/2 were 100×104_??_120×104 and 1100_??_1300 Å, respectively. 2) The <S2> versus Mw relationship was represented by the equation of <S2>=4.20×10-1•Mw1.08, and this fact suggested a random coil as a molecular form in the solution. 3) The intrinsic viscosity, [η], versus Mw relationship was represented by the equation of [η]=6.37×10-4•Mw0.74, which was considered to be useful for the purpose of estimating the molecular weight of konjac gluco-mannan by viscometric method.