Impact of heating and drying temperatures on the properties of konjac glucomannan/curdlan blend films.

The impact of preparation conditions including heating temperature (from 60 °C to 90 °C) and drying temperatures (from 25 °C to 90 °C) on the properties of pure curdlan film and konjac glucomannan (KGM) and curdlan blend films were analyzed. Microstructure analysis indicated the KGM addition could significantly improve the relatively poor film-forming property of curdlan. FTIR and X-ray analysis showed that at high heating temperature 90 °C, molecular interaction might be enhanced in the films due to the stretched structure of curdlan and dissociation of curdlan bundles or triple-helix structure. This was supported by the changes in the mechanical property, surface hydrophobicity, moisture barrier, and moisture tolerance property. The impacts of drying temperature were some different for the curdlan film and KGM/curdlan blend film, and were explained from the molecular hydrophilicity-hydrophobicity, compactness of the films, curdlan conformation, and molecular interaction. This work guided biodegradable film production especially with curdlan added.

Physicochemical and functional characterization of mannan exopolysaccharide from Weissella confusa MD1 with bioactivities.

The present study focused on production, optimization and characterization of exopolysaccharide (EPS) from Weissella confusa MD1. The purified EPS MD1 was also evaluated for in vitro biological activities. The maximum yield of EPS (10.07 ± 0.32 g/L) was obtained with optimized culture conditions of 35 °C at pH 6.5 for 36 h with 4% (w/v) galactose and 1% (w/v) ammonium nitrate supplemented in MRS broth. The crude EPS was purified with diethylamino ethanol-Sepharose Fast Flow column and Sephadex-G 75 column. The physicochemical and functional characterization of the EPS was done by high-performance thin-layer chromatography (HPTLC), high-performance gel permeation chromatography (HPGPC), fourier transform infrared (FTIR) spectroscopy, nuclear magnetic resonance (NMR), thermo gravimetric and differential scanning calorimetric (TG-DSC) analysis, x-ray diffraction (XRD) and scanning electron microscopy (SEM). HPGPC analysis showed molecular weight of purified EPS MD1 as 2.909 KDa. Monosaccharide analysis showed that EPS was a novel mannan with mannose as the only monomeric unit present, suggesting EPS to be a homopolysaccharide containing â†’ 6) α-Man p (1 â†’ linkages. Microstructure studies by SEM showed MD1 EPS has globular and porous structure. The purified EPS MD1 exhibited higher thermal stability having degradation temperature around 267.74 °C with melting enthalpy value (Δ H) of 337.7 J/g. The EPS showed promising antioxidant activities with excellent antibiofilm activity against Staphylococcus aureus, Listeria monocytogenes, Salmonella enterica and Salmonella typhi. These striking physicochemical characteristics features and bioactivities of EPS would serve as potential candidate in food processing industry to be used as food adjunct in foods with health benefits. This is the first study reporting a mannan homopolysaccharide from Weissella sp. to be structurally characterized.

Isolation, qualitative and quantitative evaluation of galactomannan during germination of Trigonella persica (Fabaceae) seed.

Galactomannan extracted from Trigonella persica endosperm like to other galactomannans is useful in the medicine and pharmaceutical industry such as drug delivery due to its unique physicochemical properties. As soon as germination takes place, the hydrolysis of galactomannan begins and its structure changes. Evaluation of galactomannan content extracted from the germinating seeds (GEGS) and the non-germinated seeds (GENGS) showed that the amount of galactomannan was highest at 24 h after imbibition and was completely consumed approximately 48 h after imbibition. It seems that galactomannan is used for storage reserve synthesis in the cotyledon during germination. Based on the quantitative assessment, FT-IR, macroscopic and microscopic observations, galactomannan of T. persica seeds have high an M/G ratio (approximately 5:1) and this ratio does not alter during germination. Therefore, changes in galactomannan structure (functional group and band) caused that GEGS have different physicochemical properties than GENGS. Based on the results, GENGS with a high M/G ratio may be suitable for drug delivery system due to some properties such as high viscosity and gelling.

Novel hard capsule prepared by tilapia (Oreochromis niloticus) scale gelatin and konjac glucomannan: Characterization, and in vitro dissolution.

A novel material for making capsules was prepared with tilapia scale gelatin and konjac glucomannan (KGM). Rheological behaviors of gelatin with KGM at different levels (0.1%, 0.15%, and 0.2%, w/w) were investigated. The highest values (P < 0.05) of gel strength (518.33 ± 6.17 g) and melting temperature (39.7 ± 0.11 °C) could be observed at the gelatin solution with 0.15% (w/w) KGM. The tensile strength (TS) and elongation at break (EAB) of the films increased with the increasing of KGM. The water contact angle was enhanced with the increasing of KGM, indicating the decrease of the film hydrophilicity. XRD and FTIR showed the interactions between gelatin and KGM. Gelatin solution with 0.15% KGM is suitable for preparing capsules. Drug dissolution test in vitro showed the shell rupture time is in range of 3-5 min, and 80% of the drugs were released within 10 min. Therefore, the composite materials made of tilapia scale gelatin and KGM can be utilized for hard capsules.

A Review on Konjac Glucomannan Gels: Microstructure and Application.

Konjac glucomannan (KGM) has attracted extensive attention because of its biodegradable, non-toxic, harmless, and biocompatible features. Its gelation performance is one of its most significant characteristics and enables wide applications of KGM gels in food, chemical, pharmaceutical, materials, and other fields. Herein, different preparation methods of KGM gels and their microstructures were reviewed. In addition, KGM applications have been theoretically modeled for future uses.

Mango kernel starch-gum composite films: Physical, mechanical and barrier properties.

Composite films were developed by the casting method using mango kernel starch (MKS) and guar and xanthan gums. The concentration of both gums ranged from 0% to 30% (w/w of starch; db). Mechanical properties, oxygen permeability (OP), water vapor permeability (WVP), solubility in water and color parameters of composite films were evaluated. The crystallinity and homogeneity between the starch and gums were also evaluated by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The scanning electron micrographs showed homogeneous matrix, with no signs of phase separation between the components. XRD analysis demonstrated diminished crystalline peak. Regardless of gum type the tensile strength (TS) of composite films increased with increasing gum concentration while reverse trend was noted for elongation at break (EAB) which found to be decreased with increasing gum concentration. The addition of both guar and xanthan gums increased solubility and WVP of the composite films. However, the OP was found to be lower than that of the control with both gums. Furthermore, addition of both gums led to changes in transparency and opacity of MKS films. Films containing 10% (w/w) xanthan gum showed lower values for solubility, WVP and OP, while film containing 20% guar gum showed good mechanical properties.

Development of microbial trigger based oral formulation of Tinidazole and its Gamma Scintigraphy Evaluation: A promising tool against anaerobic microbes associated GI problems.

Tinidazole is a versatile anti-amoebic and anti-anaerobic drug used in treatment of intestinal infection. The aim of present study was to develop and evaluate a guar gum based novel target release Tinidazole matrix tablet in animal models and healthy human volunteer using Gamma Scintigraphy technique. Anti-anaerobic and anti-protozoal activity of the developed formulation was studied in vitro against Bacteroides fragilis and Dentamoeba fragilis. Tinidazole was successful radiolabelled with (99m)Tc-pertechnetate using stannous chloride as a reducing agent and stable up to 24h in normal saline and serum. Radiolabeled formulation was evaluated in 6 Newzealand white rabbits by gamma Scintigraphy in static manner up to 24h for its retention in gastrointestinal tract (GIT). Similar set of study was conducted in 12 healthy human volunteers for similar objective Scintigraphy images of healthy human volunteer showed retention of optimized formulations in stomach up to 60min, from where it moved to duodenum further and reached ileum in around 5h. However, initiation of drug release was observed from intestine at 7h. Complete dissociation and release of drug was observed at 24h in colon due to anaerobic microbial rich environment. Results drawn from Scintigraphy images indicate that radiolabeled (99m)Tc-Tinidazole tablet transit through upper part of GI without disintegration. Hence the developed matrix tablet may have a role in treatment of intestinal infection caused by anaerobic bacteria.

Grafting of vinyl acetate-ethylacrylate binary monomer mixture onto guar gum.

Present article reports on guar gum (GG) functionalization through graftcopolymerization of vinylacetate (VAC) and ethylacrylate (EA) from their binary mixtures. The potassium persulfate/ascorbic acid (KPS/AA) redox initiator system has been used for the binary grafting under the previously optimized conditions for VAC grafting at guar gum. The concentration of ascorbic acid (AA), persulfate (KPS), and grafting temperature were varied to optimize the binary grafting. A preliminary investigation revealed that the copolymer has excellent ability to capture Hg(II) from aqueous solution. It was observed that the optimum % grafting sample (CP3) was best at Hg(II) adsorption. CP3 and mercury loaded CP3 (CP3-Hg) have been extensively characterized using Fourier transform infrared spectroscopy (FTIR), Scanning electron microscopy (SEM), and Thermo gravimetric analysis (TGA) and a plausible mechanism for the grafting has been proposed.

Preparation and characterization of pH-responsive guar gum microspheres.

Guar gum, being the natural polymer is renewable, nontoxic, biocompatible and biodegradable. Therefore, it is the perfect material to formulate particulates or microspheres for potential applications in pharmaceutical. The formulation of material in nano/microsphere scale offers new rich in application potential. In view of that, novel biodegradable and pH-sensitive hydrogels composed of pH-sensitive methacrylic acid (MAc) and a biodegradable guar gum were synthesized by grafting reactions. Water-in-oil (w/o) emulsion method was used to direct the pH-sensitive material in microspheres shape using bi-functional glutaraldehyde (GA) as crosslinker. The synthesized microspheres were characterized by FTIR and SEM (different magnification). The swelling ratios of hydrogels in buffer solutions showed a pH-dependent profile at physiological pH. In vitro release data was analyzed using Fick's law, which indicated swelling controlled super case II transport of BSA through the synthesized microspheres. Therefore, in conclusion, as ascertained from the results the introduction of -COOH moieties along the guar gum chain drastically increases the end-use performance due to pH-sensitivity.

Modification of hydroxypropyl guar gum with ethanolamine.

A new guar gum derivative containing amino group was synthesized through nucleophilic substitution of p-toluenesulfonate activated hydroxypropyl guar gum with ethanolamine. For the preparation of p-toluenesulfonate esters hydroxypropyl guar gum, the results showed that the reaction rate was optimal at 25 °C and the reaction could reach equilibrium state when it was carried out for 10h at 25 °C. For the nucleophilic substitution of tosyl group with ethanolamine, the reaction was completed after 10h reaction at 50 °C. The structures of products were characterized by NMR and FT-IR spectroscopy. The results showed that the p-toluenesulfonate esters can be effectively substituted by ethanolamine to form the hydroxyethyl amino hydroxypropyl guar gum (EAHPG). The content of nitrogen of EAHPG was determined by acid-base titration and element analysis.

Occurrence of xylan and mannan polysaccharides and their spatial relationship with other cell wall components in differentiating compression wood tracheids of Cryptomeria japonica.

Compression wood (CW) tracheids have different cell wall components than normal wood (NW) tracheids. However, temporal and spatial information on cell wall components in CW tracheids is poorly understood. We investigated the distribution of arabino-4-O-methylglucuronoxylans (AGXs) and O-acetyl-galactoglucomannans (GGMs) in differentiating CW tracheids. AGX labeling began to be detected in the corner of the S(1) layer at the early S(1) formation stage. Subsequently, the cell corner middle lamella (ccML) showed strong AGX labeling when intercellular spaces were not fully formed. AGX labeling was uniformly distributed in the S(1) layer, but showed uneven distribution in the S(2) layer. AGX labeling was mainly detected in the inner S(2) layer after the beginning of the helical cavity formation. The outer S(2) layer showed almost no labeling of low substituted AGXs. Only a very small amount of high substituted AGXs was distributed in the outer S(2) layer. These patterns of AGX labeling in the S(2) layer opposed the lignin and ß-1-4-galactan distribution in CW tracheids. GGM labeling patterns were almost identical to AGX labeling in the early stages of CW tracheids, and GGM labeling was detected in the entire S(2) layer from the early S(2) formation stage of CW tracheids with some spatial differences in labeling density depending on developmental stage. Compared with NW tracheids, CW tracheids showed significantly different AGX distributions in the secondary cell wall but similar GGM labeling patterns. No significant differences were observed in labeling after delignification of CW tracheids.

Study on swelling model and thermodynamic structure of native konjac glucomannan.

We investigated the higher structure of konjac glucomannan (KGM) in the amorphous state and solution using a laser particle size analyzer and a water activity meter. The results show that the thermodynamic structures of native KGM were primarily composed of the lamella structure units, which involve both granular crystalline and amorphous regions, and that the connection zones of such units contained both loose and tight aggregation regions. The value of surface tension (sigma) of native KGM, resting with the density of its hydroxyl groups' self-association, was an important parameter to analyze the higher structures of native KGM in the thermodynamic swelling model of native KGM.

Digestion of single crystals of mannan I by an endo-mannanase from Trichoderma reesei.

The enzymatic degradation of single crystals of mannan I with the catalytic core domain of a beta-mannanase (EC 3.2.1.78 or Man5A) from Trichoderma reesei was investigated by transmission electron microscopy and electron diffraction. The enzyme attack took place at the edge of the crystals and progressed towards their centres. Quite remarkably the crystalline integrity of the crystals was preserved almost to the end of the digestion process. This behaviour is consistent with an endo-mechanism, where the enzyme interacts with the accessible mannan chains located at the crystal periphery and cleaves one mannan molecule at a time. The endo mode of digestion of the crystals was confirmed by an analysis of the soluble degradation products.