| 1. |
- Rasheed, Faiza, et al.
(författare)
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Structural architecture and solubility of native and modified gliadin and glutenin proteins : non-crystalline molecular and atomic organization
- 2014
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Ingår i: RSC Advances. - 2046-2069. ; 4:4, s. 2051-2060
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Tidskriftsartikel (refereegranskat)abstract
- Wheat gluten (WG) and its components, gliadin and glutenin proteins, form the largest polymers in nature, which complicates the structural architecture of these proteins. Wheat gluten, gliadin and glutenin proteins in unmodified form showed few secondary structural features. Structural modification of these proteins using heat, pressure and the chemical chaperone glycerol resulted in a shift to organized structure. In modified gliadin, nano-structural molecular arrangements in the form of hexagonal closed packed (HCP) assemblies with lattice parameter of (58 angstrom) were obvious together with development of intermolecular disulphide bonds. Modification of glutenin resulted in highly polymerized structure with proteins linked not only by disulphide bonds, but also with other covalent and irreversible bonds, as well as the highest proportion of beta-sheets. From a combination of experimental evidence and protein algorithms, we have proposed tertiary structure models of unmodified and modified gliadin and glutenin proteins. An increased understanding of gliadin and glutenin proteins structure and behavior are of utmost importance to understand the applicability of these proteins for various applications including plastic materials, foams, adhesives, films and coatings.
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| 2. |
- Chen, Fei, et al.
(författare)
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Wheat gluten/chitosan blends : A new biobased material
- 2014
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Ingår i: European Polymer Journal. - : Elsevier BV. - 0014-3057 .- 1873-1945. ; 60, s. 186-197
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Tidskriftsartikel (refereegranskat)abstract
- Wheat gluten and chitosan are renewable materials that suffer from some poor properties that limit their use as a potential replacement of petroleum-based polymers. However, polymer blends based on wheat gluten and chitosan surprisingly reduced these shortcomings. Films were cast from acidic aqueous or water/ethanol solutions of wheat gluten and chitosan. Wheat gluten was the discontinuous phase in the 30-70 wt.% wheat gluten interval investigated. The most homogeneous films were obtained when reducing agents were used (alone or together with urea or glycerol). They consisted mainly of 1-2 mu m wheat gluten particles uniformly distributed in the continuous chitosan phase. Slightly smaller particles were also observed in the water/ethanol solvent system, but together with significantly larger particles (as large as 200 mu m). Both small and large particles were observed, albeit in different sizes and contents, when surfactants (both with and without a reducing agent) or urea (without a reducing agent) were used. The particles were often elongated, and preferably along the film, the most extreme case being observed when the glyoxal crosslinker was used together with sodium sulfite (reducing agent), showing particles with an average thickness of 0.6 mu m and an aspect ratio of 4.2. This film showed the highest transparency of all the blend films studied. For one of the most promising systems (with sodium sulfite), having good film homogeneity and small particles, the mechanical and moisture solubility/diffusivity properties were studied as a function of chitosan content. The extensibility, toughness and moisture solubility increased with increasing chitosan content, and the moisture diffusivity was highest for the pristine chitosan material. It is noteworthy that the addition of 30 wt.% wheat gluten to chitosan reduced the moisture uptake, while the extensibility/toughness remained unchanged.
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| 3. |
- Kuktaite, Ramune, et al.
(författare)
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Gluten biopolymer and nanoclay-derived structures in wheat gluten-urea-clay composites
- 2014
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Ingår i: ACS Sustainable Chemistry and Engineering. - : American Chemical Society (ACS). - 2168-0485. ; 2:6, s. 1439-1445
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Tidskriftsartikel (refereegranskat)abstract
- Here, we investigated the structure of natural montmorillonite (MMT) and modified Cloisite C15A (MMT pre-intercalated with a dimethyl-dehydrogenated tallow quaternary ammonium surfactant) nanoclays in the wheat gluten-urea matrix in order to obtain a nanocomposite with improved barrier and mechanical properties. Small-angle X-ray scattering indicated that the characteristic hexagonal closed packed structure of the wheat gluten-urea matrix was not found in the C15A system and existed only in the 3 and 5 wt % MMT composites. SAXS/WAXS, TGA, and water vapor/oxygen barrier properties indicated that the dispersion of the C15A clay was somewhat better than the natural MMT clay. Confocal laser scanning microscopy showed MMT clay clusters and C15A clay particles dispersed in the protein matrix, and these were preferentially oriented in the extrusion direction only at 5 wt % of the C15 clay. The water vapor/oxygen barrier properties were improved with the presence of clay. Independent of the clay content used, the stiffness decreased and the extensibility increased in the presence of C15A due to the surfactant induced changes on the protein. The opposite "more expected" clay effect (increasing stiffness and decreasing extensibility) was observed for the MMT composites.
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| 4. |
- Kuktaite, Ramune, et al.
(författare)
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Gluten Biopolymer and Nanoclay-Derived Structures in Wheat Gluten-Urea-Clay Composites: Relation to Barrier and Mechanical Properties
- 2014
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Ingår i: ACS Sustainable Chemistry & Engineering. - : American Chemical Society (ACS). - 2168-0485. ; 2:6, s. 1439-1445
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Tidskriftsartikel (refereegranskat)abstract
- Here, we investigated the structure of natural montmorillonite (MMT) and modified Cloisite C15A (MMT pre-intercalated with a dimethyl-dehydrogenated tallow quaternary ammonium surfactant) nanoclays in the wheat gluten-urea matrix in order to obtain a nanocomposite with improved barrier and mechanical properties. Small-angle X-ray scattering indicated that the characteristic hexagonal closed packed structure of the wheat gluten-urea matrix was not found in the CISA system and existed only in the 3 and 5 wt % MMT composites. SAXS/WAXS, TGA, and water vapor/oxygen barrier properties indicated that the dispersion of the C15A clay was somewhat better than the natural MMT clay. Confocal laser scanning microscopy showed MMT clay clusters and C15A clay particles dispersed in the protein matrix, and these were preferentially oriented in the extrusion direction only at 5 wt % of the CIS clay. The water vapor/oxygen barrier properties were improved with the presence of clay. Independent of the clay content used, the stiffness decreased and the extensibility increased in the presence of C15A due to the surfactant induced changes on the protein. The opposite "more expected" clay effect (increasing stiffness and decreasing extensibility) was observed for the MMT composites.
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| 5. |
- Muneer, Faraz, et al.
(författare)
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Preparation, Properties, Protein Cross-Linking and Biodegradability of Plasticizer-Solvent Free Hemp Fibre Reinforced Wheat Gluten, Glutenin, and Gliadin Composites
- 2014
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Ingår i: BioResources. - : BioResources. - 1930-2126. ; 9:3, s. 5246-5261
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Tidskriftsartikel (refereegranskat)abstract
- The present study is aimed at evaluating the use of plant-based polymers and fibres for the production of sustainable biocomposites. For the first time, plasticiser/solvent-free hemp fibre-reinforced wheat gluten and hemp-gliadin and glutenin composites were obtained by compression moulding at different temperatures. The plasticiser/solvent-free sample preparation method developed in this study facilitated the use of a powdered protein matrix with a mat of randomly oriented hemp fibres. The tensile and protein cross-linking properties, as well as the biodegradability, were investigated. The addition of hemp fibre to the protein matrix increased the E-modulus by 20 to 60% at 130 degrees C. An increase in moulding temperature from 110 to 130 degrees C resulted in an increase in maximum stress due to the formation of intermolecular bonds between protein chains. The gliadin composites had higher E-modulus and maximum stress and showed a larger increase in protein polymerisation with increased temperature compared to the gluten in composites. A comparison of tensile properties revealed that the composites were stiffer and stronger compared to several similarly produced biobased composites. The composites were found to be fully biodegradable under a simulated soil environment after 180 days. Biocomposites produced in the present study were found to be environmentally friendly with fairly good mechanical properties.
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| 6. |
- Newson, William, et al.
(författare)
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Effect of Additives on the Tensile Performance and Protein Solubility of Industrial Oilseed Residual Based Plastics
- 2014
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Ingår i: Journal of Agricultural and Food Chemistry. - : American Chemical Society (ACS). - 0021-8561 .- 1520-5118. ; 62:28, s. 6707-6715
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Tidskriftsartikel (refereegranskat)abstract
- Ten chemical additives were selected from the literature for their proposed modifying activity in protein-protein interactions. These consisted of acids, bases, reducing agents, and denaturants and were added to residual deoiled meals of Crambe abyssinica (crambe) and Brassica carinata (carinata) to modify the properties of plastics produced through hot compression molding at 130 degrees C. The films produced were examined for tensile properties, protein solubility, molecular weight distribution, and water absorption. Of the additives tested, NaOH had the greatest positive effect on tensile properties, with increases of 105% in maximum stress and 200% in strain at maximum stress for crambe and a 70% increase in strain at maximum stress for carinata. Stiffness was not increased by any of the applied additives. Changes in tensile strength and elongation for crambe and elongation for carinata were related to changes in protein solubility. Increased pH was the most successful in improving the protein aggregation and mechanical properties within the complex chemistry of residual oilseed meals.
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| 7. |
- Rasheed, Faiza, et al.
(författare)
-
Structural architecture and solubility of native and modified gliadin and glutenin proteins: non-crystalline molecular and atomic organization
- 2014
-
Ingår i: RSC Advances. - : Royal Society of Chemistry (RSC). - 2046-2069. ; 4:4, s. 2051-2060
-
Tidskriftsartikel (refereegranskat)abstract
- Wheat gluten (WG) and its components, gliadin and glutenin proteins, form the largest polymers in nature, which complicates the structural architecture of these proteins. Wheat gluten, gliadin and glutenin proteins in unmodified form showed few secondary structural features. Structural modification of these proteins using heat, pressure and the chemical chaperone glycerol resulted in a shift to organized structure. In modified gliadin, nano-structural molecular arrangements in the form of hexagonal closed pack (HCP) assemblies with lattice parameter of (58 Å) were obvious together with development of intermolecular disulphide bonds. Modification of glutenin resulted in highly polymerized structure with proteins linked not only by disulphide bonds, but also with other covalent and irreversible bonds, as well as the highest proportion of b-sheets. From a combination of experimental evidence and protein algorithms, we have proposed tertiary structure models of unmodified and modified gliadin and glutenin proteins. An increased understanding of gliadin and glutenin proteins structure and behavior are of utmost importance to understand the applicability of these proteins for various applications including plastics materials, foams, adhesives, films and coatings.
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| 8. |
- Santoro, G., et al.
(författare)
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Use of intermediate focus for grazing incidence small and wide angle x-ray scattering experiments at the beamline P03 of PETRA III, DESY
- 2014
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Ingår i: Review of Scientific Instruments. - : AIP Publishing. - 0034-6748 .- 1089-7623. ; 85:4, s. 043901-
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Tidskriftsartikel (refereegranskat)abstract
- We describe the new experimental possibilities of the micro- and nanofocus X-ray scattering beamline P03 of the synchrotron source PETRA III at DESY, Hamburg (Germany), which arise from experiments with smaller beam sizes in the micrometer range. This beamline has been upgraded recently to perform new kinds of experiments. The use of an intermediate focus allows for reducing the beam size of microfocused hard X-rays while preserving a large working distance between the focusing elements and the focus position. For the first time, this well-known methodology has been employed to grazing incidence small- and wide-angle X-ray scattering (GISAXS/GIWAXS). As examples, we highlight the applications to in situ studies using microfluidic devices in GISAXS geometry as well as the investigation of the crystallinity of thin films in GIWAXS geometry.
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| 9. |
- Amanizadeh, Farhad, et al.
(författare)
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Starve fed emulsion copolymerization of vinyl acetate and 1-hexene at ambient pressure
- 2014
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Ingår i: Polymer international. - : Wiley. - 0959-8103 .- 1097-0126. ; 63:10, s. 1850-1855
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Tidskriftsartikel (refereegranskat)abstract
- A novel emulsion copolymer of vinyl acetate (VAc) and 1-hexene was synthesized at ambient pressure. The feeding technique, initiation system and reaction time of the copolymerization were optimized based on molecular characteristics such as the weight contribution of 1-hexene in the copolymer chains and glass transition temperature (T-g) as well as on bulk properties like minimum film-formation temperature (MFFT) and solid content. According to nuclear magnetic resonance spectroscopy and differential scanning calorimetry results, the combination of starve feeding and redox initiation, within a reaction time of 4h, effectively led to the copolymerization at ambient pressure between highly reactive polar VAc monomers and non-polar 1-hexene monomers of low reactivity. The copolymer showed a lower T-g and MFFT, and a reasonable solid content compared to the poly(vinyl acetate) (PVAc) homopolymer. The consumption rate, hydrolysis of acetate groups and chain transfer reactions during the polymerization were followed using infrared spectroscopy. Based on the results, the undesirable reactions between the VAc blocks were hindered by the neighbouring 1-hexene molecules. Tensile testing revealed an improvement in the toughness and elongation at break of VAc-1-hexene films compared to PVAc films.
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| 10. |
- Andersson, Richard L., et al.
(författare)
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Antibacterial Properties of Tough and Strong Electrospun PMMA/PEO Fiber Mats Filled with Lanasol-A Naturally Occurring Brominated Substance
- 2014
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Ingår i: International Journal of Molecular Sciences. - : MDPI AG. - 1661-6596 .- 1422-0067. ; 15:9, s. 15912-15923
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Tidskriftsartikel (refereegranskat)abstract
- A new type of antimicrobial, biocompatible and toughness enhanced ultra-thin fiber mats for biomedical applications is presented. The tough and porous fiber mats were obtained by electrospinning solution-blended poly (methyl methacrylate) (PMMA) and polyethylene oxide (PEO), filled with up to 25 wt % of Lanasol-a naturally occurring brominated cyclic compound that can be extracted from red sea algae. Antibacterial effectiveness was tested following the industrial Standard JIS L 1902 and under agitated medium (ASTM E2149). Even at the lowest concentrations of Lanasol, 4 wt %, a significant bactericidal effect was seen with a 4-log (99.99%) reduction in bacterial viability against S. aureus, which is one of the leading causes of hospital-acquired (nosocomial) infections in the world. The mechanical fiber toughness was insignificantly altered up to the maximum Lanasol concentration tested, and was for all fiber mats orders of magnitudes higher than electrospun fibers based on solely PMMA. This antimicrobial fiber system, relying on a dissolved antimicrobial agent (demonstrated by X-ray diffraction and Infrared (IR)-spectroscopy) rather than a dispersed and "mixed-in" solid antibacterial particle phase, presents a new concept which opens the door to tougher, stronger and more ductile antimicrobial fibers.
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