| 1. |
- Chen, Fei, 1984-, et al.
(författare)
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Unusual Effects of Monocarboxylic Acids on The Structure and on The Transport and Mechanical Properties of Chitosan Films
- 2015
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Ingår i: Carbohydrate Polymers. - : Elsevier BV. - 0144-8617 .- 1879-1344. ; 132, s. 419-429
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Tidskriftsartikel (refereegranskat)abstract
- The purpose of this study was to study the transport of monocarboxylic acids in chitosan films, since this is important for understanding and predicting the drying kinetics of chitosan from aqueous solutions. Despite the wealth of data on chitosan films prepared from aqueous monocarboxylic acid solutions, this transport has not been reported. Chitosan films were exposed to formic, acetic, propionic and butyric acid vapours, it was found that the rate of uptake decreased with increasing molecular size. The equilibration time was unexpectedly long, especially for propionic and butyric acid, nine months. A clear two-stage uptake curve was observed for propionic acid. Evidently, the rate of uptake was determined by acid-induced changes in the material. X-ray diffraction and infrared spectroscopy indicated that the structure of the chitosan acetate and buffered chitosan films changed during exposure to acid and during the subsequent drying. The dried films previously exposed to the acid showed less crystalline features than the original material and a novel repeating structure possibly involving acid molecules. The molar mass of the chitosan decreased on exposure to acid but tensile tests revealed that the films were always ductile. The films exposed to acid vapour (propionic and butyric acid) for the longest period of time were insoluble in the size-exclusion chromatography eluent, and they were also the most ductile/extensible of all samples studied.
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| 2. |
- Kuktaite, Ramune, et al.
(författare)
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Monitoring Nanostructure Dynamics and Polymerization in Glycerol Plasticized Wheat Gliadin and Glutenin Films : Relation to Mechanical Properties
- 2016
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Ingår i: ACS Sustainable Chemistry and Engineering. - : American Chemical Society (ACS). - 2168-0485. ; 4:6, s. 2998-3007
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Tidskriftsartikel (refereegranskat)abstract
- Gliadin and glutenin proteins with 10, 20, 30 and 40% of glycerol were compression molded into films (130 °C) and evaluated for protein polymerization, β-sheet structure and nano-structural morphology. Here, for the first time we show how different amounts of glycerol impact the nano-structure and functional properties of the gliadin and glutenin films. Most polymerized protein was found in the gliadin films with 20 and 30% glycerol, and in all the glutenin films (except 10%), by RP-HPLC. A β-sheet-rich protein structure was found to be high in the 10 and 20% glycerol gliadin films, and in the 20 and 30% glycerol glutenin films by FT-IR. Glycerol content of 20, 30 and 40% impacted the nano-structural morphology of the gliadin glycerol films observed by SAXS, and to a limited extent for 10 and 20% glycerol gliadin films revealed by WAXS. No ordered nano-structure was found for the glutenin glycerol films. The 20%, 30% and 40% glycerol films were the most tunable for specific mechanical properties. For the highest stiffness and strength, the 10% glycerol protein films were the best choice.
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| 3. |
- Muneer, Faraz, et al.
(författare)
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Nanostructural Morphology of Plasticized Wheat Gluten and Modified Potato Starch Composites: Relationship to Mechanical and Barrier Properties
- 2015
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Ingår i: Biomacromolecules. - : American Chemical Society (ACS). - 1526-4602 .- 1525-7797. ; 16:3, s. 695-705
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Tidskriftsartikel (refereegranskat)abstract
- In the present study, we were able to produce composites of wheat gluten (WG) protein and a novel genetically modified potato starch (MPS) with attractive mechanical and gas barrier properties using extrusion. Characterization of the MPS revealed an altered chain length distribution of the amylopectin fraction and slightly increased amylose content compared to wild type potato starch. WG and MPS of different ratios plasticized with either glycerol or glycerol and water were extruded at 110 and 130 °C. The nanomorphology of the composites showed the MPS having semicrystalline structure of a characteristic lamellar arrangement with an approximately 100 Å period observed by small-angle X-ray scattering and a B-type crystal structure observed by wide-angle X-ray scattering analysis. WG has a structure resembling the hexagonal macromolecular arrangement as reported previously in WG films. A larger amount of β-sheets was observed in the samples 70/30 and 30/70 WG-MPS processed at 130 °C with 45% glycerol. Highly polymerized WG protein was found in the samples processed at 130 °C versus 110 °C. Also, greater amounts of WG protein in the blend resulted in greater extensibility (110 °C) and a decrease in both E-modulus and maximum stress at 110 and 130 °C, respectively. Under ambient conditions the WG-MPS composite (70/30) with 45% glycerol showed excellent gas barrier properties to be further explored in multilayer film packaging applications.
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| 4. |
- Newson, William, et al.
(författare)
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Effect of extraction routes on protein content, solubility and molecular weight distribution of Crambe abyssinica protein concentrates and thermally processed films thereof
- 2017
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Ingår i: Industrial crops and products (Print). - : Elsevier BV. - 0926-6690 .- 1872-633X. ; 97, s. 591-598
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Tidskriftsartikel (refereegranskat)abstract
- To understand if and how extraction conditions influence properties of molded protein films, Crambe abyssinica protein concentrates were produced from deoiled seed meal under various extraction conditions. Properties of the resulting hot compression molded films were evaluated through the molecular weight distribution, protein polymerization behavior and tensile tests. Precipitated protein concentrates demonstrated higher protein content and a pronounced shift to higher molecular weight distributions and reduced solubility on heating, indicating increased protein polymerization compared to those from lyophilized supernatants. Thermally processed films from isoelectrically precipitated protein concentrates show a high resistance to extraction with a combination of reducing agent and denaturant, indicating the presence of non-disulfide covalent cross linking. Also, tensile strength was higher in concentrates from precipitated proteins compared to those from supernatants. The protein concentrates resulting in thermally processed films with a high protein content, the highest levels of protein-protein interaction and high tensile strength were based on alkaline extraction and isoelectric precipitation. Therefore, a combination of alkali extraction and isoelectric precipitation is recommended to produce protein concentrates for molded film production.
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| 5. |
- Ye, Xinchen, et al.
(författare)
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Protein/Protein Nanocomposite Based on Whey Protein Nanofibrils in a Whey Protein Matrix
- 2018
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Ingår i: ACS Sustainable Chemistry and Engineering. - : American Chemical Society (ACS). - 2168-0485. ; 6:4, s. 5462-5469
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Tidskriftsartikel (refereegranskat)abstract
- This article describes nanocomposite films with separately grown protein nanofibrils (PNFs) in a nonfibrillar protein matrix from the same protein starting material (whey). Tensile tests on the glycerol-plasticized films indicate an increased elastic modulus and a decreased extensibility with increasing content of PNFs, although the films are still ductile at the maximum PNF content (15 wt %). Infrared spectroscopy confirms that the strongly hydrogen-bonded beta-sheets in the PNFs are retained in the composites. The films appear with a PNF-induced undulated upper surface. It is shown that micrometer-scale spatial variations in the glycerol distribution are not the cause of these undulations. Instead, the undulations seem to be a feature of the PNF material itself. It was also shown that, apart from plasticizing the protein film, the presence of glycerol seemed to favor to some extent exfoliation of stacked beta-sheets in the proteins, as revealed by X-ray diffraction.
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| 6. |
- Chen, Fei, et al.
(författare)
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A novel chitosan/wheat gluten biofoam fabricated by spontaneous mixing and vacuum-drying
- 2015
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Ingår i: RSC Advances. - : Royal Society of Chemistry. - 2046-2069. ; 5:114, s. 94191-94200
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Tidskriftsartikel (refereegranskat)abstract
- A new type of chitosan and wheat gluten biofoam is presented. The pore structure achieved relied solely on the specific mixing and phase distribution when a film was cast from an aqueous mixture of chitosan/wheat gluten solution, in the absence of any chemical blowing agent, porogen or expanding gas. The foam was obtained when the liquid phase was removed by vacuum drying, without the need for the traditional freeze-drying that is frequently used for pore formation. Soft foam samples could be prepared with stiffnesses from 0.3 to 1.2 MPa and a high rebound resilience (64 and 94% at compressive strains of 80 and 20%, respectively). The foams were relatively ductile and did not require any plasticiser to allow for in-plane deformation (20% compression) and smaller bending. Only open pores with sizes of the order of 70-80 μm were observed by microscopy. The density of all the foams was ∼50 kg m-3, due to the high porosity (96% air). The foams showed a rapid and large uptake of both non-polar (limonene) and polar (water) liquids. When immersed in these liquids for 1 second, the maximum uptake recorded was 40 times the initial mass of the foam for limonene and 8 times for water.
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| 7. |
- Menzel, Carolin, et al.
(författare)
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Improved material properties of solution-cast starch films : Effect of varying amylopectin structure and amylose content of starch from genetically modified potatoes
- 2015
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Ingår i: Carbohydrate Polymers. - : Elsevier BV. - 0144-8617 .- 1879-1344. ; 130, s. 388-397
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Tidskriftsartikel (refereegranskat)abstract
- High-amylose potato starches were produced through genetic modification resulting in changed granule morphology and composition, with higher amylose content and increased chain length of amylopectin. The increased amylose content and structural changes in amylopectin enhanced film-forming behavior and improved barrier and tensile properties in starch films. The molecular structure in these starches was related to film-forming properties. Solution-cast films of high-amylose starch revealed a homogeneous structure with increasing surface roughness at higher amylose content, possibly due to amylose aggregation. Films exhibited significantly higher stress and strain at break compared with films of wild-type starch, which could be attributable to the longer chains of amylopectin being involved in the interconnected network and more interaction between chains, as shown using transmission electron microscopy. The oxygen permeability of high-amylose starch films was significantly decreased compared with wild-type starch. The nature of the modified starches makes them an interesting candidate for replacement of non-renewable oxygen and grease barrier polymers used today.
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| 8. |
- Newson, William, et al.
(författare)
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Commercial potato protein concentrate as a novel source for thermoformed bio-based plastic films with unusual polymerisation and tensile properties
- 2015
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Ingår i: RSC Advances. - : Royal Society of Chemistry (RSC). - 2046-2069. ; 5:41, s. 32217-32226
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Tidskriftsartikel (refereegranskat)abstract
- Commercial potato protein concentrate (PPC) was investigated as a source of thermoformed bio-based plastic film. Pressing temperatures of 100 to 190°C with 15 to 25% glycerol were used to form PPC films. The shape of the tensile stress-strain curve in thermoformed PPC was controlled by glycerol level and was independent of processing temperature. Tensile testing revealed that elongation at break increased with processing temperature while Young's modulus was unaffected by processing temperature, both in contrast to previous results in protein based systems. Also in contrast to previous studies, Young's modulus was found to be only sensitive to glycerol level. Maximum tensile stress increased with increasing processing temperature for PPC films. Maximum stress and strain at break correlated with the extractable high molecular weight protein content of the processed films measured with size exclusion chromatography. Infrared absorption indicated that the content of β-sheet structure increased from the commercial protein concentrate to that pressed at 100°C, but did not further develop with increasing press temperature. Changes in structural arrangements were observed by small angle X-ray scattering indicating the development of different correlation distances with processing temperature but with no clear long range order at the supramolecular level. The novel Young's modulus behaviour appears to be due to constant secondary structure or the effect of aggregated protein structure formed during protein production. Unique strain at break behaviour with processing temperature was demonstrated, likely due to new connections formed between those aggregates.
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| 9. |
- Rasel, H., et al.
(författare)
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Development of bioplastics based on agricultural side-stream products : Film extrusion of Crambe abyssinica/wheat gluten blends for packaging purposes
- 2015
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Ingår i: Journal of Applied Polymer Science. - : John Wiley & Sons. - 0021-8995 .- 1097-4628. ; 133:2
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Tidskriftsartikel (refereegranskat)abstract
- The purpose of this work was to add economic value to crambe meal, the protein-rich byproduct from the industrial extraction of Crambe abyssinica seed oil, by using it as a potential feedstock for oilseed meal-based plastics. The feasibility to produce continuous, flexible plastic films of glycerol-plasticized crambe meal blended with wheat gluten (WG) to improve extrudate properties and urea as a protein denaturant using extrusion was investigated. The effect of process parameters and blend composition were studied with regard to the extrusion performance and the film properties. Tensile properties and oxygen permeability were determined, and the film morphology was analyzed with scanning electron microscopy. A die temperature between 125 and 130°C resulted in films with the most homogeneous surfaces and highest tensile strength and extensibility. The use of compression molding after extrusion improved the surface quality and film strength and lowered the oxygen permeability. A decrease in the plasticizer content (from 30 to 20 wt %) improved the extrudability and showed the highest tensile strength, whereas the extensibility was essentially unaffected. The importance of the presence of WG was shown by the fact that strength and extensibility decreased when the crambe content was increased from 60 to 80 wt %. It was shown that crambe-based biopolymer blends could be extruded as continuous flexible plastic films that exhibited promising mechanical and oxygen barrier properties. The operational window was, however, found to be narrow. The results provide a first basis to further develop the process and the blend toward industrial applications, for example, as packaging materials.
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