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  • 1.
    Altskär, Annika
    et al.
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SIK – Institutet för livsmedel och bioteknik.
    Andersson, R.
    Boldizar, A.
    Koch, K.
    Stading, Mats
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SIK – Institutet för livsmedel och bioteknik.
    Rigdahl, M.
    Some effects of processing on the molecular structure and morphology of thermoplastic starch2008In: Carbohydrate Polymers, ISSN 0144-8617, E-ISSN 1879-1344, Vol. 71, no 4, p. 591-597Article in journal (Refereed)
    Abstract [en]

    Hydroxypropylated and oxidised potato starch (HONPS) was used together with glycerol and water to produce thermoplastic starch. The amount of glycerol was kept constant at 22 parts by weight per 100 parts of dry starch. The thermoplastic starch was converted into films/sheets using three different processing techniques; casting, compression moulding and film blowing. The last two methods represent typical thermoplastic conversion techniques requiring elevated processing temperatures. By means of size-exclusion chromatography, it was found that compression moulding and film blowing led to some degradation of high-molecular weight amylopectin as well as of high-molecular weight amylose-like molecules. The degradation was significantly less pronounced for the cast films. The morphology of the specimens was quite complex and phase separations on different levels were identified. In the cast films and, to a lesser extent, in the compression-moulded specimens, a fine network structure could be distinguished. Such a structure could however not be ascertained in the film-blown material and this is discussed in terms of the thermo-mechanical treatment of the starch materials. © 2007 Elsevier Ltd. All rights reserved.

  • 2. Anthonsen, M.W.
    et al.
    Varum, K.M.
    Hermansson, Ann-Marie
    SIK – Institutet för livsmedelsforskning.
    Smidsrod, O.
    Brant, D.A.
    Aggregates in acidic solutions of chitosans detected by static laser light scattering1994In: Carbohydrate Polymers, ISSN 0144-8617, E-ISSN 1879-1344, Vol. 25, no 1, p. 13-23Article in journal (Refereed)
    Abstract [en]

    Chitosans having degrees of N-acetylation, FA, ranging from 0 to 0·6, were randomly degraded to different molecular weights and studied by multi angle static laser light scattering (LLS). Under the given experimental conditions, negative second virial coefficients of the solutions, A?2, revealed the presence of concentration dependent aggregates. Attempts to remove the aggregates, or to influence the aggregation behavior, were made by ultracentrifugation and extensive filtering of the solutions. Modification of the solvent conditions such as pH, ionic strength and temperature were carried out, and chitosan solutions were digested with an acidic proteinase. Non-degraded samples and chitosans prepared by both heterogeneous and homogeneous N-deacetylation of chitin were also studied. In all cases, the negative A?2 remained. However, it was observed that ultracentrifugation and filtering of the solutions decreased the measured molecular weights and radii of gyration, indicating that some of the material of high molecular weight and size could be removed by ultracentrifugation and filtration. The chemical nature of the physical basis of the molecular association was not revealed. Nevertheless, by the use of gel permeation chromatography coupled to an on-line low angle laser light scattering instrument and a differential refractive index concentration detector (HPSEC-LALLS-RI), a bimodal molecular weight distribution was observed in which about 5% of the sample had a very high molecular weight. These results coupled with the positive virial coefficients obtained earlier from osmotic pressure measurements suggest that a small fraction of the chitosan is aggregated to high molecular weight material, probably following a closed association model. Electron microscopy revealed the presence of some supramolecular structures. The positive second virial coefficients obtained earlier from osmometry are in harmony with these findings. The results demonstrate the occurrence of reversible aggregation in chitosan solutions. Static laser light scattering therefore cannot readily be used to determine molecular weights and sizes of chitosans under these conditions. It was not possible to correlate the extent of aggregation with the chemical composition of the chitosans. © 1994.

  • 3.
    Basu, Alex
    et al.
    Uppsala University, Sweden.
    Lindh, Jonas
    Uppsala university, Sweden.
    Ålander, Eva
    RISE - Research Institutes of Sweden, Bioeconomy.
    Strömme, Maria
    Uppsala university, Sweden.
    Ferraz, Natalia
    Uppsala university, Sweden.
    On the use of ion-crosslinked nanocellulose hydrogels for wound healing solutions: Physicochemical properties and application-oriented biocompatibility studies2017In: Carbohydrate Polymers, ISSN 0144-8617, E-ISSN 1879-1344, Vol. 174, p. 299-308Article in journal (Refereed)
    Abstract [en]

    Calcium ion-crosslinked nanofibrillated cellulose (NFC) hydrogels were investigated as potential materials for wound healing dressings. The physicochemical properties of the hydrogels were examined by rheology and water retention tests. Skin cells and monocytes were selected for application-oriented biocompatibility studies. The NFC hydrogels presented entangled fibrous networks and solid-like behavior. Water retention tests showed the materialÂŽs potential to maintain a suitable moist environment for different type of wounds. The hydrogels did not affect dermal fibroblasts monolayer cultures upon direct contact, as cell monolayers remained intact after application, incubation and removal of the materials. Inflammatory response studies with blood-derived mononuclear cells revealed the inert nature of the hydrogels in terms of cytokine secretion and reactive oxygen species production. Results highlight the great potential of ion-crosslinked NFC hydrogels for the development of advanced wound dressings, where further functionalization of the material could lead to improved properties towards the healing of specific wound types.

  • 4. Bergstrm, E.M.
    et al.
    Salmen, L.
    RISE, Innventia.
    Kochumalayil, J.
    Berglund, L.
    Plasticized xyloglucan for improved toughness: Thermal and mechanical behaviour2012In: Carbohydrate Polymers, ISSN 0144-8617, E-ISSN 1879-1344, no 4, p. 2532-2537Article in journal (Refereed)
  • 5.
    Borrega, Marc
    et al.
    Aalto university, Finland ; VTT Technical Research Centre of Finland Ltd, Finland.
    Larsson, Per Tomas
    RISE - Research Institutes of Sweden, Bioeconomy, Biorefinery and Energy.
    Ahvenainen, Patrik
    University of Helsinki, Finland.
    Ceccherini, Sara
    Aalto university, Finland.
    Maloney, Thaddeus
    Aalto university, Finland.
    Rautkari, Lauri
    Aalto university, Finland.
    Sixta, Herbert
    Aalto university, Finland.
    Birch wood pre-hydrolysis vs pulp post-hydrolysis for the production of xylan-based compounds and cellulose for viscose application2018In: Carbohydrate Polymers, ISSN 0144-8617, E-ISSN 1879-1344, Vol. 190, p. 212-221Article in journal (Refereed)
    Abstract [en]

    Hydrothermal treatments of birch wood and kraft pulp were compared for their ability to extract the xylan and produce viscose-grade pulp. Water post-hydrolysis of kraft pulp produced a high-purity cellulosic pulp with lower viscosity but higher cellulose yield than traditional pre-hydrolysis kraft pulping of wood. Post-hydrolysis of pulp also increased the crystallite dimensions and degree of crystallinity in cellulose, and promoted a higher extent of fibril aggregation. The lower specific surface area in post-hydrolyzed pulps, derived from their larger fibril aggregates, decreased the accessibility of –OH groups. However, this lower accessibility did not seem to decrease the pulp reactivity to derivatizing chemicals. In the aqueous side-stream, the xylose yield was similar in both pre- and post-hydrolysates, although conducting post-hydrolysis of pulp in a flow-through system enabled the recovery of high purity and molar mass (∌10 kDa) xylan for high-value applications.

  • 6. Chen, F.
    et al.
    Gällstedt, Mikael
    RISE, Innventia.
    Olsson, R. T.
    Gedde, U. W.
    Hedenqvist, M. S.
    Unusual effects of monocarboxylic acids on the structure and on the transport and mechanical properties of chitosan films2015In: Carbohydrate Polymers, ISSN 0144-8617, E-ISSN 1879-1344, Vol. 132, p. 419-429Article in journal (Refereed)
    Abstract [en]

    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.

  • 7. Fernandes, S.C.M.
    et al.
    Freire, C.S.R.
    Silvestre, A.J.D.
    Pascoal Neto, C.
    Gandini, A.
    Berglund, Lars A.
    Salmen, Lennart
    RISE, Innventia.
    Transparent chitosan films reinforced with a high content of nanofibrillated cellulose2010In: Carbohydrate Polymers, ISSN 0144-8617, E-ISSN 1879-1344, Vol. 81, no 2, p. 394-401Article in journal (Refereed)
    Abstract [en]

    This paper reports the preparation and characterization of nanocomposite films based on different chitosan matrices and nanofibrillated cellulose (NFC) for the purpose of improving strength properties. The nanocomposite films were prepared by a simple procedure of casting a water-based suspension of chitosan and NFC, and were characterized by several techniques: namely SEM, X-ray diffraction, visible spectrophotometry, TGA, tensile and dynamic-mechanical analysis. The films obtained were shown to be highly transparent (transmittance varying between 90 and 20% depending on the type of chitosan and NFC content), flexible, displayed better mechanical properties, with a maximum increment on the Young’s modulus of 78% and 150% for high molecular weight (HCH) and water-soluble high molecular weight (WSHCH) filled chitosans, respectively; and of 200% and 320% for low molecular weight (LCH) and water-soluble filled (WSLCH) chitosans, respectively. The filled films also showed increased thermal stability, with, for example, an increase in the initial degradation temperature (Tdi) from 227 °C in the unfilled LCH film up to 271 °C in filled LCHNFC50% nanocomposite films, and a maximum degradation temperature (Td1) raising from 304 °C to 313 °C for the same materials.

  • 8.
    Gillgren, Thomas
    et al.
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SIK – Institutet för livsmedel och bioteknik.
    Blennow, A.
    Pettersson, Anders
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SIK – Institutet för livsmedel och bioteknik.
    Stading, Mats
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SIK – Institutet för livsmedel och bioteknik.
    Modulating rheo-kinetics of native starch films towards improved wet-strength2011In: Carbohydrate Polymers, ISSN 0144-8617, E-ISSN 1879-1344, Vol. 83, no 2, p. 383-391Article in journal (Refereed)
    Abstract [en]

    Starch directly functionalised in the plant by modulation of its biosynthesis by mutagenesis and transgene technology was exploited for its extended functionality beyond the normal variation. In this study we investigated the rheological and mechanical properties of films from such structurally highly different starch types derived from potato and cereal sources of normal and mutant and transgenic backgrounds. A new improved technique was developed to permit the dynamic mechanical analysis of films in the presence of water. It was found that the amylose content was decisive for the mechanical properties of the films - an increase in the amylose content resulted in both a higher stress and strain at break. Interestingly, there was no correlation between the speed of hydration and mechanical water resistance of the films. Generally, the films were clear and transparent, even after wetting. Transgenic potato starch with a low content of phosphate displayed an extraordinary combination of high robustness, transparency, mechanical strength and extensibility even in a wet condition. The combination of optimal phosphate and amylose concentrations in this sample probably favoured hydration and amorphisation without compromising the inter-chain interactions of the polysaccharide network. © 2010 Elsevier Ltd. All rights reserved.

  • 9. Guo, J.
    et al.
    Song, K.
    Salmen, Lennart
    RISE, Innventia.
    Yin, Y.
    Changes of wood cell walls in response to hygro-mechanical steam treatment2015In: Carbohydrate Polymers, ISSN 0144-8617, E-ISSN 1879-1344, Vol. 115, p. 207-214Article in journal (Refereed)
    Abstract [en]

    The effects of compression combined with steam treatment (CS-treatment), i.e. a hygro-mechanical steam treatment on Spruce wood were studied on a cell-structure level to understand the chemical and physical changes of the secondary cell wall occurring under such conditions. Specially, imaging FT-IR microscopy, nanoindentation and dynamic vapour absorption were used to track changes in the chemical structure, in micromechanical and hygroscopic properties. It was shown that CS-treatment resulted in different changes in morphological, chemical and physical properties of the cell wall, in comparison with those under pure steam treatment. After CS-treatment, the cellular structure displayed significant deformations, and the biopolymer components, e.g. hemicellulose and lignin, were degraded, resulting in decreased hygroscopicity and increased mechanical properties of the wood compared to both untreated and steam treated wood. Moreover, CS-treatment resulted in a higher degree of degradation especially in earlywood compared to a more uniform behaviour of wood treated only by steam.

  • 10.
    Heggset, Ellinor B
    et al.
    RISE - Research Institutes of Sweden, Bioeconomy, PFI.
    Chinga-Carrasco, Gary
    RISE - Research Institutes of Sweden, Bioeconomy, PFI.
    Syverud, Kristin
    RISE - Research Institutes of Sweden, Bioeconomy, PFI. Norwegian University of Science and Technology (NTNU), Norway.
    Temperature stability of nanocellulose dispersions2017In: Carbohydrate Polymers, ISSN 0144-8617, E-ISSN 1879-1344, Vol. 157, p. 114-121Article in journal (Refereed)
    Abstract [en]

    Cellulose nanofibrils (CNF) have potential as rheology modifiers of water based fluids, e.g. drilling fluids for use in oil wells or as additives in injection water for enhanced oil recovery (EOR). The temperature in oil wells can be high (>100 °C), and the retention time long; days for drilling fluids and months for EOR fluids. Hence, it is important to assess the temperature stability over time of nanocellulose dispersions to clarify their suitability as rheology modifiers of water based fluids at such harsh conditions. Dispersions of CNF produced mechanically, by using TEMPO mediated oxidation and by using carboxymethylation as pretreatment, in addition to cellulose nanocrystals (CNC), have been subjected to heat aging. Temperature stability was best for CNC and for mechanically produced CNF that were stable after heating to 140 °C for three days. The effect of additives was evaluated; cesium formate and sodium formate increased the temperature stability of the dispersions, while there was no effect of using phosphate buffer.

  • 11.
    Hermansson, Ann-Marie
    SIK – Svenska livmedelsinstitutet.
    Rheological and microstructural evidence for transient states during gelation of kappa-carrageenan in the presence of potassium1989In: Carbohydrate Polymers, ISSN 0144-8617, E-ISSN 1879-1344, Vol. 10, no 3, p. 163-181Article in journal (Refereed)
    Abstract [en]

    Kappa-carrageenan gelation was studied by a combination of electron microscopy and dynamic viscoelastic measurements. There was an initial maximum in the storage modulus during cooling and gel formation of 1% kappa-carrageenan in the presence of potassium. The structure of the transient state was found to consist of a fine network structure, where the junction zones were believed to be double helices. The structure had the characteristics of a true gel but was unstable. When the temperature was lowered aggregation took place and the fine network structure was partly broken down. Ordered superstrands formed which aligned themselves in parallel or were densely packed together. The degree of aggregation depended on the potassium ion concentration. In the weakest gel formed in 0·01 m KCl, the superstrands did not form a network but were rather dispersed in the fine network structure. In 0·1 and 0·2 m KCl the superstrands formed a three-dimensional network, where aligned superstrands formed the junction zones and branching occurred when superstrands deviated from each other and aligned with new superstrands. In 0·1 m KCl the supermolecular network dominated but in 0·2 m KCl a mixed gel was formed of the fine network and the coarse supermolecular network. The mixed gel gave rise to the firmest gel. © 1989.

  • 12.
    Hermansson, Ann-Marie
    SIK – Svenska livmedelsinstitutet.
    Shear induced changes in the viscoelastic behaviour of heat treated potato starch dispersions1990In: Carbohydrate Polymers, ISSN 0144-8617, E-ISSN 1879-1344, Vol. 13, no 1, p. 29-45Article in journal (Refereed)
    Abstract [en]

    The viscoelastic behaviour of native potato starch dispersions was studied using dynamic viscoelastic measurements. The influence of various shear and heat treatments of gelatinized starch pastes were compared in the concentration range 4-10%. Heating had a minor effect compared to the effect of shear treatment. The complex modulus (G*) decreased to about 5% of its maximum value when the starch pastes were sheared during the heating cycle, whereas heating alone resulted in a decrease to about 60% of the maximum G* value. Shear also caused an increase in the phase angle and characteristic changes were observed with regard to frequency and strain dependencies. When samples were prepared in a Brabender viscograph, the shear induced changes took place early in the pasting cycle. The characteristics of the concentration dependence differed due to the shear history of the sample. Peculiar concentration dependencies, some even negative, could be obtained from samples with different shear histories. The results imply that even moderate shear treatment gives rise to structure changes which are reflected by a transition in the type of the viscoelastic behaviour. © 1990.

  • 13.
    Jack, Alison A.
    et al.
    Cardiff University School of Dentistry, UK.
    Nordli, Henriette R.
    NTNU, Norway.
    Powell, Lydia C.
    Cardiff University School of Dentistry, UK.
    Powell, Kate A.
    Cardiff University School of Dentistry, UK.
    Kishnani, Himanshu
    Cardiff University School of Dentistry, UK.
    Johnsen, Per Olav
    RISE - Research Institutes of Sweden, Bioeconomy, PFI.
    Pukstad, Brita
    Trondheim University Hospital, Norway.
    Thomas, David W.
    Cardiff University School of Dentistry, UK.
    Chinga-Carrasco, Gary
    RISE - Research Institutes of Sweden, Bioeconomy, PFI.
    Hill, Katja E.
    Cardiff University School of Dentistry, UK.
    The interaction of wood nanocellulose dressings and the wound pathogen P. aeruginosa2017In: Carbohydrate Polymers, ISSN 0144-8617, E-ISSN 1879-1344, Vol. 157, p. 1955-1962Article in journal (Refereed)
    Abstract [en]

    Chronic wounds pose an increasingly significant worldwide economic burden (over £1 billion per annum in the UK alone). With the escalation in global obesity and diabetes, chronic wounds will increasingly be a significant cause of morbidity and mortality. Cellulose nanofibrils (CNF) are highly versatile and can be tailored with specific physical properties to produce an assortment of three-dimensional structures (hydrogels, aerogels or films), for subsequent utilization as wound dressing materials. Growth curves using CNF (diameter <20 nm) in suspension demonstrated an interesting dose-dependent inhibition of bacterial growth. In addition, analysis of biofilm formation (Pseudomonas aeruginosa PAO1) on nanocellulose aerogels (20 g/m2) revealed significantly less biofilm biomass with decreasing aerogel porosity and surface roughness. Importantly, virulence factor production by P. aeruginosa in the presence of nanocellulose materials, quantified for the first time, was unaffected (p > 0.05) over 24 h. These data demonstrate the potential of nanocellulose materials in the development of novel dressings that may afford significant clinical potential.

  • 14. Larsson, M.
    et al.
    Viriden, A.
    Stading, Mats
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SIK – Institutet för livsmedel och bioteknik.
    Larsson, A.
    The influence of HPMC substitution pattern on solid-state properties2010In: Carbohydrate Polymers, ISSN 0144-8617, E-ISSN 1879-1344, Vol. 82, no 4, p. 1074-1081Article in journal (Refereed)
    Abstract [en]

    The solid-state properties were studied for different batches of hydroxypropyl methylcellulose (HPMC). The batches had similar chemical composition, but different degree of heterogeneity with regard to the distribution of the substituents along the polymer chains. The glass transition temperature, Tg, was analysed using a new developed method where dynamic mechanic analysis, DMA, was performed in compression mode on compacts, utilizing a wedge-shaped probe. The method was verified by conventional DMA on films. Molecular interactions were studied using FT-IR. In addition, the water vapour sorption was determined by gravimetric measurements and the plasticization by water vapour was studied on film samples using DMA. The results revealed a linear relationship between increasing Tg and increasing percent glucose liberated after enzyme hydrolysis. The percent glucose liberated can in turn be considered to account for both the heterogeneity of the substituents and the total degree of substitution. The results indicated that more heterogeneously substituted cellulose derivatives and derivates with a lower degree of substitution had stronger interactions between polymer chains. As expected from these results, some small difference in the plasticization by water vapour could be detected. However, no significant differences were found in molecular interactions using FT-IR or in the sorption of water vapour. The correlation between heterogeneity in the distribution of the substituents and Tg is of much interest as heterogeneously substituted batches of HPMC have been previously shown to exhibit very different behaviour in solution and in gelling tablets. © 2010 Elsevier Ltd.

  • 15.
    Lundin, Leif
    et al.
    SIK – Institutet för livsmedelsforskning.
    Hermansson, Ann-Marie
    SIK – Institutet för livsmedelsforskning.
    Influence of locust bean gum on the rheological behaviour and microstructure of K-?-carrageenan1995In: Carbohydrate Polymers, ISSN 0144-8617, E-ISSN 1879-1344, Vol. 28, no 2, p. 91-99Article in journal (Refereed)
    Abstract [en]

    Mixtures of ?-carrageenan-locust bean gum (LBG) were analysed by transmission electron microscopy and dynamic viscoelastic measurements. The effect of two different mannose:galactose (M:G) ratios of LBG on the rheology and microstructure of ?-carrageenan in KCl was studied. The rheological differences observed in the mixed gel as LBGs were added were found to be dependent on M:G ratio, salt concentration and LBG content. Monolayers of dilute samples of ?-carrageenan mixed with LBGs in varying ratios in 0.10 M KCl were visualised by low-angle rotary metal shadowing for transmission electron microscopy. The results obtained showed that LBG hindered the self-association of ?-carrageenan, and that the effect was enhanced at a higher M:G ratio and as the LBG contents were increased. Small deformation viscoelastic measurements were performed on ?-carrageenan-LBG mixtures in 0.050 and 0.10 M KCl at constant temperatures of 38 and 48 °C, respectively. Increased rheological stability was observed for mixtures containing a relatively high LBG content. Mixtures with a relatively low LBG content showed a maximum in storage modulus and an increase in phase angle. The stabilising effect of LBG on the rheology of the blends was more effective for the LBG with high M:G and as the LBG content was increased. © 1996.

  • 16.
    Lundin, Leif
    et al.
    SIK – Institutet för livsmedel och bioteknik.
    Hermansson, Ann-Marie
    SIK – Institutet för livsmedel och bioteknik.
    Rheology and microstructure of Ca- and Na-?-carrageenan and locust bean gum gels1998In: Carbohydrate Polymers, ISSN 0144-8617, E-ISSN 1879-1344, Vol. 34, no 4, p. 365-375Article in journal (Refereed)
    Abstract [en]

    The viscoelastic and microstructural influences of 0.1-0.6% locust bean gum on 0.5 or 1.0% ?-carrageenan gels, in different ionic environments, have been studied using small deformation oscillatory measurements and transmission electron microscopy (TEM). The results from the rheological measurements showed synergistic effects in the storage modulus, G?, as locust bean gum, of two different mannose to galactose ratios (3 and 5), was mixed with ion-exchanged Na-and Ca-?-carrageenan, in 0.25 M NaCl and 0.030 M CaCl2, respectively. The increase in G? was dependent on the mannose to galactose ratio, polymer concentrations, and ionic environment. At the supermolecular level, the microstructure of dilute samples has been visualised using low angle rotary metal shadowing for TEM. In the presence of sodium and calcium ions, the self-association of ?-carrageenan helices is moderate to low. Locust bean gum did not influence the supermolecular structure of ?-carrageenan to any large extent. The microstructure of the gels at the network level was studied using plastic embedding and thin sectioning for TEM. In both sodium and calcium ionic environments, the mixed gels showed a more homogeneous and connective network structure. © 1998 Elsevier Science Ltd. All rights reserved.

  • 17.
    Lundin, Leif
    et al.
    SIK – Institutet för livsmedelsforskning.
    Hermansson, Ann-Marie
    SIK – Institutet för livsmedelsforskning.
    Supermolecular aspects of xanthan-locust bean gum gels based on rheology and electron microscopy1995In: Carbohydrate Polymers, ISSN 0144-8617, E-ISSN 1879-1344, Vol. 26, no 2, p. 129-140Article in journal (Refereed)
    Abstract [en]

    The viscoelastic properties and supermolecular structure of synergistic gels, formed by xanthan and locust bean gum (LBG) of two different mannose:galactose ratios (M:G), have been investigated by small deformation viscoelastic measurements and by low angle rotary-shadowing for transmission electron microscopy. The rheological properties at 20 °C for mixtures subjected to heating and cooling cycles in the temperature range 30-80 °C were found to be dependent on the M:G ratio. Mixtures of xanthan and LBG mixed at temperatures ?40 °C were found to form true gels with low phase angles. Blends of xanthan and LBG with a low M:G ratio did not show any increase in synergistic effects as the temperature was increased, whilst the mixture of xanthan and LBG with a high M:G ratio showed a strong increase in synergistic effects as the temperature was raised above 60 °C. A difference in gelation temperature (Tg) of ~13 °C was observed between the mixtures of xanthan and the two LBG fractions. The Tg for xanthan with a high M:G ratio was ~53 °C, whilst the Tg for mixtures of xanthan and LBG with a low M:G ratio was ~40 °C. Results obtained using electron microscopy showed that the xanthan-LBG network was formed from xanthan supermolecular strands, and addition of LBG did not influence the xanthan structure. The observed structural features of the gels were independent of heat treatment and LBG fraction. The structural similarities and rheological differences observed between xanthan and the LBG fractions are discussed in comparison with existing interaction models at the molecular level. Based on these results, a speculative network model at the supermolecular level is presented. © 1995.

  • 18. López-Rubio, A.
    et al.
    Lagaron, J. M.
    Ankerfors, Mikael
    RISE, STFI-Packforsk.
    Lindström, Tom
    RISE, STFI-Packforsk.
    Nordqvist, D.
    Mattozzi, A.
    Hedenqvist, M. S.
    Erratum to "Enhanced film forming and film properties of amylopectin using micro-fibrillated cellulose" [Carbohydr. Polym. 68 (2007) 718-727] (DOI:10.1016/j.carbpol.2006.08.008)2008In: Carbohydrate Polymers, ISSN 0144-8617, E-ISSN 1879-1344, Vol. 71, no 3, p. 482-Article in journal (Refereed)
  • 19. Medronho, Bruno
    et al.
    Andrade, Raquel
    Vivod, Vera
    Östlund, Åsa
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SP – Sveriges Tekniska Forskningsinstitut / Material och produkter (TRm).
    Miguel, Maria Graca
    Lindman, Björn
    Voncina, Bojana
    Valente, Artur
    Cyclodextrin-Grafted Cellulose: Physico-Chemical Characterization2013In: Carbohydrate Polymers, ISSN 0144-8617, E-ISSN 1879-1344, Vol. 93, no 1, p. 324-330Article in journal (Refereed)
  • 20.
    Mericer, Caglar
    et al.
    Università degli studi di Bologna, Italy.
    Minelli, Matteo
    Università degli studi di Bologna, Italy.
    Giacinti Baschetti, Marco
    Università degli studi di Bologna, Italy.
    Lindström, Tom
    RISE - Research Institutes of Sweden, Bioeconomy.
    Water sorption in microfibrillated cellulose (MFC): The effect of temperature and pretreatment2017In: Carbohydrate Polymers, ISSN 0144-8617, E-ISSN 1879-1344, Vol. 174, p. 1201-1212Article in journal (Refereed)
    Abstract [en]

    Water sorption behavior of two different microfibrillated cellulose (MFC) films, produced by delamination of cellulose pulp after different pretreatment methods, is examined at various temperatures (16–65 °C) and up to 70% RH. The effect of drying temperature of MFC films on the water uptake is also investigated. The obtained solubility isotherms showed the typical downward curvature at moderate RH, while no upturn is observed at higher RH; the uptakes are in line with characteristic values for cellulose fibers. Enzymatically pretreated MFC dispersion showed lower solubility than carboxymethylated MFC, likely due to the different material structure, which results from the different preparation methods The experimental results are analyzed by Park and GAB models, which proved suitable to describe the observed behaviors. Interestingly, while no significant thermal effect is detected on water solubility above 35 °C, the uptake at 16 and 25 °C, at a given RH, is substantially lower than that at higher temperature, indicating that, in such range, sorption process is endothermic. Such unusual behavior for a cellulose-based system seems to be related mainly to the structural characteristics of MFC films, and to relaxation phenomena taking place upon water sorption. The diffusion kinetics, indeed, showed a clear Fickian behavior at low temperature and RH, whereas a secondary process seems to occur at high temperature and higher RH, leading to anomalous diffusion behaviors.

  • 21.
    Mira, I
    et al.
    YKI – Ytkemiska institutet.
    Persson, K
    YKI – Ytkemiska institutet.
    Villwock, VK
    On the effect of surface active agents and their structure on the temperature-induced changes of normal and waxy wheat starch in aqueous suspension. Part I. Pasting and calorimetric studies2007In: Carbohydrate Polymers, ISSN 0144-8617, E-ISSN 1879-1344, Vol. 68, p. 665-678Article in journal (Refereed)
    Abstract [en]

    Pasting and calorimetric studies of normal and waxy wheat starch were performed in the presence of a series of ionic (sulphates, trimethyl ammonium bromides) and non-ionic (monoglycerides, maltosides) short (12 carbon atoms) and long (16 carbon atoms) n-alkyl chain surfactants. With the exception of the alkyl ammonium bromides, all of the short chain surfactants lower the pasting temperature (PT) in normal wheat starch, while the long chain surfactants have the opposite effect. Contrary, regardless of their chain length, all ionic surfactants lower the PT in waxy wheat starch while the non-ionic surfactants induce small, sometimes almost negligible changes in the PT. Calorimetric studies revealed the absence of a direct connection between the effect of surfactants on the onset of the starch gelatinisation transition and the PT. However, in the presence of all surfactants, except the alkyl ammonium bromides, the PT of normal wheat starch was found to lie within or very close the temperature range within which the dissociation of the amylose-surfactant complexes takes place. Waxy wheat starch, in contrast, pasted at temperatures that fell within the temperature range of the starch gelatinisation transition. This is taken as evidence of the existence of a correlation between the PT and the dissociation of the amylose-surfactant complexes.

  • 22.
    Mira, I
    et al.
    YKI – Ytkemiska institutet.
    Villwock, VK
    Persson, K
    YKI – Ytkemiska institutet.
    On the effect of surface active agents and their structure on the temperature-induced changes of normal and waxy wheat starch in aqueous suspension. Part II. A confocal laser scanning microscopy study2007In: Carbohydrate Polymers, ISSN 0144-8617, E-ISSN 1879-1344, Vol. 68, p. 637-646Article in journal (Refereed)
    Abstract [en]

    The location and penetration patterns of two fluorescently-labelled, surface active molecules into normal and waxy wheat starch granules prior, during and after the temperature-induced gelatinisation were studied by means of confocal laser scanning microscopy (CLSM). Amphiphilic dyes were found to have a tendency to penetrate wheat starch granules in aqueous suspension. The penetration patterns were however found to be dependent on the contact time, type of starch and the chain length of the amphiphilic dye. The penetration of amphiphilic dyes through the starch granule matrix proved to be less restricted in waxy than in normal wheat starch. For a given type of starch, the penetration of the longer chain dye was more constrained than that of the shorter chain one. The extent to which the dye diffuses into the granule matrix as it gelatinizes is also affected by the chain length of the dye, diffusion of the shorter chain dye occurring more profusely and at lower temperatures than for the longer chain one. These differences are suggested to be related to the dissociation temperature of the AM-amphiphilic dye complexes.

  • 23. Moberg, T.
    et al.
    Rigdahl, M.
    Stading, Mats
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SIK – Institutet för livsmedel och bioteknik.
    Levenstam Bragd, Emma
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SIK – Institutet för livsmedel och bioteknik.
    Extensional viscosity of microfibrillated cellulose suspensions2014In: Carbohydrate Polymers, ISSN 0144-8617, E-ISSN 1879-1344, Vol. 102, no 1, p. 409-412Article in journal (Refereed)
    Abstract [en]

    The extensional properties of micro fibrillated cellulose (MFC)-suspensions at different fibril concentrations and with different amounts of added sodium chloride were evaluated. The MFC-suspensions were obtained by diluting a stock solution consisting of 0.95 wt.% cellulose with either deionized water or sodium chloride solution, giving a series of different concentrations and sodium chloride contents. The extensional viscosities of the suspensions were measured utilizing contraction flow geometry. Here the specimens were forced through a hyperbolic nozzle and the required pressure drop over the nozzle was measured. The extensional viscosity exhibited an extensional-thinning behaviour over the extensional strain rates used. Furthermore the extensional viscosity decreased with decreasing concentration of the suspensions, in similarities with the shear properties of the specimens. For the suspensions containing sodium chloride, the extensional viscosity appeared to increase when the concentration of sodium chloride was increased. But excessive amounts of added sodium chloride promoted an agglomeration of the suspensions. © 2013 Elsevier Ltd. All rights reserved.

  • 24. Mølgaard, Susanne
    et al.
    Henriksson, Marielle
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Hållbar Samhällsbyggnad.
    Cárdenas, Marité
    Svagan, Anna
    Cellulose-nanofiber/polygalacturonic acid coatings with high oxygen barrier and targeted release properties2014In: Carbohydrate Polymers, ISSN 0144-8617, E-ISSN 1879-1344, Vol. 114, p. 179-182Article in journal (Refereed)
  • 25.
    Naderi, Ali
    et al.
    RISE - Research Institutes of Sweden, Bioeconomy. RISE, Innventia.
    Koschella, A.
    Friedrich Schiller University of Jena, Germany.
    Heinze, T.
    Friedrich Schiller University of Jena, Germany.
    Shih, K. C.
    Department of Chemical & Biomolecular Engineering, US.
    Nieh, M. P.
    Department of Chemical & Biomolecular Engineering, United States.
    Pfeifer, A.
    Friedrich Schiller University of Jena, Germany.
    Chang, C. C.
    ThINC facility at Advanced Energy Research & Technology Center, US.
    Erlandsson, J.
    KTH Royal Institute of Technology, Sweden.
    Corrigendum to €œSulfoethylated nanofibrillated cellulose: Production and properties€ [Carbohydr. Polym. 169 (2017) 515–523] (S0144861717304101) (10.1016/j.carbpol.2017.04.026))2018In: Carbohydrate Polymers, ISSN 0144-8617, E-ISSN 1879-1344, Vol. 179, p. 1-1Article in journal (Other academic)
    Abstract [en]

    The author Ali Naderi regrets the wrong information given with regard to his affiliation. The author would like to apologise for any inconvenience caused.

  • 26.
    Naderi, Ali
    et al.
    RISE - Research Institutes of Sweden, Bioeconomy. RISE, Innventia. BillerudKorsnäs Frövi, Sweden.
    Koschella, Andreas
    Friedrich Schiller University of Jena, Germany.
    Heinze, Thomas
    Friedrich Schiller University of Jena, Germany.
    Shih, Kuo-Chih
    University of Connecticut, US ; Department of Agricultural Chemistry, Taiwan. .
    Nieh, Mu-Ping
    University of Connecticut, US.
    Pfeifer, Annett
    Friedrich Schiller University of Jena, Germany.
    Chang, Chung-Chueh
    Stony Brook University, US.
    Erlandsson, Johan
    KTH Royal Institute of Technology, Sweden.
    Sulfoethylated nanofibrillated cellulose: Production and properties2017In: Carbohydrate Polymers, ISSN 0144-8617, E-ISSN 1879-1344, Vol. 169, p. 515-523Article in journal (Refereed)
    Abstract [en]

    Sulfoethylated nanofibrillated cellulose (NFCSulf) was produced by an industrially relevant process. The properties of the NFCSulf were compared with those of carboxymethylated nanofibrillated cellulose (NFCCarb), which has been identified as an attractive NFC for several industrial applications. The investigations revealed that NFCSulf is characterized by a higher degree of fibrillation and has superior redispersion properties. Furthermore, NFCSulf displays higher stability in varying pH values as compared to NFCCarb. Hence, NFCSulf may be a more attractive alternative than NFCCarb in applications such as rheological modifiers or adsorbing components in personal care products, in which the performance of NFC must remain unaffected in varying ambient conditions. The superior properties of NFCSulf compared to NFCCarb were proposed to be due to the combination of the unique chemical characteristics of the sulfoethylated reagent, and the larger size of the sulfonate group compared to the carboxymethyl group.

  • 27. Nordli, H.R.
    et al.
    Chinga-Carrasco, Gary
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Rokstad, A.M.
    Pukstad, B.
    Producing ultrapure wood cellulose nanofibrils and evaluating the cytotoxicity using human skin cells2016In: Carbohydrate Polymers, ISSN 0144-8617, E-ISSN 1879-1344, Vol. 150, p. 65-73Article in journal (Refereed)
    Abstract [en]

    Wood cellulose nanofibrils (CNF) have been suggested as a potential wound healing material, but its utilization is limited by FDA requirements regarding endotoxin levels. In this study a method using sodium hydroxide followed by TEMPO mediated oxidation was developed to produce ultrapure cellulose nanofibrils, with an endotoxin level of 45 endotoxin units/g (EU/g) cellulose. Scanning transmission electron microscopy (S(T)EM) revealed a highly nanofibrillated structure (lateral width of 3.7 ± 1.3 nm). Assessment of cytotoxicity and metabolic activity on Normal Human Dermal Fibroblasts and Human Epidermal Keratinocytes was done. CNF-dispersion of 50 ÎŒg/ml did not affect the cells. CNF-aerogels induced a reduction of metabolic activity by the fibroblasts and keratinocytes, but no significant cell death. Cytokine profiling revealed no induction of the 27 cytokines tested upon exposure to CNF. The moisture-holding capacity of aerogels was relatively high (∌7500%), compared to a commercially available wound dressing (∌2500%), indicating that the CNF material is promising as dressing material for management of wounds with a moderate to high amount of exudate. .

  • 28.
    Petroudy, S.R.D
    et al.
    Norwegian University of Science and Technology(NTNU), Trondheim, Norway; Department of Pulp and Paper Industries, Faculty of Wood and Paper Engineering, Gorgan University of Agricultural Sciences and Natural Resources, Gorgan, IRAN.
    Syverud, Kristin
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Chinga-Carrasco, Gary
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Ghasemain, A
    Department of Pulp and Paper Industries, Faculty of Wood and Paper Engineering, Gorgan University of Agricultural Sciences and Natural Resources, Gorgan, IRAN.
    Resalati, H
    Department of Pulp and Paper Industries, Faculty of Wood and Paper Engineering, Gorgan University of Agricultural Sciences and Natural Resources, Gorgan, IRAN.
    Effects of bagasse microfibrillated cellulose and cationic polyacrylamide on key properties of bagasse paper2014In: Carbohydrate Polymers, ISSN 0144-8617, E-ISSN 1879-1344, Vol. 99, p. 311-318Article in journal (Refereed)
  • 29. Popescu, C.-M.
    et al.
    Larsson, P.T.
    RISE, Innventia.
    Olaru, N.
    Vasile, C.
    Spectroscopic study of acetylated kraft pulp fibers2012In: Carbohydrate Polymers, ISSN 0144-8617, E-ISSN 1879-1344, no 2, p. 530-536Article in journal (Refereed)
  • 30. Popescu, C.-M.
    et al.
    Larsson, P.T.
    RISE, Innventia.
    Vasile, C.
    Carbon-13 CP/MAS solid state NMR and X-ray diffraction spectroscopy studies on lime wood decayed by Chaetomium globosum2011In: Carbohydrate Polymers, ISSN 0144-8617, E-ISSN 1879-1344, no 2, p. 808-812Article in journal (Refereed)
  • 31. Powell, L.C.
    et al.
    Khan, S.
    Chinga-Carrasco, Gary
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Wright, C.J.
    Hill, K.E.
    Thomas, D.W.
    An investigation of Pseudomonas aeruginosa biofilm growth on novel nanocellulose fibre dressings2016In: Carbohydrate Polymers, ISSN 0144-8617, E-ISSN 1879-1344, Vol. 137, p. 191-197Article in journal (Refereed)
    Abstract [en]

    Nanocellulose from wood is a novel biomaterial, which is highly fibrillated at the nanoscale. This affords the material a number of advantages, including self-assembly, biodegradability and the ability to absorb and retain moisture, which highlights its potential usefulness in clinical wound-dressing applications. In these in vitro studies, the wound pathogen Pseudomonas aeruginosa PAO1 was used to assess the ability of two nanocellulose materials to impair bacterial growth (<48 h). The two nanocelluloses had a relatively small fraction of residual fibres (<4%) and thus a large fraction of nanofibrils (widths <20 nm). Scanning electron microscopy and confocal laser scanning microscopy imaging demonstrated impaired biofilm growth on the nanocellulose films and increased cell death when compared to a commercial control wound dressing, Aquacel®. Nanocellulose suspensions inhibited bacterial growth, whilst UV-vis spectrophotometry and laser profilometry also revealed the ability of nanocellulose to form smooth, translucent films. Atomic force microscopy studies of the surface properties of nanocellulose demonstrated that PAO1 exhibited markedly contrasting morphology when grown on the nanocellulose film surfaces compared to an Aquacel® control dressing (p < 0.05). This study highlights the potential utility of these biodegradable materials, from a renewable source, for wound dressing applications in the prevention and treatment of biofilm development.

  • 32. Richardson, G.
    et al.
    Kidman, Siw
    SIK – Institutet för livsmedel och bioteknik.
    Langton, Maud
    SIK – Institutet för livsmedel och bioteknik.
    Hermansson, Ann-Marie
    SIK – Institutet för livsmedel och bioteknik.
    Differences in amylose aggregation and starch gel formation with emulsifiers2004In: Carbohydrate Polymers, ISSN 0144-8617, E-ISSN 1879-1344, Vol. 58, no 1, p. 7-13Article in journal (Refereed)
    Abstract [en]

    The effects of different kinds of emulsifiers, polyglycerol ester and glycerol monostearate, and the surface-active lignosulfonate, on network formation and aggregation of amylose and starch in gels were studied. Pastes with emulsifier and 5% amylose or different starches were heated to between 90 and 150°C, cooled and studied by means of transmission electron microscopy. The fine-stranded amylose network aggregated into thicker strands when emulsifiers were added. At high emulsifier concentrations, spherical aggregates without internal structure formed, and the network disappeared. In wheat starch gels, a lower concentration of emulsifier was needed for amylose aggregation than in pure amylose gels. At high temperatures (> 140°C), aggregation was more ordered, and long, needle-like threads or brush-like aggregates were achieved. The amylose aggregated similarly with the complexing emulsifiers used in this work as with the non-complexing surfactant, which showed that amylose-lipid complex formation was not the primary explanation for aggregation. © 2004 Elsevier Ltd. All rights reserved.

  • 33. Richardson, G.
    et al.
    Sun, Y.
    Langton, Maud
    SIK – Institutet för livsmedel och bioteknik.
    Hermansson, Ann-Marie
    SIK – Institutet för livsmedel och bioteknik.
    Effects of Ca- and Na-lignosulfonate on starch gelatinization and network formation2004In: Carbohydrate Polymers, ISSN 0144-8617, E-ISSN 1879-1344, Vol. 57, no 4, p. 369-377Article in journal (Refereed)
    Abstract [en]

    The interaction of lignosulfonates with starches was examined by microscopy and viscosity measurements. 8% starch dispersions with Ca- or Na-lignosulfonate, or with only Ca2+ or Na+, were heated to 97°C and cooled to 50°C in a Brabender Viscograph, the gelatinization was followed by light microscopy and image analysis, and the gel network formed after cooling to 4°C was studied under the transmission electron microscope. The lignosulfonates (2%) delayed the initial granule swelling in all starches (native maize, waxy maize and waxy barley). The presence of ions enhanced amylose leakage resulting in lower peak viscosity. The viscosity during cooling increased more with Ca-LS than with Na-LS. With a low lignosulfonate concentration the network formed after cooling was homogeneous with fine strands. With Na-lignosulfonate, as well as with Na+, the network connectivity deteriorated and spherical aggregates formed. Ca-lignosulfonate induced a network with thick strands, but with Ca2+ the strands became thinner. © 2004 Elsevier Ltd. All rights reserved.

  • 34. Rindlav-Westling, A.
    et al.
    Stading, Mats
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SIK – Institutet för livsmedel och bioteknik.
    Hermansson, Ann-Marie
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SIK – Institutet för livsmedel och bioteknik.
    Gatenholm, P.
    Structure, mechanical and barrier properties of amylose and amylopectin films1998In: Carbohydrate Polymers, ISSN 0144-8617, E-ISSN 1879-1344, Vol. 36, no 42038, p. 217-224Article in journal (Refereed)
    Abstract [en]

    The effect of film formation conditions on structure, mechanical properties and barrier properties of amylose and amylopectin films was studied. The films were prepared by solution-gel-casting of amylose and amylopectin from potato, with or without the addition of glycerol as plasticizer. Transmission electron micrographs showed that the network structure characteristic for the amylose gel was also found in the film state. The amylose films without glycerol plasticization exhibited a relatively high degree of B-type crystallinity, as revealed by wide-angle X-ray diffraction, whereas the unplasticized amylopectin films were amorphous. Although the addition of glycerol did not affect the crystallinity of the amylose films, glycerol-plasticized amylopectin formed B-type crystallinity, and the degree of crystallinity was dependent on the air humidity during film formation. The degree of crystallinity affected the mechanical properties of the amylopectin films, whereas the mechanical properties of the amylose films were influenced by the network microstructure. Oxygen and water vapour permeabilities were dependent neither on the degree of crystallinity in the films nor on the network structure. © 1998 Elsevier Science Ltd. All rights reserved.

  • 35.
    Salmen, Lennart
    et al.
    RISE - Research Institutes of Sweden, Bioeconomy, Biorefinery and Energy.
    Larsson, Per A
    KTH Royal Institute of Technology, Sweden.
    On the origin of sorption hysteresis in cellulosic materials2018In: Carbohydrate Polymers, ISSN 0144-8617, E-ISSN 1879-1344, Vol. 182, p. 15-20Article in journal (Refereed)
    Abstract [en]

    Moisture sorption and moisture sorption hysteresis of carbohydrates are phenomena which affect the utilisation of products made thereof. Although extensively studied, there is still no consensus regarding the mechanisms behind sorption hysteresis. Attempts have been made to link the behaviour to molecular properties, in particular to softening properties, and the moisture sorption hysteresis has therefore here been investigated by modifying cellulosic fibres to affect their softening properties. The results show that the moisture sorption hysteresis diminishes with decreasing softening temperature, and was even completely absent at the higher degrees of modification. The moisture sorption characteristics also changed from a type II sorption to a more type III sorption behaviour, a feature more prominent the higher the degree of modification and the higher the temperature. For the highest degree of modification studied the sorption characteristics changed from sorbing less water the higher the temperature to sorbing more water with increasing temperature.

  • 36.
    Stading, Mats
    et al.
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SIK – Institutet för livsmedelsforskning.
    Hermansson, Ann-Marie
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SIK – Institutet för livsmedelsforskning.
    Rheological behaviour of mixed gels of kappa-carrageenan-locust bean gum1993In: Carbohydrate Polymers, ISSN 0144-8617, E-ISSN 1879-1344, Vol. 22, no 1, p. 49-56Article in journal (Refereed)
    Abstract [en]

    Mixed gels of the K, Na and Ca-forms of ?-carrageenan and locust bean gum at a total polysaccharide concentration of 1% (w/w) were studied by dynamic viscoelastic measurements. Synergistic effects were only observed for mixed gels with K-?-carrageenan in ?0·1 m KCl. The composition favouring maximum synergy shifted from 90%-?-carrageenan in distilled water down to 35% K-?-carrageenan in 0·1 m KCl. Gels of K-?-carrageenan/locust bean gum did not show synergistic effects at high potassium concentration (0·2 m KCl). The typical behaviour of K-?-carrageenan at ?50 mm KCl dominated the rheological behaviour of the mixed systems even when the locust bean gum content was high. The synergistic effects probably originate from different mechanisms at low, 0-10 mm KCl, and high, 50-100 mm KCl, concentrations because of differences in the potassium-induced microstructure. The mixed gels with the Na or Ca-form of ?-carrageenan showed no synergy. Addition of locust bean gum caused the storage modulus to decrease and the phase angle to increase. The gels were weak, with G? < 170 Pa for the Na form and G? < 350 Pa for the Ca form. The mixed gels with both the Na and Ca forms had a broken frequency dependence of G?(f). © 1993.

  • 37.
    Stading, Mats
    et al.
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SIK – Institutet för livsmedel och bioteknik.
    Rindlav-Westling, A.
    Gatenholm, P.
    Humidity-induced structural transitions in amylose and amylopectin films2001In: Carbohydrate Polymers, ISSN 0144-8617, E-ISSN 1879-1344, Vol. 45, no 3, p. 209-217Article in journal (Refereed)
    Abstract [en]

    The effect of humidity on the dynamic mechanical and barrier properties and on the microstructure of amylose and amylopectin films was studied. The films were solution-gel-cast, with and without glycerol as added plasticizer, and dried to equilibrium weight under various relative humidities (RH). The network microstructure of glycerol-plasticized amylose films was shown to change from dense and homogeneous to a more open structure with fluctuations in the pore size when the surrounding RH was increased. The structural change was attributed to plasticization of the amorphous areas by increased water content, leading to higher mobility in the network and subsequent inhomogeneous swelling. This structural change had a direct influence on the oxygen permeability, which drastically increased. The onset of the increase occurred at lower surrounding RH for the films containing glycerol, and these films also had higher oxygen permeability. Glycerol-plasticized amylopectin films with gradually increased crystallinity were prepared by varying the RH during film formation. Dynamic mechanical analysis at both varied temperature and RH showed that the increased crystallinity led to higher glass transition temperature, T g, and a smaller effect of the surrounding humidity on mechanical and barrier properties. The RH during the formation of glycerol-plasticized amylose films did not affect crystallinity or T g. These films formed at 70% RH were shown to have a marked heterogeneous network. © 2001 Elsevier Science Ltd.

  • 38. Strom, A.
    et al.
    Schuster, Erich
    SIK – Institutet för livsmedel och bioteknik.
    Goh, S.M.
    Rheological characterization of acid pectin samples in the absence and presence of monovalent ions2014In: Carbohydrate Polymers, ISSN 0144-8617, E-ISSN 1879-1344, Vol. 113, p. 336-343Article in journal (Refereed)
    Abstract [en]

    Pectins are traditionally divided into two groups, high methoxy and low methoxy. The groupings determine the charge of the pectin and the gelation mechanism. However, not as yet extensively studied is the impact on gelation of the distribution of the charges as characterized by an absolute degree of blockiness (DBabs). The aim of this study was to characterize rheologically the acid gelation of a pectin with a high DBabs and a degree of methyl esterification of ?37%, in the absence and presence of monovalent ions. The results obtained suggest that a pectin with a blocky charge distribution at pH conditions close to or below the pKa exhibits weak gel-like properties at intermediate frequencies, despite the absence of a permanent network structure. The addition of monovalent ions changed the rheological behavior to resemble that of a strong gel whose properties depended on the type and concentration of the ions. © 2014 The Authors.

  • 39. Svegmark, K.
    et al.
    Kidman, Siw
    SIK – Institutet för livsmedelsforskning.
    Hermansson, Ann-Marie
    SIK – Institutet för livsmedelsforskning.
    Molecular structures obtained from mixed amylose and potato starch dispersions and their rheological behaviour1993In: Carbohydrate Polymers, ISSN 0144-8617, E-ISSN 1879-1344, Vol. 22, no 1, p. 19-29Article in journal (Refereed)
    Abstract [en]

    Transmission electron microscopy (TEM) and dynamic viscoelastic measurements were used to study the effects of varying the ratio of potato starch to amylose. Solubilised amylose was mixed with two different types of potato starch: one with starch in the form of swollen granules and the other in the form of a molecular dispersion. The total concentration was kept constant at 8% (w/w). When the level of added amylose was low, the shear modulus (G*) was higher for gels with swollen granules than for molecular dispersions of starch. When the level of added amylose was high, the value of G* was approximately the same, independent of the type of starch structure. The rheological data were evaluated by a model treating the added amylose and potato starch as phase-separated systems. The model showed that the inherent amylose of potato starch did not contribute markedly to the gel strength caused by the added amylose. Potato starch alone does not form strong gels in the time scale studied. TEM studies confirmed that the inherent and the added amylose gave rise to completely different types of structure. The added amylose had an open network structure of stiff strands. This type of structure was found in the mixed systems with added amylose and starch, but not in systems with only potato starch. Solubilised amylopectin appeared to have a droplet-like structure, often found in the form of a string of beads. © 1993.

  • 40. Svegmark, Karin
    et al.
    Hermansson, Ann-Marie
    SIK – Institutet för livsmedelsforskning.
    Changes induced by shear and gel formation in the viscoelastic behaviour of potato, wheat and maize starch dispersions1991In: Carbohydrate Polymers, ISSN 0144-8617, E-ISSN 1879-1344, Vol. 15, no 2, p. 151-169Article in journal (Refereed)
    Abstract [en]

    The effect of shear and gel formation on the behaviour of heat-treated wheat, maize and potato starch dispersions was studied using dynamic viscoelastic measurements. The starch types were compared both at a concentration of 10% and at concentrations where the same level of shear forces was applied during the paste preparation procedure (11% wheat, 10% maize, and 4% potato). The cereal and the potato starch pastes initially showed similar viscoelastic properties after gelatinization, but the cereal starch pastes underwent a transition in their viscoelastic behaviour when cooled. This transition was believed to be due to the gelation of amylose. The main changes observed were a sharp increase in the shear modulus and a drop in the phase angle to below 2 degrees. No such transition occurred on cooling the potato starch pastes, at 25°C for 1 h, in the concentration range studied (4-10%).

  • 41. Svensson, A.
    et al.
    Larsson, P.T.
    RISE, Innventia.
    Salazar-Alvarez, G.
    Wågberg, L.
    Preparation of dry ultra-porous cellulosic fibres: Characterization and possible initial uses2013In: Carbohydrate Polymers, ISSN 0144-8617, E-ISSN 1879-1344, no 1, p. 141-783Article in journal (Refereed)
  • 42.
    Syverud, Kristin
    et al.
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Chinga-Carrasco, Gary
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Toledo, J.
    Toledo, P.G.
    A comparative study of Eucalyptus and Pinus Radiata pulp fibres as raw materials for production of cellulose nanofibrils2011In: Carbohydrate Polymers, ISSN 0144-8617, E-ISSN 1879-1344, Vol. 84Article in journal (Refereed)
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