| 1. |
- Asp, Nils Georg, et al.
(författare)
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Physiological effects of cereal dietary fibre
- 1993
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Ingår i: Carbohydrate Polymers. - 0144-8617. ; 21:2-3, s. 183-187
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Tidskriftsartikel (refereegranskat)abstract
- Cereal dietary fibre constitutes about half of the total fibre intake in Sweden. The amount of fibre available is 21 g/person/day or 1·75 g/MJ. Increased faecal bulk and shortening of intestinal transit time are well-documented effects, that are inversely proportional to the fermentability of the dietary fibre. Wheat bran, oat husks, and corn bran are fibre sources with high bulking effect, whereas fibre from the endosperm of cereals is more extensively fermented. Resistant starch in processed cereals has properties similar to dietary fibre, and must be considered in analysis as well as regarding physiological effects of dietary fibre. Oat groats and oat bran have serum cholesterol lowering effects related to the viscous soluble β-glucans. Rye and barley contain similar levels of viscous soluble fibre but are not as thoroughly investigated. Effects on postprandial glucose and insulin levels are also partly related to viscous soluble dietary fibre, but structural properties in, e.g., whole kernels and pasta products are more important in this respect. Phytate in whole grain flour and bran preparations inhibits iron and zinc absorption in single meal tests. Its role for mineral status in persons consuming a mixed, Western diet remains to be established.
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| 2. |
- Karlson, L, et al.
(författare)
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A rheological investigation of the complex formation between hydrophobically modified ethyl (hydroxy ethyl) cellulose and cyclodextrin
- 2002
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Ingår i: Carbohydrate Polymers. - 0144-8617. ; 50:3, s. 219-226
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Tidskriftsartikel (refereegranskat)abstract
- The thickening effect of a hydrophobically modified polymer in an aqueous solution is dependent on intermolecular hydrophobic associations, and if the polymer concentration is significantly above the overlap concentration also on chain entanglements. In this investigation we have added different cyclodextrins (CD) in order to decouple hydrophobic polymer-polymer associations via inclusion complex formation with the polymer hydrophobic tails. Both size and hydrophobicity of the cavity of the CD-molecules were found to have an effect on the process. In addition, the influence of chemical structure of the polymer hydrophobic tails was investigated. Either a linear C-14-chain or a more bulky nonylphenol group was used. The viscosity as a function of CD-concentration first decreased strongly, and then attained a constant value. At excess CD the viscosity became virtually the same as in a solution of the unmodified parent polymer, provided that complex formation was not sterically bindered. This suggests that all hydrophobic links, originating from the hydrophobic modification process, which influence the theology could be deactivated. On the other hand, with combinations where the complex formation was hindered to a certain degree the initial decrease was less accentuated, and also, the viscosity leveled out at a significantly higher value. In an attempt to rationalize the data a simple model based on the assumption that each complex formed deactivates one theologically active link was used. In combination with the Langmuir adsorption model the number of complexes as a function of CD concentration could be obtained. This model also gave a value of the complex formation constant. Furthermore, in solutions where all hydrophobic links could be deactivated the results from the model suggested that all polymer hydrophobic tails were originally active in forming the network. (C) 2002 Elsevier Science Ltd. All rights reserved.
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| 3. |
- Lundqvist, Henrik, et al.
(författare)
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Binding of hexadecyltrimethylammonium bromide to starch polysaccharides. Part 1. Surface tension measurements
- 2002
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Ingår i: Carbohydrate Polymers. - 0144-8617. ; 49:1, s. 43-55
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Tidskriftsartikel (refereegranskat)abstract
- Surface tension measurements were used to characterise the binding of the cationic surfactant hexadecyltrimethylammonium bromide, CTAB, to three starch polysaccharides, amylose from potato, amylopectin from potato and amylopectin from barley. Surface tension measurements were used according to the axisymmetric drop shape analysis. ADSA, to determine the concentration of free CTAB monomers during consecutive addition of CTAB to the polysaccharide solutions, The interaction between the starch polysaccharides and CTAB was studied at three starch concentrations. 0.1, 0.25 and 0.5% (w/w). Binding isotherms were derived from the concentration of free CTAB and the type of binding was determined with Scatchard plots. The binding capacities of CTAB correlated linearly with the polysaccharide concentration but were independent of the type of starch polysaccharide. All three starch polysaccharides were able to bind 33 mmol CTAB per mole glucose units. The binding of CTAB to amylose was cooperative while the binding of CTAB to amylopectin was of Langmuir type.
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| 4. |
- Lundqvist, Henrik, et al.
(författare)
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Binding of hexadecyltrimethylammonium bromide to starch polysaccharides. Part II. Calorimetric study
- 2002
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Ingår i: Carbohydrate Polymers. - 0144-8617. ; 49:2, s. 109-120
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Tidskriftsartikel (refereegranskat)abstract
- Isothermal titration calorimetry was used to study the interaction between hexadecyltrimethylammonium bromide, CTAB, and three starch polysaccharides, amylose from potato, amylopectin from potato and amylopectin from barley. The enthalpy change for consecutive additions of CTAB to starch polysaccharide solutions were measured at 27degreesC. The starch-CTAB interaction enthalpies, DeltaH(f), were calculated by subtracting the enthalpy of micelle dissociation and dilution from the observed heat and relating the interaction enthalpy to the amount of interacting CTAB. The interaction was studied at three polysaccharide concentrations, 0.1, 0.25 and 0.5% w/w. The exothermic interaction enthalpy was constant and quite large in the main part of the concentration range studied for all three-starch polysaccharides. Amylose had an interaction enthalpy of -55 kJ/mol CTAB while the amylopectin samples had an interaction enthalpy of -40 kJ/mol CTAB. Amylopectin and amylose seemed to have a similar interaction with CTAB, the small differences were probably due to the differences in structure between the polysaccharides.
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| 5. |
- Lundqvist, Jon, et al.
(författare)
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Characterization of galactoglucomannan extracted from spruce (Picea abies) by heat-fractionation at different conditions
- 2003
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Ingår i: Carbohydrate Polymers. - 0144-8617 .- 1879-1344. ; 51:2, s. 203-211
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Tidskriftsartikel (refereegranskat)abstract
- Water-soluble hemicelluloses were extracted from spruce chips by microwave heat-fractionation. The galactoglucomannan (GGM) extraction was evaluated on the basis of weight-average molecular weight (MW), yield and carbohydrate composition of the GGM. The MW was determined by size-exclusion chromatography with column calibration using off-line MALDI-MS analysis, and determination of mannan content in the fractions collected. Water impregnated spruce chips were heat-fractionated at three different temperatures (180, 190, and 200oC). The spruce chips were also impregnated in NaOH solutions of different concentrations, and then heat-fractionated at 190oC for 5min. The highest mannan yield (78% based on the amount in the raw material) was obtained from water impregnated spruce chips heat-fractionated at 190oC for 5min (MW of 3800). The highest MW (14,000) was obtained from impregnation with 2% NaOH (190oC, 5min), but the yield of mannan was very low (3%). Impregnation with 0.025% NaOH and heat-fractionation at 190oC for 5min resulted in extraction of GGM with MW of 9500 and a mannan yield of 31%. When the spruce chips were impregnated with =<0.05% NaOH an O-acetyl-galactoglucomannan was extracted, whereas when higher NaOH charges were used in the impregnation, the extracted GGM lacked acetyl groups.
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| 6. |
- Lundqvist, Jon, et al.
(författare)
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Isolation and characterization of galactoglucomannan from spruce (Picea abies)
- 2002
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Ingår i: Carbohydrate Polymers. - 0144-8617. ; 48:1, s. 29-39
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Tidskriftsartikel (refereegranskat)abstract
- Water-soluble hemicelluloses were extracted from spruce chips by microwave heat fractionation. The chips were impregnated with water at different pH values. Screening of heat-fractionation conditions, i.e. impregnation medium, temperature and residence time was performed with the aim to extract O-acetyl-galactoglucomannan. The impregnation and heat fractionation conditions were evaluated on the basis of the yield of dissolved mannan (oligo- and polysaccharides), molecular weight of the carbohydrates and amount of dissolved lignin. Increasing temperature and residence time increases the yield of mannan and decreases the molecular weight of dissolved carbohydrates. For a structural study of the extracted carbohydrates the chips were impregnated with water and treated at 200oC for 2min. Oligo- and polysaccharides were fractionated with preparative size-exclusion chromatography from the filtered extract.The structure of the obtained saccharides in two fractions 8 and 9 was determined by 1H NMR spectroscopy. The polysaccharides in the fractions were O-acetyl-galactoglucomannan with a degree of polymerization ~20 and ~11 for fractions 8 and 9, respectively. The molar ratio for galactose:glucose:mannose was approximately 0.1:1:4. About one-third of the d-mannosyl units are substituted by O-acetyl groups almost equally distributed between C-2 and C-3.
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| 7. |
- Nilsson, G. S., et al.
(författare)
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Microdialysis clean-up and sampling in enzyme-based methods for the characterisation of starch
- 2001
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Ingår i: Carbohydrate Polymers. - : Elsevier BV. - 0144-8617. ; 46:1, s. 59-68
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Tidskriftsartikel (refereegranskat)abstract
- Microdialysis was used for sampling enzyme hydrolysis products of starch hydrolysed with beta -amylase, pullulanase, and/or isoamylase, to obtain information about the molecular structure of starch. Starches from waxy, normal, and high amylose maize, and from normal and genetically modified potato (amylose deficient) were used, and also commercial potato amyloses. The hydrolysis products were analysed using high-performance anion-exchange chromatography with pulsed amperometric detection (HPAEC-PAD). Simultaneous sampling and sample clean-up were achieved with microdialysis, thus enabling on-line injection into the liquid chromatographic system. The molecular weight cut-off of the membrane allowed for diffusion of small molecules such as oligosaccharides through the membrane, but hindered large molecules, e.g. enzymes and large polysaccharides, from entering the chromatographic system. With microdialysis sampling, it was possible to investigate the short chain fractions of debranched starch in the presence of amylose without pre-fractionation. The microdialysis-HPAEC-PAD system was also used for determination of the A:B chain ratio and the P-limit value. After P-amylolysis, only liberated maltose diffused through the dialysis membrane, which resulted in on-line sample clean-up from branched P-limit dextrin as well as from the enzyme. The proposed method is fast and easy to handle since clean-up of the hydrolysate is achieved on-line with the chromatographic system. (C) 2001 Elsevier Science Ltd. All rights reserved.
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| 8. |
- Santacruz, S, et al.
(författare)
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Three under-utilised sources of starch from the Andena region in Ecuador. Part II. Rheological characterisation.
- 2003
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Ingår i: Carbohydrate Polymers. - 0144-8617. ; 51:1, s. 85-92
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Tidskriftsartikel (refereegranskat)abstract
- The dynamic rheological behaviour of Arracacha xanthorriza white carrot), Canna edulis (achira) and Oxalis tuberosa oca) starch gels were studied in strain-sweep mode. The starch was diluted with water to cover particle volume fractions of 1–3. The starch suspensions were heated at 89 8C for 30 min, and their swelling power and amylose leaching were measured. C. edulis showed the highest swelling power and particle rigidity (the elastic modulus, G0, of a starch gel at a particle volume fraction of 1 is defined as rigidity), forming stronger gels than O. tuberosa and A. xanthorriza. Storage of the three starch gels at 4 8C showed that A. xanthorriza formed gels which were stable in G0 and phase angle for three days of storage. C. edulis and O. tuberosa gels kept at the same refrigeration conditions showed a high increase in G0 during the first day of storage. A decrease in pH from 6.5 to 4.0 produced a loss of structure in the three starch gels, as was showed by the reduction of G0. Storage at freezing temperature (220 8C) produced higher changes in G0 than refrigeration conditions. There was a rapid formation of an elastic structure in C. edulis and O. tuberosa starch gels on the first day of storage in both refrigeration and freezing conditions.
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| 9. |
- Santacruz, Stalin, et al.
(författare)
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Three underutilised sources of starch from the Andean region in Ecuador Part 1. Physico-chemical characterisation
- 2002
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Ingår i: Carbohydrate Polymers. - 0144-8617. ; 49:1, s. 63-70
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Tidskriftsartikel (refereegranskat)abstract
- The physico-chemical aspects of three native Andean starches from Arracacha xanthorriza, Canna edulis and Oxalis tuberosa were investigated. Scanning electron microscopy-investigations showed that granules of A. xanthorriza were the smallest with irregular shape and sizes between 7 and 23 pm, whereas granules of O. tuberosa and C. edulis were both ovally shaped with granular sizes between 20 and 55 mum and 35-101 mum, respectively. All three starches revealed a B-type X-ray diffraction pattern. The gelatinisation behaviour was investigated using differential scanning calorimetry (DSC). The gelatinisation enthalpy was 14.6 J/g of starch for O. tuberosa, 15.7 J/g for C. edulis and 17.6 J/g for A. xanthorriza, and the peak temperature of the endothermic DSC-transition was 55.9, 61.2 and 60.1 degreesC, respectively. The amylose content determined by gel permeation chromatography after debranching with isoamylase was 4% for A. xanthorriza, 18.4% for O. tuberosa. and 23.8% for C. edulis. The amylopectin showed different structures among the three starches with a beta-amylolysis limit of 67.6% for C edulis, 64.5% for O. tuberosa and 56.6% for A. xanthorriza. The average chain length of the amylopectin was highest for A. xanthorriza (22.6), followed by O. tuberosa with 22.4, and lowest for C. edulis (21.9). The complexation ability of the three starches was investigated by adding sodium dodecyl sulphate (SDS), and the amylose content was positively correlated with the enthalpy of the amylose-SDS complex. (C) 2002 Elsevier Science Ltd. All rights reserved.
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| 10. |
- Svegmark, K, et al.
(författare)
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Comparison of potato amylopectin starches and potato starches - influence of year and variety
- 2002
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Ingår i: Carbohydrate Polymers. - 0144-8617. ; 47:4, s. 331-340
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Tidskriftsartikel (refereegranskat)abstract
- Starches from three potato varieties and their respective transformants producing amylopectin starch were studied over a period of 3 years. The gelatinisation, swelling and dispersion properties were studied using differential scanning calorimetry (DSC), X-ray diffraction, swelling capacity measurements and a Brabender Viscograph. The potato amylopectin starches (PAP) exhibited higher endothermic temperatures as well as higher enthalpies than the normal potato starches (NPS). PAP samples gave rise to an exceptionally sharp viscosity peak during gelatinisation and a relatively low increase in viscosity on cooling. Swelling capacity measurements showed that PAP granules swelled more rapidly, and that the dispersion of the swollen granules occurred at a lower temperature (85 degreesC). Analysis of variance (ANOVA) also revealed that the year influenced the DSC results, and that both year and variety affect some of the Brabender parameters. Furthermore, the PAP and NPS samples were subjected to heat-moisture treatment at three different moisture levels, and the Brabender viscosity properties were studied. (C) 2002 Elsevier Science Ltd. All rights reserved.
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