| 1. |
- Colsenet, Roxane, et al.
(författare)
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Diffusion of polyethyleneglycols in casein solutions and gels as studied by pulsed field gradient NMR
- 2005
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Ingår i: Magnetic Resonance Imaging. - : Elsevier BV. - 1873-5894 .- 0730-725X. ; 23:2, s. 347-348
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Tidskriftsartikel (refereegranskat)abstract
- Molecular transport characterized by diffusion coefficients is a key feature of food processes and especially in dairy processes. Caseins represent 80% of the protein content in milk and are directly involved in the formation of dairy gels. Consequently, providing a quantitative description of the solute diffusion in casein gels should contribute significantly to rationalization of the dairy processes. The objectives of this study were to study the self-diffusion coefficient of molecular probes [polyethyleneglycol (PEGs)] in casein solutions and gels, in particular with regard to the effects of the probe molecular size and casein concentration. We have shown that the PEG diffusion was an efficient tool to reveal the structural information relative to the gel matrix structure. (c) 2005 Elsevier Inc. All rights reserved.
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| 2. |
- Colsenet, Roxane, et al.
(författare)
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Effect of casein concentration in suspensions and gels on poly(ethylene glycol)s NMR self-diffusion measurements
- 2005
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Ingår i: Macromolecules. - : American Chemical Society (ACS). - 0024-9297 .- 1520-5835. ; 38:22, s. 9171-9179
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Tidskriftsartikel (refereegranskat)abstract
- PFG-NMR spectroscopy was used to study the diffusion of molecular probes (poly(ethylene glycol)s) in casein suspensions and gels in terms of the effects of probe molecular size (molecular mass between 1080 and 634 000 g/mol), casein concentrations (from 3.24 to 16.22 g/100 g), and effects of rennet coagulation. A strong dependency of diffusion on probe size was observed, both in casein suspensions and in gels: as the PEG size increased, the diffusion was reduced. This effect was more pronounced for higher casein concentrations. Changes in casein structure after addition of rennet increased the diffusion coefficient for 82 250 and 634 000 g/mol PEG. The PEG self-diffusion coefficients in casein gels were compared to the casein gel structures characterized by scanning electron microscopy. Assuming high internal micelle porosity, a diffusion model with two diffusion pathways, one outside and one inside the micelles, was used to explain the PEG diffusion in casein solutions and gels. The results were discussed in the context of variations in casein micelle voluminosity after renneting.
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| 3. |
- Colsenet, Roxane, et al.
(författare)
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Effects of ionic strength and denaturation time on polyethyleneglycol self-diffusion in whey protein solutions and gels visualized by nuclear magnetic resonance
- 2006
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Ingår i: Journal of Agricultural and Food Chemistry. - : American Chemical Society (ACS). - 0021-8561 .- 1520-5118. ; 54:14, s. 5105-5112
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Tidskriftsartikel (refereegranskat)abstract
- Pulsed field gradient NMR spectroscopy was used to determine the poly(ethylene glycol) (PEG) self-diffusion coefficient (D-PEG) as a function of NaCl concentration (C-NaCl) and denaturation time (t(D)) in whey protein solutions and gels. D-PEG in the gel decreased with increasing C-NaCl concentrations and increased with increasing t(D); the increase ceased for all PEGs when the gel was fixed. This increase was more pronounced for the 82250 g/mol PEG than the 1080 g/mol PEG. Moreover, the diffusion coefficient of nonaggregated whey protein was measured and an increase for longer t(D) was also observed. Scanning electron microscopy images and H-1 spectra demonstrated that D-PEG were related to the structure changes and to the percentage of beta-lactoglobulin denaturation.
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| 4. |
- Colsenet, Roxane, et al.
(författare)
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Pulsed field gradient NMR study of poly(ethylene glycol) diffusion in whey protein solutions and gels
- 2006
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Ingår i: Macromolecules. - : American Chemical Society (ACS). - 0024-9297 .- 1520-5835. ; 39:3, s. 1053-1059
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Tidskriftsartikel (refereegranskat)abstract
- PEG self-diffusion coefficients of poly(ethylene glycol)s (PEGs) (1080, 8500, and 82 250 g/mol) were measured by PFG-NMR spectroscopy in whey protein solutions and gels in relation to whey protein concentration effects (from 6.49 to 40.45 g/100 g) and whey protein heat denaturation effects (30 min at 70 degrees C). A strong dependency of diffusion on probe size was observed in both whey protein solutions and gels: as PEG size increased, diffusion was reduced. This effect was more pronounced for higher protein concentrations. Changes in whey structure after thermal aggregation increased the diffusion coefficient for all PEGs, particularly for the 8500 g/mol PEG. The PEG self-diffusion coefficients in whey protein gels were compared to the gel structures characterized by scanning electron microscopy. The results are discussed in relation to a reptation model and compared to PEG diffusion in casein micelle suspensions and gels.
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