| 1. |
- Börjesson, Erik, et al.
(författare)
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Entrapment of air during imbibition of agglomerated powder beds
- 2017
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Ingår i: Journal of Food Engineering. - : Elsevier BV. - 0260-8774. ; 201, s. 26-35
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Tidskriftsartikel (refereegranskat)abstract
- Complete wetting is crucial for efficient recombination of powders. On the powder bed scale, wetting is governed solely by capillary forces and the resistance to flow, i.e. spontaneous imbibition. Slow or incomplete imbibition of the powder bed may lead to gelling of the liquid front, which will stop the recombination process and cause the formation of lumps, which is usually undesirable. In this study, the spontaneous imbibition of powder beds consisting of spray-dried dairy powders with diverse morphologies has been investigated. Uniform radial spreading of the imbibition front was seen in all the beds, but a large amount of air was trapped in the inter-particle free space in the imbibed volume. A positive correlation was found between bed porosity and the fraction of air trapped in the bed after imbibition. Since the amount of trapped air was calculated as a fraction of the porosity of the dry bed, this relation was unexpected. The large fraction of air trapped in the bed and the uniform radial spreading of the imbibition front indicate considerable heterogeneity of bed on the microscopic scale, but a homogenous structure on the macroscopic scale. Possible explanations of the large fraction of trapped air are the presence of local dead-end structures in the bed and film flow of the imbibing liquid.
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| 2. |
- Börjesson, Erik, et al.
(författare)
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Evaluation of particle measures relevant for powder bed porosity-A study of spray dried dairy powders
- 2014
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Ingår i: Powder Technology. - : Elsevier BV. - 0032-5910. ; 253, s. 453-463
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Tidskriftsartikel (refereegranskat)abstract
- The formation of lumps during large scale wetting of spray dried powders is a common problem in the industry. The result is a large energy demand if an efficient mixing is to be achieved at the industrial scale. If more knowledge regarding the phenomena governing lump formation is obtained, the unit operation could be optimized and made more efficient. As a part of increasing the understanding of lump formation, the wetting of the porous media that is a powder bed needs to be understood. This wetting relates to the structure and void space (porosity) of the powder bed, which is why a relation between powder bed porosity and readily obtainable powder particle morphology parameters is sought. In this study a thorough investigation of the morphology of five different spray dried milk powders, with arbitrary particle shapes, was performed using manual image analysis of scanning electron microscope (SEM) images as well as automated methods based on light scattering and projected image analysis. The results of the automated methods, when utilized on the complexly shaped samples, were validated by a comparison to the SEM image analysis. This enabled the development of a relation between powder morphology and powder bed porosity based on data from automated methods. The results indicate that automated methods based on light scattering underestimate the particle sizes of arbitrary shaped particles. Methods based on projected image analysis, however, show a better agreement with SEM image analysis. The developed relation between powder bed porosity and powder particle morphology is based on defining the bed as having either an "Agglomerates in fines", "Bicontinuous" or "Fines in agglomerates" structure. The structure of each powder is determined based on calculation of a "BedRatio" which is a function of the phi(agglomerate) and phi(fines) both shown to be readily obtainable by automated methods. The calculated porosities of the powders investigated in this study show a good agreement with experimental measurements and are considered to correspond well to earlier literature. It is, however, clear from the a experiments that care needs to be taken during bulk density measurement of spray dried powders so that no intra particle void space is taken into consideration in the calculations. (C) 2013 Elsevier B.V. All rights reserved.
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| 3. |
- Börjesson, Erik, et al.
(författare)
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The dissolution behavior of individual powder particles
- 2013
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Ingår i: Dairy Science & Technology. - : Springer Science and Business Media LLC. - 1958-5586 .- 1958-5594. ; 93:4-5, s. 357-371
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Tidskriftsartikel (refereegranskat)abstract
- The formation of lumps is a common problem during powder reconstitution in food industry. If more knowledge regarding the phenomena controlling the process could be obtained, the process of industrial powder recombination could be optimized. This demands investigation of the process at three different levels: the scale of individual powder particles, the scale of powder beds, and the scale of industrial recombination. If knowledge from all three scales could be combined, a model of the entire process could be constructed. In this study, we present a new flow-cell-based method for investigating the dissolution rate of individual powder particles in controlled liquid flow. The flow cell allows for alteration of the flow velocity and only subjects the investigated powder particles to mild stress before the analysis. The dissolution process in the cell is recorded, and data are obtained by image analysis. Sodium caseinate has been used as a model substance in these experiments. The results show that the particle dissolution rate is a function of the flow velocity of the liquid, and the results correspond to earlier established methods. The investigation of individual particles shows a variation in dissolution rate between particles resulting from the diverse particle morphology from an industrial batch of powder. The results indicate that the dissolution interface concentration of dissolving sodium caseinate particles corresponds well to the overlap concentration of the specie.
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| 4. |
- Creamer, L K, et al.
(författare)
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Effect of genetic variation on the tryptic hydrolysis of bovine beta-lactoglobulin A, B, and C
- 2004
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Ingår i: Journal of Dairy Science. - 1525-3198. ; 87:12, s. 4023-4032
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Tidskriftsartikel (refereegranskat)abstract
- The structure, stability, and hydrolysis characteristics of beta-lactoglobulin (LG) A are different from those of either beta-LG B or beta-LG C. Purified samples of these proteins were hydrolyzed with trypsin and the rates of loss of native monomeric beta-LG structure were measured using sodium dodecyl sulfate PAGE. At the same time, the appearance of many individual peptides were identified and followed in time by HPLC, measuring their concentration as a function of solution pH, temperature, protein concentration, and added urea or palmitate. The identity of the peptides was confirmed by liquid chromatography-mass spectrometry. This semiquantitative exploration showed that the rate of hydrolysis was in the order beta-LG A > beta-LG B > beta-LG C under most circumstances, and that 12 of the 18 trypsin-susceptible bonds were cleaved at very similar rates that were governed by the variant type. Consequently, the rate of hydrolysis of the intact protein was related to the overall structural stability of the individual proteins and the accessibility of certain peptide bonds to the enzyme. The hydrolysis of mixtures of 2 or more variants or of denatured beta-LG gave more heterogeneous peptide mixtures.
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| 5. |
- Edén, Jonas, et al.
(författare)
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The influence of serum phase on the whipping time of unhomogenised cream
- 2015
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Ingår i: International Dairy Journal. - : Elsevier BV. - 0958-6946. ; 49, s. 56-61
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Tidskriftsartikel (refereegranskat)abstract
- The objective of this study was to investigate how the properties of the serum phase, including ionic strength, protein content and specific milk salts, influence the whipping time of unhomogenised cream. This study showed that decreasing the protein content of the serum phase in cream resulted in shorter whipping time. However, addition of UF permeate to both deproteinated and proteinated creams indicated that other components than the protein fraction also influence whipping time of unhomogenised cream. Increasing the ionic strength by addition of NaCl, KCl and CaCl2 decreased whipping time, with the largest effect being found for CaCl2. A further increase in ionic strength by addition of NaCl and KCl resulted in an unfavourable effect on whipping time, whereas a pronounced effect, with shorter whipping times, was found for addition of CaCl2. (C) 2015 Elsevier Ltd. All rights reserved.
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| 6. |
- Elfstrand, Lidia, et al.
(författare)
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Immunoglobulins, growth factors and growth hormone in bovine colostrum and the effects of processing
- 2002
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Ingår i: International Dairy Journal. - 0958-6946. ; 12:11, s. 879-887
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Tidskriftsartikel (refereegranskat)abstract
- In colostrum collected 0-80 h postpartum the contents of immunoglobulins (Igs), transforming growth factor beta-2 (TGF-beta2), insulin-like growth factor-1 (IGF-1) and growth hormone (GH) were analysed. Colostrum initially contained 90 mg mL(-1) IgG1, 2.8 mg mL(-1) IgG2, 1.6 mg mL(-1) IgA, 4.5 mg mL(-1) IgM, and these concentrations declined by 92%, 87%, 93% and 84%, respectively, in the samples collected later. Of the growth factors, colostrum initially contained 289-310 ng mL(-1) TGF-beta2 and the concentration diminished to 66 ng mL(-1). The content of IGF-1 and GH postpartum decreased from 870 to 150 ng mL(-1), and from 0.17 to < 0.03 ng mL(-1), respectively. Heat treatment and freeze-drying of colostral whey decreased the content of Igs to 75%, while the contents of IGF-1 and TGF-beta2 were unaffected. A similar processing, including filtration steps reduced also the IGF-1 and TGF-beta2 by 25%. IgM seems to be the most sensitive of the Igs to processing. (C) 2002 Elsevier Science Ltd. All rights reserved.
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| 7. |
- Elofsson, Ulla, et al.
(författare)
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Heat induced aggregation of b-lactoglobulin studied by dynamic light scattering
- 1996
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Ingår i: International Dairy Journal. - : Elsevier BV. - 0958-6946 .- 1879-0143. ; 6:4, s. 343-357
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Tidskriftsartikel (refereegranskat)abstract
- The in situ heat-induced aggregation of commercial β-lactoglobulin as such, or after further purification, was followed to a z-average hydrodynamic diameter of 15–20 nm at 59–63 °C by dynamic light scattering. In this temperature range, measurable increase of hydrodynamic diameter occurred after an apparent lag period, which was strongly dependent on heating temperature, pH and initial protein concentration. The changes in time scale of the aggregation process agreed with changes in amount of unfolded β-lactoglobulin, assuming a two-state model of the denaturation. The pH dependence reflected the midpoint unfolding temperature and not the sulphydryl group reactivity, suggesting that this reactivity was not rate limiting in the aggregation. The aggregation process was modelled numerically with FuchsSmoluchowski kinetics.
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| 8. |
- Freiburghaus, Catja, et al.
(författare)
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Lactoferricin treatment decreases the rate of cell proliferation of a human colon cancer cell line.
- 2009
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Ingår i: Journal of Dairy Science. - : American Dairy Science Association. - 1525-3198 .- 0022-0302. ; 92:6, s. 2477-2484
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Tidskriftsartikel (refereegranskat)abstract
- Food components modify the risk of cancer at a large number of sites but the mechanism of action is unknown. In the present investigation, we studied the effect of the peptide lactoferricin derived from bovine milk lactoferrin on human colon cancer CaCo-2 cells. The cells were either untreated or treated with 2.0, 0.2, or 0.02 microM lactoferricin. Cell cycle kinetics were investigated with a bromodeoxyuridine DNA flow cytometric method. The results show that lactoferricin treatment slightly but significantly prolonged the S phase of the cell cycle. Lactoferricin treatment lowered the level of cyclin E1, a protein involved in the regulation of genes required for G(1)/S transition and consequently for efficient S phase progression. The slight prolongation of the S phase resulted in a reduction of cell proliferation, which became more apparent after a long treatment time.
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| 9. |
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| 10. |
- Freiburghaus, Catja, et al.
(författare)
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Reduction of ultraviolet light-induced DNA damage in human colon cancer cells treated with a lactoferrin-derived peptide
- 2012
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Ingår i: Journal of Dairy Science. - : American Dairy Science Association. - 1525-3198 .- 0022-0302. ; 95:10, s. 5552-5560
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Tidskriftsartikel (refereegranskat)abstract
- Treatment of Caco-2 cells with the peptide lactoferricin(4-14), results in reduction of the growth rate by prolongation of the S phase of the cell cycle. Lactoferricin(1-25) is formed in the gut by cleavage from lactoferrin and the bioactive amino acids are found within lactoferricin(4-14). Our hypothesis is that the reduction of the rate of S phase progression may result in increased DNA repair. To test this hypothesis, Caco-2 cells were subjected to UV light that caused DNA lesions and then the cells were grown in the absence or presence of 2.0 mu M lactoferricin(4-14). Evaluation of DNA strand breaks using the comet assay showed that lactoferricin(4-14) treatment indeed resulted in a reduction of comets showing damaged DNA. In the search for a mechanism, we have investigated the levels of several proteins involved in cell cycle regulation, DNA replication, and apoptosis using Western blot. Lactoferricin(4-14) treatment resulted in an increased expression of flap endonuclease-1 pointing to increased DNA synthesis activity. Lactoferricin(4-14) treatment decreased the expression of the proapoptotic protein B-cell lymphoma 2-associated X protein (or Bax), indicating decreased cell death. As we have found previously, lactoferricin(4-14) treatment reduced the expression of cyclin E involved in the G(1)/S transition. Immunofluorescence microscopy showed that a lower gamma-H2AX expression in lactoferricin(4-14)-treated cells, pointing to more efficient DNA repair. Thus, altogether our data show that lactoferricin(4-14) treatment has beneficial effects.
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