| 1. |
- Nuzzo, Marine, et al.
(författare)
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Confocal Raman microscopy for mapping phase segregation in individually dried particles composed of lactose and macromolecules
- 2015
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Ingår i: Colloids and Surfaces A. - : Elsevier BV. - 0927-7757 .- 1873-4359. ; 481, s. 229-236
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Tidskriftsartikel (refereegranskat)abstract
- The quality of powder is determined by its functionality such as dissolution, encapsulation and flowability. The functionality of powder is in turn determined by their primary properties such as morphology and composition which need to be studied. Hence morphology and surface composition has been largely investigated in spray dried powders and individually dried particles. On the contrary, there is only scarce information regarding the internal structure. With the aim of acquiring a better understanding of the localization of different ingredients in spray dried powders we have used confocal Raman microscopy to investigate the internal microstructure of individually dried particles. In this study three different macromolecules have been investigated: bovine serum albumin, hydroxypropyl methyl cellulose, and triblock co-polymer poloxamer in a lactose matrix are compared at various macromolecule to lactose ratios. The surface and internal component distribution in response to the macromolecule concentration has been established. For the first time phase segregation in particles during a short drying time range is shown. Macromolecules were enriched at the surface of the dried particles and a macromolecule depleted layer was observed below the surface. Macromolecule enriched domains were found segregated from the amorphous lactose matrix in the internal part of the particles. Confocal Raman microscopy was found to be a powerful tool for internal mapping in individually dried particles.
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| 2. |
- Nuzzo, Marine, et al.
(författare)
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Phase segregation in individually dried particles composed of biopolymers
- 2015
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Ingår i: Langmuir. - : American Chemical Society (ACS). - 0743-7463 .- 1520-5827. ; 31:40, s. 10946-10954
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Tidskriftsartikel (refereegranskat)abstract
- Mixing of two biopolymers can results in phase separation due to their thermodynamically incompatibility under certain conditions. This phenomenon was first reported when the solution was allowed to equilibrate, but it has later been observed also as a consequence of drying. The challenges of this study were to observe phase segregation by confocal Raman microscopy and LV-SEM on dried film, individually dried particles, and spray dried particles. The influence of the solid content and the phase ratio (composition) of a HPMC/maltodextrin mixture on the localization of the ingredients in the individually dried particles was investigated. We observed that phase segregation of HPMC and maltodextrin is induced by solvent evaporation in film drying, single particle drying, as well as spray drying. The phase ratio is an important parameter that influences the localization of the HPMC-enriched phase and maltodextrin-enriched phase, i.e., to the particle surface, to the core, or in a more or less bicontinuous pattern. The drying time, affected by the solids content, was found to control the level of advancement of the phase segregation.
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| 3. |
- Nuzzo, Marine, et al.
(författare)
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Surface Composition and Morphology of Particles Dried Individually and by Spray Drying
- 2015
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Ingår i: Drying Technology. - : Informa UK Limited. - 1532-2300 .- 0737-3937. ; 33:6, s. 757-767
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Tidskriftsartikel (refereegranskat)abstract
- This study investigates how the morphology of spray-dried particles is related to the formulation and properties of the components in the formulation. Further, the scale effects in comparisons of levitation-dried single particles and spray-dried particles in a lab-scale spray dryer have been addressed. The Drying Kinetics Analyzer (TM) generates single particles from a levitated drop under simulated spray-drying conditions. A set of surface-active polymers (bovine serum albumin, hydroxypropyl methyl cellulose, and triblock co-polymer Poloxamer), in combination with lactose, were analyzed for their dynamic surface properties in solution, and their effect on particle morphology and surface composition were determined by low-vacuum SEM and XPS analyses. The morphology obtained in spray drying was reproduced in the single-particle drying. The surface compositions were also similar, but higher levels of surface-active materials were found at the surface of the single particles as compared to the spray-dried particles. Further, the adsorption rate of surface-active compounds at the drop surface estimated by dynamic surface tension was found to be an important parameter to estimate the surface composition at different drying scales. The particle morphology was primarily determined by the surface rheological properties of the feed solution and, to a lesser extent, by the surface composition.
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| 4. |
- Nuzzo, Marine, et al.
(författare)
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The morphology and internal composition of dried particles from whole milk—From single droplet to full scale drying
- 2017
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Ingår i: Food Structure. - : Elsevier BV. - 2213-3291. ; 13, s. 35-44
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Tidskriftsartikel (refereegranskat)abstract
- Powder structure and functionality are expected to be closely linked to the composition and drying process. In order to understand the optimization of the quality of a powder, e.g. encapsulation efficiency, or wetting and dispersion properties, monitoring of the particle microstructure is an attractive concept. However, to study the impact of different parameters in formulation and drying process on full scale is complicated and expensive, hence, studies on smaller scale, even single particle drying, is a potentially useful complement, as long as the results are comparable. The aim of this study is to compare morphology and internal composition of whole milk particles produced at different dryer scales to assess the development of internal structure in powder formed by spray drying. Whole milk was spray dried in the single particle dryer, laboratory dryer, pilot plant dryer and full scale dryer. The morphology and composition of the particles obtained were analyzed by low vacuum-SEM, confocal Raman microscopy and X-ray photoelectron spectroscopy. Phenomena such as adsorption of surface active compounds at the particle surface and phase segregation are observed to different extent, depending on particle size and drying time. The scale of drying influences the internal microstructure and distribution of components in the particles, and to a small extent also the external morphology. These effects are proposed to be related to the drying times for different droplet sizes, although mechanical handling effects and agglomeration in the full scale dryer may also influence the final morphology of these particles, as well as the surface composition.
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