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Experimental Study of the Impact of Pore Structure on Drying Kinetics and Sublimation Front Patterns

Freeze-drying frozen maltodextrin solutions with solid contents of 5% and 30% (w/w) was experimentally investigated using neutron imaging at PSI Villigen/Switzerland. Different solid contents, as well as annealing at −5 °C for 11 h, were used to modify the porous structure of the samples, which was...

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Autores principales: Thomik, Maximilian, Gruber, Sebastian, Kaestner, Anders, Foerst, Petra, Tsotsas, Evangelos, Vorhauer-Huget, Nicole
Formato: Online Artículo Texto
Lenguaje:English
Publicado: MDPI 2022
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9332246/
https://www.ncbi.nlm.nih.gov/pubmed/35893794
http://dx.doi.org/10.3390/pharmaceutics14081538
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author Thomik, Maximilian
Gruber, Sebastian
Kaestner, Anders
Foerst, Petra
Tsotsas, Evangelos
Vorhauer-Huget, Nicole
author_facet Thomik, Maximilian
Gruber, Sebastian
Kaestner, Anders
Foerst, Petra
Tsotsas, Evangelos
Vorhauer-Huget, Nicole
author_sort Thomik, Maximilian
collection PubMed
description Freeze-drying frozen maltodextrin solutions with solid contents of 5% and 30% (w/w) was experimentally investigated using neutron imaging at PSI Villigen/Switzerland. Different solid contents, as well as annealing at −5 °C for 11 h, were used to modify the porous structure of the samples, which was quantified using X-ray computed tomography. Annealing of the 5% (w/w) sample, with a pore size distribution (PSD) of 23.7 ± 11.1 µm, yielded a very open pore space with high porosity (ε = 0.96) and a PSD of 33.0 ± 27.0 µm. In contrast, the higher solid content resulted in small, lamellar, narrow pores with high anisotropy and a porosity of ε = 0.65, as well as a PSD of 13.5 ± 4 µm. In operando neutron imaging was used to show the impact of the structure of frozen maltodextrin on the overall drying kinetics and shape of the sublimation front during freeze-drying. For this purpose, a freeze-drying stage was employed, which allowed a novel approach to time- and space-resolved monitoring of the ice phase. The sublimation front propagation was quantitatively analyzed based on ice saturation profiles and sublimation rates. The dependence of drying velocity on structure is nicely demonstrated by the data. In addition, it is shown that the sublimation front widened during freeze-drying, resulting in either rather concave or convex shape depending on morphological parameters.
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spelling pubmed-93322462022-07-29 Experimental Study of the Impact of Pore Structure on Drying Kinetics and Sublimation Front Patterns Thomik, Maximilian Gruber, Sebastian Kaestner, Anders Foerst, Petra Tsotsas, Evangelos Vorhauer-Huget, Nicole Pharmaceutics Article Freeze-drying frozen maltodextrin solutions with solid contents of 5% and 30% (w/w) was experimentally investigated using neutron imaging at PSI Villigen/Switzerland. Different solid contents, as well as annealing at −5 °C for 11 h, were used to modify the porous structure of the samples, which was quantified using X-ray computed tomography. Annealing of the 5% (w/w) sample, with a pore size distribution (PSD) of 23.7 ± 11.1 µm, yielded a very open pore space with high porosity (ε = 0.96) and a PSD of 33.0 ± 27.0 µm. In contrast, the higher solid content resulted in small, lamellar, narrow pores with high anisotropy and a porosity of ε = 0.65, as well as a PSD of 13.5 ± 4 µm. In operando neutron imaging was used to show the impact of the structure of frozen maltodextrin on the overall drying kinetics and shape of the sublimation front during freeze-drying. For this purpose, a freeze-drying stage was employed, which allowed a novel approach to time- and space-resolved monitoring of the ice phase. The sublimation front propagation was quantitatively analyzed based on ice saturation profiles and sublimation rates. The dependence of drying velocity on structure is nicely demonstrated by the data. In addition, it is shown that the sublimation front widened during freeze-drying, resulting in either rather concave or convex shape depending on morphological parameters. MDPI 2022-07-23 /pmc/articles/PMC9332246/ /pubmed/35893794 http://dx.doi.org/10.3390/pharmaceutics14081538 Text en © 2022 by the authors. https://creativecommons.org/licenses/by/4.0/Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https://creativecommons.org/licenses/by/4.0/).
spellingShingle Article
Thomik, Maximilian
Gruber, Sebastian
Kaestner, Anders
Foerst, Petra
Tsotsas, Evangelos
Vorhauer-Huget, Nicole
Experimental Study of the Impact of Pore Structure on Drying Kinetics and Sublimation Front Patterns
title Experimental Study of the Impact of Pore Structure on Drying Kinetics and Sublimation Front Patterns
title_full Experimental Study of the Impact of Pore Structure on Drying Kinetics and Sublimation Front Patterns
title_fullStr Experimental Study of the Impact of Pore Structure on Drying Kinetics and Sublimation Front Patterns
title_full_unstemmed Experimental Study of the Impact of Pore Structure on Drying Kinetics and Sublimation Front Patterns
title_short Experimental Study of the Impact of Pore Structure on Drying Kinetics and Sublimation Front Patterns
title_sort experimental study of the impact of pore structure on drying kinetics and sublimation front patterns
topic Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9332246/
https://www.ncbi.nlm.nih.gov/pubmed/35893794
http://dx.doi.org/10.3390/pharmaceutics14081538
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