scholarly journals Editorial on Special Issues “Aerogels” and “Aerogels 2018”

Gels ◽  
2020 ◽  
Vol 6 (3) ◽  
pp. 19
Author(s):  
Françoise Quignard ◽  
Nathalie Tanchoux
Keyword(s):  
Porous Structure ◽  
Supercritical Co2 ◽  
Freeze Drying ◽  
Drying Process ◽  
Gel Structure ◽  
Supercritical Co2 Drying

Aerogels can be defined as ultralight materials with a 3D porous structure, similar to their parent wet gels, where the solvent has been replaced by a gas without a collapse of the gel structure, thanks to the drying process used (supercritical CO2 drying, freeze drying, etc [...]

scholarly journals Comparison of Supercritical CO2-Drying, Freeze-Drying and Frying on Sensory Properties of Beetroot

Foods ◽  
2020 ◽  
Vol 9 (9) ◽  
pp. 1201
Author(s):  
Nikola Tomic ◽  
Ilija Djekic ◽  
Gerard Hofland ◽  
Nada Smigic ◽  
Bozidar Udovicki ◽  
...  
Keyword(s):  
Supercritical Co2 ◽  
Freeze Drying ◽  
Sensory Quality ◽  
Quality Parameters ◽  
Acceptance Testing ◽  
Drying Methods ◽  
Promising Alternative ◽  
Supercritical Co2 Drying ◽  
Negative Effect ◽  
Drying Technology

The aim of this study was to compare the sensory quality and acceptance of dried ready-to-eat beetroot snacks as a result of different drying methods applied: supercritical CO2-drying (scCO2-drying), frying, and freeze-drying. Descriptive sensory analysis, quality rating (10 assessors), and consumer acceptance testing (n = 102) were performed. Mean overall quality scores within the range of “very good” quality were found only in non-precooked scCO2-dried samples which were characterized by typical magenta color, low level of shape and surface deformations, pronounced brittleness and crispiness, and good rehydration during mastication. The other samples were in the range of “good” quality. The pre-cooking step before scCO2-drying negatively influenced the sensory quality parameters, particularly appearance. Around 60% of tested consumers showed a preference for the fried and non-precooked scCO2-dried samples. The drivers of liking were mostly related to the characteristics of the product, which was salted, fried, and crispy, with an oily and overburnt flavor, i.e., the product most similar to commercial potato chips products. Freeze-drying had a negative effect primarily on appearance and flavor. According to the sensory evaluation conducted, direct scCO2-drying without a pre-cooking step showed itself as a promising alternative drying technology in the production of dried beetroot snacks.

scholarly journals Supercritical CO2 drying of food matrices

2018 ◽  
Author(s):  
S. Spilimbergo ◽  
A. Zambon ◽  
T. M. Vizzotto ◽  
G. Morbiato ◽  
M. Toffoletto ◽  
...  
Keyword(s):  
Supercritical Co2 ◽  
Supercritical Drying ◽  
Microbial Inactivation ◽  
Process Conditions ◽  
Drying Methods ◽  
Drying Process ◽  
Promising Alternative ◽  
Supercritical Co2 Drying ◽  
Conventional Drying ◽  
Drying Efficiency

This work explore the use of supercritical CO2 drying as alternative technique for the obtainment of pasteurized and high quality dried product. Several tests were conducted on animal, vegetable and fruit matrixes in order to investigate the effectiveness of SC-CO2 drying process at different process conditions. Design of experiment was performed to find the optimal process conditions for vegetable and fruit matrices, using the final water activity of the products as key indicator for the drying efficiency. The inactivation of naturally present microorganisms and inoculated pathogens demonstrated the capability of SC-CO2 drying process to assure a safe product. Moreover, retention of nutrients was compared with conventional drying methods. Results suggest that supercritical drying is a promising alternative technology for food drying. Keywords: supercritical drying; carbon dioxide; food drying; microbial inactivation

scholarly journals Fabrication and Characterization of Cellulose Nanofiber Aerogels Prepared via Two Different Drying Techniques

Polymers ◽  
2020 ◽  
Vol 12 (11) ◽  
pp. 2583 ◽  
Author(s):  
Zhe Wang ◽  
Wenkai Zhu ◽  
Runzhou Huang ◽  
Yang Zhang ◽  
Chong Jia ◽  
...  
Keyword(s):  
Specific Surface ◽  
Surface Area ◽  
Liquid Nitrogen ◽  
Compression Strength ◽  
Pore Volume ◽  
Supercritical Co2 ◽  
Freeze Drying ◽  
Drying Method ◽  
Drying Techniques ◽  
Supercritical Co2 Drying

Studies on the influence of drying processes on cellulose nanofiber (CNF) aerogel performance has always been a great challenge. In this study, CNF aerogels were prepared via two different drying techniques. The CNF solution was prepared via existing chemical methods, and the resultant aerogel was fabricated through supercritical CO2 drying and liquid nitrogen freeze-drying techniques. The microstructure, shrinkage, specific surface area, pore volume, density, compression strength, and isothermal desorption curves of CNF aerogel were characterized. The aerogel obtained from the liquid nitrogen freeze-drying method showed a relatively higher shrinkage, higher compression strength, lower specific surface area, higher pore volume, and higher density. The N2 adsorption capacity and pore diameter of the aerogel obtained via the liquid nitrogen freeze-drying method were lower than the aerogel that underwent supercritical CO2 drying. However, the structures of CNF aerogels obtained from these two drying methods were extremely similar.

scholarly journals Production of polylactic acid aerogels via phase separation and supercritical CO2 drying: thermodynamic analysis of the gelation and drying process

2021 ◽  
Author(s):  
Alberto Bueno ◽  
Christian Luebbert ◽  
Sabine Enders ◽  
Gabriele Sadowski ◽  
Irina Smirnova
Keyword(s):  
Phase Separation ◽  
Polylactic Acid ◽  
Ternary Phase ◽  
Life Science ◽  
Drying Process ◽  
Gel Structure ◽  
Crystallinity Degree ◽  
Application Range ◽  
Ternary Phase Diagrams ◽  
Supercritical Co2 Drying

AbstractThe application range of aerogels, especially in the life-science sector, can be extended by utilizing biocompatible polymers such as polylactic acid (PLA). However, the low glass transition temperature (Tg) of PLA and the challenging gelation techniques limit the application of supercritical CO2 (scCO2) drying and thus the PLA-aerogel production. The aim of this work is to overcome this challenge and to provide a better understanding of the thermodynamics of the process. Therefore, the gelation of amorphous PLA (PDLLA) and semicrystalline PLA (PLLA) via thermal-induced phase separation (TIPS) was studied. To identify polymer/solvent/antisolvent ratios suitable for gelation, thermodynamic modeling (PC-SAFT) was used to describe the corresponding ternary phase diagrams. scCO2 drying was used to preserve the mesoporous gel structure formed during the gelation. Due to the decrease in the Tg of PLA in the presence of CO2, this could not be applied to all gels. It was found that the critical parameter to enable the scCO2 drying of low Tg polymers is the crystallinity degree (Xc) of the polymer. Based on these results, some guidelines for producing aerogels from polymers with low Tg are formulated. Graphical abstract

Contamination Control in Supercritical CO2 Drying Process for Nano-Scale Memory Manufacturing

2013 ◽  
Vol 58 (6) ◽  
pp. 197-204
Author(s):  
H. Hayashi ◽  
H. Okuchi ◽  
H. Tomita ◽  
Y. Ono ◽  
T. Nakamori ◽  
...  
Keyword(s):  
Supercritical Co2 ◽  
Drying Process ◽  
Contamination Control ◽  
Nano Scale ◽  
Supercritical Co2 Drying

scholarly journals Production of Porous Agarose-Based Structures: Freeze-Drying vs. Supercritical CO2 Drying

Gels ◽  
2021 ◽  
Vol 7 (4) ◽  
pp. 198
Author(s):  
Mariangela Guastaferro ◽  
Lucia Baldino ◽  
Ernesto Reverchon ◽  
Stefano Cardea
Keyword(s):  
Cooling Rate ◽  
Supercritical Co2 ◽  
Freeze Drying ◽  
Average Pore Size ◽  
Mesoporous Structure ◽  
Porous Structures ◽  
Average Pore ◽  
Thermal Changes ◽  
Supercritical Co2 Drying ◽  
Fast Cooling

In this work, the effect of two processes, i.e., freeze-drying and supercritical CO2 (SC-CO2) drying, on the final morphology of agarose-based porous structures, was investigated. The agarose concentration in water was varied from 1 wt% up to 8 wt%. Agarose cryogels were prepared by freeze-drying using two cooling rates: 2.5 °C/min and 0.1 °C/min. A more uniform macroporous structure and a decrease in average pore size were achieved when a fast cooling rate was adopted. When a slower cooling rate was performed instead, cryogels were characterized by a macroporous and heterogenous structure at all of the values of the biopolymer concentration investigated. SC-CO2 drying led to the production of aerogels characterized by a mesoporous structure, with a specific surface area up to 170 m2/g. Moreover, agarose-based aerogels were solvent-free, and no thermal changes were detected in the samples after processing.

scholarly journals Microbial inactivation efficiency of supercritical CO2 drying process

2018 ◽  
Vol 36 (16) ◽  
pp. 2016-2021 ◽  
Author(s):  
Alessandro Zambon ◽  
Filippo Michelino ◽  
Siméon Bourdoux ◽  
Frank Devlieghere ◽  
Stefania Sut ◽  
...  
Keyword(s):  
Supercritical Co2 ◽  
Microbial Inactivation ◽  
Drying Process ◽  
Supercritical Co2 Drying ◽  
Inactivation Efficiency
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