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Processing of Materials by Supercritical Fluids, 3rd Edition

A special issue of Molecules (ISSN 1420-3049). This special issue belongs to the section "Green Chemistry".

Deadline for manuscript submissions: 28 February 2025 | Viewed by 694

Special Issue Editor


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Guest Editor
Department of Industrial Engineering, University of Salerno, Via Giovanni Paolo II, Fisciano, SA, Italy
Interests: supercritical-fluids-assisted processes; membranes; aerogels; scaffolds; foams; micro- and nanoparticles
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Special Issue Information

Dear Colleagues,

Supercritical fluids are characterized by unique peculiarities, such as solvent power and diffusivity comparable to those of liquid organic solvents and gaseous substances, respectively, quasi-zero surface tension, and low pollution. Consequently, several unit operations have been modified and improved using supercritical fluids, with the aim of overcoming their limitations.

Among them, processes concerning the interaction between materials (inorganic and/or organic) and supercritical fluids are becoming more attractive. Indeed, numerous fields of application relate to these processes, ranging from the chemical, pharmaceutical, and food industries to tissue, mechanical, and computer engineering. For example, numerous micronization and impregnation processes, as well as processes for generating porous structures (i.e., aerogels, membranes, scaffolds, and foams), fibers, and films, have been developed using supercritical fluids.

The aim of this Special Issue is to highlight the processing of materials by supercritical fluids. In particular, we welcome research submissions about the interaction between supercritical fluids and organic and/or inorganic materials and the study and development of processes concerning the generation of micro- and nanoparticles, fibers, foams, scaffolds, membranes, and aerogels.

Dr. Stefano Cardea
Guest Editor

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Keywords

  • supercritical fluids
  • materials
  • aerogels
  • particles
  • membranes
  • fibers
  • scaffolds

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Published Papers (1 paper)

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Research

16 pages, 13512 KiB  
Article
Green Processing of Ilex guayusa: Antioxidant Concentration and Caffeine Reduction Using Encapsulation by Supercritical Antisolvent Process
by Miguel Ángel Meneses, Jhulissa Guzmán, Jhulissa Cabrera, Jorge Magallanes, Eduardo Valarezo and María del Cisne Guamán-Balcázar
Molecules 2024, 29(22), 5309; https://doi.org/10.3390/molecules29225309 - 11 Nov 2024
Viewed by 520
Abstract
This study investigated the valorization of Ilex guayusa leaves by producing a low-caffeine, antioxidant-rich product through the supercritical antisolvent extraction (SAE) process. The objective was to concentrate the antioxidants while selectively reducing the caffeine. The SAE treatments were conducted using an ethanolic extract [...] Read more.
This study investigated the valorization of Ilex guayusa leaves by producing a low-caffeine, antioxidant-rich product through the supercritical antisolvent extraction (SAE) process. The objective was to concentrate the antioxidants while selectively reducing the caffeine. The SAE treatments were conducted using an ethanolic extract of guayusa leaves under varying pressure (80 bar–150 bar) and temperature (35–45 °C) conditions to improve the recovery of chlorogenic acid (CGA) and caffeine fractionation. The co-precipitation of antioxidants with polyvinylpyrrolidone (PVP) (ratio 1:1–1:2 mass/mass) as an encapsulant was also studied. The SAE precipitates were analyzed for their recovery yield, CGA and caffeine contents, antioxidant activity, and total phenols. Based on the statistical analysis, the optimal conditions for the SAE were 120 bar and 45 °C. Under these conditions, the CGA concentration increased from 43.02 mg/g extract to 237 mg/g precipitate, while the caffeine was reduced to less than 1% mass. Co-precipitation with PVP improved the recovery yield by more than two times than the SAE alone while maintaining the caffeine content below 1% mass. Additionally, the co-precipitation with PVP facilitated the formation of spherical microparticles, indicating successful encapsulation of the bioactive compounds, with an IC50 of 0.51 ± 0.01 mg/mL for DPPH and 0.18 ± 0.01 mg/mL for ABTS. These results highlight the effectiveness of the SAE co-precipitation process in developing low-caffeine functional ingredients with potential food and pharmaceutical applications. Full article
(This article belongs to the Special Issue Processing of Materials by Supercritical Fluids, 3rd Edition)
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