Supercritical Adsorption of Quercetin on Aerogels for Active Packaging Applications

Cellulose-Starch Composite Aerogels as Thermal Superinsulating Materials

The demand for sustainable packaging materials is rapidly increasing due to growing environmental concerns over the impact of plastic waste. In this study, biodegradable, porous, lightweight, and high-surface-area microcrystalline cellulose-starch (MCC-S) hybrid aerogels were synthesized via supercritical carbon dioxide (SC-CO2) drying. The samples were generated using five different MCC-S weight ratios and characterized for their morphology, crystallinity, and structural and thermal properties. When MCC and S were used together, aerogels with superior properties were obtained compared to those made from each component individually. Specifically, the 1:2 MCC-S aerogel exhibited the highest porosity (97%), the lowest density (0.058 g/cm3), and the lowest thermal conductivity (0.012 W/(m·K)) along with a high specific surface area (258 m2/g). Therefore, MCC-S aerogels are promising insulators for advanced packaging applications, potentially serving as a sustainable alternative to Styrofoam.

Effect of aminolysis treatment on self-healing properties and printing potentialities of banana peel and edible wax based biodegradable film

Cellulose-based materials are a viable alternative to petroleum-based sources; however, the practical applicability of cellulose films is severely limited by their poor hydrophobicity. This study explores the development of hydrophobic films with self-healing properties through the incorporation of natural wax into a cellulose matrix. Different formulations of films were developed varying the concentration of glycerol (0 % to 3.5 % v/v) and aminolysis treatment. Printability property, rubbing, acid, and water resistance property of the film were also evaluated. The self-healing efficiency of the films varied from around 30 % to 80 % based on variations in glycerol and aminolysis treatment provided. Aminolysis-treated films showed enhanced self-healing properties (Self-healing efficiency ∼77 %) compared to the control films. The films were characterized for their physical, mechanical, barrier, and thermal properties and it was found that 1.5 % had superior properties compared to other compositions. Printability properties showed that aminolysis-treated films had better wetting properties (WCA ∼ 74.46°) with a peak tact force of 8.1 N. This signifies aminolysis-treated films had better ink absorption and adhesion properties, which confirms the printability nature of the films. This study highlights the potential applications of biodegradable self-healing based film, applications with a scope of resolving environmental problems by replacing petrochemical plastics.

Preparation and characterization of quercetin@ZIF-L/GO@AgNPs nanocomposite film for room-temperature strawberry preservation

Fresh strawberries are easily contaminated by microorganisms after picking. Therefore, how to effectively store and keep fresh strawberries has been a hot topic for scientists to study. In this study, we prepared a leaf shaped metal organic framework nanomaterial loaded with quercetin (Quercetin@ZIF-L) at first, which can achieve effective loading of quercetin (96%) within 45 min and has a controlled release effect under acidic conditions. In addition, by cleverly combining satellite graphene oxide @ silver nanoparticles (GO@AgNPs) with slow precipitation performance, Quercetin@ZIF-L/GO@AgNPs nanocomposite film with larger pore size and larger specific surface area was prepared by scraping method. The characterization data of water flux, retention rate, flux recovery rate and water vapor permeability show that the composite film has good physical properties. The experiment of film packaging showed that the fresh life of strawberry could be extended from 3 to 8 days, which significantly improved the storage and freshness cycle of strawberry. At the same time, the metal migration test proved that the residual amount of silver ion in strawberry met the EU standard and zinc ions are beneficial to the health, enriching the types of high-performance fresh-keeping materials and broadening the application.

Cornstarch aerogels with thymol, citronellol, carvacrol, and eugenol prepared by supercritical CO2- assisted techniques for potential biomedical applications

This study focuses on the development of bioactive materials using environmentally friendly techniques, renewable, biocompatible, and biodegradable polysaccharide, as well as natural bioactive compounds (NBCs) found in plant extracts. First, cornstarch aerogels with a porosity of 86 % and a specific surface area of 225 m2/g were produced via supercritical CO2- assisted drying. Further, thymol, citronellol, carvacrol, and eugenol were incorporated into the aerogels by supercritical CO2- assisted impregnation, which allowed variation in loadings of NBCs (12.8-17.6 %). Interaction between cornstarch aerogels and NBCs determined impregnation rate, pore wall thickness (in the range 18-95 nm), liquid absorption capacity (from 265 to 569 %), dehydration mass loss, and release in phosphate-buffered saline. Controlled release of NBCs was maintained over a 3-day period. Moreover, impregnated aerogels showed a significant antioxidant effect with the highest value for DPPH radical inhibition of 25.5 % determined for the aerogels impregnated with eugenol. Notable antimicrobial activity against tested Gram-negative bacteria, Gram-positive bacteria, and fungi was also observed, being the highest for thymol-loaded aerogel with the diameter of the inhibition zones of up to 37.5 mm. This work shows a promising green approach for the production of bioactive two-component starch-based materials for potential applications in skin infection treatment.

Supercritical impregnation of starch aerogels with quercetin: Fungistatic effect and release modelling with a compartmental model

This work proposes the use of supercritical CO2 to impregnate starch (potato and corn) aerogels with quercetin for a potential fungistatic application. Starch aerogels were successfully produced with supercritical drying, but different results were found depending on the amylose/amylopectin ratio. A higher amount of amylose increases aerogels' specific surface area (with a structure with nanofibrils and nodes) due to the linear and amorphous character of this polymer, whereas a higher amount of amylopectin decreases this property until values of only 25 m2·g-1, obtaining an aerogel with a rough surface. These results were explained with XRD, thermogravimetric, and rheological results (triple step with two temperature sweeps and a time sweep and steady state analysis) concerning hydrogel formation. In fact, retrogradation step plays a more important role in hydrogel formation for a starch source with a higher amount of amylopectin due to an increase in the different polymers' interactions. Supercritical impregnation of quercetin on the aerogels was successfully performed (a loading around 0.30 % with respect to the amount of polymer), and in vitro results indicated that the aerogels produced a fungistatic effect on different types of fungi, but only in the first 12 h because the microorganisms adapted to the surrounding environment. Finally, a compartmental model was used to fit the drug release, which is controlled by quercetin aqueous solubility, indicating the main mass transfer resistances (mass transfer through aerogels was always around 500 min-1 and dissolution process mass transfer from 5·10-3 to 1.65·10-3 s-1) and how an increase in the specific surface area of the aerogels (in the case of corn aerogel) provided a stronger initial burst (70-80 % in 20 min). In fact, this initial burst release was mathematically related to a parameter, that varies from 0.178 to 0.036 depending on the aerogel composition. This study shows that starch aerogels can be impregnated with a hydrophobic compound with fungistatic effect by using supercritical CO2, modifying in addition the drug release by changing the native starch.

Hybrid Materials of Bio-Based Aerogels for Sustainable Packaging Solutions

This review explores the field of hybrid materials in the context of bio-based aerogels for the development of sustainable packaging solutions. Increasing global concern over environmental degradation and the growing demand for environmentally friendly alternatives to conventional packaging materials have led to a growing interest in the synthesis and application of bio-based aerogels. These aerogels, which are derived from renewable resources such as biopolymers and biomass, have unique properties such as a lightweight structure, excellent thermal insulation, and biodegradability. The manuscript addresses the innovative integration of bio-based aerogels with various other materials such as nanoparticles, polymers, and additives to improve their mechanical, barrier, and functional properties for packaging applications. It critically analyzes recent advances in hybridization strategies and highlights their impact on the overall performance and sustainability of packaging materials. In addition, the article identifies the key challenges and future prospects associated with the development and commercialization of hybrid bio-based aerogel packaging materials. The synthesis of this knowledge is intended to contribute to ongoing efforts to create environmentally friendly alternatives that address the current problems associated with conventional packaging while promoting a deeper understanding of the potential of hybrid materials for sustainable packaging solutions.

Absorbent bioactive aerogels based on germinated wheat starch and grape skin extract

This study aimed to produce water-absorbent bioactive aerogels using biodegradable raw materials, wheat starch and poly ethylene oxide (PEO), and derived from agro-industrial residues (grape skin) obtained in the wine industry. The aerogels were produced using germinated wheat starch (GWS), with and without PEO, and incorporating grape skin extract (GSE) at concentrations of 5 and 10 % (w/w). The GSE was evaluated for total and individual phenolic compounds, anthocyanins, and antioxidant activity. The starch aerogels were characterized for morphology, density, porosity, functional groups by FT-IR, relative crystallinity and diffraction pattern, water absorption capacity, antioxidant activity, and in vitro release profile of phenolic compounds in food simulant medium. The total phenolic compounds in GSE was 226.25 ± 0.01 mg equivalent of gallic acid/g GSE. The aerogels showed low density and high porosity. All aerogels demonstrated high water absorption capacity (581.4 to 997.5 %). The antioxidant activity of the aerogels increased with increasing GSE concentration and the addition of PEO. The aerogels could release GSE gradually for up to 120 days in the hydrophilic simulant medium and 240 h for the hydrophobic medium. Starch-based aerogels with GSE showed potential to be applied as exudate absorbers with antioxidant activity to develop active food packaging.

Development of highly reusable, mechanically stablecorn starch-based aerogel using glycerol for potential application in the storage of fresh spinach leaves

Impact of glycerol on the physico-functional, morphological, mechanical, and rehydration properties ofcorn starch-based aerogel has been investigated. The aerogel was prepared from hydrogel (sol-gel method) using solvent exchange and supercritical CO₂ drying. Glycerol-infused aerogel had a more connected, denser structure (0.38-0.45 g/cm³), enhanced hygroscopic behavior, and was reusable up to eight times in terms of its capacity to absorb water after being drawn from the soaked sample. However, the inclusion of glycerol reduced the aerogel's porosity (75.89-69.91 %) and water absorption rate (WAR; 118.53-84.64 %) but enhanced its percentage shrinkage (75.03-77.99 %) and compressive strength (26.01-295.06 N). The most effective models for describing the rehydration behavior of aerogel were determined to be the Page, Weibull, and Modified Peleg models. Glycerol addition improved the internal strength of the aerogel so could be recycled without significant change in the physical characteristics of the aerogel. By effectively eliminating the condensed moisture that was developed inside the packing owing to the transpiration of fresh spinach leaves, the aerogel extended the storage life of the leaves by up to eight days. The glycerol-based aerogel has the potential to be employed as a carrier matrix for various chemicals and a moisture scavenger.

Bio-aerogels: Fabrication, properties and food applications

Traditional inorganic aerogels sustainability, biodegradability, and environmental safety concerns have driven researchers to find their safe green alternatives. Recently, interest in the application of bio-aerogels has rapidly increased in the food industry due to their unique characteristics such as high specific surface area and porosity, ultralow density, tunable pore size and morphology, and superior properties (physicochemical, mechanical, and functional). Bio-aerogels, a special category of highly porous unique materials, fabricated by the sol-gel method followed by drying processes, comprising three-dimensional networks of interconnected biopolymers (e.g., polysaccharides and proteins) with numerous air-filled pores. The production of bio-aerogels begins with the formation of a homogeneously dispersed precursor solution, followed by gelation and wet gel drying procedures by employing special drying techniques including atmospheric-, freeze-, and supercritical drying. Due to their special properties, bio-aerogels have emerged as sustainable biomaterial for many industrial applications, i.e., encapsulation and controlled delivery, active packaging, heavy metals separation, water and air filtration, oleogels, and biosensors. Bio-aerogels are low-cost, biocompatible, and biodegradable sustainable material that can be used in improving the processing, storage, transportation, and bioavailability of food additives, functional ingredients, and bioactive substances for their health benefits with enhanced shelf-life.

Porous Aerogels and Adsorption of Pollutants from Water and Air: A Review

Aerogels are open, three-dimensional, porous materials characterized by outstanding properties, such as low density, high porosity, and high surface area. They have been used in various fields as adsorbents, catalysts, materials for thermal insulation, or matrices for drug delivery. Aerogels have been successfully used for environmental applications to eliminate toxic and harmful substances-such as metal ions or organic dyes-contained in wastewater, and pollutants-including aromatic or oxygenated volatile organic compounds (VOCs)-contained in the air. This updated review on the use of different aerogels-for instance, graphene oxide-, cellulose-, chitosan-, and silica-based aerogels-provides information on their various applications in removing pollutants, the results obtained, and potential future developments.

Fabrication of a Novel Protein Sponge with Dual-Scale Porosity and Mixed Wettability Using a Clean and Versatile Microwave-Based Process

An open-porous protein sponge with mixed wettability is presented made entirely from whey proteins and with promising applications in biomedicine, pharmaceutical, and food industry. The fabrication relies on an additive-free, clean and scalable process consisting of foaming followed by controlled microwave-convection drying. Volumetric heating throughout the matrix induced by microwaves causes fast expansion and elongation of the foam bubbles, retards crust formation and promotes early protein denaturation. These effects counteract collapse and shrinkage typically encountered in convection drying of foams. The interplay of high protein content, tailored gas incorporation and controlled drying result in a dried structure with dual-scale porosity composed of open macroscopic elongated foam bubbles and microscopic pores in the surrounding solid lamellae induced by water evaporation. Due to the insolubility and mixed wettability of the denatured protein network, polar and non-polar liquids are rapidly absorbed into the interconnected capillary system of the sponge without disintegrating. While non-watery liquids penetrate the pores by capillary suction, water diffuses also into the stiff protein matrix, inducing swelling and softening. Consequently, the water-filled soft sponge can be emptied by compression and re-absorbs any wetting liquid into the free capillary space.

Enhanced physical and antimicrobial properties of alginate/chitosan composite aerogels based on electrostatic interactions and noncovalent crosslinking

In this study, the alginate/chitosan composite aerogels based on electrostatic interactions and noncovalent crosslinking were fabricated using sol-gel method followed by freeze-drying process. The solution property results showed that with the addition of chitosan in alginate solution, a tighter network was induced by the more entangled molecular chains. The aerogel morphology observations showed that the pore diameter decreased with the increasing weight ratio of chitosan in the aerogels, but was even much lower after the crosslinking of excess alginate with calcium ions. After crosslinking, the aerogels presented the improved thermal stability and higher mechanical properties, as well as stronger antibacterial activities against Staphylococcus aureus and Escherichia coli. Therefore, the enhanced physical and antimicrobial properties of the alginate/chitosan aerogels may be achieved by modulation of electrostatic interactions and noncovalent crosslinking, suggesting the promising applications of these composite aerogels as active food packaging materials for antimicrobial purpose.

Biorefinery Approach for Aerogels

According to the International Energy Agency, biorefinery is "the sustainable processing of biomass into a spectrum of marketable bio-based products (chemicals, materials) and bioenergy (fuels, power, heat)". In this review, we survey how the biorefinery approach can be applied to highly porous and nanostructured materials, namely aerogels. Historically, aerogels were first developed using inorganic matter. Subsequently, synthetic polymers were also employed. At the beginning of the 21st century, new aerogels were created based on biomass. Which sources of biomass can be used to make aerogels and how? This review answers these questions, paying special attention to bio-aerogels' environmental and biomedical applications. The article is a result of fruitful exchanges in the frame of the European project COST Action "CA 18125 AERoGELS: Advanced Engineering and Research of aeroGels for Environment and Life Sciences".

Innovations in Smart Packaging Concepts for Food: An Extensive Review

Innovation in food packaging is mainly represented by the development of active and intelligent packing technologies, which offer to deliver safer and high-quality food products. Active packaging refers to the incorporation of active component into the package with the aim of maintaining or extending the product quality and shelf-life. The intelligent systems are able to monitor the condition of packaged food in order to provide information about the quality of the product during transportation and storage. These packaging technologies can also work synergistically to yield a multipurpose food packaging system. This review is a critical and up-dated analysis of the results reported in the literature about this fascinating and growing field of research. Several aspects are considered and organized going from the definitions and the regulations, to the specific functions and the technological aspects regarding the manufacturing technologies, in order to have a complete overlook on the overall topic.

Prospect of Polysaccharide-Based Materials as Advanced Food Packaging

The use of polysaccharide-based materials presents an eco-friendly technological solution, by reducing dependence on fossil resources while reducing a product's carbon footprint, when compared to conventional plastic packaging materials. This review discusses the potential of polysaccharides as a raw material to produce multifunctional materials for food packaging applications. The covered areas include the recent innovations and properties of the polysaccharide-based materials. Emphasis is given to hemicelluloses, marine polysaccharides, and bacterial exopolysaccharides and their potential application in the latest trends of food packaging materials, including edible coatings, intelligent films, and thermo-insulated aerogel packaging.