Anti-oxidative and UV-absorbing biohybrid film of cellulose nanofibrils and tannin extract

Periodate oxidation-mediated nanocelluloses: Preparation, functionalization, structural design, and applications

In recent years, the remarkable progress in nanotechnology has ignited considerable interest in investigating nanocelluloses, an environmentally friendly and sustainable nanomaterial derived from cellulosic feedstocks. Current research primarily focuses on the preparation and applications of nanocelluloses. However, to enhance the efficiency of nanofibrillation, reduce energy consumption, and expand nanocellulose applications, chemical pre-treatments of cellulose fibers have attracted substantial interest and extensive exploration. Various chemical pre-treatment methods yield nanocelluloses with diverse functional groups. Among these methods, periodate oxidation has garnered significant attention recently, due to the formation of dialdehyde cellulose derived nanocellulose, which exhibits great promise for further modification with various functional groups. This review seeks to provide a comprehensive and in-depth examination of periodate oxidation-mediated nanocelluloses (PONCs), including their preparation, functionalization, hierarchical structural design, and applications. We believe that PONCs stand as highly promising candidates for the development of novel nano-cellulosic materials.

Eco-friendly cellulose-based antioxidation film by partial esterification

Cellulose nanocrystals (CNCs) have received increasing attention because of their superior dispersion and thermal stability. In this study, TEMPO-oxidized cellulose nanocrystal (TOCNC) multifunctional antioxidationantioxidation films (TOCNC-GA film) were prepared by the esterification of TOCNC and gallic acid (GA). TOCNC-GAX films, where X represents the ratio of the amount of GA to the amount of TOCNC, were characterized using scanning electron microscopy, Fourier transform infrared spectroscopy, and X-ray photoelectron spectroscopy. The films with the GA:TOCNC ratio of 1:1 achieved higher interfacial compatibility than the other films. The mechanical properties and water resistance of the TOCNC-GA films were superior than those of pure TOCNC films. Moreover, the original TOCNC structure changed owing to the presence of GA, which endowed a certain thermoplasticity owing to the formation of ester groups. The antioxidation properties of the TOCNC-GA1 films reached 43.8 % and 71.85 % after 6 and 24 h, respectively, as evaluated by the 2,2-biphenyl-1-picrylhydrazyl method and the free radical scavenging activities of the TOCNC-GA1 films. The innovative development of the functional antioxidation film presented in this paper has great potential for use in antioxidation packaging materials and food preservation.

Current progress in functionalization of cellulose nanofibers (CNFs) for active food packaging

There is a growing interest in utilizing renewable biomass resources to manufacture environmentally friendly active food packaging, against the petroleum-based polymers. Cellulose nanofibers (CNFs) have received significant attention recently due to their sustainability, biodegradability, and widely available sources. CNFs are generally obtained through chemical or physical treatment, wherein the original surface chemistry and interfacial interactions can be changed if the functionalization process is applied. This review focuses on promising and sustainable methods of functionalization to broaden the potential uses of CNFs in active food packaging. Novel aspects, including functionalization before, during and after cellulose isolation, and functionalization during and after material processing are addressed. The CNF-involved structural construction including films, membranes, hydrogels, aerogels, foams, and microcapsules, is illustrated, which enables to explore the correlations between structure and performance in active food packaging. Additionally, the enhancement of CNFs on multiple properties of active food packaging are discussed, in which the interaction between active packaging systems and encapsulated food or the internal environment are highlighted. This review emphasizes novel approaches and emerging trends that have the potential to revolutionize the field, paving the way for advancements in the properties and applications of CNF-involved active food packaging.

Application progress of nanocellulose in food packaging: A review

With the increasing environmental and ecological problems caused by petroleum-based packaging materials, the focus has gradually shifted to natural resources for the preparation of functional food packaging materials. In addition to biodegradable properties, nanocellulose (NC) mechanical properties, and rich surface chemistry are also fascinating and desired to be one of the most probable green packaging materials. In this review, we firstly introduce the recent progress of novel applications of NC in food packaging, including intelligent packaging, nano(bio)sensors, and nano-paper; secondly, we focus on the modification techniques of NC to summarize the properties (antimicrobial, mechanical, hydrophobic, antioxidant, and so on) that are required for food packaging, to expand the new synthetic methods and application areas. After presenting all the latest advances related to material design and sustainable applications, an overview summarizing the safety of NC is presented to promote a continuous and healthy movement of NC toward the field of truly sustainable packaging.

Integration of wood-based components - Cellulose nanofibrils and tannic acid - into a poly(vinyl alcohol) matrix to improve functional properties

Poly(vinyl alcohol) (PVA) biocomposite films reinforced with cellulose nanofibrils (CNF) and biologically active tannic acid (TA) were prepared. The influence of different concentrations of CNF and TA in the PVA polymer matrix was investigated in terms of mechanical properties, thermal properties and hydrophobicity improvement of the prepared films. The results showed that in all cases the addition of CNF and TA improved the values of tensile strength and elastic modulus. The PVA film with 10 % CNF exhibited a 30 % higher tensile strength, and the three-component PVA film with 2 % CNF and 10 % TA (P2C10T) exhibited a 40 % higher tensile strength compared to the neat PVA film. The thermal properties (Tg, Tonset) of the PVA biocomposite films were greatly improved, with a significant effect observed for the three-component PVA films. The Tg of the PVA film with 10 % CNF and 10 % TA was 87 °C, 12 °C higher than that of the neat PVA film. For three-component PVA biocomposites with 4 % and 6 % CNF and with all weight percentages of TA, the Tonset shifted to a higher temperature range by about 30 °C compared to the neat PVA film. The PVA film with 2 % CNF and 10 % TA exhibited about a 20° higher contact angle than the neat PVA film. Moreover, the addition of both fillers to the PVA matrix resulted in PVA biocomposites with lower water absorption. PVA film with 10 % TA absorbed about 90 % less water and PVA film with 10 % CNF and 10 % TA absorbed about 80 % less water than the neat PVA film after the films were soaked in water for one hour. The better properties of the composite films produced are due to hydrogen and ester bonds between the components of the composite, which was confirmed by FT-IR spectroscopy. Antioxidant effective films were also obtained due to the biologically active TA to the PVA and PVA/CNF systems.

Effect of rosin based quaternary ammonium salt on mechanical, hydrophily, antibacterial of cornstarch/polydopamine film for food packaging

Food packaging made of biobased materials is environmentally friendly, among which starch film is a type of biobased packaging with great development value. Some existing studies have attempted to add polydopamine (PDA) to enhance cross-linking, but there are still problems such as weakness and hydrophilicity, which greatly limit its application. Therefore, this study synthesized rosin based quaternary ammonium salt-modified cornstarch (ST-B), which was used to replace part of unmodified cornstarch (ST). In the prepared ST/PDA0.5/ST-B5 film, the introduction of a rigid rosin structure increased the stress and water contact angle of the ST/PDA0.5 film by 62 % and 26 %, respectively, while reducing its wettability and WVP; thus, further enhancing its antioxidant activity. Due to the antibacterial ability of rosin quaternary ammonium cations, the packaging film containing 7 wt% ST-B can kill >94.6 % of S. aureus and 99.9 % of E. coli, and can also extend the shelf life of strawberries. In addition, it is proven that the packaging film has good biocompatibility and high safety within cytotoxicity tests and 30-day gavage tests in mice. Therefore, the prepared ST/PDA/ST-B film has more potential for application in food preservation.

Mechanically strong, hydrostable, and biodegradable all-biobased transparent wood films with UV-blocking performance

Petroleum-based plastics are useful but they pose a great threat to the environment and human health. It is highly desirable yet challenging to develop sustainable structural materials with excellent mechanical and optical properties for plastic replacement. Here, we report a simple and efficient method to manufacture high-performance all-biobased structural materials from cellulosic wood skeleton (WS) and gelatin via oxidation and densification. Specifically, gelatin was grafted to the oxidized cellulose wood skeletons (DAWS) and then physically crosslinked via Tannic acid (TA), resulting in a significant enhancement of the material properties. Notably, only a mild pressure was applied during the drying process to form a densified TA/Gelatin/transparent wood film(TWF). The developed TA/Gelatin/TWF (thickness:100 ± 12 μm) exhibited a desirable combination of high strength (∼154.59 MPa), light transmittance (86.2 % at 600 nm), low haze (16.7 %), high water stability (wet strength: ∼130.13 MPa) and ultraviolet blocking efficacy which surpass most of the petroleum-based plastics. In addition, due to the all bio-based origins (wood and gelatin), TA/Gelatin/TWF are easily biodegradable under natural conditions, leading to less impact on the environment. These findings would hold promises for exploring high-quality all bio-based wood composites as eco-friendly alternatives to substitute plastics with wide applications, e.g. anti-counterfeiting, UV protection, and flexible electricals.

Preparation of robust, water-resistant, antibacterial, and antioxidant chitosan-based films by incorporation of cinnamaldehyde-tannin acid-zinc acetate nanoparticles

Chitosan (CS) films have poor mechanical property, low water-resistance and limited antimicrobial activity, which hinder their application in food preservation industry. Cinnamaldehyde-tannic acid-zinc acetate nanoparticles (CTZA NPs) assembled from edible medicinal plant extracts were successfully incorporated into CS films to solve these issues. The tensile strength and water contact angle of the composite films increased about 5.25-fold and 17.55°. The addition of CTZA NPs reduced the water sensitivity of CS films, which could undergo appreciable stretching in water without breaking. Furthermore, CTZA NPs significantly enhanced the UV adsorption, antibacterial, and antioxidant properties of the films, while reduced their water vapor permeability. Moreover, it was possible to print inks onto the films because the presence of the hydrophobic CTZA NPs facilitated the deposition of carbon powder onto their surfaces. The films with great antibacterial and antioxidant activities can be applied for food packaging application.

Cellulose/Grape-Seed-Extract Composite Films with High Transparency and Ultraviolet Shielding Performance Fabricated from Old Cotton Textiles

Plastics displaying many merits have been indispensable in daily life and they still maintain the strong momentum of development. Nevertheless, petroleum-based plastics possess a stable polymer structure and most of them are incinerated or accumulated in the environment, leading to devastating impacts on our ecology system. Thus, exploiting renewable and biodegradable materials to substitute or replace these traditional petroleum-derived plastics is an urgent and important task. In this work, renewable and biodegradable all-biomass cellulose/grape-seed-extract (GSEs) composite films with high transparency and anti-ultraviolet performance were fabricated successfully from pretreated old cotton textiles (P-OCTs) using a relatively simple, green, yet cost-effective, approach. It is proved that the obtained cellulose/GSEs composite films exhibit good ultraviolet shielding performance without sacrificing their transparency, and their UV-A and UV-B blocking values can reach as high as nearly 100%, indicating the good UV-blocking performance of GSEs. Meanwhile, the cellulose/GSEs film show higher thermal stability and water vapor transmission rate (WVTR) than most common plastics. Moreover, the mechanical property of the cellulose/GSEs film can be adjusted by the addition of a plasticizer. Briefly, the transparent all-biomass cellulose/grape-seed-extracts composite films with high anti-ultraviolet capacity were manufactured successfully and they can be used as potential materials in the packaging field.

Phenolic Compounds in Active Packaging and Edible Films/Coatings: Natural Bioactive Molecules and Novel Packaging Ingredients

In recent years, changing lifestyles and food consumption patterns have driven demands for high-quality, ready-to-eat food products that are fresh, clean, minimally processed, and have extended shelf lives. This demand sparked research into the creation of novel tools and ingredients for modern packaging systems. The use of phenolic-compound-based active-packaging and edible films/coatings with antimicrobial and antioxidant activities is an innovative approach that has gained widespread attention worldwide. As phenolic compounds are natural bioactive molecules that are present in a wide range of foods, such as fruits, vegetables, herbs, oils, spices, tea, chocolate, and wine, as well as agricultural waste and industrial byproducts, their utilization in the development of packaging materials can lead to improvements in the oxidative status and antimicrobial properties of food products. This paper reviews recent trends in the use of phenolic compounds as potential ingredients in food packaging, particularly for the development of phenolic compounds-based active packaging and edible films. Moreover, the applications and modes-of-action of phenolic compounds as well as their advantages, limitations, and challenges are discussed to highlight their novelty and efficacy in enhancing the quality and shelf life of food products.

Bioactive Edible Sodium Alginate Films Incorporated with Tannic Acid as Antimicrobial and Antioxidative Food Packaging

Currently, biodegradable and functional food packaging materials have attracted more and more attention due to their potential advantages. Biopolymers are one of the promising materials used to produce biodegradable food packaging films, and sodium alginate (SA) is one of the most used polysaccharides. In this work, we explored a novel edible sodium alginate (SA)/tannic acid (TA) film as biodegradable active food packaging material. The impact of TA concentration on the UV light blocking ability, transparency, water vapor barrier ability, mechanical strength, antioxidant, and antimicrobial activity of the SA-TA films was comprehensively investigated. Fourier transform infrared spectroscopy results revealed that strong hydrogen bonding was the main intermolecular interaction between SA and TA. As TA concentration in the films increased, the water vapor permeability (WVP) decreased from 1.24 × 10^-6 to 0.54 × 10^-6 g/m/h/Pa, the DPPH radical scavenging activity increased from 0.008% to 89.02%. Moreover, the incorporation of TA effectively blocked UV light and elevated antimicrobial activity against Escherichia coli. Overall, the SA films with TA exhibited better water vapor barrier ability, remarkable UV-light barrier ability and antioxidant activity while showing a slight decrease in light transmittance. These results indicated the potential application of TA as a functional additive agent for developing multifunctional food packaging materials.

High-performance multifunctional polyvinyl alcohol/starch based active packaging films compatibilized with bioinspired polydopamine nanoparticles

Bioinspired polydopamine (PDA) nanoparticles were synthesized and explored as functional compatibilizers in polyvinyl alcohol/starch (PVA/ST) matrix to develop high-performance multifunctional packaging film. The effect of the addition of PDA on the microstructural, mechanical, thermal, water vapor barrier, ultraviolet (UV)/high-energy blue light (HEBL) blocking, thermal insulating and antioxidant properties of PVA/ST composite films was fully investigated. Results demonstrated that the added PDA nanoparticles were evenly dispersed in the PVA/ST matrix, providing compact and dense nanocomposite films due to their compatibilization effect. Compared with virgin PVA/ST film, the resulting PVA/ST/PDA nanocomposite films exhibited greatly improved tensile strength, toughness, thermal stability, and water vapor barrier ability. Furthermore, the presence of PDA endowed PVA/ST composite film with excellent UV/HEBL blocking, thermal insulating as well as antioxidant functions. Thus, such high-performance multifunctional nanocomposite films hold the potential of protecting food quality against photothermal oxidative deterioration and extend food shelf life.

Preparation of chitosan/tannin and montmorillonite films as adsorbents for Methyl Orange dye removal

A series of novel chitosan/tannin/montmorillonite (Cs/Tn/MMT) films were synthesised by loading different (from 0.2 to 0.5 wt%) and MMT (from 0.5 to 1.5 wt%) ratios, to be used as promising low-cost biosorbents for methyl orange (MO) removal from aqueous media. The prepared films were characterised using different techniques such as x-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), water contact angle, optical properties, colourimetric measurement, porosity, swelling and thickness. The effects of various parameters, i.e. initial MO concentration, adsorbent dose, pH and temperature, were studied. The Cs/Tn0.2/MMT1 film showed a high removal efficiency of 95.62% and maximum adsorption capacity of 57.37 mg/g under the optimum adsorption conditions (initial methyl orange concentration 60 mg/L, pH 7 and 25 °C). The adsorption kinetic followed the pseudo second order kinetic model and the experimental data were a good fit for the Langmuir isotherm indicating a homogeneous and monolayer adsorption process. The thermodynamic parameters suggested physical adsorption and exothermic behaviour. Consequently, Cs/Tn/MMT films showed effective potential for the uptake of anionic dyes.

Effect of cationization pretreatment on the properties of cationic Eucalyptus micro/nanofibrillated cellulose

Micro/nanofibrillated celluloses (M/NFCs) have attracted considerable research interest over the past few decades, with various pretreatments being used to reduce energy consumption and/or increase fibrillation. To date, few studies have considered cationization as a pretreatment for their preparation. In this work, quaternary ammonium groups were attached to cellulose fibers by a direct reaction with 2,3-epoxypropyltrimethylammonium chloride or by a two-step method (periodate oxidation + Girard's reagent T). The cationic fibers with degrees of substitution (DS) between 0.02 and 0.36, were subjected to homogenization treatment. The morphological properties, chemical composition, and rheological behavior were evaluated to assess the effect of DS and the effect of the cationization method (for samples with similar DS). The two-step cationization resulted in significant degradation of the cellulose structure, leading to the formation of short fibrils and solubilization of the material, ranging from 6% to almost complete solubilization at a DS of 0.36. Direct cationization resulted in longer fibrils with an average diameter of 1 μm, and no significant cellulose degradation was observed, leading to a more cohesive gel-like material (at 1 wt%). These observations clearly show the strong influence of the cationization method on the final properties of the cationic cellulosic materials.

Condensed Tannins, a Viable Solution To Meet the Need for Sustainable and Effective Multifunctionality in Food Packaging: Structure, Sources, and Properties

Condensed tannins (CT) have been the focus of increasing interest in the last years as a result of their potent biological properties, which have prompted their use in the food and feed sector as functional ingredients. The possible exploitation of these compounds as multifunctional additives for the implementation of active food packaging has also been recently appreciated. In this perspective, an overview of the structural features, accessible sources, methods of analysis, and functional properties of CT is provided, with the aim of critically emphasizing the opportunities offered by this widespread class of natural phenolic compounds for the rational design of multifunctional and sustainable food packaging materials.

Bioactive Films from Willow Bark Extract and Nanocellulose Double Network Hydrogels

In nature, the protection of sensitive components from external threats relies on the combination of physical barriers and bioactive secondary metabolites. Polyphenols and phenols are active molecules that protect organisms from physical and chemical threats such as UV irradiation and oxidative stress. The utilization of biopolymers and natural bioactive phenolic components as protective coating layers in packaging solutions would enable easier recyclability of materials and greener production process compared with the current plastic-based products. Herein, we produce a fully wood-based double network material with tunable bioactive and optical properties consisting of nanocellulose and willow bark extract. Willow bark extract, embedded in nanocellulose, was cross-linked into a polymeric nanoparticle network using either UV irradiation or enzymatic means. Based on rheological analysis, atomic force microscopy, antioxidant activity, and transmittance measurements, the cross-linking resulted in a double network gel with enhanced rheological properties that could be casted into optically active films with good antioxidant properties and tunable oxygen barrier properties. The purely biobased, sustainably produced, bioactive material described here broadens the utilization perspectives for wood-based biomass, especially wood-bark extractives. This material has potential in applications where biodegradability, UV shielding, and antioxidant properties of hydrogels or thin films are needed, for example in medical, pharmaceutical, food, and feed applications, but also as a functional barrier coating in packaging materials as the hydrogel properties are transferred to the casted and dried films.

Microfibrillated cellulose films containing chitosan and tannic acid for wound healing applications

The effectiveness of tannic acid as antimicrobial and wound healing for burns have been shown for a century; however, uncontrolled target dosage may result in undesirable side-effects. Remarkably, tannic acid polyphenols compounds crosslinked with polymeric materials produce a strong composite containing the beneficial properties of this tannin. However, investigation of the crosslink structure and its antibacterial and regenerative properties are still unknown when using nanocellulose by mechanical defibrillation; additionally, due to the potential crosslink structure with chitosan, its structure can be complex. Therefore, this work uses bleach kraft nanocellulose in order to investigate the effect on the physical and regenerative properties when incorporated with chitosan and tannic acid. This film results in increased rigidity with a lamellar structure when incorporated with tannic acid due to its strong hydrogen bonding. The release of tannic acid varied depending on the structure it was synthesised with, whereas with chitosan it presented good release model compared to pure cellulose. In addition, exhibiting similar thermal stability as pure cellulose films with antibacterial properties tested against S. aureus and E. coli with good metabolic cellular viability while also inhibiting NF-κB activity, a characteristic of tannic acid.

Versatile nanocellulose-based nanohybrids: A promising-new class for active packaging applications

The food packaging industry is rapidly growing as a consequence of the development of nanotechnology and changing consumers' preferences for food quality and safety. In today's globalization of markets, active packaging has achieved many advantages with the capability to absorb or release substances for prolonging the food shelf life over the traditional one. Therefore, it is critical to developing multifunctional active packaging materials from biodegradable polymers with active agents to decrease environmental challenges. This review article addresses the recent advances in nanocelluloses (NCs)- baseds nanohybrids with new function features in packaging, focusing on the various synthesis methods of NCs-based nanohybrids, and their reinforcing effects as active agents on food packaging properties. The applications of NCs-based nanohybrids as antioxidants, antimicrobial agents, and UV blocker absorbers for prolonging food shelf-life are also reviewed. Overall, these advantages make the CNs-based nanohybrids with versatile properties promising in food and packaging industries, which will impact more readership with concern for future research.

Tannin polymerization: an overview

This review critically addresses the most relevant and innovative techniques for obtaining polymers from tannins.

Nanocellulose in food packaging: A review

The research in eco-friendly and sustainable materials for packaging applications with enhanced barrier, thermo-mechanical, rheological and anti-bacterial properties has accelerated in the last decade. Last decade has witnessed immense interest in employing nanocellulose (NC) as a sustainable and biodegradable alternative to the current synthetic packaging barrier films. This review article gathers the research information on NC as a choice for food packaging material. It reviews on the employment of NC and its various forms including its chemico-physical treatments into bio/polymers and its impact on the performance of nanocomposites for food packaging application. The review reveals the fact that the research trends towards NC based materials are quite promising for Active Packaging (AP) applications, including the Controlled Release Packaging (CRP) and Responsive Packaging (RP). Finally, it summarizes with the challenges of sustainable packaging, gray areas that need an improvement/focus in order to commercially exploit this wonderful material for packaging application.

Tannin-Based Hybrid Materials and Their Applications: A Review

Tannins are eco-friendly, bio-sourced, natural, and highly reactive polyphenols. In the past decades, the understanding of their versatile properties has grown substantially alongside a continuously broadening of the tannins' application scope. In particular, recently, tannins have been increasingly investigated for their interaction with other species in order to obtain tannin-based hybrid systems that feature advanced and/or novel properties. Furthermore, in virtue of the tannins' chemistry and their high reactivity, they either physicochemically or physically interact with a wide variety of different compounds, including metals and ceramics, as well as a number of organic species. Such hybrid or hybrid-like systems allow the preparation of various advanced nanomaterials, featuring improved performances compared to the current ones. Consequently, these diverse-shaped materials have potential use in wastewater treatment or catalysis, as well as in some novel fields such as UV-shielding, functional food packaging, and biomedicine. Since these kinds of tannin-based hybrids represent an emerging field, thus far no comprehensive overview concerning their potential as functional chemical building blocks is available. Hence, this review aims to provide a structured summary of the current state of research regarding tannin-based hybrids, detailed findings on the chemical mechanisms as well as their fields of application.

Hydrolyzable vs. Condensed Wood Tannins for Bio-based Antioxidant Coatings: Superior Properties of Quebracho Tannins

Tannins have always been the subject of great interest for their countless properties, first of all their ability to produce functional coatings on a variety of materials. We report herein a comparative evaluation of the antioxidant properties of wood tannin-based coated substrates. In particular, nylon membrane filters were functionalized with chestnut (hydrolyzable) or quebracho (condensed) tannins by dip coating under different conditions. The efficiency of functionalization was evaluated by the 2,2-diphenyl-1-picrylhydrazyl (DPPH) and ferric reducing/antioxidant power (FRAP) assays, which invariably highlighted the superior ability of condensed tannins to induce the formation of a functional and robust coating. The results of the antioxidant assays revealed also the deleterious effects of aerial or enzymatic oxidation conditions on substrate functionalization, being more significant in the case of hydrolyzable tannins. On the other hand, the use of oxidizing conditions allowed to obtain more stable coatings, still exhibiting good antioxidant properties, in the case of condensed tannins. The presence of iron ions did not lead to a significant improvement of the coating efficiency for either tannins. The systematic approach used in this work provides novel and useful information for the optimal exploitation of tannins in antioxidant functional coatings.

Polyphenols and their applications: An approach in food chemistry and innovation potential

Polyphenols are compounds naturally present in fruits and vegetables that are gaining more and more attention due to their therapeutic effects and their potential technological applications. In this review, we intend to demonstrate the importance of some phenolic compounds, addressing their biological effects and potential for applications in various industrial fields. The intake of these compounds in appropriate concentrations can present promising effects in the prevention of diseases such as diabetes, obesity, Parkinson's, Alzheimer's, and others. They can also be used to improve the physicochemical properties of starch, in the preservation of foods, as natural dyes, prebiotic ingredients, hydrogels and nanocomplexes. In addition, these compounds have potential for innovation in the most diverse technological fields, including organic fine chemistry, basic materials chemistry, pharmaceuticals, food chemistry, chemical engineering, etc.

Antioxidant Properties of Agri-food Byproducts |and Specific Boosting Effects of Hydrolytic Treatments

Largely produced agri-food byproducts represent a sustainable and easily available source of phenolic compounds, such as lignins and tannins, endowed with potent antioxidant properties. We report herein the characterization of the antioxidant properties of nine plant-derived byproducts. 2,2-Diphenyl-1-picrylhydrazyl (DPPH) and ferric reducing/antioxidant power (FRAP) assays indicated the superior activity of pomegranate peels and seeds, grape pomace and pecan nut shell. An increase in the antioxidant potency was observed for most of the waste materials following a hydrolytic treatment, with the exception of the condensed tannin-rich pecan nut shell and grape pomace. UV-Vis and HPLC investigation of the soluble fractions coupled with the results from IR analysis and chemical degradation approaches on the whole materials allowed to conclude that the improvement of the antioxidant properties was due not only to removal of non-active components (mainly carbohydrates), but also to structural modifications of the phenolic compounds. Parallel experiments run on natural and bioinspired model phenolic polymers suggested that these structural modifications positively impacted on the antioxidant properties of lignins and hydrolyzable tannins, whereas significant degradation of condensed tannin moieties occurred, likely responsible for the lowering of the reducing power observed for grape pomace and pecan nut shell. These results open new perspectives toward the exploitation and manipulation of agri-food byproducts for application as antioxidant additives in functional materials.

Cogrinding Wood Fibers and Tannins: Surfactant Effects on the Interactions and Properties of Functional Films for Sustainable Packaging Materials

We report on the combination of cellulose nanofibrils (CNFs) and condensed tannins from Acacia mearnsii for the development of hybrid, functional films. The tannins are fractionated and concentrated in polyphenolics that are used for functional components in the hybrid materials. Cogrinding of wood fibers with the tannins in aqueous media allows simultaneous fiber deconstruction and in situ binding of tannins on the freshly exposed cellulosic surfaces. Hence, a tightly bound bicomponent system is produced, which is otherwise not possible if typical adsorption protocols are followed, mainly due to the extensive hydration typical of CNFs. A nonionic surfactant is used to tailor the cellulose–tannin interactions. The proposed strategy not only enables the incorporation of tannins with CNFs but also endows a high and prolonged antioxidant effect of films formed by filtration. Compared to tannin-free films, those carrying tannins are considerably more hydrophobic. In addition, they show selective absorption of ultraviolet light while maintaining optical transparency in the visible range. The proposed simple protocol for incorporating tannins and surfactants with CNFs is suitable to produce functional materials. This is possible by understanding associated interfacial phenomena in the context of sustainable materials within the concept of the circular bioeconomy.

Antioxidant and UV-Blocking Leather-Inspired Nanocellulose-Based Films with High Wet Strength

The mechanical performance in the wet state needs to be significantly improved and the intrinsic functionalities should be fully utilized to promote the replacement of fossil-based plastics with renewable biobased materials. We demonstrate a leather-inspired approach to produce multifunctional materials with a high wet strength that is based on tannin-induced precipitation of gelatin grafted onto surface-modified cellulose nanofibrils (CNF). The leather-inspired CNF-based films had a wet tensile strength of 33 MPa, a Young’s modulus of 310 MPa, and a strain at failure of 22%, making the wet materials stronger than, for example, dry conventional low-density polyethylene and more ductile than paper-based food packaging materials. The tannin-containing films displayed excellent antioxidant and UV-blocking properties, rapidly scavenging more than 90% of added free radicals and absorbing 100% of light in the UV-B/UV-C range. This work illustrates the prospect of combining renewable materials in a leather-inspired approach to form wet strong and multifunctional films with potential application in food packaging.

Use of Deep Eutectic Solvents in Polymer Chemistry-A Review

This review deals with two overlapping issues, namely polymer chemistry and deep eutectic solvents (DESs). With regard to polymers, specific aspects of synthetic polymers, polymerization processes producing such polymers, and natural cellulose-based nanopolymers are evaluated. As for DESs, their compliance with green chemistry requirements, their basic properties and involvement in polymer chemistry are discussed. In addition to reviewing the state-of-the-art for selected kinds of polymers, the paper reveals further possibilities in the employment of DESs in polymer chemistry. As an example, the significance of DES polarity and polymer polarity to control polymerization processes, modify polymer properties, and synthesize polymers with a specific structure and behavior, is emphasized.

Recent Developments in the Reduction of Oxidative Stress through Antioxidant Polymeric Formulations

Reactive oxygen and nitrogen species (RONS) are produced endogenously in our body, or introduced through external factors, such as pollution, cigarette smoke, and excessive sunlight exposure. In normal conditions, there is a physiological balance between pro-oxidant species and antioxidant molecules that are able to counteract the detrimental effect of the former. Nevertheless, when this homeostasis is disrupted, the resulting oxidative stress can lead to several pathological conditions, from inflammation to cancer and neurodegenerative diseases. In this review, we report on the recent developments of different polymeric formulations that are able to reduce the oxidative stress, from natural extracts, to films and hydrogels, and finally to nanoparticles (NPs).

Preparation of transparent anti-pollution cellulose carbamate regenerated cellulose membrane with high separation ability

In this study, cellulose pulp and urea were used to synthesize cellulose carbamate (nitrogen content reaches 4.5%) by low-cost and environmentally friendly solid-liquid phase method. Cellulose carbamate fluid was prepared by using sodium hydroxide aqueous solution as solvent. The fluid was regenerated and formed in a coagulation bath, and finally a regenerated cellulose membrane with high transparency and separation ability was obtained. The simple chemical treatment of cellulose not only greatly increased the mass fraction of cellulose dissolution (It has reached 15%) and retains the original crystal form and thermal stability of cellulose. The surface of the membrane was relatively dense, and the inside has regular microchannel. The factors affect the transparency and water flux of regenerated cellulose membranes were discussed by orthogonal experimental range analysis. The ability of the regenerated cellulose membrane to reject dyes was tested. The results showed that the rejection of methyl blue and congo red reached 100%, and the rejection rate of methyl orange reached 60%. The oil/water separation ability and the anti-pollution ability of the regenerated cellulose membrane were tested. The oil/water separation effect reached 100%. This membrane may have application prospect in water treatment, biotechnology.