Nanocellulose-based multilayer barrier coatings for gas, oil, and grease resistance

A feasibility study on femtosecond laser texturing of sprayed nanocellulose coatings

Nanocelluloses are emerging as natural materials with favourable properties for coating industry and can be applied by state-of-the-art spraying technology. While additional functionalities are commonly introduced through chemical modification, the surface microstructuring of nanocellulose coatings with high throughput methods remains unexplored. Here, a femtosecond laser is used for texturing spray-coated coatings made of cellulose nanofibrils (CNF) or cellulose nanocrystals (CNC). For coating thickness of 1.5 to 8 μm, processing limits were determined with maximum ablation energy linearly increasing with coating thickness and minimum ablation energy decreasing or increasing depending on the apparent coating density. Within applicable processing window of pulse rate and power setting, the operational ranges were determined for creating one-dimensional and two-dimensional surface patterns, requiring a higher laser energy for CNC compared to CNF coatings and yielding thinnest possible resolved patterns of 17 μm as determined by the laser spot diameter. The laser ablation under low energy corresponds to an increase in surface roughness and intensifies surface hydrophilicity, while the line patterns are able to pin water droplets with rising water contact angles up to 90°. Present feasibility study opens future possibilities for managing surface properties of nanocellulose coatings in applications where tuning of surface hydrophilicity is required.

Extracellular polymeric substances as paper coating biomaterials derived from anaerobic granular sludge

Recovering extracellular polymeric substances (EPS) from waste granular sludge offers a cost-effective and sustainable approach for transforming wastewater resources into industrially valuable products. Yet, the application potential of these EPS in real-world scenarios, particularly in paper manufacturing, remains underexplored. Here we show the feasibility of EPS-based biomaterials, derived from anaerobic granular sludges, as novel coating agents in paper production. We systematically characterised the rheological properties of various EPS-based suspensions. When applied as surface sizing agents, these EPS-based biomaterials formed a distinct, ultra-thin layer on paper, as evidenced by scanning electron microscopy. A comprehensive evaluation of water and oil penetration, along with barrier properties, revealed that EPS-enhanced coatings markedly diminished water absorption while significantly bolstering oil and grease resistance. Optimal performance was observed in EPS variants with elevated protein and hydrophobic contents, correlating with their superior rheological characteristics. The enhanced water-barrier and grease resistance of EPS-coated paper can be attributed to its non-porous, fine surface structure and the functional groups in EPS, particularly the high protein content and hydrophobic humic-like substances. This research marks the first demonstration of utilizing EPS from anaerobic granular sludge as paper-coating biomaterials, bridging a critical knowledge gap in the sustainable use of biopolymers in industrial applications.

Enzymatic approaches for diversifying bioproducts from cellulosic biomass

Cellulosic biomass is the most abundantly available natural carbon-based renewable resource on Earth. Its widespread availability, combined with rising awareness, evolving policies, and changing regulations supporting sustainable practices, has propelled its role as a crucial renewable feedstock to meet the escalating demand for eco-friendly and renewable materials, chemicals, and fuels. Initially, biorefinery models using cellulosic biomass had focused on single-product platform, primarily monomeric sugars for biofuel. However, since the launch of the first pioneering cellulosic plants in 2014, these models have undergone significant revisions to adapt their biomass upgrading strategy. These changes aim to diversify the bioproduct portfolio and improve the revenue streams of cellulosic biomass biorefineries. Within this area of research and development, enzyme-based technologies can play a significant role by contributing to eco-design in producing and creating innovative bioproducts. This Feature Article highlights our strategies and recent progress in utilizing the biological diversity and inherent selectivity of enzymes to develop and continuously optimize sustainable enzyme-based technologies with distinct application approaches. We have advanced technologies for standalone platforms, which produce various forms of cellulose nanomaterials engineered with customized and enhanced properties and high yields. Additionally, we have tailored technologies for integration within a biorefinery concept. This biorefinery approach prioritizes designing tailored processes to establish bionanomaterials, such as cellulose and lignin nanoparticles, and bioactive molecules as part of a new multi-bioproduct platform for cellulosic biomass biorefineries. These innovations expand the range of bioproducts that can be produced from cellulosic biomass, transcending the conventional focus on monomeric sugars for biofuel production to include biomaterials biorefinery. This shift thereby contributes to strengthening the Bioeconomy strategy and supporting the achievement of several Sustainable Development Goals (SDGs) of the 2030 Agenda for Sustainable Development.

Emerging nanocellulose from agricultural waste: Recent advances in preparation and applications in biobased food packaging

With the increasing emphasis on sustainability and eco-friendliness, a novel biodegradable packaging materials has received unprecedented attention. Nanocellulose, owing to its high crystallinity, degradability, minimal toxicity, and outstanding biocompatibility, has gained considerable interest in the field of sustainable packaging. This review provided a comprehensive perspective about the recent advances and future development of cellulose nanocrystals (CNCs) and cellulose nanofibers (CNFs). We first introduced the utilization of agricultural waste for nanocellulose production, such as straw, bagasse, fruit byproducts, and shells. Next, we discussed the preparation process of nanocellulose from various agricultural wastes and expounded the advantages and shortcomings of different methods. Subsequently, this review offered an in-depth investigation on the application of nanocellulose in food packaging, especially the function and packaged form of nanocellulose on food preservation. Finally, the safety evaluation of nanocellulose in food packaging is conducted to enlighten and promote the perfection of relevant regulatory documents. In short, this review provided valuable insights for potential research on the biobased materials utilized in future food packaging.

Sustainable production of cellulosic biopolymers for enhanced smart food packaging: An up-to-date review

Biodegradable and sustainable food packaging (FP) materials have gained immense global importance to reduce plastic pollution and environmental impact. Therefore, this review focused on the recent advances in biopolymers based on cellulose derivatives for FP applications. Cellulose, an abundant and renewable biopolymer, and its various derivatives, namely cellulose acetate, cellulose sulphate, nanocellulose, carboxymethyl cellulose, and methylcellulose, are explored as promising substitutes for conventional plastic in FP. These reviews focused on the production, modification processes, and properties of cellulose derivatives and highlighted their potential for their application in FP. Finally, we reviewed the effects of incorporating cellulose derivatives into film in various aspects of packaging properties, including barrier, mechanical, thermal, preservation aspects, antimicrobial, and antioxidant properties. Overall, the findings suggest that cellulose derivatives have the potential to replace conventional plastics in food packaging applications. This can contribute to reducing plastic pollution and lessening the environmental impact of food packaging materials. The review likely provides insights into the current state of research and development in this field and underscores the significance of sustainable food packaging solutions.

Periodate oxidation of nanofibrillated cellulose films for active packaging applications

An alternative packaging material based on cellulose that possesses excellent barrier properties and is potentially useful for active packaging has been developed. Cellulose nanofibril was efficiently and selectively oxidized with sodium periodate generating reactive aldehyde groups. These groups formed hemiacetal and hemialdal bonds during film formation and, consequently, highly transparent, elastic and strong films were created even under moisture saturation conditions. The periodate oxidation treatment additionally decreased the polarity of the films and considerably enhanced their water barrier properties. Thus, the water contact angle of films treated for 3 and 6 h was 97° and 102°, their water drop test value was higher than in untreated film (viz., 138 and 141 min with 3 and 6 h of treatment) and their water vapour transmission rate was substantially better (3.31 and 0.78 g m-2 day-1 with 3 and 6 h, respectively). The presence of aldehyde groups facilitated immobilization of the enzyme laccase, which efficiently captures oxygen and prevents food decay as a result. Laccase-containing films oxidized 80 % of Methylene Blue colorant and retained their enzymatic activity after storage for 1 month and 12 reuse cycles, opening the door to the possible creation of a reusable packaging to replace the single-use packaging.

Development of high-barrier composite films for sustainable reduction of non-biodegradable materials in food packaging application

Widely employed petroleum-based food packaging materials have inflicted irreparable harm on ecosystems, primarily stemming from their non-biodegradable attributes and recycling complexities. Inspired by natural nacre with a layered aragonite platelet/nanofiber/protein multi-structure, we prepared high-barrier composite films by self-assembly of cellulose nanofibrils (CNF), cellulose nanocrystals (CNC), montmorillonite (MMT), polyvinyl alcohol (PVA) and alkyl ketene dimer (AKD). The composite films demonstrated outstanding barrier properties with oxygen vapor transmission of 0.193 g·mm·m-2·day-1 and water vapor transmission rates of 0.062 cm3·mm·m-2·day-1·0.1 MPa-1, which were significantly lower than those of most biomass-degradable packaging materials. Additionally, the impacts of mixing nanocellulose with various aspect ratios on the tensile strength and folding cycles of the films were examined. The exceptional resistance of the composite films to oil and water provides a novel and sustainable approach to reduce non-biodegradable plastic packaging.

Pickering emulsions of thyme oil in water using oxidized cellulose nanofibers: Towards bio-based active packaging

The antioxidant and antimicrobial properties of thyme essential oil (TEO) are useful for active food packaging, but its poor aqueous solubility restricts its applications. This work involves anionic cellulose nanofibers (CNFs) as the sole stabilizing agent for TEO-in-water emulsions, with oil concentrations ranging from 10 mL/L to 300 mL/L. A double mechanism was proposed: the adsorption of CNFs at oil/water interfaces restricted coalescence to a limited extent, while thickening (rheological stabilization) was required to avoid the buoyance of large droplets (>10 μm). Thickening effects comprised both higher viscosity (over 0.1 Pa·s at 10 s-1) and yield stress (approximately 0.9 Pa). Dilute emulsions had good film-forming capabilities, whereas concentrated emulsions were suitable for paper coating. Regarding antimicrobial activity, CNF-stabilized TEO-in-water emulsions successfully inhibited the growth of both Gram-negative (E. coli, S. typhimurium) and Gram-positive bacteria (L. monocytogenes). As for the antioxidant properties, approximately 50 mg of paper or 3-5 mg of film per mL of food simulant D1 were required to attain 50 % inhibition in radical scavenging tests. Nonetheless, despite the stability and the active properties of these bio-based hydrocolloids, providing this antioxidant and antimicrobial activity was incompatible with maintaining the organoleptic properties of the foodstuff unaltered.

The reduce of water vapor permeability of polysaccharide-based films in food packaging: A comprehensive review

Polysaccharide-based films are favored in the food packaging industry because of their advantages of green and safe characters, as well as natural degradability, but due to the structural defects of polysaccharides, they also have the disadvantages of high water vapor permeability (WVP), which greatly limits their application in the food packaging industry. To break the limitation, numerous methods, e.g., physical and/or chemical methods, have been employed. This review mainly elaborates the up-to-date research status of the application of polysaccharide-based films (PBFs) in food packaging area, including various films from cellulose and its derivatives, starch, chitosan, pectin, alginate, pullulan and so on, while the methods of reducing the WVP of PBFs, mainly divided into physical and chemical methods, are summarized, as well as the discussions about the existing problems and development trends of PBFs. In the end, suggestions about the future development of WVP of PBFs are presented.

The emergence of hybrid cellulose nanomaterials as promising biomaterials

Cellulose nanomaterials (CNs) are promising green materials due to their unique properties as well as their environmental benefits. Among these materials, cellulose nanofibrils (CNFs) and nanocrystals (CNCs) are the most extensively researched types of CNs. While they share some fundamental properties like low density, biodegradability, biocompatibility, and low toxicity, they also possess unique differentiating characteristics such as morphology, rheology, aspect ratio, crystallinity, mechanical and optical properties. Therefore, numerous comparative studies have been conducted, and recently, various studies have reported the synergetic advantages resulting from combining CNF and CNC. In this review, we initiate by addressing the terminology used to describe combinations of these and other types of CNs, proposing "hybrid cellulose nanomaterials" (HCNs) as the standardized classifictation for these materials. Subsequently, we briefly cover aspects of properties-driven applications and the performance of CNs, from both an individual and comparative perspective. Next, we comprehensively examine the potential of HCN-based materials, highlighting their performance for various applications. In conclusion, HCNs have demonstraded remarkable success in diverse areas, such as food packaging, electronic devices, 3D printing, biomedical and other fields, resulting in materials with superior performance when compared to neat CNF or CNC. Therefore, HCNs exhibit great potential for the development of environmentally friendly materials with enhanced properties.

Stabilization of Beeswax-In-Water Dispersions Using Anionic Cellulose Nanofibers and Their Application in Paper Coating

Beeswax is a bio-sourced, renewable, and even edible material that stands as a convincing option to provide paper-based food packaging with moisture resistance. Nonetheless, the difficulty of dispersing it in water limits its applicability. This work uses oxidized, negatively charged cellulose nanofibers along with glycerol to stabilize beeswax-in-water emulsions above the melting point of the wax. The synergistic effects of nanocellulose and glycerol granted the stability of the dispersion even when it cooled down, but only if the concentration of nanofibers was high enough. This required concentration (0.6-0.9 wt%) depended on the degree of oxidation of the cellulose nanofibers. Rheological hindrance was essential to prevent the buoyancy of beeswax particles, while the presence of glycerol prevented excessive aggregation. The mixtures had yield stress and showed pseudoplastic behavior at a high enough shear rate, with their apparent viscosity being positively influenced by the surface charge density of the nanofibers. When applied to packaging paper, the nanocellulose-stabilized beeswax suspensions not only enhanced its barrier properties towards liquid water (reaching a contact angle of 96°) and water vapor (<100 g m-2 d-1), but also to grease (Kit rating: 5) and airflow (>1400 Gurley s). While falling short of polyethylene-coated paper, this overall improvement, attained using only one layer of a biobased coating suspension, should be understood as a step towards replacing synthetic waxes and plastic laminates.

Evaluation of a Hydrophobic Coating Agent Based on Cellulose Nanofiber and Alkyl Ketone Dimer

In this study, we report on the development and testing of hydrophobic coatings using cellulose fibers. The developed hydrophobic coating agent secured hydrophobic performance over 120°. In addition, a pencil hardness test, rapid chloride ion penetration test, and carbonation test were conducted, and it was confirmed that concrete durability could be improved. We believe that this study will promote the research and development of hydrophobic coatings in the future.

Endoglucanase pretreatment aids in isolating tailored-cellulose nanofibrils combining energy saving and high-performance packaging

Cellulose nanofibrils (CNFs) have emerged as a potential alternative to synthetic polymers in packaging applications owing to their oxygen and grease barrier performance and mechanical properties. However, the performance of CNF films is dependent on the intrinsic characteristics of fibers, which are changed during CNF isolation. Understanding the variations in these characteristics during CNF isolation is crucial for tailoring CNF film properties to achieve optimum performance in packaging applications. In this study, CNFs were isolated by endoglucanase-assisted mechanical ultra-refining. The changes in the intrinsic characteristics of CNFs and their impact on CNF films were systematically investigated as functions of the degree of defibrillation, enzyme loading, and reaction time using the design of experiments. Enzyme loading had a significant effect on the crystallinity index, crystallite size, surface area, and viscosity. Meanwhile, the degree of defibrillation greatly influenced the aspect ratio, degree of polymerization, and particle size. CNF films prepared from CNFs isolated under two optimized scenarios (casting and coating applications) exhibited high thermal stability (approximately 300 °C), high tensile strength (104-113 MPa), high oil resistance (kit n°12), and low oxygen transmission rate (1.00-3.17 cc·m^-2.day^-1). Therefore, endoglucanase pretreatment can obtain CNFs at lower energy consumption, resulting in films with higher transmittance, higher barrier performance, and lower surface wettability than the control samples without enzymatic pretreatment and other unmodified net CNF films reported in the literature without intensive loss of mechanical and thermal performance.

Understanding Nanocellulose-Water Interactions: Turning a Detriment into an Asset

Modern technology has enabled the isolation of nanocellulose from plant-based fibers, and the current trend focuses on utilizing nanocellulose in a broad range of sustainable materials applications. Water is generally seen as a detrimental component when in contact with nanocellulose-based materials, just like it is harmful for traditional cellulosic materials such as paper or cardboard. However, water is an integral component in plants, and many applications of nanocellulose already accept the presence of water or make use of it. This review gives a comprehensive account of nanocellulose-water interactions and their repercussions in all key areas of contemporary research: fundamental physical chemistry, chemical modification of nanocellulose, materials applications, and analytical methods to map the water interactions and the effect of water on a nanocellulose matrix.

Review on Hybrid Reinforced Polymer Matrix Composites with Nanocellulose, Nanomaterials, and Other Fibers

The use of composite materials has seen many new innovations for a large variety of applications. The area of reinforcement in composites is also rapidly evolving with many new discoveries, including the use of hybrid fibers, sustainable materials, and nanocellulose. In this review, studies on hybrid fiber reinforcement, the use of nanocellulose, the use of nanocellulose in hybrid forms, the use of nanocellulose with other nanomaterials, the applications of these materials, and finally, the challenges and opportunities (including safety issues) of their use are thoroughly discussed. This review will point out new prospects for the composite materials world, enabling the use of nano- and micron-sized materials together and creating value-added products at the industrial scale. Furthermore, the use of hybrid structures consisting of two different nano-materials creates many novel solutions for applications in electronics and sensors.

Micro-/Nanofibrillated Cellulose-Based Coating Formulations: A Solution for Improving Paper Printing Quality

The use of micro-/nanofibrillated celluloses (M/NFCs) is often considered for the enhancement of paper properties, while it is still challenging to use them in lower weight gain coatings. This work explores how they might be used on the paper surface to improve the printing quality. In this regard, M/NFCs were produced using different pre-treatment methods, including mechanical (m-MFC), enzymatic (e-MFC), TEMPO-mediated oxidation (t-NFC) and cationization (c-NFC), and uniform coating formulations were developed through the cooking of starch and M/NFCs simultaneously. The formulations, at 6-8% of total solid concentration, were applied to the paper surface by roll coating, resulting in a dry coating weight of 1.5 to 3 g/m2. Besides M/NFCs, other components such as starch betainate (a cationic starch ester; SB), Pluronics^® (a triblock co-polymer), precipitated calcium carbonate (PCC) and betaine hydrochloride (BetHCl) were also used in the M/NFC-based coating formulations to observe their combined influence on the printing quality. The presence of M/NFCs improved the paper printing quality, which was further enhanced by the increase in cationic charge density due to the presence of BetHCl/SB, and also by Pluronics^®. The cationic charge of c-NFC was also found to be effective for improving the gamut area and optical density of coated papers, whereas whiteness was often reduced due to the quenching of the brightening agent. BetHCl, on the other hand, improved the printing quality of the coated papers, even though it was more effective when combined with M/NFCs, PCC and Pluronics^®, and also helped to retain paper whiteness.

Nanocellulose for Paper and Textile Coating: The Importance of Surface Chemistry

Nanocellulose has received enormous scientific interest for its abundance, easy manufacturing, biodegradability, and low cost. Cellulose nanocrystals (CNCs) and cellulose nanofibers (CNFs) are ideal candidates to replace plastic coating in the textile and paper industry. Thanks to their capacity to form an interconnected network kept together by hydrogen bonds, nanocelluloses perform an unprecedented strengthening action towards cellulose- and other fiber-based materials. Furthermore, nanocellulose use implies greener application procedures, such as deposition from water. The surface chemistry of nanocellulose plays a pivotal role in influencing the performance of the coating: tailored surface functionalization can introduce several properties, such as gas or grease barrier, hydrophobicity, antibacterial and anti-UV behavior. This review summarizes recent achievements in the use of nanocellulose for paper and textile coating, evidencing critical aspects of coating performances related to deposition technique, nanocellulose morphology, and surface functionalization. Furthermore, beyond focusing on the aspects strictly related to large-scale coating applications for paper and textile industries, this review includes recent achievements in the use of nanocellulose coating for the safeguarding of Cultural Heritage, an extremely noble and interesting emerging application of nanocellulose, focusing on consolidation of historical paper and archaeological textile. Finally, nanocellulose use in electronic devices as an electrode modifier is highlighted.

Composites of cellulose nanocrystals in combination with either cellulose nanofibril or carboxymethylcellulose as functional packaging films

Cellulose nanocrystals (CNC) were mixed with either cellulose nanofibril (CNF) or carboxymethylcellulose (CMC) in variable proportions (0/100, 20/80, 40/60, 50/50, 60/40, 80/20 and 100/0) to obtain cast films with acceptable barrier and mechanical properties as replacements for food packaging plastics. Both CNF and CMC improved tensile strength, elongation, UV opacity, air resistance, hydrophobicity (WCA-water contact angle), water vapor transmission rate (WVTR) and oxygen impermeability in pure CNC. WVTR and oxygen permeability were strongly dependent on relative humidity (RH). Interestingly, the greatest effect on WVTR was observed at RH = 90% in films containing CMC in proportions above 60%. CMC- and CNF-containing films had oxygen impermeability up to an RH level of 80% and 60%, respectively. The previous effects were confirmed by food packaging simulation tests, where CMC-containing films proved the best performers. The composite films studied were biodegradable-which constitutes a major environmental related advantage-to an extent proportional to their content in CMC or CNF.

Influence of Functional Bio-Based Coatings including Chitin Nanofibrils or Polyphenols on Mechanical Properties of Paper Tissues

The paper tissue industry is a constantly evolving sector that supplies markets that require products with different specific properties. In order to meet the demand of functional properties, ensuring a green approach at the same time, research on bio-coatings has been very active in recent decades. The attention dedicated to research on functional properties has not been given to the study of the morphological and mechanical properties of the final products. This paper studied the effect of two representative bio-based coatings on paper tissue. Coatings based on chitin nanofibrils or polyphenols were sprayed on paper tissues to provide them, respectively, with antibacterial and antioxidant activity. The chemical structure of the obtained samples was preliminarily compared by ATR-FTIR before and after their application. Coatings were applied on paper tissues and, after drying, their homogeneity was investigated by ATR-FTIR on different surface areas. Antimicrobial and antioxidant properties were found for chitin nanofibrils- and polyphenols-treated paper tissues, respectively. The mechanical properties of treated and untreated paper tissues were studied, considering as a reference the same tissue paper sample treated only with water. Different mechanical tests were performed on tissues, including penetration, tensile, and tearing tests in two perpendicular directions, to consider the anisotropy of the produced tissues for industrial applications. The morphology of uncoated and coated paper tissues was analysed by field emission scanning electron microscopy. Results from mechanical properties evidenced a correlation between morphological and mechanical changes. The addition of polyphenols resulted in a reduction in mechanical resistance, while the addition of chitin enhanced this property. This study evidenced the different effects produced by two novel coatings on paper tissues for personal care in terms of properties and structure.

A Critical Review of the Performance and Soil Biodegradability Profiles of Biobased Natural and Chemically Synthesized Polymers in Industrial Applications

This review explores biobased polymers for industrial applications, their end fate, and most importantly, origin and key aspects enabling soil biodegradation. The physicochemical properties of biobased synthetic and natural polymers and the primary factors governing degradation are explored. Current and future biobased systems and factors allowing for equivalent comparisons of degradation and possible sources for engineering improved biodegradation are reviewed. Factors impacting ultraviolet (UV) stability of biopolymers have been described including methods to enhance photoresistance and impact on biodegradation. It discusses end-fate of biopolymers in soil and impact of residues on soil health. A limited number of studies examine side effects (e.g., microbial toxicity) from soil biodegradation of composites and biopolymers. Currently available standards for biodegradation and composting have been described with limitations and scope for improvements. Finally, design considerations and implications for sustainable polymers used, under consideration, and to be considered within the context of a rational biodegradable strategy are elaborated.

Micro- and nanocelluloses from non-wood waste sources; processes and use in industrial applications

In addition to renewability and abundance, nanocellulose materials have tremendous (and variable) properties for different applications, ranging from bulk applications, such as paper and packaging reinforcement, to emerging high added-value applications, such as substrates for optoelectronics. Lignocellulosic biomass from agricultural and industrial waste sources is readily available and shows great promise as an inexpensive and sustainable raw material for nanocellulose production. However, the understanding of the potential of using non-wood based biowaste sources is not established and systematic comparisons of versatile agricultural and industrial waste sources can elucidate this complex topic. Here we present an overview of the most studied and most promising sources from agro-industrial waste, the processes to convert them into nanocellulose, some of the established and emerging applications, and discuss the advancements that are still needed for large-scale production. Sugarcane bagasse and oil palm empty fruit bunch have been the most researched waste-based sources for nanocellulose production and demonstrate the most promise due to availability and access. Industrial sources seem to have advantages over agricultural sources in collectability and ease of access. This work gives insight on the potential and the challenges of nanocellulose production from waste sources and discusses how the criteria set for nanocellulose materials in different applications can be met, thus opening new routes for circular economy.

A review of nanocellulose as a new material towards environmental sustainability

Synthetic polymers, commonly referred to as plastics, are anthropogenic contaminants that adversely affect the natural ecosystems. The continuous disposal of long lifespan plastics has resulted in the accumulation of plastic waste, leading to significant pollution of both marine and terrestrial habitats. Scientific pursuit to seek environment-friendly materials from renewable resources has focused on cellulose, the primary reinforcement component of the cell wall of plants, as it is the most abundantly available biopolymer on earth. This paper provides an overview on the current state of science on nanocellulose research; highlighting its extraction procedures from lignocellulosic biomass. Literature shows that the process used to obtain nanocellulose from lignocellulosic biomass greatly influences its morphology, properties and surface chemistry. The efficacy of chemical methods that use alkali, acid, bleaching agents, ionic liquids, deep eutectic solvent for pre-treatment of biomass is discussed. There has been a continuous endeavour to optimize the pre-treatment protocol as it is specific to lignocellulosic biomass and also depends on factors such as nature of the biomass, process and environmental parameters and economic viability. Nanofibers are primarily isolated through mechanical fibrillation while nanocrystals are predominantly extracted using acid hydrolysis. A concise overview on the ways to improve the yield of nanocellulose from cellulosic biomass is also presented in this review. This work also reviews the techniques used to modify the surface properties of nanocellulose by functionalizing surface hydroxyl groups to impart desirable hydrophilic-hydrophobic balance. An assessment on the emerging application of nanocellulose with an emphasis on development of nanocomposite materials for designing environmentally sustainable products is incorporated. Finally, the status of the industrial production of nanocellulose presented, which indicates that there is a continuously increased demand for cellulose nanomaterials. The demand for cellulose is expected to increase further due to its increasing and broadening applications.

Study of tobacco-derived proteins in paper coatings

Replacing synthetic polymers with renewable alternatives is a critical challenge for the packaging industry. This research investigated the use of leaf-based proteins as a sustainable co-binder in the coating formulations for paper-based packaging and other applications. Protein isolates from tobacco leaf and alfalfa concentrates were characterized using the Pierce protein assay, Kjeldahl nitrogen, and gel electrophoresis. The proteins were tested as co-binders in a typical latex-based paper coating formulation. The rheology and water retention properties of the wet coating and the surface, optical, structural, and strength properties of coated papers were measured. The coating performance was affected by the purity, solubility, and molecular weight of the tobacco protein and exhibited a shear-thinning behavior with lower water retention than soy protein. Analysis by scanning electron microscopy and time of flight secondary ion mass spectroscopy on the dried coating layer containing tobacco protein showed enhanced porosity (advantageous for package glueability) relative to the control latex coating. The tobacco protein offers adequate coverage and coating pigment distribution, indicating that this protein can be a suitable option in coatings for packaging applications.

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.

Plant celluloses, hemicelluloses, lignins, and volatile oils for the synthesis of nanoparticles and nanostructured materials

A huge variety of plants are harvested worldwide and their different constituents can be converted into a broad range of bionanomaterials. In parallel, much research effort in materials science and engineering is focused on the formation of nanoparticles and nanostructured materials originating from agricultural residues. Cellulose (40-50%), hemicellulose (20-40%), and lignin (20-30%) represent major plant ingredients and many techniques have been described that separate the main plant components for the synthesis of nanocelluloses, nano-hemicelluloses, and nanolignins with divergent and controllable properties. The minor components, such as essential oils, could also be used to produce non-toxic metal and metal oxide nanoparticles with high bioavailability, biocompatibility, and/or bioactivity. This review describes the chemical structure, the physical and chemical properties of plant cell constituents, different techniques for the synthesis of nanocelluloses, nanohemicelluloses, and nanolignins from various lignocellulose sources and agricultural residues, and the extraction of volatile oils from plants as well as their use in metal and metal oxide nanoparticle production and emulsion preparation. Furthermore, details about the formation of activated carbon nanomaterials by thermal treatment of lignocellulose materials, a few examples of mineral extraction from agriculture waste for nanoparticle fabrication, and the emerging applications of plant-based nanomaterials in different fields, such as biotechnology and medicine, environment protection, environmental remediation, or energy production and storage, are also included. This review also briefly discusses the recent developments and challenges of obtaining nanomaterials from plant residues, and the issues surrounding toxicity and regulation.

Graphene Derivatives in Biopolymer-Based Composites for Food Packaging Applications

This review aims to showcase the current use of graphene derivatives, graphene-based nanomaterials in particular, in biopolymer-based composites for food packaging applications. A brief introduction regarding the valuable attributes of available and emergent bioplastic materials is made so that their contributions to the packaging field can be understood. Furthermore, their drawbacks are also disclosed to highlight the benefits that graphene derivatives can bring to bio-based formulations, from physicochemical to mechanical, barrier, and functional properties as antioxidant activity or electrical conductivity. The reported improvements in biopolymer-based composites carried out by graphene derivatives in the last three years are discussed, pointing to their potential for innovative food packaging applications such as electrically conductive food packaging.

Nanocellulose Bio-Based Composites for Food Packaging

The food industry is increasingly demanding advanced and eco-friendly sustainable packaging materials with improved physical, mechanical and barrier properties. The currently used materials are synthetic and non-degradable, therefore raising environmental concerns. Consequently, research efforts have been made in recent years towards the development of bio-based sustainable packaging materials. In this review, the potential of nanocelluloses as nanofillers or as coatings for the development of bio-based nanocomposites is discussed, namely: (i) the physico-chemical interaction of nanocellulose with the adjacent polymeric phase, (ii) the effect of nanocellulose modification/functionalization on the final properties of the composites, (iii) the production methods for such composites, and (iv) the effect of nanocellulose on the overall migration, toxicity, and the potential risk to human health. Lastly, the technology readiness level of nanocellulose and nanocellulose based composites for the market of food packaging is discussed.

Multilayer packaging: Advances in preparation techniques and emerging food applications

In recent years, with advantages of versatility, functionality, and convenience, multilayer food packaging has gained significant interest. As a single entity, multilayer packaging combines the benefits of each monolayer in terms of enhanced barrier properties, mechanical integrity, and functional properties. Of late, apart from conventional approaches such as coextrusion and lamination, concepts of nanotechnology have been used in the preparation of composite multilayer films with improved physical, chemical, and functional characteristics. Further, emerging techniques such as ultraviolet and cold plasma treatments have been used in manufacturing films with enhanced performance through surface modifications. This work provides an up-to-date review on advancements in the preparation of multilayer films for food packaging applications. This includes critical considerations in design, risk of interaction between the package and the food, mathematical modeling and simulation, potential for scale-up, and costs involved. The impact of in-package processing is also explained considering cases of nonthermal processing and advanced thermal processing. Importantly, challenges associated with degradability and recycling multilayer packages and associated implications on sustainability have been discussed.