Improving barrier and antibacterial properties of chitosan composite films by incorporating lignin nanoparticles and acylated soy protein isolate nanogel

An all-natural strategy for versatile biomass-based active food packaging film with superior biodegradability, antioxidant and antimicrobial activity

To advance "green" food development, the use of more versatile biomass-based, biodegradable food packaging has been frequently proposed. Specifically, an innovative biomass-based active food packaging film (SEC) was hereby introduced based on an all-natural strategy with natural soy protein isolate (SPI) and carboxymethyl chitosan (CMCS) as raw materials. The results demonstrated the SEC had favorable anti-UV (UV blocking reached 98.5 %), antioxidant activity, biocompatibility and biodegradability, and the inhibition rates for Escherichia coli and Staphylococcus aureus reached 99.37 % and 97 %, respectively. Finally, the grape preservation experiment revealed that SEC could extend the shelf life of grapes more than 15 days. This study utilizes the active functional groups such as hydroxyl and amino groups on CMCS, which can undergo addition reactions with the epoxy groups on EGDE. This innovation not only maximizes the recycling value of natural biomass but also offers a novel approach to the sustainable production of green food packaging.

Lignin reinforced eco-friendly and functional nanoarchitectonics materials with tailored interfacial barrier performance

Exploring innovative and sustainable routes for the production of biodegradable biomass-based materials is critical to promote a circular carbon economy and carbon neutrality goals. Fossil-based non-biodegradable plastic waste poses a nonnegligible threat to humans and the ecological environment, and biomass-based functional materials are becoming increasingly viable alternatives. Lignin, a naturally occurring macromolecular polymer, is green and renewable resource rich in aromatic rings, with biodegradability, biocompatibility, and excellent processability for eco-friendly composites. Moreover, versatile and high tunable lignins can be valorized into functional materials, which are crucial building blocks in the fabrication of biomass-derived composites. Lignin's unique chemical structure, solvent resistance, anti-aging, and anti-ultraviolet functional properties make it highly potential for the fabrication of sustainable biobased barrier materials. This review systematically summarizes the progress in the fabrication and application of lignin-based functional composites, with a particular focus on barrier materials. First, the structural diversity of lignins from different sources and fractionation methods, and the structural modification strategies of lignins are briefly introduced. Then, the multiple barrier performances of lignin-based composites are listed, and the fabrication methods of different composites based on the polymer matrix systems are elaborated. In terms of diverse applications, this review highlights the multifaceted barrier properties of lignin-based composites in oxygen barrier, water vapor barrier, ultraviolet barrier, flame retardant and antibacterial applications. These functional barrier materials are widely used in food/pharmaceutical packaging, agricultural protection, construction, etc., providing an excellent option for sustainable materials with high barrier performance requirements. Finally, the main challenges faced by lignin-based barrier materials and the future directions are proposed.

Drug Repurposing: Unique Carbon Dot Antibacterial Films for Fruit Postharvest Preservation

Fruit spoilage caused by oxidation and microbial infection exacerbates resource wastage. Although starch films including chitosan possessed admirable biocompatibility owing to great biodegradability compared with conventional plastics, deficient antibacterial and antioxidant capacity restricted food shelf life. Herein, an environmentally friendly antibacterial film (CS/G-CDs) was constructed by carbon dots derived from Cirsii Herba (CDs), which was formed through high affinity resulting from hydrogen bonding between chitosan molecules and hydroxyl originating from CDs. The prepared CDs presented homogeneous and monodisperse spherical structures with an ultrasmall size, providing favorable conditions for uniform film formation. Encouragingly, the antioxidant capacity of CS/G-CDs increased 5.00-fold, followed by an antibacterial rate of up to 97.0%. Dramatically, CS/G-CDs revealed glorious UV shielding efficacy (99.9% for UVB and 98.2% for UVA), and its preservation time for blueberries was remarkably extended 8 days longer than that of the chitosan film. Overall, Chinese herb-derived antibacterial films exhibited magnified antibacterial/antioxidant properties and great biocompatibility, which provided a promising strategy for sustainable development of packaging materials.

Bioactive nanocellulose films by incorporation of enzymatically polymerized lignin nanoparticles

In the search of new bioactive and biobased films, the use of lignin nanoparticles (LNP) and cellulose nanofibers (CNF) has gained potential relevance in the last years. In this context, an enzymatic and environmentally friendly pretreatment with laccases has been proposed in this work to modify the properties of the developed cellulose-lignin nanocomposite films. Thus, the laccase treatment successfully polymerized kraft lignin as indicated by the increase in weight average molecular weight (from 3621 to 5681 Da) and the reduction in phenolic content (from 552 to 324 mg GAE/g lignin). Moreover, this polymerization also caused a significant reduction in the size of the resulting LNP (6.8 ± 2.4 nm) compared to those obtained from untreated lignin (62 ± 22 nm). The incorporation of both untreated and treated LNP conferred antioxidant, antibacterial and UV-shielding capabilities to the final LNP-CNF films, observing higher antioxidant and UV-shielding values with polymerized LNP probably due to its tiny size and conjugated functional groups, respectively. Furthermore, films with 5 % LNP also showed better thermal stability, elongation at break, water vapor permeability and transparency, compared to CNF control films.

Bio-based composite hydrogel/film reinforced by hyperbranched lignin nanoparticles: Robustness, thermostability, thermal insulation and UV shielding

Most of the bio-based hydrogels tend to malfunction under a high-temperature condition, as the crosslinked network structure readily disintegrates, failing to meet the demands of hot environment. Herein, we exploit a thermostable composite hydrogel (CH) mainly using bio-based hyperbranched lignin nanoparticles (H-LNPs), TEMPO-oxidized cellulose nanofibers (TOCN), and scleroglucan (Slg), followed by a slow evaporation to form a multifunctional CH film. Thanks to the uniform distribution of H-LNPs and TOCN, which are rich in hydroxyl groups, within the hydrogel matrix, the crosslinking density, storage modulus, loss modulus, and thermal stability of the CHs are remarkably enhanced. As a result, the optimum CH demonstrates excellent thermal resistance and structural stability even after 196 h at 140 °C. Moreover, the resultant CH film exhibits outstanding UV shielding (>99.8 %) and solar radiation shielding (cooling 6.6 °C), endowing it as an ideal candidate for thermal insulation. These findings underscore the potential of H-LNPs in the development of robust, thermostable, and thermally insulating hydrogels for industrial applications in extreme environments.

Solid-state tailored silver nanocomposites from chitosan: Synthesis, antimicrobial evaluation and molecular docking

This study thoroughly explores the synthesis, characterization, and antimicrobial efficacy of three α-aminophosphonate-chitosan (α-AP-Cs) compounds and their nano‑silver functionalized organic hybrids. α-AP-Cs derivatives (CU, CT and CSC) were synthesized via an in-situ, one-pot reaction using chitosan and triphenyl-phosphite, with different carbamide-glutaraldehyde crosslinkers; urea-glutaraldehyde, thiourea-glutaraldehyde and semicarbazide-glutaraldehyde, respectively. Subsequently, their corresponding α-AP-Cs‑silver nanocomposites (CU-Ag0NPs, CT-Ag0NPs and CSC-Ag0NPs) were synthesized via solid-state approach. Their physicochemical and morphological profiles were fully characterized and compared against chitosan-Ag0NPs (Cs-Ag0NPs) and their bare organic-cores via CHNS/P/O, FT-IR, XRD, TEM, EDX, XPS and UV-visible analysis. The synthesis procedure, including phosphonation and carbamide-glutaraldehyde crosslinking, was confirmed through spectroscopic and elemental analyses. XPS and XRD affirmed the metallic silver with FCC structure. The UV-visible absorption peak was ⁓399 nm with averaging TEM size of the semi-spherical Ag0NPs around 30.4 nm. Thereafter, antimicrobial properties were systematically explored and optimized by evaluating minimum inhibition concentration, dose-killing, growth kinetics curves, protein leakage, and antibiofilm activity against bacterial strains (Streptococcus mutans and Pseudomonas aeruginosa) and fungal strains (Candida albicans and Rhizopus oryzae). Notably, incorporating α-aminophosphonate and Ag0NPs into chitosan-backbone markedly enhanced its antimicrobial efficacy against bacterial and fungal biofilms. Finally, a detailed structure-activity relationship study was conducted to elucidate the antimicrobial mechanisms.

Utilization of structure-specific lignin extracted from coconut fiber via deep eutectic solvents to enhance the functional properties of PVA nanocomposite films

This study utilized deep eutectic solvents (DES) based on choline chloride/lactic acid (ChCl/LA) to deconstruct coconut fibers. The effects of DES with different temperatures and molar ratios on the yield of lignin, recovery rate of residues, structural changes in lignin and solid residues, and saccharification efficiency were investigated. The results showed that acidic DES treatment effectively deconstructed the coconut fibers, resulting in a high lignin yield of 68.51 % while enhancing the enzymatic saccharification of cellulose, reaching a glucose yield of 85.88 %. The structural characterization of lignin revealed that acidic DES primarily cleaved β-O-4 bonds, yielding coconut fiber lignin with lower molecular weight and higher phenolic hydroxyl groups. Uniform and smooth coconut fiber lignin nanoparticles (CFLNPs) with excellent antioxidant activity were finally obtained by antisolvent method. Furthermore, PVA/CFLNPs nanocomposite films were prepared based on acidic DES CFLNPs. The results of the structural and functional analysis showed that CFLNPs significantly improved the thermal stability, mechanical properties, hydrophobicity, antioxidant and antibacterial activity of the nanocomposite films. In general, this work achieved efficient deconstruction of coconut fibers, providing insights for biorefining in the future, and more importantly, the potential to use the CFLNPs as a choice for active food packaging.

Development, characterization, and biological activity of composite films: Eugenol-zein nanoparticles in pea starch/soy protein isolate films

With an increasing emphasis on environmental protection and sustainability, natural polymers like proteins and polysaccharides are being utilized more frequently in the development of biodegradable food packaging. However, the limited properties of these biopolymers have restricted their widespread applicability within the food industry. To address this issue, eugenol-loaded zein nanoparticles (ZE NPs) were incorporated into pea starch/soy protein-based films, and their effect on the physicochemical properties of these films were investigated. The ZE NPs exhibited high compatibility with the pea starch-soy protein isolate (PES/SPI) matrix, enhancing the structural properties of the films by forming hydrogen bonds between the nanoparticles and the biopolymer network. Incorporating the nanoparticles enhanced the mechanical properties, thermal stability, ultraviolet shielding, surface hydrophobicity, and moisture barrier performance of the films. Furthermore, the films containing ZE NPs exhibited significant antioxidant and antibacterial activity, suggesting their potential application as preservatives in active food packaging materials. In conclusion, the incorporation of ZE NPs significantly enhanced the performance of PES/SPI-based films, which should expand their application as food packaging materials.

Active bio-nanocomposites from litchi seed starch, tamarind kernel xyloglucan, and lignin nanoparticles to improve the shelf-life of banana (Musa acuminata)

Valorization of agricultural byproducts to biodegradable packaging films aids in reducing plastic dependency and addressing plastic perils. Herein, starch (LSS) from litchi seeds and xyloglucan (XG) from tamarind kernels were recovered, and composite films were developed. The XG addition strengthened the weak polymer networks of LSS and improved rheological, molecular, morphological, mechanical, and water vapor barrier properties. The incorporation of lignin nanoparticles (LNPs) into the LSS-XG network further increased the tensile strength (14.83 MPa), elastic modulus (0.41 GPa), and reduced surface wettability (80.07°), and water vapor permeability (5.63 ± 0.38 × 10-7 g m-1s-1Pa-1). The phenolic hydroxyls of LNPs imparted strong UV-shielding and free radical scavenging abilities to films. These attributes aided in preserving the quality of coated banana fruits with minimal weight loss and color change. Overall, this research highlights the potential transformation of underutilized abundant byproducts into sustainable active bio-nanocomposites for food packaging and shelf-life extension of fruits.

Preparation and Characterization of Poly(vinyl-alcohol)/Chitosan Polymer Blend Films Chemically Crosslinked with Glutaraldehyde: Mechanical and Thermal Investigations

In this study, poly(vinyl-alcohol) (PVA)/chitosan (CS) polymer blend films with different amounts of CS (0, 5, 20 and 35 wt. %) crosslinked by glutaraldehyde (GA) were prepared. The structure and properties of the prepared polymer films were studied by means of dynamic mechanical analysis (DMA), differential scanning calorimetry (DSC), and the time-lag permeation technique. The DMA analysis showed that CS reduces the crystallinity degree of PVA, leading to a higher amount of the amorphous phase contributing to the α relaxation that corresponds to the glass-to-rubber transition. However, the mobility of the amorphous phase can be restricted with crosslinking with 1 wt. % GA. Interaction between the PVA and the CS was confirmed by DCS analysis. Additionally, the influence of the CS and crosslinking on the permeation of nitrogen molecules was investigated. The permeation was examined by the time-lag method. It was found that the addition of CS and GA to PVA improves barrier properties.

Improving Antimicrobial Properties of Biopolymer-Based Films in Food Packaging: Key Factors and Their Impact

Biodegradable films derived from polysaccharides are increasingly considered eco-friendly alternatives to synthetic packaging in the food industry. The study's purpose was to improve the antimicrobial properties of biopolymer-based films made from starch, chitosan, alginate, and their blends (starch/chitosan and starch/alginate) and to evaluate the effects of modifiers, i.e., plant extracts, plasticizers, cross-linking agents, and nanofillers. Films were prepared via the Solution Casting Method and modified with various plasticizers, calcium chloride, oxidized sucrose, and nanofiber cellulose (NC). Chestnut, nettle, grape, and graviola extracts were tested for antimicrobial activity against Staphylococcus epidermidis, Escherichia coli, and Candida albicans. The film's mechanical and hydrophilic properties were studied as well. The chestnut extract showed the strongest antimicrobial properties, leading to its incorporation in all the films. The chitosan films displayed better antibacterial activity against Gram-positive than Gram-negative bacteria but were ineffective against C. albicans. NC significantly improved the mechanical and antimicrobial properties of the chitosan films. The alginate films, modified with various plasticizers cross-linked with calcium chloride, demonstrated the highest antimicrobial efficacy against E. coli. The starch films, cross-linked with oxidized sucrose, exhibited slightly lower antimicrobial resistance due to a more compact structure. Films such as ALG6 and ALG5, including plasticizers EPGOS and PGOS, respectively, indicated optimal hydrophilicity and mechanical properties and achieved the best antimicrobial performance against all the investigated microorganisms. All these findings highlight the potential of these biodegradable films for food packaging, offering enhanced antimicrobial activity that prolongs shelf life and reduces spoilage, making them promising candidates for sustainable food preservation.

Film-forming modifications and mechanistic studies of soybean protein isolate by glycerol plasticization and thermal denaturation: A molecular interaction perspective

Plasticizer and thermal denaturation are indeed important factors for soybean protein film formation. The objective of the study was to investigate the effects of glycerol and thermal denaturation on the film-forming performances of soybean protein isolate (SPI) and elucidate the underlying mechanisms. From the results, glycerol had almost no effect on the protein's secondary and tertiary structures. Indeed, the dispersion of glycerol diminished the intra- or intermolecular hydrogen bonding of SPI and interacted with the amino acids of subunits through hydrogen bonding and van der Waals forces. By interfering with protein network interactions, the glycerol molecule achieved a plasticizing effect on SPI films. The effects of heat treatment on SPI film properties were mainly realized through the changes in molecular conformation caused by protein denaturation, which manifested in the enhancement of light barrier and mechanical capabilities, and markedly altered the distribution of water states within the film network. This study provided valuable insights to clarify the mechanism of protein film formation.

A stable delivery system for curcumin: Fabrication and characterization of self-assembling acylated kidney bean protein isolate nanogels

The construction of protein-based nano-gels as curcumin delivery system effectively enhances the stability and bioavailability of curcumin. In this study, acylation modification and self-assembly techniques were jointly employed to construct acylated kidney bean protein isolate (AKBPI)-nanogels. Optimal conditions for AKBPI-nanogels were determined to be pH 7, concentration of 2 mg/mL, and temperature at 90℃ for 30 min. The optimized AKBPI-nanogels exhibited excellent uniformity as evidenced by decreasing average particle size (137.35 nm) and polydispersity index (0.38). Acylation enhanced the intermolecular interactions within the nanogel by reducing the polarity of tyrosine microenvironment and free sulfhydryl groups. AKBPI-nanogels demonstrated remarkable characteristics in terms of pH sensitivity, salt concentration, and storage tolerance. The curcumin-loaded AKBPI-nanogels exhibited an encapsulation efficiency of 92.30 % and maintained high antioxidant activity. In simulated gastrointestinal digestion, AKBPI-nanogels facilitated the controlled release and higher bioavailability of curcumin. Therefore, AKBPI-nanogels can be a stable tool for delivering curcumin.

Reducing cherry rain-cracking: Enhanced wetting and barrier properties of chitosan hydrochloride-based coating with dual nanoparticles

The synergistic effects of phosphorylated zein nanoparticles (PZNP) and cellulose nanocrystals (CNC) in enhancing the wetting and barrier properties of chitosan hydrochloride (CHC)-based coating are investigated characterized by Fourier Transform Infrared Spectra (FTIR), X-ray Diffraction (XRD), atomic force microscopy and by investigating the mechanical properties, etc., with the aim of reducing cherry rain cracking. FTIR and XRD showed dual nanoparticles successfully implanted into CHC, CHC-PZNP-CNC combined moderate ductility (elongation at break: 7.8 %), maximum tensile strength (37.5 MPa). The addition of PZNP alone significantly improved wetting performance (Surface Tension, CHC: 55.3 vs. CHC-PZNP: 48.9 mN/m), while the addition of CNC alone led to a notable improvement in the water barrier properties of CHC (water vapor permeability, CHC: 6.75 × 10-10 vs. CHC-CNC: 5.76 × 10-10 gm-1 Pa-1 s-1). The final CHC-PZNP-CNC coating exhibited enhanced wettability (51.2 mN/m) and the strongest water-barrier property (5.32 × 10-10 gm-1 Pa-1 s-1), coupled with heightened surface hydrophobicity (water contact angle: 106.4°). Field testing demonstrated the efficacy of the CHC-PZNP-CNC coating in reducing cherry rain-cracking (Cracking Index, Control, 42.3 % vs. CHC-PZNP-CNC, 19.7 %; Cracking Ratio, Control, 34.6 % vs. CHC-PZNP-CNC, 15.8 %). The CHC-PZNP-CNC coating is a reliable option for preventing rain-induced cherry cracking.

Impact of production methods on properties of natural rosin added polylactic acid/sodium pentaborate and polylactic acid/calcium carbonate films

Nowadays biopolymers play an important role in packaging materials due to their protection properties against physical and chemical degradation or mechanical resistance. In this study, sodium pentaborate anhydride (B5NaO8), eggshell (CaCO3) nanoparticles, and natural rosin additives were introduced to pure PLA to produce a biofilm protecting from UV rays. The impact of the preparation method of hybrid biocomposite films was carried out based on the polymer casting method and using in the first case only magnetic mixing whereas magnetic mixing coupled with ultrasonic homogenizer was used in the second case. All biocomposite films were obtained for a nanoparticle content fixed at 7.5 wt% and various rosin rates (1, 5, 10, and 40 wt%). This study aims to expand the UV protection zone in PLA films. The thermal and mechanical properties, transmittance of UV-visible rays, microstructure analysis, and contact angle values were evaluated to detect the effect of the preparation method on the final properties. The results showed that the homogeneous distribution of the particles was more effective using an ultrasonic homogenizer. The increase of the rosin amount exhibited a reduction of the UV-visible light transmittance and the wettability was observed, demonstrating a potential use of these films in packaging.

Fabrication and characterization of chitosan/anthocyanin intelligent packaging film fortified by cellulose nanocrystal for shrimp preservation and visual freshness monitoring

In this study, a multi-functional packaging film was fabricated, utilizing the natural polysaccharide chitosan (CS) as the base material, integrating natural blueberry anthocyanin (AN) as pH-responsive indicator, and reinforced with cellulose nanocrystals (CNCs). The implications of addition levels of CNCs on the characteristics of the films were systematically investigated, resulting in that CS-AN-CNCs 9 % film exhibited optimal performance. Specifically, the film showed a substantial enhancement in maximum tensile strength from 15 MPa to 35 MPa; On the other hand, the swelling degree properties, the oxygen permeability and water vapor permeability decreased from 159.2 % to 92.0 %, from 51.7 g/(m2d) to 12.2 g/(m2d), from 31.6 × 10-12 g/(m·s·Pa) to 1.6 × 10-12 g/(m·s·Pa), respectively. Moreover, the CS-AN-CNCs 9 % film exhibited antioxidant, antibacterial, coupled with a color metrically responsive to pH variations, displaying great potential in indicating the shrimp freshness and delaying spoilage. Another notable advantage of the-prepared packaging material lies in its completely biodegradability, therefore meeting the requirement of environmental protection. Therefore, the prepared CS-AN-CNCs film as an intelligent packaging solution with potential applications in food preservation and freshness monitoring applications.

Enhancement of mechanical and barrier properties of chitosan-based bionanocomposites films reinforced with eggshell-derived hydroxyapatite nanoparticles

In this study, Hydroxyapatite nanoparticles (HANPs), derived from eggshell waste, were employed to reinforce chitosan biopolymer-based films through the solvent-casting method. The impact of varying HANPs content (1%, 3%, 5%, and 10 wt %) in bionanocomposites was investigated. The influence of HANPs addition on the final film properties was comprehensively analyzed using Thermogravimetric Analysis (TGA), Differential Scanning Calorimetry (DSC), Dynamic Mechanical Analysis (DMA), mechanical (tensile) testing, and Water Vapor Permeability (WVP). The morphological aspects of bionanocomposites and the dispersion of nanoparticles within the matrix were studied using Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), and X-ray Diffraction (XRD). The structural changes in the films were probed using Fourier-Transform Infrared Spectroscopy (FTIR) and X-ray Photoelectron Spectroscopy (XPS) techniques. Results indicated that the addition of 1% and 3% of HANPs exhibited a higher glass transition temperature and improved thermal stability in bionanocomposites. Films with 3% HANPs content exhibited a notable increase in tensile strength, showing a 61.54% increase, while films with 1% HANPs content displayed a 52% reduction in WVP compared to pristine chitosan films. These findings underscore the significant potential of chitosan-hydroxyapatite bionanocomposite films for applications in food packaging applications.

Design and preparation of novel antioxidant and antibacterial films containing procyanidins and phycocyanin for food packaging

The purpose of this study was to design a novel antioxidant and antibacterial film for food packaging using food-grade raw materials. The films were designed and fabricated based on carboxymethyl chitosan and pectin incorporated with procyanidins (PCs) and phycocyanin (Phy) by the tape casting method. The effects of different proportions of PCs and Phy on the properties and functions of the prepared films were studied. The results showed that the thickness of films could range from 55 to 70 μm, with dense network structure and uniform distribution of elements. Compared with C-Film group, the film loaded with PCs and Phy had lower water solubility and swelling rate, and higher tensile strength and elongation at break. FITR and XRD spectra revealed the molecular interaction mechanism among carboxymethyl chitosan, pectin, PCs and Phy, which could effectively endow the films with ultraviolet barrier properties. Moreover, the addition of PCs and Phy could effectively improve the antioxidant capacity and antibacterial effect of films, for example, the free radical scavenging abilities of most films were above 80% when the concentration of PCs was 40 μg mL-1. In view of these functional properties, the prepared film containing PCs and Phy have been successfully used in food packaging, which was proved by the preservation experiment of grapes. This study can provide theoretical and technical guidance for the preparation of biodegradable antibacterial films, and their application in the food packaging field.

Preparation and characterization of active films based on oregano essential oil microcapsules/soybean protein isolate/sodium carboxymethyl cellulose

This study aimed to prepare oregano essential oil microcapsules (EOMs) by the active coalescence method using gelatin and sodium alginate as wall materials and oregano essential oil (OEO) as the core material. EOMs were added to the soybean protein isolate (SPI)/sodium carboxymethyl cellulose (CMC) matrix to prepare SPI-CMC-EOM active films, and the physical and chemical features of the active films and EOMs were characterized. The results showed that the microencapsulated OEO could protect its active ingredients. Scanning electron microscopy results showed that EOMs were highly compatible with the film matrix. The solubility of active films decreased upon adding EOMs, and their ultraviolet resistance and thermal stability also improved. When the added amount of EOMs was 5 %, the active films had the best mechanical properties and the lowest water vapor permeability. The active films prepared under this condition had excellent comprehensive performance. Also, adding EOMs considerably enhanced the antioxidant of the active films and endowed them with antibacterial properties. The application of the SPI-CMC-EOM films to A. bisporus effectively delayed senescence and maintained the freshness of the postharvest A. bisporus. This study provided a theoretical foundation for the incorporation of EOMs into active films based on biological materials.

Sustainable lignin nanoparticles from coconut fiber waste for enhancing multifunctional properties of macroalgae biofilms

Multifunctional and sustainable packaging biofilms felicitous to changeable conditions are in large demand as substitutes to petroleum-derived synthetic films. Macroalgae with noticeable film-formation, abundant, low-cost, and edible properties is a promising bioresource for sustainable and eco-friendly packaging materials. However, the poor hydrophobicity and mechanical properties of sustainable macroalgae biofilms seriously impede their practical applications. Herein, lignin nanoparticles (LNPs) produced by a sustainable approach from black liquor of coconut fiber waste were incorporated in the macroalgae matrix to improve the water tolerance and mechanical characteristics of the biofilms. The effect of different LNPs loadings on the performance of biofilms, such as physical, morphological, surface roughness, structural, water resistance, mechanical, and thermal behaviors, were systematically evaluated and found to be considerably improved. Biofilm with 6 % LNPs presented the optimum enhancement in most ultimate performances. The optimized biofilm exhibited great hydrophobic features with a water contact angle of over 100° and high enhancement in the tensile strength of >60 %. This study proposes a facile and sustainable approach for designing and developing LNPs-macroalgae biofilms with excellent and multifunctional properties for sustainable high-performance packaging materials.

Modified polysaccharides for food packaging applications: A review

Development of new food packaging materials is crucial to reduce the use of single-use plastics and to limit their destructive impact on the environment. Polysaccharides provide an alternative solution to this problem. This paper summarizes and discusses recent research results on the potential of modifying polysaccharides as materials for film and coating applications. Modifications of polysaccharides significantly affect their properties, as well as their application usability. Although modifications of biopolymers for packaging applications have been widely studied, polysaccharides have attracted little attention despite being a prospective, environmentally friendly, and economically viable packaging alternative. Therefore, this paper discusses approaches to the development of biodegradable, polysaccharide-based food packaging materials and focuses on modifications of four polysaccharides, such as starch, chitosan, sodium alginate and cellulose. In addition, these modifications are presented not only in terms of the selected polysaccharide, but also in terms of specific properties, i.e. hydrophilic, barrier and mechanical properties, of polysaccharides. Such a presentation of results makes it much easier to select the modification method to improve the unsatisfactory properties of the material. Moreover, very often it happens that the applied modification improves one and worsens another property, which is also presented in this review.

Advances of blend films based on natural food soft matter: Multi-scale structural analysis

The blend films made of food soft matter are of growing interest to the food packaging industries as a pro-environment packaging option. The blend films have become a novel pattern to replace traditional plastics gradually due to their characteristics of biodegradability, sustainability, and environmental friendliness. This review discussed the whole process of the manufacturing of food soft matter blend films from the raw material to the application due to multi-scale structural analysis. There are 3 stages and 12 critical analysis points of the entire process. The raw material, molecular self-assembly, film-forming mechanism and performance test of blend films are investigated. In addition, 11 kinds of blend films with different functional properties by casting are also preliminarily described. The industrialization progress of blend films can be extended or facilitated by analysis of the 12 critical analysis points and classification of the food soft matter blend films which has a great potential in protecting environment by developing sustainable packaging solutions.

Construction of a sustainable and hydrophobic high-performance all-green pineapple peel cellulose nanocomposite film for food packaging

The increasing global awareness of environmental issues has led to a growing interest in research on cellulose-based film. However, several limitations hinder their development and industrial application, such as hydrophilicity, inadequate mechanical properties and barrier properties, and a lack of activity. This study aimed to create a sustainable and hydrophobic high-performance all-green pineapple peel cellulose nanocomposite film for food packaging by incorporating natural carnauba wax and cellulose nanofibers (CNF) into a pineapple peel cellulose matrix. The results showed that adding carnauba wax to the cellulose matrix converted the surface wettability of the cellulose-based film from hydrophilic to hydrophobic (water contact angle over 100). Additionally, the film exhibited ultraviolet resistance and antioxidation properties. The incorporation of CNF further improved the barrier properties, mechanical properties, and thermal stability of the cellulose nanocomposite film. In applied experiments, the cellulose nanocomposite film delayed post-harvest deterioration and maintained storage quality of cherry tomatoes. Importantly, the cellulose nanocomposite film could be degraded in soil within 30 days. It can be concluded that the cellulose nanocomposite film has great potential to alleviate the environmental problems and human health problems caused by non-degradable petroleum-based plastic packaging.

Animal derived biopolymers for food packaging applications: A review

It is essential to use environment-friendly, non-toxic, biodegradable and sustainable materials for various applications. Biopolymers are derived from renewable sources like plants, microorganisms, and agricultural wastes. Unlike conventional polymers, biopolymer has a lower carbon footprint and contributes less to greenhouse gas emission. All biopolymers are biodegradable, meaning natural processes can break them down into harmless products such as water and biomass. This property is of utmost importance for various sustainable applications. This review discusses different classifications of biopolymers based on origin, including plant-based, animal-based and micro-organism-based biopolymers. The review also discusses the desirable properties that are required in materials for their use as packaging material. It also discusses the different processes used in modifying the biopolymer to improve its properties. Finally, this review shows the recent developments taking place in using specifically animal origin-based biopolymer and its use in packaging material. It was observed that animal-origin-based biopolymers, although they possess unique properties however, are less explored than plant-origin biopolymers. The animal-origin-based biopolymers covered in this review are chitosan, gelatin, collagen, keratin, casein, whey, hyaluronic acid and silk fibroin. This review will help in renewing research interest in animal-origin biopolymers. In summary, biopolymer offers a sustainable and environment-friendly alternative to conventional polymers. Their versatility, biocompatibility will help create a more sustainable future.

Antibacterial mechanism of lignin and lignin-based antimicrobial materials in different fields

The control of microbial infection transmission often relies on the utilization of synthetic and metal-based antimicrobial agents. However, their non-biodegradability and inadequate disposal practices lead to significant environmental contamination. To address this concern, the quest for natural alternatives has gained paramount importance. Lignin, a widely available renewable aromatic compound, emerges as a promising candidate owing to its inherent phenolic moiety, which lends itself well to acting as a natural antimicrobial agent either independently or in combination with other agents. This article provides a comprehensive account of the structure and primary classes of lignin. Additionally, it elucidates the antimicrobial mechanism of lignin, the factors influencing its efficacy, and the methods employed for its detection. Moreover, it describes the progress made in developing the antimicrobial capacity of lignin in different areas. In conclusion, this paper not only outlines the current state of research on the antimicrobial function of lignin, but also identifies challenges and future possibilities for enhancing its antimicrobial properties. This work holds great significance in the ongoing endeavor to contribute to high-impact research on natural alternatives for controlling infections and fostering environmentally conscious practices.

Intelligent packaging based on chitosan/fucoidan incorporated with coleus grass (Plectranthus scutellarioides) leaves anthocyanins and its application in monitoring the spoilage of salmon (Salmo salar L.)

The innovation of this study was to develop a novel biodegradable intelligent packaging based on chitosan/fucoidan combined with different amounts (1, 3 and 5 wt% on chitosan basis) of coleus grass (Plectranthus scutellarioides) leaves anthocyanins (CGL) to monitor the spoilage of salmon (Salmo salar L.). The addition of fucoidan improved the barrier and mechanical properties of the chitosan films (CS) due to hydrogen bonds and intermolecular electrostatic interactions. Moreover, the addition of CGL not only improved the physical properties but also improved the biological activity of chitosan/fucoidan film (CF). The DPPH and ABTS radical scavenging activity of CF contained 5 wt% CGL was 1.83 and 1.75 times than CF, respectively. The inhibition zone size of CF films containing 5 wt% CGL (CF-5%CGL) was approximately 2.04 (Escherichia coli) and 2.16 (Staphylococcus aureus) times higher than that of CF. Moreover, CF-CGL displayed obvious color changes in different pH environments and is highly sensitive to ammonia gas. The CF-CGL has visible color changes during the monitoring of salmon spoilage and extended the shelf life of salmon. According to our findings, CF-CGL film might be employed as a possible intelligent packaging material for monitoring and preserving salmon in the future.

Production of PVA-chitosan films using green synthesized ZnO NPs enriched with dragon fruit extract envisaging food packaging applications

In this work, the PVA-chitosan composite packaging films doped with biomass-fabricated zinc oxide nanoparticles (ZnO NPs) and dragon fruit waste extract (DFE) were developed for potential use in food packaging applications. ZnO NPs were synthesized using a sustainable method employing C. sinensis waste extract as a reducing agent. Chitosan and PVA were blended in a specific ratio (1: 1 w/w) to obtain a film-forming solution, into which the ZnO NPs and dragon fruit waste extract were incorporated. The resulting solution was cast into films, which were characterized using various analytical techniques. Mechanical properties, water solubility, and thermal stability of the films were also evaluated. The results demonstrated that the incorporation of green ZnO NPs and dragon fruit waste extract enhanced the mechanical strength and thermal stability of the films while reducing water vapor permeability. Moreover, the films exhibited biocidal and excellent 2,2-diphenyl-1-picrylhydrazyl (DPPH) scavenging properties, indicating their use in the food packaging sector. The production of these films offers a practical approach to produce bioactive food packaging materials. The use of plant extract and waste material as reducing agents can reduce the overall cost of production while providing added benefits, such as antioxidant and antibacterial properties.

Polysaccharides and proteins based bionanocomposites as smart packaging materials: From fabrication to food packaging applications a review

Food industry is the biggest and rapidly growing industries all over the world. This sector consumes around 40 % of the total plastic produced worldwide as packaging material. The conventional packaging material is mainly petrochemical based. However, these petrochemical based materials impose serious concerns towards environment after its disposal as they are nondegradable. Thus, in search of an appropriate replacement for conventional plastics, biopolymers such as polysaccharides (starch, cellulose, chitosan, natural gums, etc.), proteins (gelatin, collagen, soy protein, etc.), and fatty acids find as an option but again limited by its inherent properties. Attention on the initiatives towards the development of more sustainable, useful, and biodegradable packaging materials, leading the way towards a new and revolutionary green era in the food sector. Eco-friendly packaging materials are now growing dramatically, at a pace of about 10-20 % annually. The recombination of biopolymers and nanomaterials through intercalation composite technology at the nanoscale demonstrated some mesmerizing characteristics pertaining to both biopolymer and nanomaterials such as rigidity, thermal stability, sensing and bioactive property inherent to nanomaterials as well as biopolymers properties such as flexibility, processability and biodegradability. The dramatic increase of scientific research in the last one decade in the area of bionanocomposites in food packaging had reflected its potential as a much-required and important alternative to conventional petroleum-based material. This review presents a comprehensive overview on the importance and recent advances in the field of bionanocomposite and its application in food packaging. Different methods for the fabrication of bionanocomposite are also discussed briefly. Finally, a clear perspective and future prospects of bionanocomposites in food packaging were presented.

Prospects of Using Chitosan-Based Biopolymers in the Treatment of Peripheral Nerve Injuries

Peripheral nerve injuries are common neurological disorders, and the available treatment options, such as conservative management and surgical repair, often yield limited results. However, there is growing interest in the potential of using chitosan-based biopolymers as a novel therapeutic approach to treating these injuries. Chitosan-based biopolymers possess unique characteristics, including biocompatibility, biodegradability, and the ability to stimulate cell proliferation, making them highly suitable for repairing nerve defects and promoting nerve regeneration and functional recovery. Furthermore, these biopolymers can be utilized in drug delivery systems to control the release of therapeutic agents and facilitate the growth of nerve cells. This comprehensive review focuses on the latest advancements in utilizing chitosan-based biopolymers for peripheral nerve regeneration. By harnessing the potential of chitosan-based biopolymers, we can pave the way for innovative treatment strategies that significantly improve the outcomes of peripheral nerve injury repair, offering renewed hope and better prospects for patients in need.

A comparative study between two carboxymethylated polysaccharides/protein electrostatic and cross-linked nanogels constructed for caffeic acid and eugenol delivery

In response to the pressing demand for functional nanomaterials synthesis and applications, two polyelectrolyte complexes (PECs) [electrostatic and cross-linked nanogels (NGs)] loaded individually with caffeic acid (CafA) and eugenol (Eug) demonstrating multifunctionalities were proposed for the first time. Curdlan (Curd) and glucomannan (GM) were carboxymethylated (CMCurd and CMGM) successfully and polymeric ratios of 1:1 and 4:1 (v/v) for chitosan (Cs): CMCurd and lactoferrin (Lf): CMGM were selected for the synthesis of Cs/CMCurd and Lf/CMGM NGs. Due to the use of EDC/NHS, Cs/CMCurd/CafA and Lf/CMGM/Eug NGs possessed very uniform particles sizes of 177 ± 18 and 230 ± 17 nm with marked encapsulation efficiencies (EEs) of 76 ± 4 and 88 ± 3 %, respectively. The formation of a carbonyl-amide linkage in both cross-linked NGs was confirmed by FTIR. It should be noted, the self-assembly was not reliable in retaining enough of the encapsulated compounds. Owing to the excellent physicochemical characteristics of the loaded cross-linked NGs, they were prioritized over the electrostatic ones. Both Cs/CMCurd/CafA and Lf/CMGM/Eug NGs exhibited high colloidal stability over 12 weeks, elevated hemocompatibility, and in vitro serum stability. The generated NGs were also tailored to possess controlled release profiles for CafA and Eug over 72 h. Cs/CMCurd/CafA and Lf/CMGM/Eug NGs had promising antioxidant efficacies and could remarkably inhibit 4 bacterial pathogens at low 2-16 μg/mL concentration of encapsulated NGs compared to their unencapsulated counterparts. Interestingly, the respective NGs could significantly decline the IC₅₀ against colorectal cancer HCT-116 than conventional drugs. Based on these data, it was conferred that the investigated NGs could be promising candidates for functional foods and pharmaceutics.

Characterization and Antibacterial Properties of Egg White Protein Films Loaded with ε-Polylysine: Evaluation of Their Degradability and Application

There is an ongoing trend to design new kinds of food packaging materials with excellent properties which are environmentally friendly enough. The aim of this study was to prepare and characterize egg white protein (EWP)-based composite films with and without ε-polylysine (Lys), as well as to compare their physical-chemical properties, structural properties, degradation and antibacterial properties. The results showed that with the addition of Lys, the composite films showed a decreasing tendency of the water permeability due to the enhanced interaction between proteins and water molecules. As indicated by the structural properties, stronger cross-linking and intermolecular interactions happened with increasing concentration of Lys. In addition, the composite films presented excellent antibacterial activities against Escherichia coli and Staphylococcus aureus on chilled pork in the presence of Lys. Therefore, our prepared films might be used as a freshness-keeping material with an application in meat preservation. The biodegradation evaluation demonstrated that the composite films were environmental-friendly and have potential applications in the field of food packaging.

Development and characterization of active packaging based on chitosan/chitin nanofibers incorporated with scallion flower extract and its preservation in fresh-cut bananas

The aim of this study was to develop a novel active packaging using chitosan (CS) and esterified chitin nanofibers (CF) combined with different contents (1, 2 and 4 wt% on CS basis) of scallion flower extract (SFE) to protect banana samples. The addition of CF significantly improved the barrier and mechanical properties of the CS films (p < 0.05) due to hydrogen bonds and electrostatic interactions. Moreover, the addition of SFE not only improved the physical properties of the CS film but also improved the CS film biological activity. The oxygen barrier property and antibacterial ability of CF-4%SFE were approximately 5.3 and 1.9 times higher than those of the CS film, respectively. In addition, CF-4%SFE had strong DPPH radical scavenging activity (74.8 ± 2.3 %) and ABTS radical scavenging activity (84.06 ± 2.08 %). Fresh-cut bananas stored in CF-4%SFE showed less weight loss, starch loss, color and appearance change than those stored in traditional polyethylene film, which indicated that CF-4%SFE was much better at storing fresh-cut bananas than conventional plastic packaging. For these reasons, CF-SFE films have great potential as a candidate to replace traditional plastic packaging and extend the shelf life of packaged foods.

Sustainable Starch/Lignin Nanoparticle Composites Biofilms for Food Packaging Applications

Construction of sustainable composite biofilms from natural biopolymers are greatly promising for advanced packaging applications due to their biodegradable, biocompatible, and renewable properties. In this work, sustainable advanced food packaging films are developed by incorporating lignin nanoparticles (LNPs) as green nanofillers to starch films. This seamless combination of bio-nanofiller with biopolymer matrix is enabled by the uniform size of nanofillers and the strong interfacial hydrogen bonding. As a result, the as-prepared biocomposites exhibit enhanced mechanical properties, thermal stability, and antioxidant activity. Moreover, they also present outstanding ultraviolet (UV) irradiation shielding performance. As a proof of concept in the application of food packaging, we evaluate the effect of composite films on delaying oxidative deterioration of soybean oil. The results indicate our composite film could significantly decrease peroxide value (POV), saponification value (SV), and acid value (AV) to delay oxidation of soybean oil during storage. Overall, this work provides a simple and effective method for the preparation of starch-based films with enhanced antioxidant and barrier properties for advanced food packaging applications.

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.

Targeted pH-responsive chitosan nanogels with Tanshinone IIA for enhancing the antibacterial/anti-biofilm efficacy

Persistent bacterial infection caused by biofilms is one of the most serious problems that threatened human health. The development of antibacterial agents remains a challenge to penetrate biofilm and effectively treat the underlying bacterial infection. In the current study, chitosan-based nanogels were developed for encapsulating the Tanshinone IIA (TA) to enhance the antibacterial and anti-biofilm efficacy against Streptococcus mutans (S. mutans). The as-prepared nanogels (TA@CS) displayed excellent encapsulation efficiency (91.41 ± 0.11 %), uniform particle sizes (393.97 ± 13.92 nm), and enhanced positive potential (42.27 ± 1.25 mV). After being coated with CS, the stability of TA under light and other harsh environments was greatly improved. In addition, TA@CS displayed pH responsiveness, allowing it to selectively release more TA in acidic conditions. Furthermore, the positively charged TA@CS were equipped to target negatively charged biofilm surfaces and efficiently penetrate through biofilm barriers, making it promising for remarkable anti-biofilm activity. More importantly, when TA was encapsulated into CS nanogels, the antibacterial activity of TA was enhanced at least 4-fold. Meanwhile, TA@CS inhibited 72 % of biofilm formation at 500 μg/mL. The results demonstrated that the nanogels constituted CS and TA had antibacterial/anti-biofilm properties with synergistic enhanced effects, which will benefit pharmaceutical, food, and other fields.

Fabrication of multifunctional materials based on chitosan/gelatin incorporating curcumin-clove oil emulsion for meat freshness monitoring and shelf-life extension

A new multifunctional film with active and intelligent effects was developed by incorporating curcumin-clove oil emulsion into natural materials. The basic properties, functional characteristics, and pH/NH₃-sensitivity of films were investigated, and then these films were applied to extend shelf-life and monitor freshness of meat. Curcumin solution and emulsion illustrated significant color variations at different pH values. The incorporation of emulsion improved the UV-vis barrier and water resistance properties of films, which blocked most of UV-light and its water contact angle reached 100.03°. Meanwhile, the films had stronger mechanical strength and higher thermal stability, with elongation at break reaching 79.18 % and the maximum degradation temperature rising to 316 °C. Moreover, emulsion made films have a slow-release effect on clove oil, which not only enhanced the antioxidant property but also significantly improved their antibacterial activity. Additionally, the multifunctional films presented a significant color response to acidic/alkaline environments over a short time interval and could be easily identified by naked eyes. Finally, the films effectively extended the shelf-life of fresh meat by 3 days at 4 °C and visually monitored freshness through color changes in real-time. This knowledge provides insights and ideas for the development of novel food packaging with both active and intelligent functions.

Enhanced Functional Properties of Bioplastic Films Using Lignin Nanoparticles from Oil Palm-Processing Residue

The development of bioplastic materials that are biobased and/or degradable is commonly presented as an alleviating alternative, offering sustainable and eco-friendly properties over conventional petroleum-derived plastics. However, the hydrophobicity, water barrier, and antimicrobial properties of bioplastics have hindered their utilization in packaging applications. In this study, lignin nanoparticles (LNPs) with a purification process were used in different loadings as enhancements in a Kappaphycus alvarezii matrix to reduce the hydrophilic nature and improve antibacterial properties of the matrix and compared with unpurified LNPs. The influence of the incorporation of LNPs on functional properties of bioplastic films, such as morphology, surface roughness, structure, hydrophobicity, water barrier, antimicrobial, and biodegradability, was studied and found to be remarkably enhanced. Bioplastic film containing 5% purified LNPs showed the optimum enhancement in almost all of the ultimate performances. The enhancement is related to strong interfacial interaction between the LNPs and matrix, resulting in high compatibility of films. Bioplastic films could have additional advantages and provide breakthroughs in packaging materials for a wide range of applications.