Effect of SiO2 nanoparticle on the physical and chemical properties of eco-friendly agar/sodium alginate nanocomposite film

The latest research progress on polysaccharides-based biosensors for food packaging: A review

In recent years, polysaccharide-based biosensors have emerged as promising technologies for intelligent food packaging, offering innovative solutions to enhance food quality and safety. This review highlights advancements in designing, developing, and applying these biosensors, particularly those utilizing polysaccharides such as chitosan, cellulose and alginate. Engineered with nanomaterials like ZnO, silver, and carbon nano-tubes demonstrated high sensitivity in real-time monitoring of food spoilage indicators, including pH changes, volatile nitrogen compounds and microbial activity. We discuss the electrochemical properties of these biosensors, highlighting how the integration of electrochemical methods significantly improves their detection capabilities within packaging environments, leading to sensor sensitivity enhancement, greater accuracy, and spoilage detection, ultimately extending the shelf life of perishable food products. Additionally, the review addresses the practical challenges of industrial implementation and explores future research directions for optimizing sensor functionality and scalability. The findings underscore the potential of polysaccharide-based intelligent packaging as a sustainable and effective alternative to conventional methods, paving the way for broader commercial adoption.

Multifunctional and novelty green composite film containing sodium alginate, chitosan, rice husk and curcumin

Foodborne diseases are a global public health issue, with their causes often originating from lapses in food production or transportation leading to food contamination. Therefore, food packaging plays a crucial role in preserving the safety and quality of food. In pursuit of sustainable development, this study aims to utilize agricultural waste-derived functional mesoporous silica nanoparticles in combination with biodegradable molecules to create food packaging films. Through recycling and the use of environmentally friendly green films, the goal is to achieve sustainability and the objectives of green chemistry. The study anticipates the production of biodegradable films and the testing of their antibacterial capabilities, antioxidant properties, biocompatibility, and film stress coefficients. This research will provide robust support for advancing green packaging technology to address the challenges of global food safety and environmental sustainability. The experiment is divided into two parts. The first part involves the synthesis of multifunctional mesoporous silica nanoparticles with antibacterial properties derived from rice husk (Rice husk mesoporous silica nanoparticles, rMSN) as nano-fillers. These nanoparticles are surface modified with a biodegradable polymer, chitosan (Chi), that interacts with the material. Natural extract curcumin (Cur), known for its antioxidant capabilities, is loaded into the pores, and the material's inherent antibacterial properties are utilized. The second part involves blending the material with the natural polymer sodium alginate (SA) to form a film (rMSN-Chi@Cur/Alg film). The film's thickness, stress strength, antibacterial, and antioxidant capabilities are tested to ensure the material possesses antibacterial and antioxidant properties.

Fabrication of silica/calcium alginate nanocomposite based on rice husk ash for efficient adsorption of phenol from water

The current work discusses the synthesis of three different solid adsorbents: silica nanoparticles derived from rice husk (RS), calcium alginate beads (AG), and silica/alginate nanocomposite (RSG). The fabricated solid adsorbents were characterized by using different physicochemical techniques such as TGA, XRD, nitrogen adsorption/desorption analysis, ATR-FTIR, pHPZC, SEM, and TEM. The adsorption efficiencies of the prepared solid adsorbents were considered for the removal of phenol as a selected hazardous pollutant. Because of its improved adsorption capacity and environmentally friendly character, a composite made of biosilica nanoparticles and naturally occurring alginate biopolymer by click chemistry is significant in environmental treatment. Adding silica nanoparticles to the alginate biopolymer hydrogel has many advantages, including increased surface area, easier recovery of the solid adsorbent, and additional surface chemical functional groups. The silica/alginate nanocomposite showed surface heterogeneity with many chemical functional groups present, whereas silica nanoparticles had the highest surface area (893.1 m2 g-1). It has been found that the average TEM particle size of RS, AG, and RSG was between 18 and 82 nm. RSG displayed the maximum adsorption capacity of phenol (100.55 mg g-1) at pH 7 and 120 min as equilibrium adsorption time. Adsorption of phenol onto the solid adsorbents fit well with a nonlinear Langmuir isotherm with favorable adsorption. Kinetic and thermodynamic studies prove that the adsorption process follows a pseudo-second-order kinetic model, endothermic process, physical, and spontaneous adsorption. Sodium hydroxide is effective in desorbing 94% of the loaded phenols, according to desorption investigations. Solid reusability tests showed that, after seven cycles of phenol adsorption/desorption, RSG lost only 8.8% of its adsorption activity.

Sodium alginate/ager colourimetric film on porous substrate layer: Potential in intelligent food packaging

Colourimetric indicators have potential applications in monitoring food freshness and offer a simple, rapid, effective, and economical approach. Blending sodium alginate (SA) with agar (AG), an ideal choice for solid substrates in colourimetric indicators, can modify mechanical compliance and optical properties. However, the limitations in the water-sustaining capacity and dye migration of hydrogel substrates significantly impede the scalability and commercial application of these indicators. In this study, we designed and prepared a bilayer-structured indicator featuring an SA/AG colourimetric film on a porous Polypropylene fluoride (PVDF)/SiO2 encapsulation film. This design aims to enhance the water-sustaining capacity and reduce dye migration from the SA/AG colourimetric film. The PVDF/SiO2 composite film was prepared using a peeling-assisted phase-conversion process, which enabled the indicator to selectively allow gas, but not water, to pass through its porous substrate. Furthermore, we tested the layered indicator film by monitoring changes in shrimp freshness. The results revealed significant and distinguishable colour changes in the indicators corresponding to the freshness and spoilage of the shrimp.

Nanofillers in Novel Food Packaging Systems and Their Toxicity Issues

Background: Environmental concerns about petroleum-based plastic packaging materials and the growing demand for food have inspired researchers and the food industry to develop food packaging with better food preservation and biodegradability. Nanocomposites consisting of nanofillers, and synthetic/biopolymers can be applied to improve the physiochemical and antimicrobial properties and sustainability of food packaging. Scope and approach: This review summarized the recent advances in nanofiller and their applications in improved food packaging systems (e.g., nanoclay, carbon nanotubes), active food packaging (e.g., silver nanoparticles (Ag NPs), zinc oxide nanoparticles (ZnO NPs)), intelligent food packaging, and degradable packaging (e.g., titanium dioxide nanoparticles (e.g., TiO2 NPs)). Additionally, the migration processes and related assessment methods for nanofillers were considered, as well as the use of nanofillers to reduce migration. The potential cytotoxicity and ecotoxicity of nanofillers were also reviewed. Key findings: The incorporation of nanofillers may increase Young's modulus (YM) while decreasing the elongation at break (EAB) (y = -1.55x + 1.38, R2 = 0.128, r = -0.358, p = 0.018) and decreasing the water vapor (WVP) and oxygen permeability (OP) (y = 0.30x - 0.57, R2 = 0.039, r = 0.197, p = 0.065). Meanwhile, the addition of metal-based NPs could also extend the shelf-life of food products by lowering lipid oxidation by an average of approx. 350.74% and weight loss by approx. 28.39% during the longest storage period, and significantly increasing antibacterial efficacy against S. aureus compared to the neat polymer films (p = 0.034). Moreover, the migration process of nanofillers may be negligible but still requires further research. Additionally, the ecotoxicity of nanofillers is unclear, as the final distribution of nanocomposites in the environment is unknown. Conclusions: Nanotechnology helps to overcome the challenges associated with traditional packaging materials. Strong regulatory frameworks and safety standards are needed to ensure the appropriate use of nanocomposites. There is also a need to explore how to realize the economic and technical requirements for large-scale implementation of nanocomposite technologies.

Antibacterial and Antifungal Activities of Cimbopogon winterianus and Origanum syriacum Extracts and Essential Oils against Uropathogenic Bacteria and Foodborne Fungal Isolates

This study focused on testing the antibacterial and antifungal activity of Origanum syriacum (O. syriacum) and Cimbopogon winterianus (C. winterianus) extracts and their essential oils (EOs). The bacteria were isolated from urine samples and identified by a VITEK assay, and the fungi were isolated from spoiled food samples and further identified by MALDI-TOF. The susceptibility of the microbial isolates was assessed by determining the bacteriostatic and bactericidal/fungicidal effects by the minimum inhibitory concentration (MIC) and minimum bactericidal/fungicidal concentration (MBC/MFC) broth microdilution assay and time-kill test. The antibiofilm activities were assessed by the antibiofilm screening assays. The bacterial isolates included three Gram-negative isolates (Escherichia coli, Klebsiella pneumonia, and Citrobacter freundii) and two Gram-positive isolates (Staphylococcus aureus and Streptococcus intermedius). The fungal isolates included Candida albicans and Aspergillus niger. The O. syriacum and C. winterianus extracts exhibited bacteriostatic and fungistatic activities (MIC 1.25-2.5 mg/mL for the bacterial isolates and 2.5-5 mg/mL for the fungal isolates). However, their EOs exhibited bactericidal (MBC 5-20%) and fungicidal (MFC 1.25-10%) activities, meaning that the EOs had a better antimicrobial potential than the extracts. The antibiofilm activities of the mentioned extracts and their EOs were relatively weak. The O. syriacum extract inhibited S. aureus, S. intermedius, and K. pneumonia biofilms at a concentration of 0.3125 mg/mL and C. albicans and A. niger biofilms at 0.625 mg/mL. No antibiofilm activity was recorded for C. winterianus extract. In addition, the packaging of grapes with C. winterianus extract preserved them for about 40 days. The results reflect the significant antimicrobial activity of O. syriacum and C. winterianus extracts and their EOs, thus suggesting their potential in food packaging and preservation.

Sodium-alginate-based indicator film containing a hydrophobic nanosilica layer for monitoring fish freshness

In this study, hydrophobic sodium alginate/anthocyanin/cellulose nanocrystal indicator films were fabricated by incorporating nanosilica (NS) as a waterproofing layer. The concentrations and formation methods (spraying (S), coating (C), and impregnation (I)) of the NS layer (denoted as NSS, NSC, NSI, respectively) were optimized. The results indicated that the optimum concentration of the NS layer was 5 % at a water contact angle (WCA) 110.5°. Further, Fourier transform infrared spectra showed the presence of SiOSi and SiCH3 groups in the NSS, NSC, and NSI films, and X-ray diffraction spectra indicated that original structures of these films were disordered. Moreover, the surface morphology, mechanical properties, and light transmission were affected by the NS layer, and the optimal layer was found to be NSI. After 10 days of storage at 100 % humidity, the NSI film exhibited low water vapor adsorption (37.22 g) and permeability (0.1484 g/m·s·Pa·10-11) and a high WCA (110.2°). In addition, the NSI film exhibited a visible color shift with an increasing pH of the buffer solution. A monitoring test of fish freshness showed that the NSI film displayed a distinctive color change corresponding to fish spoilage during 14 days of storage. This indicates that NSI has high potential in indicator film applications.

One-Step Microfluidic Fabrication of Bioinspired Microfibers with a Spindle-Knot Structure for Fog Harvest

Many biomimetic microfibers have been designed from spider silk to collect water efficiently from humid air as a result of its periodic spindle-knot structure, which enhances the direct movement and convergence of captured fog droplets. Here, a hydrodynamic flow-focusing microfluidic device with a theta-shaped tube is designed for the one-step fabrication of bioinspired microfibers with a spindle-knot structure for fog harvest. The morphology of the structured microfibers, including height, width, and spacing of spindle knots, can be adjusted readily by regulating the flow rate of specific phases. The production rate of these structured microfibers can reach 1100 cm/min. Moreover, the capture, transportation, and collection performance of fog droplets on various microfibers are investigated in a fog collection platform. It is demonstrated that our one-step microfluidic device presents a ready method for the fabrication of structured microfibers with spindle knots, which provide a significant facilitation on efficient fog capture and water collection.

Effect of Nano-Silica and Sorbitol on the Properties of Chitosan-Based Composite Films

Chitosan and its derivatives are widely used in food packaging, pharmaceutical, biotechnology, medical, textile, paper, agriculture, and environmental industries. However, the flexibility of chitosan films is extremely poor, which limits its relevant applications to a large extent. In this paper, chitosan/sorbitol/nano-silica (CS/sorbitol/SiO2) composite films were prepared by the casting film method using chitosan, sorbitol, Tween-80 and nano-SiO2 as raw materials. The structure of the films was characterized by infrared spectroscopy, electron scanning microscopy, and X-ray diffraction analysis. The effects of sorbitol and nano-silica dosage on the mechanical properties, thermal properties and water vapor barrier properties of the composite film were investigated. The results show that with the gradual increase in sorbitol (≤75 wt %), the elongation at the break of chitosan/sorbitol films significantly increased. When the addition of sorbitol was 75 wt %, the elongation at break of the chitosan/sorbitol composite film was 13 times higher than that of the chitosan film. Moreover, nano-SiO2 can further improve the mechanical properties and thermal stability of the chitosan/sorbitol composite films. When the amount of nano-silica was 4.5 wt %, the composite film became more flexible, with a maximum elongation of 90.8% (which is 14 times that of chitosan film), and its toughness increased to 10.52 MJm-3 (which is 6 times that of chitosan film). This study balances the tensile strength and elongation at break of the composite films by adding a plasticizer and nano-filler, providing a reference for the preparation of chitosan composites or their blending with other polymers, and has practical guiding significance for the industrial production of biomass plastics.

Characterization of Nano-SiO2/Zein Film Prepared Using Ultrasonic Treatment and the Ability of the Prepared Film to Resist Different Storage Environments

This study has developed, ultrasound-assisted, a novel food packaging film (U-zein/SiO2) for food packaging applications. Incorporating an optimal concentration of 18 mg/mL of nano-SiO2 and subjecting the film to 10 min of ultrasonic treatment resulted in a remarkable increase of 32.89% in elongation at break and 55.86% in tensile strength. In addition, the incorporation of nano-SiO2 effectively reduces the water content and solubility of the composite film, resulting in improved water/oxygen barrier properties. These physiochemical properties were further improved with the application of ultrasound. The analysis of attenuated total reflectance-Fourier transform infrared, X-ray diffraction, differential scanning calorimetry, and scanning electronic microscope demonstrated that the ultrasound treatment improved the hydrogen bonds, improved thermal stability, molecular arrangement, structure stability, and intermolecular compatibility of the composite film, resulting in enhanced physio-mechanical properties of the film. In addition, the ultrasound treatment led to a smoother film surface and reduced the pores on the film's cross-section. Moreover, the U-zein/SiO2 film exhibited excellent mechanical and water/oxygen barrier properties in different storage environments over a period of 30 days. These results offer sound theoretical support for the practical application of the prepared preservative film.

Modulation of physicochemical properties and antimicrobial activity of sodium alginate films through the use of chestnut extract and plasticizers

Due to the growing demand for robust and environmentally friendly antimicrobial packaging materials, biopolymers have recently become extensively investigated. Although biodegradable biopolymers usually lack mechanical properties, which makes it inevitable to blend them with plasticizers. The purpose of this study was to investigate plasticization efficiency of bio-based plasticizers introduced into sodium alginate compositions containing chestnut extract and their effect on selected film properties, including primarily mechanical and antibacterial properties. The films were prepared by the casting method and sodium alginate was cross-linked with calcium chloride. Six different plasticizers, including three commercially available ones (glycerol, epoxidized soybean oil and palm oil) and three synthesized plasticizers that are mixtures of bio-based plasticizers, were used to compare their influence on the film properties. Interactions between the polymer matrix and the plasticizers were investigated using Fourier transform infrared spectroscopy. The morphological characteristics of the films were characterized by scanning electron microscopy. Thermal properties, tensile strength, elongation at break, hydrophilic, and barrier properties of the obtained films were also determined. To confirm the obtaining of active films through the use of chestnut extract and to study the effect of the proposed plasticizers on the antibacterial activity of the extract, the obtained films were tested against bacteria cultures. The final results showed that all of the obtained films exhibit a hydrophilic character and high barrier effect to oxygen, carbon dioxide and water vapor. In addition, sodium alginate films prepared with chestnut extract and the plasticizer proposed by us, showed better mechanical and antimicrobial properties than the films obtained with chestnut extract and the commercially available plasticizers.

Biopolymer-Based Sustainable Food Packaging Materials: Challenges, Solutions, and Applications

Biopolymer-based packaging materials have become of greater interest to the world due to their biodegradability, renewability, and biocompatibility. In recent years, numerous biopolymers-such as starch, chitosan, carrageenan, polylactic acid, etc.-have been investigated for their potential application in food packaging. Reinforcement agents such as nanofillers and active agents improve the properties of the biopolymers, making them suitable for active and intelligent packaging. Some of the packaging materials, e.g., cellulose, starch, polylactic acid, and polybutylene adipate terephthalate, are currently used in the packaging industry. The trend of using biopolymers in the packaging industry has increased immensely; therefore, many legislations have been approved by various organizations. This review article describes various challenges and possible solutions associated with food packaging materials. It covers a wide range of biopolymers used in food packaging and the limitations of using them in their pure form. Finally, a SWOT analysis is presented for biopolymers, and the future trends are discussed. Biopolymers are eco-friendly, biodegradable, nontoxic, renewable, and biocompatible alternatives to synthetic packaging materials. Research shows that biopolymer-based packaging materials are of great essence in combined form, and further studies are needed for them to be used as an alternative packaging material.

Bacteria-Polymer Composite Material for Glycerol Valorization

Bacterial immobilization is regarded as an enabling technology to improve the stability and reusability of biocatalysts. Natural polymers are often used as immobilization matrices but present certain drawbacks, such as biocatalyst leakage and loss of physical integrity upon utilization in bioprocesses. Herein, we prepared a hybrid polymeric matrix that included silica nanoparticles for the unprecedented immobilization of the industrially relevant Gluconobacter frateurii (Gfr). This biocatalyst can valorize glycerol, an abundant by-product of the biodiesel industry, into glyceric acid (GA) and dihydroxyacetone (DHA). Different concentrations of siliceous nanosized materials, such as biomimetic Si nanoparticles (SiNps) and montmorillonite (MT), were added to alginate. These hybrid materials were significantly more resistant by texture analysis and presented a more compact structure as seen by scanning electron microscopy. The preparation including 4% alginate with 4% SiNps proved to be the most resistant material, with a homogeneous distribution of the biocatalyst in the beads as seen by confocal microscopy using a fluorescent mutant of Gfr. It produced the highest amounts of GA and DHA and could be reused for up to eight consecutive 24 h reactions with no loss of physical integrity and negligible bacterial leakage. Overall, our results indicate a new approach to generating biocatalysts using hybrid biopolymer supports.

Programmable Interactions of Cellulose Acetate with Octadecyltrichlorosilane-Functionalized SiO2 Nanoparticles

It is significant to understand the interfacial interactions involved between the cellulose acetate (CA) and dispersed nanomaterials, in which the enhanced interaction improves the mechanical behavior of CA. In this work, the amendments of CA with SiO₂ nanoparticles have been found to be endowed by grafting varying concentrations (0, 3, 5, and 6%) of octadecyltrichlorosilane (OTS). Aided by SiO₂ colloid probe atomic force microscopy (AFM with a probe diameter of 20 μm), the adhesion force between CA and SiO₂ is found to be programmable by tuning OTS concentrations functionalized onto SiO₂ surfaces. The adhesion forces of 5% OTS-functionalized SiO₂ with CA are the strongest, followed by the ones of 0, 3, and 6% OTS, resulting in a smoother and denser morphology on the film with 5% OTS. The AFM-measured approaching force-distance curves have been further compared to predictions by the extended Derjaguin-Landau-Verwey-Overbeek (XDLVO) theory, in which the XDLVO force is summed as the Liftshitz-van der Waals force (F^LW), the electrostatic double-layer force (F^EL), and the acid-base interaction force (F^AB). F^LW and F^EL do not change significantly with OTS concentrations functionalized onto SiO₂. However, F^AB is sensitive to the functionalized OTS concentration onto SiO₂ and significantly contributes to the interaction force of the composite films with 5% OTS, promoting the formation of a smooth and dense surface feature with a considerable mechanical performance demonstrated by load-displacement curves from a nanoindenter. This is highly encouraging and suggests that nanomaterials can be incorporated into CA to effectively improve their mechanical compatibility by programming the interaction between the CA matrix and nanomaterials.

Latest Trends in Sustainable Polymeric Food Packaging Films

Food packaging is the best way to protect food while it moves along the entire supply chain to the consumer. However, conventional food packaging poses some problems related to food wastage and excessive plastic production. Considering this, the aim of this work was to examine recent findings related to bio-based alternative food packaging films by means of conventional methodologies and additive manufacturing technologies, such as 3D printing (3D-P), with potential to replace conventional petroleum-based food packaging. Based on the findings, progress in the development of bio-based packaging films, biopolymer-based feedstocks for 3D-P, and innovative food packaging materials produced by this technology was identified. However, the lack of studies suggests that 3D-P has not been well-explored in this field. Nonetheless, it is probable that in the future this technology will be more widely employed in the food packaging field, which could lead to a reduction in plastic production as well as safer food consumption.

pH-Responsive Drug Delivery and Imaging Study of Hybrid Mesoporous Silica Nanoparticles

A system of pH-responsive and imaging nanocarriers was developed using mesoporous silica nanoparticles (MSNs), in which gadolinium (Gd) was doped through in situ doping (Gd₂O₃@MSN). Sodium alginate (SA) was attached to the surfaces of the amino groups of MSNs (NH₂-Gd₂O₃@MSN) through the electrostatic adsorption between the amino groups and the carboxyl groups with the formation of hybrid SA-Gd₂O₃@MSN nanoparticles (NPs). The SA-coated NPs were spherical or near-spherical in shape with an average size of nearly 83.2 ± 8.7 nm. The in vitro drug release experiments of a model rhodamine B (RhB) cargo were performed at different pH values. The result confirmed the pH-responsiveness of the nanocarriers. The results of the cytotoxicity studies indicated that the SA-Gd₂O₃@MSN NPs were not cytotoxic by themselves. The results of the in vivo safety evaluation and the hemolysis assay confirmed that the system is highly biocompatible. It is noteworthy that the T1 contrast of the system was significantly enhanced by the Gd, as indicated by the result of the MR imaging. This study confirms that the synthesized hybrid nanosystem is promising for pH-responsive drug delivery and MR imaging for cancer diagnosis and treatment.

Polysaccharides: Sources, Characteristics, Properties, and Their Application in Biodegradable Films

Biodegradable films emerge as alternative biomaterials to conventional packaging from fossil sources, which, in addition to offering protection and increasing the shelf life of food products, are ecologically sustainable. The materials mostly used in their formulation are based on natural polysaccharides, plasticizing agents, and bioactive components (e.g., antimicrobial agents or antioxidants). The formulation of biodegradable films from polysaccharides and various plasticizers represents an alternative for primary packaging that can be assigned to specific food products, which opens the possibility of having multiple options of biodegradable films for the same product. This review describes the main characteristics of the most abundant polysaccharides in nature and highlights their role in the formulation of biodegradable films. The compilation and discussion emphasize studies that report on the mechanical and barrier properties of biodegradable films when made from pure polysaccharides and when mixed with other polysaccharides and plasticizing agents.

Preparation of sodium alginate/konjac glucomannan active films containing lycopene microcapsules and the effects of these films on sweet cherry preservation

In this study, lycopene microcapsules (LMs) were prepared using chitosan (CS) and carboxymethyl CS (CMCS) as the wall materials. Sodium alginate (SA) and konjac glucomannan (KGM) were used as substrates to fabricate LM/SA/KGM composite films. Results showed that when 2.0 % CMCS was employed, the resulting LMs had the maximum embedding rate of 83.17 %, smallest particle sizes, and stable zeta potentials. The LMs still had a high retention rate after 10 days of storage at 4 and 25 °C. When 2.0 % LMs were used, the corresponding composite film exhibited the best antibacterial properties, oxidation resistance, a high transparency (82.3 %), and a strong water vapor barrier (2.39 × 10^-10 g/m·s·Pa). Finally, the effects of the as-prepared composite films on the preservation of sweet cherries stored at 0 °C for 15 days were investigated. The results indicated that the LM/SA/KGM composite film effectively prolonged the shelf lives of sweet cherries and efficiently delayed the decline in the decay rate, pH, contents of soluble solids, and other indicators. The application of LM/SA/KGM composite films in fruit and vegetable preservation has development prospects and provides a reference for expanding the application range of lycopene and enhancing fruit and vegetable preservation.

Biopolymer-Based Films from Sodium Alginate and Citrus Pectin Reinforced with SiO2

Blend films based on sodium alginate (SA) and citrus pectin (P) reinforced with different concentrations of SiO₂ (0–10% w/w) were developed in this study. From the morphological (SEM) and structural (FT-IR) evaluation, it was verified that the incorporation of the reinforcing agent did not drastically modify the microstructure of the films, nor did new chemical bonds form. However, the XRD results suggested a slight reduction in the crystallinities of the blends by the incorporation of SiO₂. Among the formulations prepared, the addition of a 5% reinforcing agent was responsible for the simultaneous improvement of mechanical and barrier properties. Comparing the control sample (SA/P) with the SA/P/5.0%SiO₂ film, the tensile strength increased from 27.7 ± 3.7 to 40.6 ± 4.5 MPa, and the water-vapor transmission rate decreased from 319.8 ± 38.7 to 288.9 ± 23.5 g m⁻² day⁻¹. Therefore, SiO_2, as a reinforcing agent in SA/P blends, represents a simple and effective strategy for improving the properties of biopolymer-based films in applications, such as packaging.

Deeper Insight into the Role of Organic Ammonium Cations in Reducing Surface Defects of the Perovskite Film

Organic ammonium salts (OASs) have been widely used to passivate perovskite defects. The passivation mechanism is usually attributed to coordination of OASs with unpaired lead or halide ions, yet ignoring their interaction with excess PbI₂ on the perovskite film. Herein, we demonstrate that OASs not only passivate defects by themselves, but also redistribute excess aggregated PbI₂ into a discontinuous layer, augmenting its passivation effect. Moreover, alkyl OAS is more powerful to disperse PbI₂ than a F-containing one, leading to better passivation and device efficiency because F atoms restrict the intercalation of OAS into PbI₂ layers. Inspired by this mechanism, exfoliated PbI₂ nanosheets are adopted to provide better dispersity of PbI₂ , further boosting the efficiency to 23.14 %. Our finding offers a distinctive understanding of the role of OASs in reducing perovskite defects, and a route to choosing an OAS passivator by considering substitution effects rather than by trial and error.

Novel electrosprayed enhanced microcapsules with different nanoparticles containing healing agents in a single multicore microcapsule

A novel method was employed to synthesize microcapsules containing both epoxy and hardener healing agents in a single microcapsule using a two-step electrospraying technique. Moreover, the sodium alginate microcapsule shell was enhanced with three types of nanoparticles, including MWCNT, nanoclay, and nanosilica. The surface morphology of fabricated microcapsules was examined using FESEM and AFM images. The TEM and elemental mapping images illustrated that the added nanoparticles into sodium alginate microcapsule shells were dispersed homogeneously. In addition, the mechanical properties of microcapsule shells were obtained using nanoindentation tests. Based on this research, the addition of nanoparticles increased the size and the roughness of microcapsules and improved the elastic modulus and the hardness of microcapsule's outer shells, significantly. For instance, the elastic modulus and the hardness of incorporated microcapsule shells with MWCNT increased by 85.5% and 91.3%, respectively, compared to neat sodium alginate multicore microcapsules, due to intrinsic high strength and high aspect ratio of MWCNT.

Carboxymethyl chitosan incorporated with gliadin/phlorotannin nanoparticles enables the formation of new active packaging films

Advanced carboxymethyl chitosan (CMCS) based functional films were fabricated by involving some amounts of gliadin/phlorotannin nanoparticles (GPNPs) using a solution casting method. GPNPs were synthesized by an antisolvent precipitation approach, and they presented a spherical morphology with a mean diameter of 145.30 ± 2.06 nm. The effect of GPNPs concentration on the structural, physical, antioxidant and antimicrobial properties of CMCS-GPNPs (C-G) functional films was evaluated. It was found that the added GPNPs were homogeneously distributed over the whole CMCS matrix, allowing to reduce the free volume of the nanocomposite matrix and subsequently improve the physical properties of the final film (evidenced by mechanical and water barrier properties). FT-IR spectra indicated the intermolecular interactions, such as hydrogen bonds and electrostatic interaction, within the matrix of the nanocomposite films were increased. Impressively, the anti-ultraviolet properties, antioxidant activity and antimicrobial behaviors of the as-formed C-G functional films were greatly enhanced compared to the pure CMCS film. All these results suggested that our as-prepared C-G nanocomposite films could be a promising food packaging material.

Improving the mechanical properties and thermal stability of sodium alginate/hydrolyzed collagen films through the incorporation of SiO2

Biopolymer-based films have become leading alternatives to traditional fossil-based packaging plastics. Among the countless types of biopolymers with potential for such applications, films containing hydrolyzed collagen in their composition were scarcely explored. This study determined the effect of different loads of nano-SiO₂ (0, 2, 6, 8 and 10% w/w of sodium alginate) in the sodium alginate (SA) and hydrolyzed collagen (HC) blend films in terms of structure, thickness, mechanical properties, and thermal stability. The results indicated an improvement in the general mechanical and thermal behavior. Tensile strength increased from 18.2 MPa (control sample) to 25.4 MPa for the SA/HC film incorporated with 10% nano-SiO₂. In the same condition, the film's elongation at break improved impressively (from 19.5 to 35.8%). Thermal stability improved slightly for all proportions of nano-SiO₂. Therefore, the addition of nano-SiO₂ can be an easy and simple strategy to improve crucial properties of SA/HC blend films, increasing its performance for future application as sustainable packaging.

Chitosan-silica with hops β-acids added films as prospective food packaging materials: Preparation, characterization, and properties

In this study, silica (SiO₂) and β-acids were added to the chitosan films in order to improve the film's properties. Scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), and X-ray diffraction analysis (XRD) were used to explore the structure of film. The results of mechanical test indicated that the film containing SiO₂ (0.3%) and β-acids (0.3%) could obtain a significant tensile strength (10.04 MPa). The complex films possessed a good inhibitory effect on three types of bacteria, and good antioxidant activity (>56%, DPPH). The release mechanism of β-acids from the films exhibited Fickian diffusion (n < 0.45). During the storage of soybean oil, the films could well control the changes of the peroxide value, acid value and thiobarbituric acid reactant content. Overall, the biofilms not only possess good physical and chemical properties, but also prolongs the time of food storage.

Characterization and antioxidant properties of chitosan film incorporated with modified silica nanoparticles as an active food packaging

In this study, two modified silica nanoparticles (SiO₂-GA NPs) were successfully obtained by covalently grafting gallic acid onto silica nanoparticles. The mean particle diameters of their were 112.7 ± 0.55 nm (1-SiO₂-GA NPs) and 408.7 ± 3.20 nm (4-SiO₂-GA NPs), respectively. Novel antioxidant active packaging composite films were prepared by incorporation of 1-SiO₂-GA NPs or 4-SiO₂-GA NPs into chitosan. The structure analysis of the composite films showed that intermolecular hydrogen bonds were formed between the two modified silica nanoparticles and chitosan. Compared with the chitosan film, the mechanical properties, water vapor barrier property and UV light barrier ability of the composite films were significantly improved. Moreover, the incorporated of the two modified silica nanoparticles significantly increased antioxidant activity of the composite films. This study indicates that composite films incorporated with modified silica nanoparticles, especially the incorporation of 1-SiO₂-GA NPs can be used as novel antioxidant food packaging composite films.

Polysaccharide-Based Nanocomposites for Food Packaging Applications

The article presents a review of the literature on the use of polysaccharide bionanocomposites in the context of their potential use as food packaging materials. Composites of this type consist of at least two phases, of which the outer phase is a polysaccharide, and the inner phase (dispersed phase) is an enhancing agent with a particle size of 1-100 nm in at least one dimension. The literature review was carried out using data from the Web of Science database using VosViewer, free software for scientometric analysis. Source analysis concluded that polysaccharides such as chitosan, cellulose, and starch are widely used in food packaging applications, as are reinforcing agents such as silver nanoparticles and cellulose nanostructures (e.g., cellulose nanocrystals and nanocellulose). The addition of reinforcing agents improves the thermal and mechanical stability of the polysaccharide films and nanocomposites. Here we highlighted the nanocomposites containing silver nanoparticles, which exhibited antimicrobial properties. Finally, it can be concluded that polysaccharide-based nanocomposites have sufficient properties to be tested as food packaging materials in a wide spectrum of applications.

Seaweed Polysaccharide in Food Contact Materials (Active Packaging, Intelligent Packaging, Edible Films, and Coatings)

Food contact materials (FCMs) are materials that come in contact with food products such as food packaging which play a significant role in the food quality and safety. Plastic, which is a major food packaging material, harms the eco-system, wildlife, and the environment. As a result, numerous researches have been in progress on alternative polymers, which has similar properties as plastic but is also environmentally friendly (biodegradable). In recent years, the utilization of seaweed polysaccharides has piqued interest due to its biodegradability, non-toxicity, antioxidant capabilities, and excellent film formation ability. However, it has a number of drawbacks such as low tensile strength, water solubility, and moderate antibacterial characteristics, among others. The addition of other biopolymers, nanoparticles, or natural active agents improves these features. In this review article, we have summarized the current state of seaweed polysaccharide research in active packaging, intelligent packaging, edible films, and coatings. It also highlights the physical, thermal, antioxidant, and other properties of these materials. Finally, the article discusses the relevant legislation as well as the field’s future prospects. Research shows that seaweeds polysaccharide looks promising as a sustainable food contact material, but there is always a potential for development to make it market feasible.

Antimicrobial Properties of Food Nanopackaging: A New Focus on Foodborne Pathogens

Food products contaminated by foodborne pathogens (bacteria, parasites, and viruses) cause foodborne diseases. Today, great efforts are being allocated to the development of novel and effective agents against food pathogenic microorganisms. These efforts even might have a possible future effect in coronavirus disease 2019 (COVID-19) pandemic. Nanotechnology introduces a novel food packaging technology that creates and uses nanomaterials with novel physiochemical and antimicrobial properties. It could utilize preservatives and antimicrobials to extend the food shelf life within the package. Utilizing the antimicrobial nanomaterials into food packaging compounds typically involves incorporation of antimicrobial inorganic nanoparticles such as metals [Silver (Ag), Copper (Cu), Gold (Au)], and metal oxides [Titanium dioxide (TiO2), Silicon oxide (SiO2), Zinc oxide (ZnO)]. Alternatively, intelligent food packaging has been explored for recognition of spoilage and pathogenic microorganisms. This review paper focused on antimicrobial aspects of nanopackaging and presented an overview of antibacterial properties of inorganic nanoparticles. This article also provides information on food safety during COVID-19 pandemic.

Recent advances in composite hydrogels prepared solely from polysaccharides

The proliferating demand for sustainable, biodegradable, and biologically safe materials has triggered the development of polysaccharide-based hydrogels. The translation of research on single polysaccharide-based hydrogels into their desired clinical or industrial application is minimal. This is attributable to their lack of mechanical strength, inadequate stability, and constrained the possibility of their modulation to obtain the desired property. Polysaccharide-based composite hydrogels (PCHs) have proven their mantle to counteract this issue while expanding the horizons for their applications. PCHs can be fabricated by physical and/or chemical interlinking techniques, which entails the association of macromolecular chain linkages. The resulting composites can impart remarkably higher stability and elevate the suitability and efficiency of the system. Owing to these advantages, the research on PCHs has been gaining momentum. They are emerging as a lucrative alternative for the conventional molecules used for the fabrication of such materials. The review would initially focus on providing a detailed outlook for the various physical/chemical techniques involved in the preparation of PCHs. Subsequently, the characterization techniques used to understand the structural and chemical behavior of PCHs would be discussed. The article would also elaborate on the various fields of application and the possible areas for future research of PCHs.

Effect of low concentrations of SiO2 nanoparticles on the physical and chemical properties of sodium alginate-based films

This work investigated the effect of adding low concentrations of nano-SiO₂ (0.5, 1.0 and 1.5%) in the properties of films based on sodium alginate, to identify lower thresholds in the proportion of the reinforcing agent. It was found that, even in the smallest proportion, thermal stability of the nanocomposites improved significantly (with degradation onset increased by almost 15% compared with the control film). The surface morphology showed pronounced roughness at nano-SiO₂ concentrations greater than 1.0%, indicating agglomeration of part of the nanomaterial. Mechanical properties were reduced for the samples with concentrations equal to 1.0 and 1.5%, however, without significant differences between them. Conversely, water vapor and light barrier properties have not undergone significant changes in any formulation. Therefore, the use of 0.5% nano-SiO₂ in alginate films would be an easy and economically interesting way to improve thermal stability, without significantly reducing mechanical properties of the pure material.

Polysaccharide-Based Packaging Functionalized with Inorganic Nanoparticles for Food Preservation

Functionalization of polysaccharide-based packaging incorporating inorganic nanoparticles for food preservation is an active research area. This review summarizes the use of polysaccharide-based materials functionalized with inorganic nanoparticles (TiO2, ZnO, Ag, SiO2, Al2O3, Fe2O3, Zr, MgO, halloysite, and montmorillonite) to develop hybrid packaging for fruit, vegetables, meat (lamb, minced, pork, and poultry), mushrooms, cheese, eggs, and Ginkgo biloba seeds preservation. Their effects on quality parameters and shelf life are also discussed. In general, treated fruit, vegetables, mushrooms, and G. biloba seeds markedly increased their shelf life without significant changes in their sensory attributes, associated with a slowdown effect in the ripening process (respiration rate) due to the excellent gas exchange and barrier properties that effectively prevented dehydration, weight loss, enzymatic browning, microbial infections by spoilage and foodborne pathogenic bacteria, and mildew apparition in comparison with uncoated or polysaccharide-coated samples. Similarly, hybrid packaging showed protective effects to preserve meat products, cheese, and eggs by preventing microbial infections and lipid peroxidation, extending the food product’s shelf life without changes in their sensory attributes. According to the evidence, polysaccharide-hybrid packaging can preserve the quality parameters of different food products. However, further studies are needed to guarantee the safe implementation of these organic–inorganic packaging materials in the food industry.

pH-sensitive soluble soybean polysaccharide/SiO2 incorporated with curcumin for intelligent packaging applications

In the present work, the effect of various concentrations of SiO2 nanoparticles (5, 10, and 15%) on physicochemical and antimicrobial properties of soluble soybean polysaccharide (SSPS)-based film was investigated. Then, the migration of SiO2 nanoparticles to ethanol as a food simulant was evaluated. Subsequently, curcumin was added to the nanocomposite formulation to sense the pH changes. Finally, the cytotoxicity of the developed packaging system was investigated. With increasing nanoparticle concentration, the film thickness, water solubility, and water vapor permeability decreased and mechanical performance of the films improved. SSPS/SiO2 nanocomposite did not show antibacterial activity. SEM analysis showed that SiO2 nanoparticles are uniformly distributed in the SSPS matrix; however, some outstanding spots can be observed in the matrix. A very homogeneous surface was observed for neat SSPS film with R a and R q values of 3.48 and 4.26, respectively. With the incorporation of SiO2 (15%) into SSPS film, R a and R q values increased to 5.67 and 5.98, respectively. Small amount of SiO2 nanoparticles was released in food simulant. The nanocomposite incorporated with curcumin showed good physical properties and antibacterial activity. A strong positive correlation was observed between TVBN content of shrimp and a* values of the films during storage time (Pearson's correlation = 0.985).

Polysaccharides-based bio-nanostructures and their potential food applications

Polysaccharides are omnipresent biomolecules that hold great potential as promising biomaterials for a myriad of applications in various biotechnological and industrial sectors. The presence of diverse functional groups renders them tailorable functionalities for preparing a multitude of novel bio-nanostructures. Further, they are biocompatible and biodegradable, hence, considered as environmentally friendly biopolymers. Application of nanotechnology in food science has shown many advantages in improving food quality and enhancing its shelf life. Recently, considerable efforts have been made to develop polysaccharide-based nanostructures for possible food applications. Therefore, it is of immense importance to explore literature on polysaccharide-based nanostructures delineating their food application potentialities. Herein, we reviewed the developments in polysaccharide-based bio-nanostructures and highlighted their potential applications in food preservation and bioactive "smart" food packaging. We categorized these bio-nanostructures into polysaccharide-based nanoparticles, nanocapsules, nanocomposites, dendrimeric nanostructures, and metallo-polysaccharide hybrids. This review demonstrates that the polysaccharides are emerging biopolymers, gaining much attention as robust biomaterials with excellent tuneable properties.

Sustainable nanocomposite films based on SiO2 and biodegradable poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBH) for food packaging

Sustainable nanocomposites with transparent, biodegradable, and enhanced mechanical and barrier properties were prepared by the incorporation of SiO2 into poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBH) films and subsequent solvent casting. The crystallinity of composites could be increased by 67% with appropriate contents of SiO2, which proved that SiO2 were effective nucleating agents for PHBH. And it was worth mentioning that the contributions of SiO2 to the crystallization and thermal stability of composites are proved effectively by Avrami relationship and Horowitz and Metzger method. More importantly, compared with PHBH, it had not only an enhancement about 40% and 60% on the tensile strength and elastic modulus, respectively, but also half the reduction of the moisture and oxygen permeability which were much higher than the values of conventional plastics. The above, in conjunction with the low migration rate measured in food substitutes, illustrated unambiguously that the nanocomposites might be suitable for potential application in food packaging.

Effect of locust bean gum-sodium alginate coatings incorporated with daphnetin emulsions on the quality of Scophthalmus maximus at refrigerated condition

In this study, the microbiological, physicochemical, and flavor changes of turbot (Scophthalmus maximus) coated with a composite active coating of locust bean gum (LBG) and sodium alginate (SA) supplemented with daphnetin emulsions (0.16, 0.32, 0.64 mg·mL^-1) were determined during 18 days of refrigerated storage (4 ± 1 °C). Results showed that LBG-SA coatings containing 0.32 mg·mL^-1 daphnetin emulsions could significantly lower the total viable count (TVC), psychrophiles, Pseudomonas spp. and H₂S-producing bacteria counts, and inhibit the productions of off-flavor compounds including the total volatile basic nitrogen (TVB-N), trimethylamine (TMA) and ATP-related compounds. 32 volatile compounds were identified by solid phase microextraction combined with gas chromatography-mass spectrometer method (SPME-GC/MS) during refrigerated storage and the treated turbot samples significantly lowered the relative content of fishy flavor compounds. Further, the LBG-SA coatings containing daphnetin could also delay the myofibril degradation of the turbot samples. These results indicated that the LBG-SA coatings with 0.32 mg·mL^-1 daphnetin were a potential alternative way to improve the quality of turbot during refrigerated storage.

Investigation of the structural, physical properties, antioxidant, and antimicrobial activity of chitosan- nano-silicon aerogel composite edible films incorporated with okara powder

The chitosan/okra powder/nano-silicon aerogel composite films were prepared by casting method and their physicochemical properties and structural characterization were studied. The results showed that the composite film had good mechanical properties, barrier properties and optical properties. The composite film has strong flexibility. The surface glossiness of C/D/S1.5:1:0.1 film was 14.4Gu. As for the antibacterial activity, all the composite films had strong antibacterial activity against Gram-negative (E. coli) and Gram-positive (S. aureus), and the inhibition zone of C/D/S1.5:1:0.10 against E. coli reached 551.96 mm2, the inhibition zone for S. aureus was 350.29 mm2. The composite film had uniform, non-porous, continuous and dense surface characteristics. The structural characterization confirmed that there was good compatibility between chitosan, okara powder and nano-silicon aerogel. In summary, the composite films had excellent performance and structure, which promoted the research of functional packaging films.