Edible coating using carbon quantum dots for fresh produce preservation: A review of safety perspectives.

Fresh produce deteriorates and spoils after harvest due to its perishable nature. Deterioration in quality over time has become a major problem for the food industry, placing an undue burden on the economy and agriculture. Food scientists have developed various methods and technologies to prevent spoilage of fruits and vegetables during storage and logistics. Utilizing carbon quantum dots (CQDs) in the form of active packaging and coatings has been a popular strategy recently. CQDs have recently attracted attention as sustainable and functional nanomaterials. CQDs are popular among food scientists due to their easy and economical synthesis, sustainability, non-toxicity, biocompatibility, edibility, UV protection, and antibacterial and antioxidant activities. Although many studies have been conducted and reviewed on the utilization of CQDs in the manufacture of flexible active packaging materials, relatively few studies have investigated the use of CQDs in edible coating formulations for fresh produce. The main reasons for this are concerns about the potential toxicity and edibility of CQDs if they are coated directly on fresh produce. Therefore, this review aims to address these issues by investigating the dose-dependent non-toxicity and biocompatibility of sustainable CQDs along with other important properties from a food packaging perspective. Additionally, this review focuses on the studies performed so far on the direct coating of CQD-based formulations on fresh and fresh-cut fruits and vegetables and discusses the important impact of CQDs on the quality of coated agricultural products. This review is intended to provide food packaging researchers with confidence and prospects for utilizing sustainable CQDs in direct coating formulations for food.

Application of bacteriophages in biopolymer-based functional food packaging films.

Recently, food spoilage caused by pathogens has been increasing. Therefore, applying control strategies is essential. Bacteriophages can potentially reduce this problem due to their host specificity, ability to inhibit bacterial growth, and extend the shelf life of food. When bacteriophages are applied directly to food, their antibacterial activity is lost. In this regard, bacteriophage-loaded biopolymers offer an excellent option to improve food safety by extending their shelf life. Applying bacteriophages in food preservation requires comprehensive and structured information on their isolation, culturing, storage, and encapsulation in biopolymers for active food packaging applications. This review focuses on using bacteriophages in food packaging and preservation. It discusses the methods for phage application on food, their use for polymer formulation and functionalization, and their effect in enhancing food matrix properties to obtain maximum antibacterial activity in food model systems.

Sulfur quantum dots as sustainable materials for biomedical applications: Current trends and future perspectives.

Discovered over a decade ago, sulfur quantum dots (SQDs) have rapidly emerged as a sustainable, safe, and inexpensive quantum material. Sustainably synthesizing SQDs using sublimed sulfur powders, typically produced as waste in industrial petrochemical refining processes, has attracted researchers to use these functional quantum materials in various research fields. SQDs quickly found applications in various research fields, such as electronics, environmental sensing, food packaging, and biomedical engineering. Although low production yields, time-consuming and energy-intensive synthetic methods, and low photoluminescence quantum yield (PLQY) have been some problems, researchers have found ways to improve synthetic methods, develop passivating agents, and systematically modify reaction schemes and energy sources to achieve large-scale synthesis of stable SQDs with high PLQY. Nonetheless, SQDs have succeeded tremendously in biomedical and related applications due to their low toxicity, antibacterial and antioxidant properties, biocompatibility, appropriate cellular uptake, and photoluminescent properties. Although the bioimaging applications of SQDs have been extensively studied, their other reported properties indicate their suitability for use as antimicrobial agents, free radical scavengers, and drug carriers in other biomedical applications, such as tissue regeneration, wound healing, and targeted drug delivery.

Advances in sustainable food packaging applications of chitosan/polyvinyl alcohol blend films.

Researchers are addressing environmental concerns related to petroleum-based plastic packaging by exploring biopolymers from natural sources, chemical synthesis, and microbial fermentation. Despite the potential of individual biopolymers, they often exhibit limitations like low water resistance and poor mechanical properties. Blending polymers emerges as a promising strategy to overcome these challenges, creating films with enhanced performance. This review focuses on recent advancements in chitosan/polyvinyl alcohol (PVA) blend food packaging films. It covers molecular structure, properties, strategies for performance improvement, and applications in food preservation. The blend's excellent compatibility and intermolecular interactions make it a promising candidate for biodegradable films. Future research should explore large-scale thermoplastic technologies and investigate the incorporation of additives like natural extracts and nanoparticles to enhance film properties. Chitosan/PVA blend films offer a sustainable alternative to petroleum-based plastic packaging, with potential applications in practical food preservation.

Anti-inflammatory and antioxidant activity of elemental sulfur-derived sustainable sulfur quantum dots.

Sulfur quantum dots (SQDs) are attracting increasing attention in the biomedical field due to their unique properties, such as antibacterial activity, free radical scavenging potential, optical properties, biocompatibility, and non-toxicity. Ethylenediamine passivated SQDs (ED-SQDs) were synthesized using a hydrothermal method. Cytotoxicity evaluation of ED-SQDs on RAW264.7 cells showed more than 90% cell viability even at 500 µg/mL of ED-SQDs, with an established IC50 value of 880.9 µg/mL. In addition, ED-SQDs showed potent antioxidant activity in vitro, effectively scavenging ABTS and DPPH free radicals at concentrations below 100 µg/mL, comparable to ascorbic acid. ED-SQD reduced lipopolysaccharide (LPS)-induced nitric oxide and reactive oxygen species in macrophages, lowered pro-inflammatory cytokines, and inactivated LPS-activated STAT3. In addition, ED-SQD increased nuclear NRF2 and the expression of genes encoding antioxidant enzymes in LPS-stimulated cells. These results reveal the antioxidant and anti-inflammatory potential of ED-SQDs at non-toxic concentrations, providing evidence for their potential anti-inflammatory applications.

Carboxymethylcellulose/Agar-Based Multifunctional Films Incorporated with Zn-Doped SnO2 Nanoparticles for Active Food Packaging Application.

SnO2 and Zn-SnO2 nanoparticles were prepared by chemical precipitation, and the rutile phase of SnO2 was confirmed through X-ray diffraction studies. X-ray photoelectron spectroscopy (XPS) confirmed the doping of SnO2 with Zn and elucidated the surface chemistry before and after doping. The average sizes of SnO2 and Zn-SnO2 nanoparticles determined using TEM were 3.96 ± 0.85 and 3.72 ± 0.9 nm, respectively. UV-visible and photoluminescence spectrophotometry were used to evaluate the optical properties of SnO2 and Zn-SnO2 nanoparticles, and their energy gaps (Eg) were 3.8 and 3.9 eV, respectively. The antibacterial activity of these nanoparticles against Salmonella enterica and Staphylococcus aureus was evaluated under dark and light conditions. Antibacterial activity was higher in light, showing the highest activity (99.5%) against S. enterica. Carboxymethylcellulose (CMC)/agar-based functional composite films were prepared by adding different amounts of SnO2 and Zn-SnO2 nanoparticles (1 and 3 wt % of polymers). The composite film showed significantly increased UV barrier properties while maintaining the mechanical properties, water vapor barrier, and transparency compared to the neat CMC/agar film. These composite films showed significant antibacterial activity; however, the Zn-SnO2-added film showed stronger antibacterial activity (99.2%) than the SnO2-added film (15%).

Recent progress in pectin extraction, characterization, and pectin-based films for active food packaging applications: A review.

Pectin is an abundant complex polysaccharide obtained from various plants. Safe, biodegradable, and edible pectin has been extensively utilized in the food industry as a gelling agent, thickener, and colloid stabilizer. Pectin can be extracted in a variety of ways, thus affecting its structure and properties. Pectin's excellent physicochemical properties make it suitable for many applications, including food packaging. Recently, pectin has been spotlighted as a promising biomaterial for manufacturing bio-based sustainable packaging films and coatings. Functional pectin-based composite films and coatings are useful for active food packaging applications. This review discusses pectin and its use in active food packaging applications. First, basic information and characteristics of pectin, such as the source, extraction method, and structural characteristics, were described. Then, various methods of pectin modification were discussed, and the following section briefly described pectin's physicochemical properties and applications in the food sector. Finally, the recent development of pectin-based food packaging films and coatings and their use in food packaging were comprehensively discussed.

Cellulose nanofiber-based multifunctional films integrated with carbon dots and anthocyanins from Brassica oleracea for active and intelligent food packaging applications.

A new generation of carbon dot-based active and intelligent packaging films with UV blocking, antibacterial, and real-time sensing potentials was fabricated using Brassica oleracea (BO) extract. The cellulose nanofiber (CNF) was used to prepare the multifunctional intelligent nanocomposite film integrated with BO anthocyanins (BOA) and BO-biowaste-derived carbon dots (BO-CDs). The incorporation of 1.5 % BO-CD and 6 % BOA in the CNF matrix improved the physicochemical and UV blocking (>189 % increase) properties of the fabricated films. The synthesized BO-CD exhibits high fluorescence, UV absorption, antibacterial and antioxidant functions. It showed strong radical scavenging activity against ABTS (~90 %) and DPPH (~80 %) compared to the neat CNF film. Scanning electron microscopy and X-ray photoelectron spectroscopy (XPS) have shown enhanced compatibility and elemental composition of the BO-CDs/BOA additives in the CNF-polymer matrix. Packaging tests showed that the prepared film worked efficiently and non-destructively and was able to monitor the freshness of minced pork, fish, and shrimp in real-time through a distinct visual change from red to colorless/yellow during storage at 25 °C for 48 h. Active and intelligent films developed based on CNF/BO-CDs/BOA are expected to be applied as multifunctional packaging materials that can indicate quality changes and extend the shelf life of packaged perishable foods.

Recent advances in metal sulfide nanoparticle-added bionanocomposite films for food packaging applications.

Metal sulfide nanoparticles have recently attracted much attention due to their unique physical and functional properties. Metal sulfide nanoparticles used as optoelectronic and biomedical materials in the past decades are promising for making functional nanocomposite films due to their low toxicity and strong antibacterial activity. Recently, copper sulfide and zinc sulfide nanomaterials have been used to produce food packaging films for active packaging. Metal sulfide nanoparticles added as nanofillers are attracting attention in packaging applications due to their excellent potential to improve mechanical, barrier properties, and antibacterial activity. This review covers the fabrication process and important applications of metal sulfide nanoparticles. The development of metal sulfides reinforcing mainly copper sulfide and zinc sulfide nanomaterials as multifunctional nanofillers in bio-based films for active packaging applications has been comprehensively reviewed. As the recognition of metal sulfide nanoparticles as a functional filler increases, the development and application potential of active packaging films using them is expected to increase.

3D-Printed Pectin/Carboxymethyl Cellulose/ZnO Bio-Inks: Comparative Analysis with the Solution Casting Method.

Bio-inks consisting of pectin (Pec), carboxymethyl cellulose (CMC), and ZnO nanoparticles (ZnO) were used to prepare films by solution casting and 3D-printing methods. Field emission scanning electron microscopy (FE-SEM) was conducted to observe that the surface of samples made by 3D bioprinter was denser and more compact than the solution cast samples. In addition, Pec/CMC/ZnO made by 3D-bioprinter (Pec/CMC/ZnO-3D) revealed enhanced water vapor barrier, hydrophobicity, and mechanical properties. Pec/CMC/ZnO-3D also showed strong antimicrobial activity within 12 h against S. aureus and E. coli O157: H7 bacterial strains compared to the solution cast films. Further, the nanocomposite bio-inks used for 3D printing did not show cytotoxicity towards normal human dermal fibroblast (NDFB) cells but enhanced the fibroblast proliferation with increasing exposure concentration of the sample. The study provided two important inferences. Firstly, the 3D bioprinting method can be an alternative, better, and more practical method for fabricating biopolymer film instead of solution casting, which is the main finding of this work defining its novelty. Secondly, the Pec/CMC/ZnO can potentially be used as 3D bio-inks to fabricate functional films or scaffolds and biomedical applications.

Gelatin/agar-based multifunctional film integrated with copper-doped zinc oxide nanoparticles and clove essential oil Pickering emulsion for enhancing the shelf life of pork meat.

This work reports the fabrication of copper-modified zinc oxide nanoparticles (ZnO@Cu) added gelatin/agar-based multifunctional films loaded with clove essential oil Pickering emulsion (PEC). The ZnO@Cu particles were prepared using a simple precipitation method, and their successful synthesis was verified by X-ray Photoelectron Spectroscopy (XPS), X-ray Diffraction (XRD), and Field Emission Scanning Electron Microscopy (FESEM) analysis. The clove oil Pickering emulsion was developed using nanocellulose as a solid base. The addition of nanofillers (ZnO@Cu and PEC) improved the films' physical performance. The films' UV-shielding property was âˆ¼ 99% enhanced without a significant decrease in their transparency, and the incorporation of fillers also enhanced their mechanical properties. The gelatin/agar films also showed strong antimicrobial activity on ZnO@Cu and PEC addition, where a 100% eradication of L. monocytogenes and âˆ¼ 50% decrease in the E. coli population was detected. Further, the antioxidant activity of the functional films was twice the original value obtained for neat films due to the presence of PEC. The developed multifunctional film was applied to wrap the pork belly meat before vacuum packaging, which helped significantly reduce its total aerobic bacterial count and lipid oxidation. The multifunctional film could successfully improve the shelf life of wrapped meat.

Alginate-based multifunctional films incorporated with sulfur quantum dots for active packaging applications.

Sulfur quantum dots (SQDs) were fabricated using a facile hydrothermal method and used for the preparation of functional food packaging film and compared the properties with other sulfur-based fillers like elemental sulfur (ES) and sulfur nanoparticles (SNP). The SQDs have an average size of 5.3 nm and were very stable in aqueous suspension. Unlike other sulfur-based fillers, the SQD showed high antioxidant, antibacterial and antifungal activity, but no cytotoxicity was found for L929 mouse fibroblasts even after long-term exposure of 48 h. When sulfur-based fillers were added to the alginate film, SQD was more evenly dispersed in the polymer matrix than SNP and ES. The addition of SQD to the alginate film increased the film's UV barrier property by 82% and tensile strength by 18%. Also, the addition of SQDs to the films did not affect the stiffness (elastic modulus, EM) and water vapor barrier permeability (WVP) of the films. In addition, SQD-added films exhibited excellent antioxidant and strong antibacterial activity against bacterial (E. coli and L. monocytogenes) and fungal (A. niger and P. chrysogenum) food pathogens. When the film was applied as a bread packaging test, the SQD-added film prevented mold growth for 14 days, unlike the ES and SNP-added films.

Curcumin and its uses in active and smart food packaging applications - a comprehensive review.

Active and intelligent food packaging is an innovative technology to prevent food contamination and ensure food quality and safety. Active packaging protects the food from microbial contamination, while smart or intelligent packaging enables monitoring the freshness of the food or quality change in real-time. Curcumin, one of the most well-known natural colorants, has received a lot of attention for its excellent functional properties and ability to change color with changes in pH. Curcumin, the golden component of turmeric, a spice widely used in food since ancient times, is a cost-effective and abundant biomaterial with various biological properties such as antioxidant, antibacterial, antiviral, antitumor, and anti-inflammatory. Recently, active packaging or intelligent packaging systems have been actively developed using the functional properties of curcumin. In this review, we briefly reviewed curcumin's basic biological functions and discussed comprehensive and recent progress in using curcumin in various polymer-based active and smart food packaging applications.

Development of Multifunctional Pullulan/Chitosan-Based Composite Films Reinforced with ZnO Nanoparticles and Propolis for Meat Packaging Applications.

Pullulan/chitosan-based multifunctional edible composite films were fabricated by reinforcing mushroom-mediated zinc oxide nanoparticles (ZnONPs) and propolis. The ZnONPs were synthesized using enoki mushroom extract and characterized using physicochemical methods. The mushroom-mediated ZnONPs showed an irregular shape with an average size of 26.7 ± 8.9 nm. The combined incorporation of ZnONPs and propolis pointedly improved the composite film's UV-blocking property without losing transparency. The reinforcement with ZnONPs and propolis improved the mechanical strength of the pullulan/chitosan-based film by ~25%. Additionally, the water vapor barrier property and hydrophobicity of the film were slightly increased. In addition, the pullulan/chitosan-based biocomposite film exhibited good antioxidant activity due to the propolis and excellent antibacterial activity against foodborne pathogens due to the ZnONPs. The developed edible pullulan/chitosan-based film was used for pork belly packaging, and the peroxide value and total number of aerobic microorganisms were significantly reduced in meat wrapped with the pullulan/chitosan/ZnONPs/propolis film.

Silver ion loaded 3-aminopropyl trimethoxysilane -modified Fe3O4 nanoparticles for the fabrication of carrageenan-based active packaging films.

Fe3O4 nanoparticle loaded with silver ion was prepared as a more efficient, safer, and less environmentally hazardous silver-based antibacterial nanomaterial. The Fe3O4 nanoparticle was modified using 3-aminopropyl trimethoxysilane (APTMS) to enhance the silver ion adsorption capacity and antibacterial activity. Silver ions were adsorbed on pristine Fe3O4 and Fe3O4@NH2 to enhance antibacterial activity. Energy dispersive spectroscopy (EDS) results showed that Fe3O4 adsorbed 2.74 wt% of Ag, whereas Fe3O4@NH2 adsorbed 9.88 wt%. Pristine Fe3O4NP, silver ion loaded Fe3O4 (Fe3O4-Ag), and silver ion loaded Fe3O4@NH2 (Fe3O4@NH2-Ag) were used to manufacture carrageenan-based composite films. Compared with Fe3O4-Ag, Fe3O4@NH2-Ag exhibited stronger antimicrobial activity against E. coli (8.82 vs. 5.02 log reduction) and L. monocytogenes (10.09 vs. 3.93 log reduction). While the addition of Fe3O4 significantly reduced the WCA of the carrageenan films from 61.1 ± 5.4 ° to 37.2 ± 2.1 °, the additions of Fe3O4-Ag and Fe3O4@NH2-Ag reduced the WCA of the film to a lesser extent (56.9 ± 4.6 ° and 56.9 ± 4.6 °, respectively). Fe3O4NP also improved the thermal stability of carrageenan over Fe3O4@NH2-Ag (22 °C vs. 13 °C) and UV blocking properties (T280, 0.1 ± 0.0 % vs. 3.3 ± 1.5 %).

Pectin/pullulan blend films for food packaging: Effect of blending ratio.

Edible films were prepared using various pectin and pullulan mixing ratios and evaluated for their properties in food packaging applications. FTIR characterization showed that an intermolecular H-bond was formed between the hydroxyl group of pullulan and the carboxyl group of pectin. As observed by FE-SEM, as the pullulan content increased, the film's surface became smoother and formed a film with a denser structure, leading to an increased water vapor barrier. The blend film with a 50:50 ratio of pullulan and pectin exhibited the highest thermal stability and surface hydrophobicity. Blending also increased strength while maintaining flexibility and stiffness compared to the individual films. Besides, the films with ratios above 50:50 displayed the least water and oil absorption values.

pH-responsive color indicator films based on methylcellulose/chitosan nanofiber and barberry anthocyanins for real-time monitoring of meat freshness.

A new pH-responsive color indicator film was prepared by blending barberry anthocyanin (BA) with methylcellulose (MC)/chitosan nanofiber (ChNF) composite film. The addition of ChNF and BA increased the mechanical and water barrier properties but reduced the UV-vis light transmittance of the composite film. Anthocyanin showed proper compatibility with the composite film. The color indicator film showed an apparent color change in response to pH changes and ammonia gas, being suitable for indicating the change in food pH, the formation of volatile nitrogen compounds, and food decay. The color indicator film changed clearly from reddish-pink to pale peach and finally to yellow when exposed to different pH buffers. However, in response to ammonia vapor, the color changed from pink to pale green and yellow. Besides, the color indicator film exhibited remarkable antioxidant activity. Therefore, the pH-sensing color indicator film can be used as a smart indicator for real-time freshness monitoring of meat and seafood products.

Nanoporous Sodium Carboxymethyl Cellulose-g-poly (Sodium Acrylate)/FeCl3 Hydrogel Beads: Synthesis and Characterization.

Novel sodium carboxymethyl cellulose-g-poly (sodium acrylate)/Ferric chloride (CMC-g-PNaA/FeCl3) nanoporous hydrogel beads were prepared based on the ionic cross-linking between CMC-g-PNaA and FeCl3. The structure of CMC and CMC-g-PNaA were elucidated by Fourier transform infrared spectroscopy (FTIR) and nuclear magnetic resonance (NMR) spectroscopy, and the elemental composition was analyzed by energy dispersive X-ray analysis (EDX). The physicochemical properties of the CMC-g-PNaA/FeCl3 hydrogel beads were analyzed by X-ray diffraction (XRD), scanning electron microscopy (SEM), atomic force microscopy (AFM) and thermogravimetric analysis (TGA). The swelling percentage of hydrogel beads was studied at different time periods. The obtained CMC-g-PNaA/FeCl3 hydrogel beads exhibited a higher nanoporous morphology than those of CMC-g-PNaA and CMC beads. Furthermore, an AFM image of the CMC-g-PNaA/FeCl3 beads shows granule type topology. Compared to the CMC-g-PNaA (189 °C), CMC-g-PNaA/FeCl3 hydrogel beads exhibited improvement in thermal stability (199 °C). Furthermore, CMC-g-PNaA/FeCl3 hydrogel beads depicted a higher swelling percentage capacity of around 1452%, as compared to CMC-g-PNaA (1096%). Moreover, this strategy with preliminary results could be useful for the development of polysaccharide-based hybrid hydrogel beads for various potential applications.

Green and facile synthesis of carboxymethylcellulose/ZnO nanocomposite hydrogels crosslinked with Zn2+ ions.

A green method was used for the preparation of functional carboxymethyl cellulose (CMC) hydrogel crosslinked by divalent zinc ions and incorporated with zinc oxide nanoparticles (ZnO) without using alkaline reagents. In the process, sodium carboxymethyl cellulose was used not only as a hydrogel matrix but also for the release of free hydroxyl groups, which increases the pH of the reaction mixture, consequently leading to the formation of ZnO. The chemical structure and morphology of the hydrogels were characterized using FTIR and FE-SEM analysis, respectively. The water absorption capacity of the hydrogels was studied as a function of temperature and pH. The results of FE-SEM showed the formation of ZnO particles in the hydrogel, while the water absorption capacity results supported the formation of zinc ion cross-linking within the carboxymethylcellulose chains. The CMC/ZnO nanocomposite hydrogel exhibited strong antimicrobial activity against pathogenic bacteria E. coli and L. monocytogenes.

Redox responsive xylan-SS-curcumin prodrug nanoparticles for dual drug delivery in cancer therapy.

Chemotherapeutic agents with different anticancer mechanisms could enhance therapeutic effect in cancer therapy by their combined application. In this study, redox-sensitive prodrug nanoparticles based on Xyl-SS-Cur conjugate were developed for co-delivery of curcumin and 5-FU in cancer therapy. The Xyl-SS-Cur conjugate was synthesized via covalent conjugation of curcumin to xylan through a disulphide (-S-S-) linkage. The Xyl-SS-Cur conjugate could self-assemble in aqueous medium into nanoparticles and the lipophilic 5-fluorouracil-stearic acid (5-FUSA) prodrug was encapsulated into the hydrophobic core of Xyl-SS-Cur NPs through dialysis membrane method. The obtained Xyl-SS-Cur/5-FUSA NPs had an appropriate size (∼217 ±â€¯2.52 nm), high drug loading of curcumin (∼ 31.4 wt%) and 5-FUSA (∼ 11.8 wt%) and high stability. The interaction of Xyl-SS-Cur/5-FUSA NPs with blood components was investigated by hemolysis study. The cytotoxicity study demonstrated that Xyl-SS-Cur/5-FUSA NPs induced higher cytotoxicity than free drugs against the Human colorectal cancer cells (HT-29, HCT-15). These results indicate that Xyl-SS-Cur/5-FUSA NPs can serve as a promising drug delivery system in cancer therapy.