Chitosan-based nanocomposites as coatings and packaging materials for the postharvest improvement of agricultural product: A review

Visible light-responsive TiO2-based hybrid nanofiller reinforced multifunctional chitosan film for effective fruit preservation

In this study, we developed a multifunctional chitosan film with visible light-responsive photocatalytic properties by incorporating a novel nanofiller-a nanohybrid particle of poly(tannic acid) (PTA) and TiO2 (TP-NPs). Firstly, the hybridization of TiO2 with PTA not only improved its dispersion but also obtained TP-NPs with smaller band gaps (from 3.11 eV to 1.55 eV) and higher separation efficiency of photogenerated e--h+ (about 1.5-fold enhancement), thereby producing more reactive oxygen species and enhancing the antibacterial efficacy (compared with TiO2, the antibacterial effect of TP-NPs on Staphylococcus aureus and Escherichia coli was heightened by about 2 times under visible light for 1 h). Secondly, TP-NPs were hydrogen bonded with chitosan, strengthening its mechanical and barrier properties, while imparting exceptional antibacterial efficacy. Moreover, the multifunctional properties enabled the active film to effectively delay the quality deterioration of grapes and kiwifruit. Hence, this study presented a multifunctional active packaging film tailored for fruit preservation.

Application of chitosan in fruit preservation: A review

Fruit preservation after harvest is one of the key issues in current agriculture, rural areas, and for farmers. Using chitosan to keep fruits fresh, which can reduce the harm caused by chemical preservative residue to human health. It also helps avoid the disadvantages of the high cost of physical preservation and the challenges associated with difficult operation. This review focuses on the application progress of chitosan in fruit preservation. Studies have shown that chitosan inhibits the growth of bacteria and fungi, and delays fruit aging and decay. Furthermore, it can regulate the respiration and physiological metabolism of fruit, helping to maintain its quality and nutritional value. The preservation mechanism of chitosan includes its antibacterial properties, film-forming properties, and its effects on the physiological processes of fruit. However, in practical applications, issues such as determining the optimal concentration and treatment of chitosan still require further research and optimization.

Impact of Silver Nanoparticle Treatment and Chitosan on Packaging Paper's Barrier Effectiveness

In this study, a comparative analysis of silver nanoparticles treatment and chitosan coating on packaging paper barrier properties was carried out. In order to examine the water, grease, and antibacterial barrier properties of silver nanoparticle-treated and chitosan-coated laboratory-obtained paper samples, a mixture of bleached softwood and hardwood celluloses was used. In order to conduct the comparative analysis SEM, water contact angle, Cobb60, and Kit tests were carried out on a cellulose sample, and four paper samples (three of them treated with silver nanoparticles-1, 2, and 3 mL/20 cm2 or chitosan coated-0.5, 1, and 2 g/m2) together with the inhibition activity against nine Gram-positive and Gram-negative bacteria, yeast, and fungal strains. The study found out that increasing the silver nanoparticle treatment and chitosan coating led to improved water resistance, while grease resistance was improved only for chitosan coated paper samples. Additionally, paper treated with 3 mL/20 cm2 of silver nanoparticles had the highest antibacterial protection (81.6%) against the Gram-positive bacterium Staphylococcus aureus, followed by Gram-negative Escherichia coli (75.8%). For the rest of the studied microorganisms, the average efficiency of the treated paper was 40.79%. The treatment of the paper with 1 and 2 mL/20 cm2 of silver nanoparticles was less effective-27.13 and 39.83%, respectively. The antibacterial protection of 2 g/m2 chitosan-coated paper samples was the most effective (average 79%) against the tested bacterial, yeast, and fungal strains. At 1 and 0.5 g/m2 chitosan coatings, the efficiency was 72.38% and 54.67%, respectively. Gram-positive bacteria, yeasts, and fungal strains were more sensitive to chitosan supplementation.

Chitosan nanocomposites as a nano-bio tool in phytopathogen control

Chitosan, an economically viable and versatile biopolymer, exhibits a wide array of advantageous physicochemical and biological properties. Chitosan nanocomposites, formed by the amalgamation of chitosan or chitosan nanoparticles with other nanoparticles or materials, have garnered extensive attention across agricultural, pharmaceutical, and biomedical domains. These nanocomposites have been rigorously investigated due to their diverse applications, notably in combatting plant pathogens. Their remarkable efficacy against phytopathogens has positioned them as a promising alternative to conventional chemical-based methods in phytopathogen control, thus exploring interest in sustainable agricultural practices with reduced reliance on chemical interventions. This review aims to highlight the anti-phytopathogenic activity of chitosan nanocomposites, emphasizing their potential in mitigating plant diseases. Additionally, it explores various synthesis methods for chitosan nanoparticles to enhance readers' understanding. Furthermore, the analysis delves into elucidating the intricate mechanisms governing the antimicrobial effectiveness of these composites against bacterial and fungal phytopathogens.

Rhizopus stolonifer and related control strategies in postharvest fruit: A review

Rhizopus stolonifer is one of the main pathogens in postharvest storage logistics of more than 100 kinds of fruit, such as strawberries, tomatoes and melons. In this paper, the research on the morphology and detection, pathogenicity and infection mechanism of Rhizopus stolonifer was reviewed. The control methods of Rhizopus stolonifer in recent years was summarized from three dimensions of physics, chemistry and biology, including the nanomaterials, biological metabolites, light control bacteria, etc. Future direction of postharvest Rhizopus stolonifer infection control was analyzed from two aspects of pathogenic mechanism research and new composite technology. The information provided in this review will help researchers and technicians to deepen their understanding of the pathogenicity of Rhizopus stolonifer, and develop more effective control methods in the future.

Moisture loss inhibition with biopolymer films for preservation of fruits and vegetables: A review

In cold storage, fruits and vegetables still keep a low respiratory rate. Although cold storage is beneficial to maintain the quality of some fruits and vegetables, several factors (temperature and humidity fluctuations, heat inflow, air velocity, light, etc.) will accelerate moisture loss. Biopolymer films have attracted great attention for fruits and vegetables preservation because of their biodegradable and barrier properties. However, there is still a certain amount of water transfer occurring between storage environment/biopolymer films/fruits and vegetables (EFF). The effect of biopolymer films to inhibit moisture loss of fruits and vegetables and the water transfer mechanism in EFF system need to be studied systematically. Therefore, the moisture loss of fruits and vegetables, crucial properties, major components, fabrication methods, and formation mechanisms of biopolymer films were reviewed. Further, this study highlights the EFF system, responses of fruits and vegetables, and water transfer in EFF. This work aims to clarify the characteristics of EFF members, their influence on each other, and water transfer, which is conducive to improving the preservation efficiency of fruits and vegetables purposefully in future studies. In addition, the prospects of studies in EFF systems are shown.

Design of a delivery vehicle chitosan-based self-assembling: controlled release, high hydrophobicity, and safe treatment of plant fungal diseases

BACKGROUND

Traditional pesticides are poorly water-soluble and suffer from low bioavailability. N-succinyl chitosan (NSCS) is a water-soluble chitosan derivative, has been recently used to encapsulate hydrophobic drugs to improve their bioavailability. However, it remains challenging to synthesize pesticides of a wide variety of water-soluble drugs and to scale up the production in a continuous manner.

RESULTS

A synthetic method for preparing water-soluble nanopesticides with a polymer carrier was applied. The bioactive molecule BTL-11 was loaded into hollow NSCS to promote drug delivery, improve solubility and anti-fungal activity. The synthesized nanopesticides had well controlled sizes of 606 nm and the encapsulation rate was 80%. The release kinetics, drug toxicity and drug activity were further evaluated. The inhibitory activity of nanopesticides against Rhizoctonia solani (R. solani) was tested in vivo and in vitro. In vivo against R. solani trials revealed that BTL-11 has excellent control efficiency for cultivated rice leaf and sheath was 79.6 and 76.5%, respectively. By contrast, for BTL-11@NSCS NPs, the anti-fungal ability was strongly released and afforded significant control efficiencies of 85.9 and 81.1%. Those effects were significantly better than that of the agricultural fungicide azoxystrobin (51.5 and 66.5%). The proposed mechanism was validated by successfully predicting the synthesis outcomes.

CONCLUSIONS

This study demonstrates that NSCS is a promising biocompatible carrier, which can enhance the efficacy of pesticides, synergistically improve plant disease resistance, protect crop growth, and can be used for the delivery of more insoluble pesticides.

Nano/Micro-Structural Supramolecular Biopolymers: Innovative Networks with the Boundless Potential in Sustainable Agriculture

Sustainable agriculture plays a crucial role in meeting the growing global demand for food while minimizing adverse environmental impacts from the overuse of synthetic pesticides and conventional fertilizers. In this context, renewable biopolymers being more sustainable offer a viable solution to improve agricultural sustainability and production. Nano/micro-structural supramolecular biopolymers are among these innovative biopolymers that are much sought after for their unique features. These biomaterials have complex hierarchical structures, great stability, adjustable mechanical strength, stimuli-responsiveness, and self-healing attributes. Functional molecules may be added to their flexible structure, for enabling novel agricultural uses. This overview scrutinizes how nano/micro-structural supramolecular biopolymers may radically alter farming practices and solve lingering problems in agricultural sector namely improve agricultural production, soil health, and resource efficiency. Controlled bioactive ingredient released from biopolymers allows the tailored administration of agrochemicals, bioactive agents, and biostimulators as they enhance nutrient absorption, moisture retention, and root growth. Nano/micro-structural supramolecular biopolymers may protect crops by appending antimicrobials and biosensing entities while their eco-friendliness supports sustainable agriculture. Despite their potential, further studies are warranted to understand and optimize their usage in agricultural domain. This effort seeks to bridge the knowledge gap by investigating their applications, challenges, and future prospects in the agricultural sector. Through experimental investigations and theoretical modeling, this overview aims to provide valuable insights into the practical implementation and optimization of supramolecular biopolymers in sustainable agriculture, ultimately contributing to the development of innovative and eco-friendly solutions to enhance agricultural productivity while minimizing environmental impact.

A review of chitosan nanoparticles: Nature's gift for transforming agriculture through smart and effective delivery mechanisms

Chitosan nanoparticles (CNPs) have emerged as a promising tool in agricultural advancements due to their unique properties including, biocompatability, biodegradability, non-toxicity and remarkable versatility. These inherent properties along with their antimicrobial, antioxidant and eliciting activities enable CNPs to play an important role in increasing agricultural productivity, enhancing nutrient absorption and improving pest management strategies. Furthermore, the nano-formulation of chitosan have the ability to encapsulate various agricultural amendments, enabling the controlled release of pesticides, fertilizers, plant growth promoters and biocontrol agents, thus offering precise and targeted delivery mechanisms for enhanced efficiency. This review provides a comprehensive analysis of the latest research and developments in the use of CNPs for enhancing agricultural practices through smart and effective delivery mechanisms. It discusses the synthesis methods, physicochemical properties, and their role in enhancing seed germination and plant growth, crop protection against biotic and abiotic stresses, improving soil quality and reducing the environmental pollution and delivery of agricultural amendments. Furthermore, the potential environmental benefits and future directions for integrating CNPs into sustainable agricultural systems are explored. This review aims to shed light on the transformative potential of chitosan nanoparticles as nature's gift for revolutionizing agriculture and fostering eco-friendly farming practices.

Chitosan-encapsulated microbial biofertilizer: A breakthrough for enhanced tomato crop productivity

Encapsulation technology protects the beneficial microorganisms, which are the sources of Nitrogen (N), Phosphorus (P), and Potassium (K), with a carrier material and improves the nutrient uptake from the soil. Pseudomonas fluorescens, gram-negative bacteria, was selected as the microorganism for encapsulation. A chitosan carrier (3 %), a polysaccharide, was chosen for the encapsulation of the bacterial strain to use as biofertilizers by standardization with two carriers, sodium alginate and chitosan. P. fluorescens encapsulated with chitosan showed a higher shelf life than sodium alginate. The shelf life of the encapsulated culture (7 × 1010 CFU/mL) was maintained for ten months. Studies were performed with the encapsulated P. fluorescens to analyze its nature and characteristics. The pot and field studies were conducted with the encapsulated P. fluorescens for the tomato crop. The difference between the treated and control plants was observed based on biometric parameters like shoot length and root length, fruit weight, and number of branches and fruits per plant. This study reveals that encapsulated P. fluorescens improved the yield of the crops. In addition, soil health and fertility were also enhanced. Thus, encapsulated P. fluorescens could be a superior solution for promoting soil health and crop productivity for sustainable agriculture.

Advances in chitosan and chitosan derivatives for biomedical applications in tissue engineering: An updated review

In recent years, chitosan (CS) has received much attention as a functional biopolymer for various applications, especially in the biomedical field. It is a natural polysaccharide created by the chemical deacetylation of chitin (CT) that is nontoxic, biocompatible, and biodegradable. This natural polymer is difficult to process; however, chemical modification of the CS backbone allows improved use of functional derivatives. CS and its derivatives are used to prepare hydrogels, membranes, scaffolds, fibers, foams, and sponges, primarily for regenerative medicine. Tissue engineering (TE), currently one of the fastest-growing fields in the life sciences, primarily aims to restore or replace lost or damaged organs and tissues using supports that, combined with cells and biomolecules, generate new tissue. In this sense, the growing interest in the application of biomaterials based on CS and some of its derivatives is justifiable. This review aims to summarize the most important recent advances in developing biomaterials based on CS and its derivatives and to study their synthesis, characterization, and applications in the biomedical field, especially in the TE area.

Impacts of Selenium-Chitosan Treatment on Color of "Red Globe" Grapes during Low-Temperature Storage

Maintaining the vibrant color of fruit is a longstanding challenge in fruit and vegetable preservation. Chitosan and selenium, known for their protective and antioxidant properties, have been applied to preserve these produce. This study aimed to investigate the influence of selenium-chitosan treatment (comprising 25 mg L-1 selenium and 1.0% chitosan) on the color of "Red Globe" grapes and to analyze the relative expression of genes associated with anthocyanin synthesis enzymes (VvCHS, VvCHI, VvF3H, VvF3'H, VvF3'5'H, VvDFR, VvLDOX, VvUFGT, VvOMT, Vv5GT, and VvGST) using RT-qPCR. Our goal was to uncover the regulatory mechanisms governing grape color. Comparing various treatments, we observed that selenium-chitosan treatment had a significant effect in reducing decay, maintaining the soluble solids content of grape flesh, and preserving the vivid color of grape. This research indicated that selenium-chitosan treatment slowed down browning and prevented the reduction in total phenolic, flavonoids, and anthocyanin in the grape. Moreover, gene expression analysis revealed that selenium-chitosan treatment increased the expression of VvCHS, VvF3H, VvF'3'H, VvLDOX, and Vv5GT, while also stabilized the expression of VvCHI, VvF3'H, and VvDFR in grape skins. These findings shed light on the potential mechanism by which selenium-chitosan impacts grape color. This study established a theoretical foundation for investigating the molecular mechanisms behind selenium-chitosan's ability to slow down grape browning and provides a novel approach to enhancing fruit and vegetable preservation techniques.

Carvacrol Encapsulation in Chitosan-Carboxymethylcellulose-Alginate Nanocarriers for Postharvest Tomato Protection

Advancements in polymer science and nanotechnology hold significant potential for addressing the increasing demands of food security, by enhancing the shelf life, barrier properties, and nutritional quality of harvested fruits and vegetables. In this context, biopolymer-based delivery systems present themselves as a promising strategy for encapsulating bioactive compounds, improving their absorption, stability, and functionality. This study provides an exploration of the synthesis, characterization, and postharvest protection applications of nanocarriers formed through the complexation of chitosan oligomers, carboxymethylcellulose, and alginate in a 2:2:1 molar ratio. This complexation process was facilitated by methacrylic anhydride and sodium tripolyphosphate as cross-linking agents. Characterization techniques employed include transmission electron microscopy, energy-dispersive X-ray spectroscopy, infrared spectroscopy, thermal analysis, and X-ray powder diffraction. The resulting hollow nanospheres, characterized by a monodisperse distribution and a mean diameter of 114 nm, exhibited efficient encapsulation of carvacrol, with a loading capacity of approximately 20%. Their suitability for phytopathogen control was assessed in vitro against three phytopathogens-Botrytis cinerea, Penicillium expansum, and Colletotrichum coccodes-revealing minimum inhibitory concentrations ranging from 23.3 to 31.3 μg·mL-1. This indicates a higher activity compared to non-encapsulated conventional fungicides. In ex situ tests for tomato (cv. 'Daniela') protection, higher doses (50-100 μg·mL-1, depending on the pathogen) were necessary to achieve high protection. Nevertheless, these doses remained practical for real-world applicability. The advantages of safety, coupled with the potential for a multi-target mode of action, further enhance the appeal of these nanocarriers.

Advancing agriculture through bioresource technology: The role of cellulose-based biodegradable mulches

Agriculture plays a pivotal role in meeting the world's ever-growing food demands. However, traditional agricultural practices often have negative consequences for the environment, such as soil erosion and chemical runoff. Recently, there has been a pressing need for advance agricultural practices. Cellulose-based mulches offer a solution by optimizing agricultural productivity while minimizing harm. These mulches are made from renewable bioresources derived from cellulose-rich materials. Compared to plastic mulches, cellulose-based alternatives show potential in improving nutrient retention, soil health, weed suppression, water conservation, and erosion mitigation. The article investigates the characteristics and application methods of cellulose-based mulches, highlighting their biodegradability, water retention, crop protection, and weed suppression capabilities. It also evaluates their economic feasibility, emphasizing their potential to transform sustainable farming practices. Overall, cellulose-based mulches have the potential to revolutionize agriculture, addressing environmental concerns while optimizing productivity. They represent a significant step toward a more sustainable and resilient agricultural system.

Effect of Combined Chitosan and Hyperbranched Poly-L-Lysine Based Coating on Prolonging the Shelf Life of Oyster Mushroom (Pleurotus ostreatus)

To extend the shelf life of oyster mushroom (Pleurotus ostreatus), the effects of chitosan (CS) and hyperbranched poly-L-lysine (HBPL) combined treatment on quality characteristics, nutritional quality, storage characteristics, and enzyme activity of oyster mushroom during postharvest storage at 4 °C were investigated. The results showed that CS-HBPL combined treatment could significantly reduce rot degree and weight loss and significantly inhibit the browning of oyster mushroom. At the same time, the loss of reducing sugar, vitamin C, soluble protein, and total phenolic was significantly reduced. Compared with the control, CS-HBPL combined treatment could also significantly inhibit an increase in malondialdehyde (MDA) and significantly decrease the relative electrolyte leakage of oyster mushroom. In addition, the activities of catalase (CAT), superoxide dismutase (SOD), phenylalnine ammonialyase (PAL), and peroxidase (POD) were significantly improved, and the activity of polyphenol oxidase (PPO) was significantly inhibited in oyster mushroom. In conclusion, CS-HBPL combined treatment had a good protective effect on the membrane permeability damage of oyster mushroom and could effectively delay the oxidation of phenolic substances and browning of oyster mushroom. Therefore, CS-HBPL combined treatment can be used as a potential strategy to extend the storage time of oyster mushroom.

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.

The antioxidant activity of polysaccharides: A structure-function relationship overview

Over the last years, polysaccharides have been linked to antioxidant effects using both in vitro chemical and biological models. The reported structures, claimed to act as antioxidants, comprise chitosan, pectic polysaccharides, glucans, mannoproteins, alginates, fucoidans, and many others of all type of biological sources. The structural features linked to the antioxidant action include the polysaccharide charge, molecular weight, and the occurrence of non-carbohydrate substituents. The establishment of structure/function relationships can be, however, biased by secondary phenomena that tailor polysaccharides behavior in antioxidant systems. In this sense, this review confronts some basic concepts of polysaccharides chemistry with the current claim of carbohydrates as antioxidants. It critically discusses how the fine structure and properties of polysaccharides can define polysaccharides as antioxidants. Polysaccharides antioxidant action is highly dependent on their solubility, sugar ring structure, molecular weight, occurrence of positive or negatively charged groups, protein moieties and covalently linked phenolic compounds. However, the occurrence of phenolic compounds and protein as contaminants leads to misleading results in methodologies often used for screening and characterization purposes, as well as in vivo models. Despite falling in the concept of antioxidants, the role of polysaccharides must be well defined according with the matrices where they are involved.

Selenium nanoparticles based on Amphipterygium glaucum extract with antibacterial, antioxidant, and plant biostimulant properties

BACKGROUND

In recent years, crop production has expanded due to the variety of commercially available species. This increase in production has led to global competition and the search for biostimulant products that improve crop quality and yield. At the same time, agricultural products that protect against diseases caused by phytopathogenic microorganisms are needed. Thus, the green synthesis of selenium nanoparticles (SeNPs) is a proposal for achieving these needs. In this research, SeNPs were synthesized from methanolic extract of Amphipterygium glaucum leaves, and chemically and biologically characterized.

RESULTS

The characterization of SeNPs was conducted by ultraviolet-visible spectrophotometry (UV-Vis), scanning electron microscopy (SEM), electron microscopy transmission (TEM), Dynamic Light Scattering (DLS), energy dispersion X-ray spectroscopy (EDX), and infrared spectrophotometry (FTIR) techniques. SeNPs with an average size of 40-60 nm and spherical and needle-shaped morphologies were obtained. The antibacterial activity of SeNPs against Serratia marcescens, Enterobacter cloacae, and Alcaligenes faecalis was evaluated. The results indicate that the methanolic extracts of A. glaucum and SeNPs presented a high antioxidant activity. The biostimulant effect of SeNPs (10, 20, 50, and 100 µM) was evaluated in vinca (Catharanthus roseus), and calendula (Calendula officinalis) plants under greenhouse conditions, and they improved growth parameters such as the height, the fresh and dry weight of roots, stems, and leaves; and the number of flowers of vinca and calendula.

CONCLUSIONS

The antibacterial, antioxidant, and biostimulant properties of SeNPs synthesized from A. glaucum extract demonstrated in this study support their use as a promising tool in crop production.

Plant-Based Nano-Emulsions as Edible Coatings in the Extension of Fruits and Vegetables Shelf Life: A Patent Review

Fresh fruits and vegetables are important sources of minerals, vitamins, fibers, and antioxidants, essential for human well-being. However, some fruits and vegetables are highly perishable with a very short shelf life during storage. Serious consumer concern over the use of chemical preservatives for this purpose has led to a green revolution and a sustainable era where the design and fabrication of edible coatings have attracted considerable interest. In recent years, scientific communities have paid great attention to the development of bio-based edible coatings to extend the postharvest shelf life of fruits and vegetables. Furthermore, nanotechnology has been distinguished as a great strategy for improving coating properties, including a better water barrier and better mechanical, optical, and microstructural properties, as well as gradual and controlled release of bioactive compounds. In this work, patent articles on plant-based nano-emulsions as edible coatings in the extension of fruit and vegetable shelf life were reviewed. The Patentscope search service and Espacenet portal were used, applying a query strategy composed of mesh terms and inclusion criteria. Through database searching, a total of 16 patent documents met the inclusion criteria. Further, to demonstrate the innovation trends in this topic, all relevant patents are described at the end of the study, along with the components, technology, application, and advantages of developed preparations.

Chitosan-Based Antibacterial Films for Biomedical and Food Applications

Antibacterial chitosan films, versatile and eco-friendly materials, have garnered significant attention in both the food industry and medicine due to their unique properties, including biodegradability, biocompatibility, and antimicrobial activity. This review delves into the various types of chitosan films and their distinct applications. The categories of films discussed span from pure chitosan films to those enhanced with additives such as metal nanoparticles, metal oxide nanoparticles, graphene, fullerene and its derivatives, and plant extracts. Each type of film is examined in terms of its synthesis methods and unique properties, establishing a clear understanding of its potential utility. In the food industry, these films have shown promise in extending shelf life and maintaining food quality. In the medical field, they have been utilized for wound dressings, drug delivery systems, and as antibacterial coatings for medical devices. The review further suggests that the incorporation of different additives can significantly enhance the antibacterial properties of chitosan films. While the potential of antibacterial chitosan films is vast, the review underscores the need for future research focused on optimizing synthesis methods, understanding structure-property relationships, and rigorous evaluation of safety, biocompatibility, and long-term stability in real-world applications.

Facile Synthesis and Characterization of Chitosan Functionalized Silver Nanoparticles for Antibacterial and Anti-Lung Cancer Applications

In the treatment of bacterial contamination, the problem of multi-drug resistance is becoming an increasingly pressing concern. Nanotechnology advancements enable the preparation of metal nanoparticles that can be assembled into complex systems to control bacterial and tumor cell growth. The current work investigates the green production of chitosan functionalized silver nanoparticles (CS/Ag NPs) using Sida acuta and their inhibition efficacy against bacterial pathogens and lung cancer cells (A549). Initially, a brown color formation confirmed the synthesis, and the chemical nature of the synthesized NPs were examined by UV-vis spectroscopy, Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) coupled with energy dispersive spectroscopy (EDS), and transmission electron microscopy (TEM). FTIR demonstrated the occurrence of CS and S. acuta functional groups in the synthesized CS/Ag NPs. The electron microscopy study exhibited CS/Ag NPs with a spherical morphology and size ranges of 6-45 nm, while XRD analysis demonstrated the crystallinity of Ag NPs. Further, the bacterial inhibition property of CS/Ag NPs was examined against K. pneumoniae and S. aureus, which showed clear inhibition zones at different concentrations. In addition, the antibacterial properties were further confirmed by a fluorescent AO/EtBr staining technique. Furthermore, prepared CS/Ag NPs exhibited a potential anti-cancer character against a human lung cancer cell line (A549). In conclusion, our findings revealed that the produced CS/Ag NPs could be used as an excellent inhibitory material in industrial and clinical sectors.

Mechanism of Heterogeneous Alkaline Deacetylation of Chitin: A Review

This review provides an analysis of experimental results on the study of alkaline heterogeneous deacetylation of chitin obtained by the authors and also published in the literature. A detailed analysis of the reaction kinetics was carried out considering the influence of numerous factors: reaction reversibility, crystallinity and porosity of chitin, changes in chitin morphology during washing, alkali concentration, diffusion of hydroxide ions, and hydration of reacting particles. A mechanism for the chitin deacetylation reaction is proposed, taking into account its kinetic features in which the decisive role is assigned to the effects of hydration. It has been shown that the rate of chitin deacetylation increases with a decrease in the degree of hydration of hydroxide ions in a concentrated alkali solution. When the alkali concentration is less than the limit of complete hydration, the reaction practically does not occur. Hypotheses have been put forward to explain the decrease in the rate of the reaction in the second flat portion of the kinetic curve. The first hypothesis is the formation of “free” water, leading to the hydration of chitin molecules and a decrease in the reaction rate. The second hypothesis postulates the formation of a stable amide anion of chitosan, which prevents the nucleophilic attack of the chitin macromolecule by hydroxide ions.

Processing, Characterization and Disintegration Properties of Biopolymers Based on Mater-Bi® and Ellagic Acid/Chitosan Coating

Among the most promising synthetic biopolymers to replace conventional plastics in numerous applications is MaterBi^® (MB), a commercial biodegradable polymer based on modified starch and synthetic polymers. Actually, MB has important commercial applications as it shows interesting mechanical properties, thermal stability, processability and biodegradability. On the other hand, research has also focused on the incorporation of natural, efficient and low-cost active compounds into various materials with the aim of incorporating antimicrobial and/or antioxidant capacities into matrix polymers to extend the shelf life of foods. Among these is ellagic acid (EA), a polyphenolic compound abundant in some fruits, nuts and seeds, but also in agroforestry and industrial residues, which seems to be a promising biomolecule with interesting biological activities, including antioxidant activity, antibacterial activity and UV-barrier properties. The objective of this research is to develop a film based on commercial biopolymer Mater-Bi^® (MB) EF51L, incorporating active coating from chitosan with a natural active compound (EA) at two concentrations (2.5 and 5 wt.%). The formulations obtained complete characterization and were carried out in order to evaluate whether the incorporation of the coating significantly affects thermal, mechanical, structural, water-vapor barrier and disintegration properties. From the results, FTIR analysis yielded identification, through characteristic peaks, that the type of MB used is constituted by three polymers, namely PLA, TPS and PBAT. With respect to the mechanical properties, the values of tensile modulus and tensile strength of the MB-CHI film were between 15 and 23% lower than the values obtained for the MB film. The addition of 2.5 wt.% EA to the CHI layer did not generate changes in the mechanical properties of the system, whereas a 5 wt.% increase in ellagic acid improved the mechanical properties of the CHI film through the addition of natural phenolic compounds at high concentrations. Finally, the disintegration process was mainly affected by the PBAT biopolymer, causing the material to not disintegrate within the times indicated by ISO 20200.

Postharvest Biology and Technology of Loquat (Eriobotrya japonica Lindl.)

Loquat (Eriobotrya japonica Lindl.) fruit is a rich source of carotenoids, flavonoids, phenolics, sugars, and organic acids. Although it is classified as a non-climacteric fruit, susceptibility to mechanical and physical bruising causes its rapid deterioration by moisture loss and postharvest decay caused by pathogens. Anthracnose, canker, and purple spot are the most prevalent postharvest diseases of loquat fruit. Cold storage has been used for quality management of loquat fruit, but the susceptibility of some cultivars to chilling injury (CI) consequently leads to browning and other disorders. Various techniques, including cold storage, controlled atmosphere storage, hypobaric storage, modified atmosphere packaging, low-temperature conditioning, heat treatment, edible coatings, and postharvest chemical application, have been tested to extend shelf life, mitigate chilling injury, and quality preservation. This review comprehensively focuses on the recent advances in the postharvest physiology and technology of loquat fruit, such as harvest maturity, fruit ripening physiology, postharvest storage techniques, and physiological disorders and diseases.