Chitin/Chitosan — Safe, Ecofriendly Packaging Materials with Multiple Potential Uses

PEG-crosslinked O-carboxymethyl chitosan films with degradability and antibacterial activity for food packaging

This study developed a kind of PEG-crosslinked O-carboxymethyl chitosan (O-CMC-PEG) with various PEG content for food packaging. The crosslinking agent of isocyanate-terminated PEG was firstly synthesized by a simple condensation reaction between PEG and excess diisocyanate, then the crosslink between O-carboxymethyl chitosan (O-CMC) and crosslinking agent occurred under mild conditions to produce O-CMC-PEG with a crosslinked structure linked by urea bonds. FT-IR and 1H NMR techniques were utilized to confirm the chemical structures of the crosslinking agent and O-CMC-PEGs. Extensive research was conducted to investigate the impact of the PEG content (or crosslinking degree) on the physicochemical characteristics of the casted O-CMC-PEG films. The results illuminated that crosslinking and components compatibility could improve their tensile features and water vapor barrier performance, while high PEG content played the inverse effects due to the microphase separation between PEG and O-CMC segments. The in vitro degradation rate and water sensitivity primarily depended on the crosslinking degree in comparison with the PEG content. Furthermore, caused by the remaining -NH2 groups of O-CMC, the films demonstrated antibacterial activity against Escherichia coli and Staphylococcus aureus. When the PEG content was 6% (medium crosslinking degree), the prepared O-CMC-PEG-6% film possessed optimal tensile features, high water resistance, appropriate degradation rate, low water vapor transmission rate and fine broad-spectrum antibacterial capacity, manifesting a great potential for application in food packaging to extend the shelf life.

Chitin-induced disease resistance in plants: A review

Chitin is composed of N-acetylglucosamine units. Chitin a polysaccharide found in the cell walls of fungi and exoskeletons of insects and crustaceans, can elicit a potent defense response in plants. Through the activation of defense genes, stimulation of defensive compound production, and reinforcement of physical barriers, chitin enhances the plant's ability to defend against pathogens. Chitin-based treatments have shown efficacy against various plant diseases caused by fungal, bacterial, viral, and nematode pathogens, and have been integrated into sustainable agricultural practices. Furthermore, chitin treatments have demonstrated additional benefits, such as promoting plant growth and improving tolerance to abiotic stresses. Further research is necessary to optimize treatment parameters, explore chitin derivatives, and conduct long-term field studies. Continued efforts in these areas will contribute to the development of innovative and sustainable strategies for disease management in agriculture, ultimately leading to improved crop productivity and reduced reliance on chemical pesticides.

Review on emerging trends and challenges in the modification of xanthan gum for various applications

This review explores the realm of structural modifications and broad spectrum of their potential applications, with a special focus on the synthesis of xanthan gum derivatives through graft copolymerization methods. It delves into the creation of these derivatives by attaching functional groups (-OH and -COOH) to xanthan gum, utilizing a variety of initiators for grafting, and examining their diverse applications, especially in the areas of food packaging, pharmaceuticals, wastewater treatment, and antimicrobial activities. Xanthan gum is a biocompatible, biodegradable, less toxic, bioactive, and cost-effective natural polymer derived from Xanthomonas species. The native properties of xanthan gum can be improved by cross-linking, grafting, curing, blending, and various modification techniques. Grafted xanthan gum has excellent biodegradability, metal binding, dye adsorption, immunological properties, and wound healing ability. Owing to its remarkable properties, such as biocompatibility and its ability to form gels resembling the extracellular matrix of tissues, modified xanthan gum finds extensive utility across biomedicine, engineering, and the food industry. Furthermore, the review also covers various modified derivatives of xanthan gum that exhibit excellent biodegradability, metal binding, dye adsorption, immunological properties, and wound healing abilities. These applications could serve as important resources for a wide range of industries in future product development.

Enhanced antimicrobial and antioxidant properties of Nano chitosan and pectin based biodegradable active packaging films incorporated with fennel (Foeniculum vulgare) essential oil and potato (Solanum tuberosum) peel extracts

Active packaging materials are generally prepared by incorporating antimicrobial agents. The main objective of the present research is the development and characterization of active packaging with Nano chitosan and pectin. Active packaging film was prepared by incorporating essential oil of Fennel (EOF) along with potato peel extract (PPE) to improve the antioxidant and antimicrobial property of the film. Incorporation of EOF into Nano chitosan and pectin-based films increased antimicrobial activity, whereas; PPE increased the antioxidant property of the films. In the present study, thickness, optical property, mechanical property, antioxidant and antimicrobial property, total soluble matter, morphological study, FTIR analysis, and microbial degradation study of the prepared active packaging material was done. The addition of the PPE and EOF together improved the surface, optical, mechanical, antimicrobial and antioxidant properties of the packaging film. Enhanced antimicrobial and antioxidant property of the Nano chitosan-PPE-PVA-EOF and pectin-PPE-PVA-EOF-based packaging films can extend the shelf life of the packed food; hence it is suggested for the active packaging for perishable food commodity. In short, the prepared active packaging film with biodegradable property is suggested as an effective packaging material to replace synthetic plastic packages for food and hence reduce plastic pollution.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13197-021-05333-9.

Supramolecular Binding with Lectins: A New Route for Non-Covalent Functionalization of Polysaccharide Matrices

The chemical functionalization of polysaccharides to obtain functional materials has been of great interest in the last decades. This traditional synthetic approach has drawbacks, such as changing the crystallinity of the material or altering its morphology or texture. These modifications are crucial when a biogenic matrix is exploited for its hierarchical structure. In this work, the use of lectins and carbohydrate-binding proteins as supramolecular linkers for polysaccharide functionalization is proposed. As proof of concept, a deproteinized squid pen, a hierarchically-organized β-chitin matrix, was functionalized using a dye (FITC) labeled lectin; the lectin used was the wheat germ agglutinin (WGA). It has been observed that the binding of this functionalized protein homogenously introduces a new property (fluorescence) into the β-chitin matrix without altering its crystallographic and hierarchical structure. The supramolecular functionalization of polysaccharides with protein/lectin molecules opens up new routes for the chemical modification of polysaccharides. This novel approach can be of interest in various scientific fields, overcoming the synthetic limits that have hitherto hindered the technological exploitation of polysaccharides-based materials.

Plastic Waste Management in India: Challenges, Opportunities, and Roadmap for Circular Economy

Plastic waste (PW) is one of the most rapid-growing waste streams in municipal solid waste all over the world. India has become a global player in the plastic value chain. Despite low consumption, domestic generation and imports create a significant burden on the overall waste management system, which requires in-depth understanding of the scenario and pathways that can mitigate the crisis. Although Indian researchers have widely researched technology-related issues in academic papers, a substantial knowledge gap exists in understanding the problem’s depth and possible solutions. This review article focuses on current plastic production, consumption, and waste generation in India. This review article mainly analyzes data and information regarding Indian PW management and highlights some critical issues such as reverse supply chain, effective PW management, source-specific recovery, and PW rules in India. Comprehensively, this review will help to identify implementable strategies for policymakers and research opportunities for future researchers in holistic PW management and recycling in India, focusing on the circular economy and sustainable development goals.

Crystalline polysaccharides: A review

The biodegradability and mechanical properties of polysaccharides are dependent on their architecture (linear or branched) as well as their crystallinity (size of crystals and crystallinity percent). The amount of crystalline zones in the polysaccharide significantly governs their ultimate properties and applications (from packaging to biomedicine). Although synthesis, characterization, and properties of polysaccharides have been the subject of several review papers, the effects of crystallization kinetics and crystalline domains on the properties and application have not been comprehensively addressed. This review places focus on different aspects of crystallization of polysaccharides as well as applications of crystalline polysaccharides. Crystallization of cellulose, chitin, chitosan, and starch, as the main members of this family, were discussed. Then, application of the aforementioned crystalline polysaccharides and nano-polysaccharides as well as their physical and chemical interactions were overviewed. This review attempts to provide a complete picture of crystallization-property relationship in polysaccharides.

Environmental impact of bioplastic use: A review

Throughout their lifecycle, petroleum-based plastics are associated with many environmental problems, including greenhouse gas emissions, persistence in marine and terrestrial environments, pollution, etc. On the other hand, bioplastics form a rapidly growing class of polymeric materials that are commonly presented as alternatives to conventional petroleum-based plastics. However, bioplastics also have been linked to important environmental issues such as greenhouse gas emissions and unfavorable land use change, making it necessary to evaluate the true impact of bioplastic use on the environment. Still, while many reviews discuss bioplastics, few comprehensively and simultaneously address the positives and negatives of bioplastic use for the environment. The primary focus of the present review article is to address this gap in present research. To this end, this review addresses the following questions: (1) what are the different types of bioplastics that are currently in commercial use or under development in the industry; (2) are bioplastics truly good for the environment; and (3) how can we better resolve the controversial impact of bioplastics on the environment? Overall, studies discussed in this review article show that the harms associated with bioplastics are less severe as compared to conventional plastics. Moreover, as new types of bioplastics are developed, it becomes important that future studies conduct thorough life cycle and land use change analyses to confirm the eco-friendliness of these new materials. Such studies will help policymakers to determine whether the use of new-generation bioplastics is indeed beneficial to the environment.

Advances in bio food packaging - An overview

In recent years, there has been an increase in demand for bioactive techniques in the food packaging industry. Although edible packaging is popular, it has yet to be effectively implemented into the market. Packaging made of plastics and chemicals is widely employed in the market today, posing a threat to the environment and living creatures. This research attempts to show current breakthroughs and progress in the field of biodegradable packaging. When compared to ancient packaging materials, bio-based packaging materials are safer. Sustainable biodegradable packaging materials can be made from edible films, coatings, and other bio food packaging techniques made from various biological resources. This paper discusses the important qualities and advantages of several bio-based packing materials. It is highlighted the advantages of bio-based packaging materials over synthetic packaging materials. It has been debated the importance of employing bio-based packaging to mitigate the environmental risks associated with traditional packaging technologies. Many researchers may be prompted by this study to focus on packaging reformulation options. Thus, we can attain food packing materials by considering customer's economic and sustainability aspects.

A comprehensive review on the applications of functionalized chitosan in petroleum industry

The biomaterials have gained the attention for utilization as sustainable alternatives for petroleum-derived products due to the rapid depletion of petroleum resources and environmental issues. Chitosan is an economical, renewable and abundant polysaccharide having unique molecular characteristics. Chitosan is derived by deacetylation of chitin, a natural polysaccharide existing in insects' exoskeleton, outer shells of crustaceans, and some fungi cell walls. Chitosan is widely used in numerous domains like agriculture, food, water treatment, medicine, cosmetics, fisheries, packaging, and chemical industry. This review aims to account for all the efforts made towards chitosan and its derivatives for utilization in the petroleum industry and related processes including exploration, extraction, refining, transporting oil spillages, and wastewater treatment. This review includes a compilation of various chemical modifications of chitosan to enhance the petroleum field's performance and applicability.

Prospects of Polymeric Nanofibers Loaded with Essential Oils for Biomedical and Food-Packaging Applications

Essential oils prevent superbug formation, which is mainly caused by the continuous use of synthetic drugs. This is a significant threat to health, the environment, and food safety. Plant extracts in the form of essential oils are good enough to destroy pests and fight bacterial infections in animals and humans. In this review article, different essential oils containing polymeric nanofibers fabricated by electrospinning are reviewed. These nanofibers containing essential oils have shown applications in biomedical applications and as food-packaging materials. This approach of delivering essential oils in nanoformulations has attracted considerable attention in the scientific community due to its low price, a considerable ratio of surface area to volume, versatility, and high yield. It is observed that the resulting nanofibers possess antimicrobial, anti-inflammatory, and antioxidant properties. Therefore, they can reduce the use of toxic synthetic drugs that are utilized in the cosmetics, medicine, and food industries. These nanofibers increase barrier properties against light, oxygen, and heat, thereby protecting and preserving the food from oxidative damage. Moreover, the nanofibers discussed are introduced with naturally derived chemical compounds in a controlled manner, which simultaneously prevents their degradation. The nanofibers loaded with different essential oils demonstrate an ability to increase the shelf-life of various food products while using them as active packaging materials.

A comparative study on the raw chitin and chitosan yields of common bio-waste from Philippine seafood

Bio-waste materials from aquatic species are alternative sources of chitin and chitosan-high-value natural biodegradable and biocompatible polymers. More than 250,000 metric tons of shell, scale, and carapace waste are produced in the Philippines. An evaluation of the quality of raw chitin and chitosan yields from the bio-waste materials of Asian green mussel (Perna viridis), tropical oyster (Crassostrea iredalei), milkfish (Chanos chanos), tilapia (Oreochromis niloticus), and king mangrove crab (Scylla serrata) is needed for the sustainable sourcing. The mild extraction method done in this study showed significantly higher yields of chitin and chitosan for S. serrata and P. viridis (p = 0.001), with chemical structure confirmed through FTIR-ATR analysis. Elemental analysis showed pure extracts from S. serrata, P. viridis, and C. iredalei (N = 6.43-7.01%; DA = 98.7-104.1%). Extracts from the fish scales have high moisture content and glycoprotein contamination. Protein content, determined using UV-VIS spectrophotometry, was found to be significantly less in P. viridis and may be related to the fineness of particle size after grinding. It is recommended to improve the protocol to increase yield across all bio-waste materials, including additional tests to determine the quality of chitin and chitosan extracted, and to check water and oil holding capacities of the extracts to identify the best downstream applications of the varied chitin and chitosan qualities from each source.

A review on the synthesis of graft copolymers of chitosan and their potential applications

Chitosan is an antimicrobial, biodegradable and biocompatible natural polymer, commercially derived from the partial deacetylation of chitin. Currently modified chitosan has occupied a major part of scientific research. Modified chitosan has excellent biotic characteristics like biodegradation, antibacterial, immunological, metal-binding and metal adsorption capacity and wound-healing ability. Chitosan is an excellent candidate for drug delivery, food packaging and wastewater treatment and is also used as a supporting object for cell culture, gene delivery and tissue engineering. Modification of pure chitosan via grafting improves the native properties of chitosan. Chitosan grafted copolymers exhibit high significance and are extensively used in numerous fields. In this review, modifications of chitosan through several graft copolymerization techniques such as free radical, radiation, and enzymatic were reported and the properties of grafted chitosan were discussed. This review also discussed the applications of grafted chitosan in the fields of drug delivery, food packaging, antimicrobial, and metal adsorption as well as dye removal.

Xylan-Derived Light Conversion Nanocomposite Film

A new type of sustainable light conversion nanocomposite film was fabricated by using carboxymethyl xylan as matrix and xylan-derived carbon dots (CDs) as both light conversion regents and nano reinforcements. The results demonstrate that CDs can not only significantly enhance the mechanical strength of the nanocomposite film because of chemical reaction between CDs and carboxymethyl xylan, but also impart the film with excellent optical properties. With 1.92 wt% CDs, the tensile strength and elastic modulus of the film are increased by 114.3% and 90.7%, respectively. Moreover, the film has typical excitation and emission spectra, enabling the efficient absorption of UV and the conversion of UV to blue light. This xylan-derived light conversion nanocomposite film is expected to be used in agricultural planting and food packaging.

Simultaneous deacetylation and degradation of chitin hydrogel by electrical discharge plasma using low sodium hydroxide concentrations

Electrical discharge plasma occurring in a liquid phase, so called solution plasma, can generate highly active species, e.g. free radicals, which can involve in various chemical reactions, leading to less chemical uses. In this study, solution plasma was applied to deacetylation of chitin aiming to reduce the use of alkali. It was found that solution plasma could induce deacetylation of chitin hydrogels that were dispersed in MeOH/water solutions containing low NaOH concentrations (1-12%). Due to the action of free radicals, some extent of chain session of the polymer occurred during the plasma treatment. The degree of deacetylation and molecular weight of the obtained chitosan were 78% and 220 kDa, respectively, after the plasma treatment for five cycles (1 h/cycle) by using 90% MeOH/water solution containing 12% NaOH. The obtained chitosan could completely dissolve in 2% acetic acid solution and had antibacterial activities against S. aureus and E. coli.

Polysaccharide-based component and their relevance in edible film/coating: a review

Purpose

The purpose of this paper is to present an overview of functional properties of the polysaccharide-based component and their application in developing edible film and coating for the food processing sector.

Design/methodology/approach

In this review study, approximately 271 research and review articles focusing on studies related to polysaccharide-based components and their film-forming properties. This article also focused on the application of polysaccharide-based edible film in the food sector.

Findings

From the literature reviewed, polysaccharide components and components-based edible film/coating is the biodegradable and eco-friendly packaging of the materials and directly consumed by the consumer with food. It has been reported that the polysaccharide components have excellent properties such as being nontoxic, antioxidant, antimicrobial, antifungal and with good nutrients. The polysaccharide-based edible film has lipid and gas barrier properties with excellent transparency and mechanical strength. In various studies, researchers worked on the development of polysaccharide-based edible film and coating by incorporating plant based natural antioxidants. This was primarily done for obtaining improved physical and chemical properties of the edible film and coating. In future, the technology of developing polysaccharide-based edible film and coating could be used for extending the shelf life and preserving the quality of fruits and vegetables at a commercial level. There is more need to understand the role of edible packaging and sustainability in the food and environment sector.

Originality/value

Through this review paper, possible applications of polysaccharide-based components and their function property in the formation of the edible film and their effect on fruits, vegetables and other food products are discussed after detailed studies of literature from thesis and journal article.

Structural, Physical, and Antifungal Characterization of Starch Edible Films Added with Nanocomposites and Mexican Oregano (Lippia berlandieri Schauer) Essential Oil

The aim of this study was to evaluate the structural, physical, and antifungal characteristics of starch edible films added with nanocomposites and Mexican oregano (Lippia berlandieri Schauer) essential oil (EO). Starch edible films were formulated with Mexican oregano EO (0%, 1%, or 2% v/v) and bentonite or halloysite (2%). Physical properties such as L* (luminosity), hue, film thickness, and O₂ and CO₂ permeability were determined. Structural analysis was carried out via atomic force microscopy (AFM). Antifungal activity against Aspergillus niger, Fusarium spp., and Rhizopus spp. was evaluated. The addition of EO and nanocomposites reduced luminosity, providing color to the edible films. Film thickness increased through the addition of EO concentration. O₂ and CO₂ permeability was increased by bentonite/EO films, and for halloysite films, CO₂ permeability decreased as EO concentration increased. The addition of EO with both nanocomposites shows an evident morphological change in film structure, decreasing pore density and increasing pore size. In general, Mexican oregano EO added to edible starch films has an adequate fungicidal effect. The most sensitive microorganism tested was A. niger. Edible films added with Mexican oregano EO and nanocomposites show better physical and antifungal properties due to an adequate structural change in the biopolymer matrix.

Bio- and Fossil-Based Polymeric Blends and Nanocomposites for Packaging: Structure⁻Property Relationship

In the present review, the possibilities for blending of commodities and bio-based and/or biodegradable polymers for packaging purposes has been considered, limiting the analysis to this class of materials without considering blends where both components have a bio-based composition or origin. The production of blends with synthetic polymeric materials is among the strategies to modulate the main characteristics of biodegradable polymeric materials, altering disintegrability rates and decreasing the final cost of different products. Special emphasis has been given to blends functional behavior in the frame of packaging application (compostability, gas/water/light barrier properties, migration, antioxidant performance). In addition, to better analyze the presence of nanosized ingredients on the overall behavior of a nanocomposite system composed of synthetic polymers, combined with biodegradable and/or bio-based plastics, the nature and effect of the inclusion of bio-based nanofillers has been investigated.

A New Method for Estimating the Clamping Force of Shrink Sleeve Labels

The paper presents an original method for estimating the shrink sleeve label compressive force on packaging. One of the most popular methods of measuring deformations was used, i.e., the electrical resistance strain gauge measurement. It was assumed that the packaging was a thin-walled axially symmetrical vessel. The packing walls on one side are loaded with internal pressure generated by heating the liquid contained inside the packaging. On the other side, the film shrinking on the packaging generates additional deformation. By measuring the changes in circumferential deformations in the shrinking process at various packaging heights, it is possible to infer the uniformity of the film compressive force. Results of research on changes of these deformations over time with different intensity values of the shrinkage medium were presented.

Study on the effect of graphene and glycerol plasticizer on the properties of chitosan-graphene nanocomposites via in situ green chemical reduction of graphene oxide

Unplasticized and glycerol plasticized chitosan/graphene (CS/GS) nanocomposites were synthesized via in situ chemical reduction of graphene oxide sheets (GO) with l-ascorbic acid (L-AA) as reductant by solution casting. The reduction of GO with L-AA was investigated to establish the optimal amount of reductant required to produce chemically reduced graphene sheets (GS). The combine effect of both nanofiller and glycerol on the structure, thermal, mechanical, and electrical properties of CS/GS nanocomposite films was evaluated. Materials were characterized by FT-IR, NMR, UV-Vis, XPS, XRD, Raman, SEM, TEM, and TGA. The results showed that GS sheets were homogeneously dispersed throughout the CS matrix, and that interactions between CS and the surface of GS took place. When compared with neat CS, nanocomposites showed a decrease in the crystallinity, better thermal stability under oxidative atmosphere, and improved mechanical properties, while maintained the thermal properties of CS under inert conditions. Combined use of glycerol and GS led to substantially enhanced mechanical properties. The electrical conductivity was increased with increasing GS loading in nanocomposite. This study demonstrates how CS/GS nanocomposites performance properties can be tailored by controlling GsS and plasticizer content.

Study of the UV protective and antibacterial properties of aqueous polyurethane dispersions extended with low molecular weight chitosan

A series of aqueous dispersions of polyurethane (PU) and low molecular weight chitosan (CS_(LMW)) has been prepared in two steps synthetic process. In first step PU prepolymer, with NCO termini were prepared by reacting isophrone diisocyanate (IPDI), poly (caprolactone) diol (CAPA, Mn 1000), and 2,2-dimethylol propionic acid (DMPA), followed by neutralization of PU prepolymer with triethylamine (TEA). In second step PU prepolymer chain was extended by low molecular weight chitosan followed by dispersion formation by adding calculated volume of water. Molecular characterization of CS_(LMW)-PU finishes was done by FTIR and application on poly-cotton blended fabric samples was confirmed by scanning electron microscopy (SEM). Antimicrobial and UV protective performance of treated fabrics was performed by AATCC 100 and AATCC TM183 methods respectively. Furthermore, it shows that the addition of chitosan remarkably increases antimicrobial and UV protective properties of PUs.

Structural analysis, and antioxidant and antibacterial properties of chitosan-poly (vinyl alcohol) biodegradable films

The development and characterization of biodegradable blend films based on chitosan and poly (vinyl alcohol) for possible use in a variety of biological activities are reported. Fourier transform infrared spectroscopy (FTIR) spectra of chitosan-poly (vinyl alcohol) (Ch/PVA) films showed characteristics peaks shifting to a lower frequency range due to hydrogen bonding between -OH of PVA and -NH2 of chitosan. The chitosan and PVA polymers presented good compatibility. The morphology study of chitosan and composite films showed a compact and homogenous structure. The tensile strength and elongation at break increased with PVA content. In fact, the highest tensile strength and elongation at break (53.58 MPa and 454 %) occurs with pure PVA film. The results showed that PVA incorporation in the blends contributes to increase the intermolecular interactions, thus improving the mechanical properties. In addition, the prepared films demonstrated high antioxidant activities monitored by 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical-scavenging, reducing power, and β-carotene bleaching activity. Nevertheless, PVA addition reduced antioxidant and antibacterial activities against Gram-positive and Gram-negative bacteria tested.

Polysaccharide-Based Membranes in Food Packaging Applications

Plastic packaging is essential nowadays. However, the huge environmental problem caused by landfill disposal of non-biodegradable polymers in the end of life has to be minimized and preferentially eliminated. The solution may rely on the use of biopolymers, in particular polysaccharides. These macromolecules with film-forming properties are able to produce attracting biodegradable materials, possibly applicable in food packaging. Despite all advantages of using polysaccharides obtained from different sources, some drawbacks, mostly related to their low resistance to water, mechanical performance and price, have hindered their wider use and commercialization. Nevertheless, with increasing attention and research on this field, it has been possible to trace some strategies to overcome the problems and recognize solutions. This review summarizes some of the most used polysaccharides in food packaging applications.

Effects of chitin nanowhiskers on the thermal, barrier, mechanical, and rheological properties of polypropylene nanocomposites

Incorporation of chitin nanowhiskers into polypropylene shows improvements in both water barrier and mechanical properties.

Solid-state fluorescent composite phosphor based on cellulose grafted with carbon dots for temperature sensing

Blue phosphors consisting of cellulose and carbon dots (CDs) have been prepared successfully for the first time, which show excellent fluorescent temperature sensing properties.

Effect of γ-rays on carboxymethyl chitosan for use as antioxidant and preservative coating for peach fruit

Carboxymethyl chitosan (CMCS) was synthesized by alkylation of chitosan using monochloroacetic acid and characterized by FTIR and (1)H-NMR spectroscopies. Different molecular weights (Mws) of CMCS were prepared by radiation degradation of CMCS in the solution form at different irradiation doses. The structural changes and Mw of degraded CMCS were confirmed by UV-Vis, FTIR and GPC. The antioxidant activity of CMCS was evaluated using scavenging effect on DPPH radicals, reducing power and ferrous ion chelating activity assays. The antioxidant activity of CMCS enhanced with decreasing CMCS Mw. The possible practical use of CMCS as preservative coating for peach fruit by dipping treatment after 10 days of storage at ambient temperature was investigated. The CMCS with lower Mw had a good effect on delaying spoilage and decreasing malondialdehyde (MDA) content of peach fruits suggesting their possible use as antioxidant and preservative coating.