Improving the functionality of chitosan-based packaging films by crosslinking with nanoencapsulated clove essential oil

Development and characterization of soluble soybean polysaccharide/pullulan blend films enriched with essential oils

Soluble soybean polysaccharide (SSPS)/pullulan (PUL) blend films enriched with lavender essential oil (LEO) or clove essential oil (CEO) were prepared using the solution casting method. The structural, optical, mechanical, barrier, thermal, antioxidant, and antibacterial properties of the SSPS/PUL/LEO and SSPS/PUL/CEO films were investigated and compared. Scanning electron microscopy micrographs revealed randomly distributed micropores within the SSPS/PUL matrix after enrichment with essential oils (EOs). The addition of EOs significantly improved the UV-blocking performance, elongation at break (EAB), water resistance, antioxidant activity and hydrophobicity of the films. The results showed that the SSPS/PUL/CEO films exhibited nearly 100 % UV-blocking efficiency in the wavelength range of 190-290 nm, while achieving a maximum EAB of 90.6 ± 5.3 %. However, the tensile strength of the films decreased from 10.8 MPa to 5.6 MPa or 4.8 MPa upon the addition of 15 % LEO or CEO, respectively. Thermogravimetric analysis indicated that the addition of EOs had little effect on the thermal properties of the SSPS/PUL films. Both SSPS/PUL/LEO and SSPS/PUL/CEO films exhibited good antioxidant and antibacterial properties, with the SSPS/PUL/CEO film showing superior performance in both aspects. The results preliminarily suggest that the SSPS/PUL/EOs films have great potential to be used as active food packaging materials.

Tuning the optical, electrical, anti-microbial, and swelling activity of nanowires manganese dioxide-loaded chitosan matrix

Skin wound healing is undoubtedly a complex and challenging process. Creating innovative bio-nanocomposites for skin care and wound healing/dressing applications are currently an urgent need. In this context, a mixture of chitosan (CS) and MnO2 nanowires (NWs), as potential wound dressing nano-film, are systematically investigated for optical, electrical, and antibacterial applications. The crystallinity of the materials was investigated through XRD, while FTIR was used to examine the interactions between the CS films and the MnO2 nanofiller. The resulting nanocomposite membranes exhibit superior swelling capacity than that of the pure CS membrane. Additionally, the thermal stability of the films was evaluated, demonstrating the highest stability of composite samples. The optical properties, including bandgap energies and refractive indices, can be adjusted by tuning the content of MnO2. Remarkably, the refractive index dropped from 3.76 in pure CS film to 3.4 in the highest fraction of MnO2 (CS-4 wt% MnO2). The impedance analysis was further improved for the (CS-4 wt% MnO2) sample, posing lower interfacial resistance. A comprehensive investigation of the antibacterial performance of the prepared films was carried out against five bacteria types. The pure CS film exhibited mostly inhibitory effects against Gram-positive bacteria (i.e., B. subtilis, and S. aureus) between the 19 and 14 mm range, while the Gram-negative bacteria (i.e., E. coli, and P. aeruginosa) showed activity between the 19 and 20 mm range, with an effect on A. niger and C. albicans 17 and 22 mm. However, the addition of MnO2 has significantly increased its antimicrobial activity. Overall, the prepared CS films demonstrate great potential for multifunctional applications, including antibacterial, wound healing, and optoelectronics.

The encapsulation strategies of clove essential oil enhance its delivery effect in food preservation applications

Food supply chain faces challenges from quality degradation, microbial contamination, and chemical synthetic fungicides. Recently, the remarkable food preserving ability and biological activity of natural clove essential oil (CEO) has gained significant attention. However, its application is limited by volatility, photothermal sensitivity, and inherent odor. To this end, encapsulation strategies have been attempted on CEO to enhance its bioavailability, as well as their efficacy in food preservation scenarios. This study outlines CEO's chemistry and delves into its antimicrobial/antioxidant mechanisms. Subsequently, latest advances in encapsulation strategies for CEO in food preservation are comprehensively reviewed, including film blending, emulsification techniques, polyelectrolyte complexation, ion gelation, etc. The encapsulation enhances CEO's benefits, augmenting its long-term bioavailability in diverse food preservation systems. Finally, CEO's security and limitations are also discussed in-depth. This work aims to compile recent trends in encapsulation strategies for active substances and guide judicious utilize for natural CEO preservative.

Efficacy of Pogostemon cablin essential oil loaded chitosan nanoemulsion as novel coating agent for inhibition of potato sprouting and maintenance of storage quality

Application of synthetic compounds to inhibit potato sprouting is a major challenge in the storage conditions. The replacement of synthetic compounds by essential oils for inhibition of potato sprouting is of current research hotspot. This is the first time investigation on encapsulation of Pogostemon cablin essential oil into chitosan nanoemulsion (Ne-PCEO) and its application as coating agent for anti-sprouting activity of potato tubers. The Ne-PCEO was characterized through SEM, DLS, FTIR, and XRD assay along with controlled delivery of PCEO. The Ne-PCEO coating inhibited in-vivo potato sprouting and regulated gibberellins (GA3) and aminocyclopropane-1-carboxylate (ACC) content along with impediment of respiration rate over 90 days of storage at 25 ± 2 °C (RH ∼ 70 %). The Ne-PCEO coating also prevented the weight loss, starch degradation, and increased the reducing sugar content of tubers without affecting the sensory qualities (p < 0.05), which strongly recommends its potential application as novel anti-sprouting coating agent for maintenance of potato storage quality.

Characterization and application of Cinnamaldehyde-loaded zein nanoparticles in a polyvinyl alcohol/chitosan film for silver pomfret (Pampus argenteus) packaging

This study aims to prepare and characterize cinnamaldehyde-loaded zein/sodium alginate nanoparticles (ZCNPs) and incorporate them into polyvinyl alcohol/chitosan (PVA/CS) bioactive films (PSCN) to investigate their compatibility, physicochemical properties, and their application as a preservation material for pomfret fish. The results indicate that the anionic sodium alginate coating improved the particle size, zeta potential, and PDI of zein nanoparticles. The ZCNPs were uniformly dispersed within the films, enhancing the mechanical properties and water vapor barrier performance. The X-ray diffraction (XRD) and Fourier transform infrared (FTIR) analyses confirmed the amorphous structure of the films and the formation of hydrogen bonds. In the PVA/CS film, with the increase of ZCNPs, the thermal decomposition temperature of the film increased from 298 °C to 308 °C, while the film thickness and water contact angle were not significantly affected, remaining around 0.31 cm and 23°, respectively. Additionally, after the incorporation of ZCNPs, the DPPH radical scavenging rate of the film increased from 14.58 % to 95.38 %, significantly delaying the quality deterioration of pomfret during storage.

Development of polyvinyl alcohol/carboxymethylcellulose-based bio-packaging film with citric acid crosslinking and clove essential oil encapsulated chitosan nanoparticle pickering emulsion

This study developed polyvinyl alcohol (PVA)/carboxymethylcellulose (CMC)-based films, using citric acid (CA) as a non-toxic crosslinking agent, to enhance the shelf life of water-soluble packaging films. Clove essential oil (CEO)-loaded chitosan nanoparticles (CSNPs) were prepared via Pickering emulsion and incorporated into PVA/CMC/CA composite films. The encapsulation of CEO was confirmed by FTIR and optical microscopy. Thermal properties were analyzed using thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC), revealing improved thermal stability and a decrease in glass transition temperature (Tg) upon crosslinking. The formation of ester bonds was confirmed by ATR-FTIR and 13CNMR. Water contact angle (WCA) measurements showed a decrease in hydrophilicity, enhancing the barrier properties of the films. SEM images demonstrated good dispersion of CSNP/CEO within the matrix, improving mechanical and barrier properties. The films exhibited a 30 % reduction in water vapor permeability and water solubility. Controlled release studies indicated that the composite films sustained CEO release, extending the shelf life of cherry tomatoes. Thus, these PVA/CMC/CA-CSNP/CEO composite films offer strong potential for food preservation applications.

Multi-functional reinforced food packaging using delivery carriers: A comprehensive review of preparation, properties, and applications

With the rapid development of globalization, food packaging takes on more responsibility, while guaranteeing product quality and safety. In this context, the health risks associated with chemically synthesized additives and inorganic nanoparticles have opened a new chapter in the reinforcement of food packaging with natural active ingredients. Various delivery carriers have been developed to overcome the limitations of poor stability, uneven dispersion, and low bioavailability of natural active ingredients. The combination of encapsulation technologies can increase the biocompatibility of the active ingredient with the packaging material. Moreover, the protective and slow-release effects of the carrier matrix on the active ingredients are desirable for the reinforcement of food packaging. This review presents the latest advances in the application of delivery systems in food packaging, including the types of delivery systems used in food packaging, reinforced properties of food packaging, and potential applications in the food industry. Previous scientific studies found that active ingredient-loaded delivery carriers increased the effectiveness of food packaging in preventing food spoilage. Furthermore, the integration of active packaging with smart food packaging exhibits the synergistic effects of freshness monitoring and quality preservation. This review also discusses the challenges and trends in reinforcing food packaging with delivery carriers under a synergistic strategy that will provide new ideas and insights for the development and application of innovative food packaging.

Polyvinyl alcohol/soybean isolate protein composite pad with enhanced antioxidant and antimicrobial properties induced by novel ternary nanoparticles for fresh pork preservation

In this study, oregano essential oil (OEO)-loaded soluble soybean polysaccharide (SSPS) -nisin nanoparticles (ONSNPs) were formulated through electrostatic attraction-driven and hydrophobic interactions utilizing SSPS, nisin, and OEO as raw materials. ONSNPs were integrated into polyvinyl alcohol (PVA) and soybean protein isolate (SPI) matrices to create composite pads (PS-ONSNPs) by physically cross-linked using a simple freeze-thaw cycling process. The effects of ONSNPs content on the structure and physicochemical properties were evaluated. The results revealed that strong intermolecular interactions between ONSNPs and the PS matrices affected the crystallinity, microstructure, and thermal stability of the pads. Upon incorporating 5 % to 15 % ONSNPs, the structure of composite pads became denser, and the mechanical properties and water resistance were enhanced. Concurrently, the PS-ONSNPs pads facilitated the protection and controlled release of OEO. Furthermore, ONSNPs significantly improved the antioxidant activity of the pads and effectively inhibited the growth of Staphylococcus aureus and Escherichia coli. The prepared PS-ONSNPs 15 % pad was applied to storage experiments of fresh pork, which could extend the shelf life of meat to 10-12 days under 4 °C storage conditions. Therefore, the composite pad devised in this research holds promise as a viable option for intelligent active packaging of fresh meat.

An antibacterial film using κ-carrageenan loaded with benzyl isothiocyanate nanoemulsion: Characterization and application in beef preservation

Benzyl isothiocyanate (BITC) is a naturally active bacteriostatic substance and κ-carrageenan (KC) is a good film-forming substrate. In the present study, a nanoemulsion incorporating BITC was fabricated with a particle size of 224.1 nm and an encapsulation efficiency of 69.2 %. Subsequently, the acquired BITC nanoemulsion (BITC-NE) was incorporated into the KC-based film, and the light transmittance of the prepared composite films was lower than that of the pure KC film. Fourier transform infrared spectroscopy and scanning electron microscopy revealed that BITC-NE was compatible with the KC matrix. BITC-NE incorporation enhanced the tensile strength of the KC-based films by 33.7 %, decreased the elongation at break by 33.8 %, decreased the water vapor permeability by 60.1 %, increased the maximum thermal degradation temperature by 48.8 %, and decreased the oxygen permeability by 42 % (p < 0.05). Furthermore, the composite films showed enhanced antimicrobial activity against Staphylococcus aureus, Salmonella typhimurium, and Pseudomonas fluorescens. The developed KC-based composite films were applied to wrap raw beef, which significantly delayed the increase in total viable count, total volatile base nitrogen content, and thiobarbituric acid reactive substances, and prolonged the shelf-life of the raw beef by up to 10 days. These results indicated that the composite films prepared by incorporating BITC nanoemulsions into KC matrices have great antimicrobial application potential.

Fabrication and characterization of Karaya gum-based films reinforced with bacterial nanocellulose stabilized valerian root extract Pickering emulsion for lamb meat preservation

A novel biodegradable film was fabricated by incorporating bacterial nanocellulose stabilized valerian root extract (VRE) Pickering emulsion into karaya gum with better antioxidant and antibacterial properties for lamb meat preservation. The valerian root extract Pickering emulsion (VPE) exhibited 98 ± 1.84 % encapsulating efficiency and excellent physical stability with an average particle size of 274.6 nm. The incorporation of VPE-5 into the film matrix increased its elongation at break (EAB), and improved water resistance and barrier properties against oxygen, water vapor, and UV light. Moreover, the antioxidant and anti-bacterial properties against S.aerous and E. coli were also improved based on VPE-5 concentration. The SEM images showed a uniform distribution of VPE-5 while FTIR and XRD revealed its compatibility with karaya gum, which improved its thermal stability. The active films showed a significant preservative effect by reducing the pH, total volatile basic nitrogen (TVB-N), thiobarbituric acid reactive substances (TBARS), and total viable count (TVC) value of lamb meat and maintained its texture and color during the storage period of 9 days at 4 °C. These results demonstrated the inclusion of VPE-5 into Karaya gum was a promising technique and offers a great potential application as a bioactive material in food packaging.

Emulsification and stabilisation technologies used for the inclusion of lipophilic functional ingredients in food systems

Food industry is increasingly using functional ingredients to improve the food product quality. Lipid-containing functional ingredients are important sources of nutrients. This review examines the current state of emulsification and stabilisation technologies for incorporating lipophilic functional ingredients into food systems. Lipophilic functional ingredients, such as omega-3 fatty acids, carotenoids, and fat-soluble vitamins, offer numerous health benefits but present challenges due to their limited solubility in water-based food matrices. Emulsification techniques enable the dispersion of these ingredients in aqueous environments, facilitating their inclusion in a variety of food products. This review highlights recent advances in food emulsion formulation, emulsification methods and stabilisation techniques which, together, improve the stability and bioavailability of lipophilic compounds. The role of various emulsifiers, stabilizers, and encapsulation materials in enhancing the functionality of these ingredients is also explored. Furthermore, the review discusses different stabilisation techniques which can yield in emulsion in a solid or liquid state. By providing a comprehensive overview of current technologies, this review aims to guide future research and application in the development of functional foods enriched with lipophilic ingredients.

Incorporation of essential oils in polymeric films for biomedical applications

Natural and synthetic biodegradable polymers are widely used to obtain more sustainable films with biological, physicochemical, and mechanical properties for biomedical purposes. The incorporation of essential oils (EOs) in polymeric films can optimize the biological activities of these EOs, protect them from degradation, and serve as a prototype for new biotechnological products. This article aims to discuss updates over the last 10 years on incorporating EOs into natural and synthetic biodegradable polymer films for biomedical applications. Chitosan, alginates, cellulose, and proteins such as gelatine, silk, and zein are among the natural polymers most commonly used to prepare biodegradable films for release EOs. In addition to these, the most cited synthetic biodegradable polymers are poly(L-lactide) (PLA), poly(vinyl alcohol) (PVA), and poly(ε-caprolactone) (PCL). The EOs of clove, cinnamon, tea tree, eucalyptus, frankincense, lavender, thyme and oregano incorporated into polymeric films have been the most studied EOs in recent years in the biomedical field. Biomedical applications include antimicrobial activity against pathogenic bacteria and fungi, anticancer activity, potential for tissue engineering and regeneration with scaffolds and wound healing as dressings. Thus, this article reports on the importance of incorporating EOs into biodegradable polymer films, making these systems especially attractive for various biomedical applications.

Effects of chitosan-based packaging film crosslinked with nanoencapsulated star anise essential oil and superchilled storage on the quality of rabbit meat patties

In this paper, the effects of chitosan film containing star anise essential oil nanofiltration (CFSAO) and superchilled (SC) temperature on the changes of physicochemical and microbiological indexes of rabbit meat patties within 15 days of storage were studied. The total aerobic bacteria counts, malondialdehyde content, protein carbonyl content, total sulfhydryl content, and metmyoglobin content continued to grow throughout the entire experimental period, and the maximum absorption peak at the soret region of myoglobin gradually decreased. Along with the storage time extended, the brightness and redness of rabbit meat significantly decreased (P < 0.05), while the yellowness significantly increased (P < 0.05). The results of storage experiments showed that chitosan composite films and SC temperature had good inhibition on lipid oxidation, myoglobin oxidation and degradation, sulfhydryl content reduction, and microbial growth of rabbit meat after 15 days of storage, and could slow down the change of rabbit meat color.

Preparation of Fresh-Keeping Paper Using Clove Essential Oil through Pickering Emulsion and Maintaining the Quality of Postharvest Cherry Tomatoes

This study focused on developing a Pickering emulsion fresh-keeping paper that contained clove essential oil (CEO). Cherry tomatoes served as the test material for assessing the preservative efficacy of fresh-keeping paper. The results showed that Pickering emulsion had strong stability. Additionally, the fresh-keeping paper had a good antioxidant activity and sustained-release effect on CEO. In terms of the preservation effect, 0.75 wt% CEO Pickering emulsion paper reduced the decay incidence and weight loss of cherry tomatoes during 12-day storage. Fresh-keeping paper could also play a positive role in protecting the sensory index and color difference of tomatoes. It slowed the decline rate of soluble solid concentration (SSC) and titrable acid (TA). The vitamin C (Vc) and hardness of preserved tomatoes using fresh-keeping paper were maintained at a high level. The paper also inhibited the growth of microorganisms significantly. Therefore, 0.75 wt% CEO Pickering emulsion fresh-keeping paper displayed considerable potential for application in the preservation of postharvest fruits and vegetables. It is a novel fruit and vegetable preservation material worthy of development.

Preparation and characterization of zein-tannic acid nanoparticles/chitosan composite films and application in the preservation of sugar oranges

Chitosan-based food packaging film was prepared by incorporating zein-tannic acid nanoparticles (ZTNPs) into chitosan and was evaluated in terms of structure, physical, mechanical and functional properties. Results showed that there were hydrogen bonding interactions between ZTNPs and chitosan matrix, which is conductive to mechanical enhancements of chitosan films. Compared with the pure chitosan film, the composite films with 10% ZTNPs at pH 4 showed the increased tensile strength by 196.58%, increased elongation at break by 161.37%, decreased water vapor permeability by 70.76% and decreased oxygen permeability by 40.68%. The highest inhibition rates of this composite film-forming fluid against Escherichia coli and Staphylococcus aureus reached 83.32% and 72.35%, respectively. The composite film forming solution formed by adding 10% ZTNPs was used for sugar orange preservation. The weight loss rate of oranges was reduced and the nutrient retention rate was improved. This study expanded the application of chitosan-based packaging materials in fruit preservation.

Biodegradable bio-film based on Cordyceps militaris and metal-organic frameworks for fruit preservation

In this study, Cordyceps militaris matrix was employed for the first time to fabricate a biodegradable food packaging. Carmine and Ag@CuBTC were introduced to cross-link with mycelium and were uniformly dispersed within the matrix to enhance the water resistance, antimicrobial, and antioxidant properties of the bio-films. The bio-film displayed high biodegradability, with nearly 100 % degradation achieved after three weeks. The bio-film exhibited exceptional resistance to oxidation (49.30 % DPPH and 93.94 % ABTS•+), as well as effective inhibitory capabilities against E. coli and S. aureus, respectively. The composite film maintained a high CO2/O2 selective permeability, which was advantageous for mitigating fruit metabolism and extending shelf life. Simultaneously, food preservation experiments confirmed that these bio-films can decelerate the spoilage of fruits and effectively prolong the shelf-life of food. The experimental findings indicated that the prepared Bio-R-Ag@Cu film held promise as an environmentally friendly biodegradable material for food packaging.

Modified polysaccharides for food packaging applications: A review

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

Fabrication of ammonia and acetic acid-responsive intelligent films based on grape skin anthocyanin via adjusting the pH of film-forming solution

pH-responsive intelligent films for food freshness monitoring have attracted great attentions recently. In this study, several intelligent films based on chitosan (CS), polyvinyl alcohol (PVA), and grape skin anthocyanin (GSA) were prepared, and the effect of film-forming solution pH on the properties of intelligent films was investigated. The results of SEM, FTIR, XRD and TGA displayed that the hydrogen bond between CS and GSA was strong at strong acidic conditions (2.0-2.5), and it weakened at weak acidic conditions (3.0-4.5). Meanwhile, the hydrogen bond between PVA and GSA was negligible under strong acidic conditions, and it appeared under weak acidic conditions. Consequently, the films fabricated under weak acidic conditions displayed lower water solubility, lower water vapor permeability, and higher elongation at break. The tensile strength of films increased firstly and subsequently decreased with pH increasing, reaching a maximum value of 31.44 MPa at pH 3.5. Additionally, the films prepared at pH 2.5 and 4.0 showed the best color responsiveness to ammonia and acetic acid, respectively. Overall, the intelligent films prepared under variant pH have the potential to realize the goal of monitoring the freshness of different types of food, thereby expanding the application subject of anthocyanins-based intelligent films.

Nanoscale Pickering emulsion food preservative films/coatings: Compositions, preparations, influencing factors, and applications

Pickering emulsion (PE) technology effectively addresses the issues of poor compatibility and low retention of hydrophobic active ingredients in food packaging. Nonetheless, it is important to recognize that each stage of the preparation process for PE films/coatings (PEFCs) can significantly influence their functional properties. With the fundamental considerations of environmental friendliness and human safety, this review extensively explores the potential of raw materials for PEFC and introduces the preparation methods of nanoparticles, emulsification technology, and film-forming techniques. The critical factors that impact the performance of PEFC during the preparation process are analyzed to enhance food preservation effectiveness. Moreover, the latest advancements in PE packaging across diverse food applications are summarized, along with prospects for innovative food packaging materials. Finally, the preservation mechanism and application safety have been systematically elucidated. The study revealed that the PEFCs provide structural flexibility, where designable nanoparticles offer unique functional properties for intelligent control over active ingredient release. The selection of the dispersed and continuous phases, along with component proportions, can be customized for specific food characteristics and storage conditions. By employing suitable preparation and emulsification techniques, the stability of the emulsion can be improved, thereby enhancing the effectiveness of the films/coatings in preserving food. Including additional substances broadens the functionality of degradable materials. The PE packaging technology provides a safe and innovative solution for extending the shelf life and enhancing the quality of food products by protecting and releasing active components.

Preparation of curcumin-loaded pectin-nisin copolymer emulsion and evaluation of its stability

In the paper, Nisin was grafted onto native pectin by the 1-ethyl-(3-dimethylaminopropyl) carbodiimide hydrochloride (EDC·HCl) method. Structure characterisation showed that the carboxyl group of pectin interacted with the amino group of Nisin and formed an amide bond. The highest grafting ratio of the modified pectin was up to 24.89 %. The emulsifying property of modified pectin, significantly improved, and emulsification performance improved with increasing grafting ratio. Emulsifying activity, emulsion stability, Zeta potential, and droplet morphology data demonstrate a notable enhancement in pectin's emulsifying properties due to Nisin's introduction, with the degree of grafting showing a direct correlation with the improvement observed. Pectin-based emulsion is utilized to load curcumin, enhancing its stability and bioavailability. Research findings highlight that the incorporation of Nisin-modified pectin significantly elevates curcumin encapsulation efficiency, while decelerating its release rate. Moreover, the stability of curcumin loaded in the modified pectin under light exposure, alkaline conditions, and long-term storage is also significantly improved. Ultimately, the bioavailability of curcumin escalates from 0.368 to 0.785.

Development, characterization and functional properties of sodium alginate-based films incorporated with Schisandra chinensis extract-natamycin complex

Because of the impact of petroleum-based polymers on environmental deterioration and the need for safe, efficient, and functional packaging films, a sodium alginate (SA)-based film incorporating a Schisandra chinensis extract (SCE)-natamycin (NA) complex was developed for the desired physical and functional properties. The incorporation of SCE-NA into SA-based films decreased the water vapor transmission rate (WVTR), moisture content (MC), and hydrophilicity of the films and improved their opacity, elongation at break (EAB), and thermal stability. Scanning Electron Microscopy (SEM), Fourier Transform Infrared (FTIR), X-ray photoelectron spectroscopy (XPS), and X-ray Diffraction (XRD) analyses showed that SA, SCE, and NA had positive interactions and compatibility. In addition, the antimicrobial activity analysis indicated that the SA-SCE-NA film-forming solutions had satisfactory antimicrobial activity against Staphylococcus aureus, Escherichia coli, Saccharomyces cerevisiae, and Aspergillus niger. SA-based composite films have been used to coat cucumbers and blueberries to extend their shelf life. Compared to the neat SA film, the shelf life of cucumbers treated with the SA-SCE-NA film increased by 6 days compared to that in the untreated group at 28 °C, and the shelf life of blueberries increased by 5 days at 4 °C, revealing its potential utilization in food packaging.

The Extraction and Impact of Essential Oils on Bioactive Films and Food Preservation, with Emphasis on Antioxidant and Antibacterial Activities-A Review

Essential oils, consisting of volatile compounds, are derived from various plant parts and possess antibacterial and antioxidant properties. Certain essential oils are utilized for medicinal purposes and can serve as natural preservatives in food products, replacing synthetic ones. This review describes how essential oils can promote the performance of bioactive films and preserve food through their antioxidant and antibacterial properties. Further, this article emphasizes the antibacterial efficacy of essential oil composite films for food preservation and analyzes their manufacturing processes. These films could be an attractive delivery strategy for improving phenolic stability in foods and the shelf-life of consumable food items. Moreover, this article presents an overview of current knowledge of the extraction of essential oils, their effects on bioactive films and food preservation, as well as the benefits and drawbacks of using them to preserve food products.

Films Based on Biopolymers Incorporated with Active Compounds Encapsulated in Emulsions: Properties and Potential Applications-A Review

The rising consumer demand for safer, healthier, and fresher-like food has led to the emergence of new concepts in food packaging. In addition, the growing concern about environmental issues has increased the search for materials derived from non-petroleum sources and biodegradable options. Thus, active films based on biopolymers loaded with natural active compounds have great potential to be used as food packaging. However, several lipophilic active compounds are difficult to incorporate into aqueous film-forming solutions based on polysaccharides or proteins, and the hydrophilic active compounds require protection against oxidation. One way to incorporate these active compounds into film matrices is to encapsulate them in emulsions, such as microemulsions, nanoemulsions, Pickering emulsions, or double emulsions. However, emulsion characteristics can influence the properties of active films, such as mechanical, barrier, and optical properties. This review addresses the advantages of using emulsions to encapsulate active compounds before their incorporation into biopolymeric matrices, the main characteristics of these emulsions (emulsion type, droplet size, and emulsifier nature), and their influence on active film properties. Furthermore, we review the recent applications of the emulsion-charged active films in food systems.

Effect of Essential Oils from Lemongrass and Tahiti Lime Residues on the Physicochemical Properties of Chitosan-Based Biodegradable Films

This work aimed to evaluate the impact of adding two essential oils (EO) from lemongrass (LEO) and Tahiti lime (TLEO) on the physical, mechanical, and thermal properties of chitosan-based biodegradable films. Six film formulations were prepared: two controls with chitosan concentrations of 1% and 1.5% v/w, two formulations combining the two chitosan concentrations with 1% LEO v/v, and two formulations combining the two chitosan concentrations with 1% TLEO v/v. The films' morphological, water affinity, barrier, mechanical, and thermal properties were evaluated. The films' surface showed a heterogeneous morphology without cracks, whereas the cross-section showed a porous-like structure. Adding EO to the films promoted a 35-50% decrease in crystallinity, which was associated with an increase in the elasticity (16-35%) and a decrease in the tensile strength (9.3-29.2 MPa) and Young's modulus (190-1555 MPa) on the films. Regarding the optical properties, the opacity of the films with TLEO increased up to 500% and 439% for chitosan concentrations of 1% and 1.5%, respectively. While the increase in opacity for the films prepared with LEO was 357% and 187%, the reduction in crystallinity also reduced the resistance of the films to thermal processes, which could be explained by the reduction in the enthalpy of fusion. The thermal degradation of the films using TLEO was higher than those where LEO was used. These results were indicative of the great potential of using TLEO and LEO in biodegradable films. Likewise, this work showed an alternative for adding value to the cultivation of Tahiti lime due to the use of its residues, which is in accordance with the circular economy model. However, it was necessary to deepen the study and the use of these essential oils in the preparation of biodegradable films.

A hydroxypropyl methylcellulose/hydroxypropyl starch nanocomposite film reinforced with chitosan nanoparticles encapsulating cinnamon essential oil: Preparation and characterization

Active packaging derived from polysaccharides plays an important role in prolonging the shelf life of food. In this study, cinnamon essential oil (CEO)-loaded chitosan nanoparticles (CNs) were prepared and embedded in hydroxypropyl methylcellulose (HPMC)/hydroxypropyl starch (HPS) blends to enhance the physicochemical and biofunctional properties of the formed films. Different concentrations (25, 50, 75, and 100 μL/mL) of CEOs were encapsulated with CNs to form CEO-CNs, as confirmed by Fourier Transform Infrared Spectrometer (FTIR), X-Ray Diffraction (XRD), and scanning electron microscope (SEM) images. The prepared CEO-CNs were incorporated into the HPMC/HPS film-forming matrix to prepare reinforced nanocomposite films. SEM images showed that the CEO-CNs were dispersed in the HPMC/HPS matrix, thus filling the void space in the composite matrix and significantly improving the mechanical and barrier properties of the bio-nanocomposite films. The elongation at break of the reinforced films improved from 8.54 ± 0.53 MPa to 24.81 ± 0.47 MPa, and the water vapor permeability was reduced by nearly 30 %. FTIR and XRD analyses indicated the formation of hydrogen bonds between CEO-CNs and HPMC/HPS polymer molecules. Release studies showed that the nanocomposite film was capable of sustained release of CEO, which imparted antioxidant (radical scavenging activity of 27.66-42.19 %) and antimicrobial properties (inhibition of Escherichia coli and Aspergillus flavus growth). Therefore, these HPMC/HPS nanocomposite films with enhanced properties may have great potential for food preservation.

Preparation of robust, water-resistant, antibacterial, and antioxidant chitosan-based films by incorporation of cinnamaldehyde-tannin acid-zinc acetate nanoparticles

Chitosan (CS) films have poor mechanical property, low water-resistance and limited antimicrobial activity, which hinder their application in food preservation industry. Cinnamaldehyde-tannic acid-zinc acetate nanoparticles (CTZA NPs) assembled from edible medicinal plant extracts were successfully incorporated into CS films to solve these issues. The tensile strength and water contact angle of the composite films increased about 5.25-fold and 17.55°. The addition of CTZA NPs reduced the water sensitivity of CS films, which could undergo appreciable stretching in water without breaking. Furthermore, CTZA NPs significantly enhanced the UV adsorption, antibacterial, and antioxidant properties of the films, while reduced their water vapor permeability. Moreover, it was possible to print inks onto the films because the presence of the hydrophobic CTZA NPs facilitated the deposition of carbon powder onto their surfaces. The films with great antibacterial and antioxidant activities can be applied for food packaging application.

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

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

Edible films/coatings containing bioactive ingredients with micro/nano encapsulation: A comprehensive review of their fabrications, formulas, multifunctionality and applications in food packaging

Due to the consumer's pursuit of safe, nontoxic and nutritious foods, edible and/or biodegradable materials have stood out in food packaging and preservation. In this context, the preparation and application of micro/nano encapsulated active ingredients (M/N-E-BAIs) represent a step toward reinforcing the properties of sustainable and controllable food packaging, particularly for the successful incorporation of new substances and functionalities into traditional edible films/coatings. This review, from the preparation of M/N-E-BAIs, the fabrication of edible film/coating containing M/N-E-BAIs to their characterization of multifunction and the application in food, makes a systematic summary and in-depth discussion. Food-grade polymers can encapsulate bioactive ingredients (BAIs) by chemical, physicochemical and mechanical methods, thereby forming M/N-E-BAIs with suitable sustained-release and unique biological activities. Furthermore, M/N-E-BAIs is incorporated into biopolymer substrates by solvent casting, 3D printing or electrostatic spinning to obtain novel edible films/coatings. This advanced packaging material exhibits superior physicochemical and functional properties over traditional food films/coatings. Besides, their applications in foods as active and intelligent packaging can improve food quality, prolong shelf life and monitor food corruption. Even so, there are still many challenges and limitations in formulation, preparation and application of this new packaging technology that need to be addressed in the future.

Recent progress in using zein nanoparticles-loaded nanocomposites for food packaging applications

Biopolymers are important due to their exceptional functional and barrier properties and also their non-toxicity and eco-friendly nature for various food, biomedical, and pharmaceutical applications. However, biopolymers usually need reinforcement strategies to address their poor mechanical, thermal, and physical properties as well as processability aspects. Several natural nanoparticles have been proposed as reinforcing agents for biopolymeric food packaging materials. Among them, zein nanoparticles (ZNPs) have attracted a lot of interest, being an environmentally friendly material. The purpose of the present review paper is to provide a comprehensive overview of the ZNPs-loaded nanocomposites for food packaging applications, starting from the synthesis, characteristics and properties of ZNPs, to the physicochemical properties of the ZNPs-loaded nanocomposites, in terms of morphology, permeability, solubility, optical features, hydrophobic/hydrophilic behavior, structural characteristics, thermal features, and mechanical attributes. Finally, at the end of this review, some considerations about the safety issues and gastrointestinal fate of ZNPs, as well as the use of ZNPs-based nanocomposites as food packaging, are reported, taking into account that, despite the enormous benefits, nanotechnology also presents some risks associated to the use of nanometric materials.

Chitosan based film reinforced with EGCG loaded melanin-like nanocomposite (EGCG@MNPs) for active food packaging

In this study, EGCG loaded melanin-like nanoparticles (EGCG@MNPs) were incorporated into chitosan matrix to prepare an active nanocomposite food packaging film, chitosan-EGCG@MNPs (CH-EM). The influence of EGCG@MNPs on the physical and biological properties of the chitosan film was investigated. The EGCG@MNPs nanoparticles were cross-linked with chitosan through intermolecular hydrogen bonds and uniformly distributed in the matrix. Besides, the incorporation of EGCG@MNPs tremendously improved the solubility, swelling ratio and water vapor barrier properties of the film, and permitted superior ultraviolet rays blocking property. In addition, the mechanical properties, thermal stability and surface hydrophobicity have also been significantly improved. The CH-EM^2.0 nanocomposite films also showed excellent oxidation resistance (58.4 ± 4.4%, DPPH and 92.4 ± 1.3%, ABTS⁺), and strong inhibitory ability against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus). The experimental results comprehensively showed that the prepared chitosan-EGCG@MNPs nanocomposite film offering excellent potential for eco-friendly active food packaging.

Genipin-crosslinked amphiphilic chitosan films for the preservation of strawberry

As a material for films used to keep fruits fresh, chitosan has attracted extensive interest because of its advantages of degradability, environmental friendliness, and biocompatibility. In this study, two amphiphilic chitosan derivative films were prepared by crosslinking N-2-hydroxypropyl-3-butyl ether-O-carboxymethyl chitosan (HBCC) and N-2-hydroxypropyl-3-(2-ethylhexyl glycidyl ether)-O-carboxymethyl chitosan (H2ECC)) with genipin, an excellent natural cross-linking agent. The microstructures, mechanical properties, water vapor permeability, swelling ratios, light transmittance, wettability, thermal stability, antibacterial properties, and biocompatibility of the crosslinked films were characterized. The results showed that the crosslinked films had compact structures, low moisture permeability, strong water resistance, strong ultraviolet resistance, unaffected visible light transmittance, and good hydrophilicity. Compared with the uncrosslinked films, the tensile strength of the genipin-crosslinked ones was increased by 328.33 % (HBCC) and 397.83 % (H2ECC). More importantly, the crosslinked films had strong antibacterial activity against Staphylococcus aureus and Escherichia coli and were non-toxic to endothelial cells. The crosslinked films could effectively prolong the preservation time of strawberries, inhibit the decay of strawberries, and inhibit the reduction of vitamin C in strawberries. In conclusion, genipin-crosslinked HBCC and H2ECC films are potential fruit preservation materials.