Development and characterization of active packaging based on chitosan/chitin nanofibers incorporated with scallion flower extract and its preservation in fresh-cut bananas

Preparation and characterization of polyvinyl alcohol and chitosan composite film with cassia oil encapsulated in β-cyclodextrin and its application in fresh banana

In this study, composite films were developed by encapsulating cassia oil (CO) with β-cyclodextrin through a microencapsulation technique and incorporating it into a chitosan (CS), polyvinyl alcohol (PVA) and glycerol matrix. The primary objective of the film was to inhibit bacterial growth on the surface of fresh bananas and extend their shelf life. Characterization methods were employed to evaluate the physical properties and functionality of the composite films. FTIR, XRD, and SEM analyses demonstrated that cassia oil microcapsules (COM) were uniformly dispersed throughout the film and exhibited excellent compatibility with the matrix. The inclusion of 30 % COM improved the film's UV-blocking properties from 86.15 % to 91.03 %. Additionally, due to its hydrophobic nature, CO significantly reduced the water content to 9.02 % and 10.67 %. Furthermore, the COM enhanced the film's tensile strength from 21.18 MPa to 43.21 MPa, and increased its antioxidant capacity to 36.87 %. The results also indicated that 30 % COM significantly enhanced the film's antimicrobial activity against Escherichia coli and Staphylococcus aureus with inhibition zone diameters of 12.5 mm and 11.5 mm, while maintaining biosafety, as evidenced by unaltered cell survival rates in BEAS-2B and L02 cells. The film containing 30 % COM exhibited excellent preservation capacity for bananas, effectively extending their shelf life. These findings suggest that films containing COM have the potential to replace traditional plastic packaging in practical applications.

Emerging chitosan systems incorporated with polyphenols: Their applications in intelligent packaging, active packaging, and nutraceutical systems - A comprehensive review

Chitosan, a biodegradable anionic polysaccharide, has been increasingly investigated for food packaging and nutraceutical applications. In recent years, chitosan has been combined with polyphenols, a group of health promoting bioactive compounds, to enhance their physicochemical, functional, and biological properties. The synergistic functional attributes of chitosan and polyphenols have led to the development of several novel food packaging materials and nutraceuticals. Despite, several investigations being conducted on chitosan-polyphenol materials (e.g., films, coating, nanoparticles, complexes, emulsion gels), currently there is a lack of studies that comprehensively evaluate the combined effect of chitosan and polyphenol in development of both food packaging materials and nutraceuticals. Therefore, in this review, novel packaging materials and nutraceuticals developed employing chitosan-polyphenol in recent years (2018-2024) are thoroughly investigated. This review initiates with the source, production strategies, and techniques employed to improve the functionality of chitosan. Secondly, the findings associated with important intelligent packaging materials, including pH indicator, time-temperature indicator, and freshness indicator, developed using chitosan-polyphenol is investigated. Following that, the applications of chitosan-polyphenol materials in active food packaging (i.e., antimicrobial, antioxidant, oxygen scavenger, ethylene scavenger, and moisture scavenger) are explored. Notably, chitosan-based delivery systems that are employed to improve the chemical stability, bioaccessibility, and biological properties of polyphenols for nutraceutical applications are summarized. Finally, the challenges associated with the industrial application of chitosan-polyphenol materials are addressed. Overall, this review would benefit a wide range of scientists from food packaging to ingredient sectors by providing the current knowledge associated with chitosan-polyphenol materials.

Photodynamic inactivation mediated by natural alizarin on bacteria for the safety of fresh-cut apples

Most photosensitizers have limited responsiveness to visible light, however, visible light is a light source with a wide range of wavelengths and the most common in daily life, and making full use of visible light can help to enhance the photodynamic antimicrobial properties of photosensitizers. To tackle this issue, this study confirmed that alizarin has a good absorption capacity for visible light by UV-DRS analysis. Theoretical calculations showed that alizarin might be excited through the charge transfer (CT) mechanism. Under simulated light conditions, alizarin exhibited significant photodynamic inactivation, with a bactericidal efficiency of 99.91 % against S. aureus and L. monocytogenes within 40 min. Meanwhile, the cytolytic rate of alizarin was less than 5 % and the free radical scavenging rate was more than 90 %. To improve the freshness of fresh-cut fruits, we prepared alizarin-pectin (Ali-Pec) coatings using a one-step synthesis method. FT-IR spectroscopic showed the possible presence of hydrogen bonding. It was further found that during storage, the coating-treated fresh-cut apples in the experimental group showed an 8 % reduction in the variation of L-value and a 50 % reduction in the variation of a*-value, and effectively maintained the pH, VC, PPO, and T-AOC levels of the fresh-cut apples, which prolonged the shelf-life of the fresh-cut apples.

Polycaprolactone/polylactic acid nanofibers incorporated with butyl hydroxyanisole /HP-β-CD assemblies for improving fruit storage quality

In this study, the inclusion complex was prepared with butyl hydroxyanisole (BHA) as the functional substance and 2-hydroxypropyl beta-cyclodextrin (HP-β-CD) as the main molecule by ultrasound mediation. The inclusion complex was mixed with polycaprolactone (PCL)/polylactic acid (PLA), and nanofiber films loaded with different concentrations of BHA/HP-β-CD inclusion complex were prepared by electrospinning for fruit preservation. The scanning electron microscopy and infrared spectroscopy characterization results showed that HP-β-CD successfully embedded BHA in the cavity. The encapsulation of BHA increases the fiber diameter and thermal stability and decreases the crystallinity and hydrophobicity. The oxidation resistance experiment showed that the nanofiber film had a strong free radical scavenging ability. The BHA release rate of the nanofiber membrane was determined by high-performance liquid chromatography, and the release curve results showed that the inclusion complex prepared by ultrasonic self-assembly could significantly prolong the BHA release time. In addition, nanofiber films containing inclusion complex showed an effective fresh-keeping effect within 7 days of mango storage. In conclusion, a series of characterization tests show that the nanofiber film prepared in this study has a good market prospect in food preservation.

Using natural starch granules to disperse solid beeswax into micron-sized droplets in emulsion

Use of beeswax together with starch to manufacture emulsion for fruit preservation has attracted wide attention in food packaging. In this paper, esterified starch (M-PS) granules prepared from natural potato starch were used to replace nanocrystals to prepare beeswax emulsion. The swelling property of M-PS granules was used to solve the problem of uneven dispersion of beeswax. Atomic force microscope (AFM) images showed that the network gel structure formed by M-PS granules limited the movement of beeswax droplets, and the droplet size was <1.0 μm. When the beeswax emulsion was added to the starch paste, the resulting starch-beeswax composite emulsion had a stable gel structure. Bananas were coated with the composite emulsion. After 7 days of storage, compared with the test data of bare bananas, the weight loss rate decreased by 42 %, the titratable acidity increased by 21 %, and the vitamin C was higher by 20 % of coated bananas. The formed coating effectively inhibited the decline of banana quality.

Development, characterization and application of chitosan/locust bean gum based multifunctional green food packaging containing Koelreuteria paniculata Laxm. bracts extract and Ti-carbon dots

Multifunctional green food packaging films were developed by incorporating Koelreuteria paniculata Laxm. bract extract (KBE) and bio-waste-derived Ti-doped carbon dots (Ti-CDs) into a chitosan/locust bean gum (CG) matrix for the first time. Results from FTIR and XRD demonstrated the precise bonding of Ti-CDs to CG through a Schiff base reaction and hydrogen bonding, while KBE was effectively immobilized within the film matrix via hydrogen bonding. SEM and TGA analysis demonstrated enhanced thermal stability and density of the films. Addition of Ti-CDs synergistically improved the barrier properties and mechanical strength of the films through enhanced hydrogen bonding and Schiff base reactions. Specifically, the incorporation of 3 wt% Ti-CDs increased the oxygen barrier properties, tensile strength, water resistance, and vapor permeability of CG films by approximately 1.18, 0.75, and 1.51 times, respectively. Furthermore, the antimicrobial and antioxidant capabilities were significantly improved with the addition of KBE to films. The CG-3%CDs-KBE film coating effectively prolonged the shelf life of strawberries. Additionally, these films exhibited superior pH responsiveness and ammonia-sensitivity, enabling visual monitoring of shrimp freshness during storage. Importantly, CG-3%CDs-KBE films exhibited biodegradability in soil and displayed good biosafety. Overall, these findings underscore the promising potential of CG-3%CDs-KBE films as multifunctional green food packaging materials.

Manufacture of Bioplastics Prepared from Chitosan Functionalized with Callistemon citrinus Extract

The exploration of natural resources in bioplastics has advanced the development of bio-based materials. Utilizing the casting, chitosan (CH)-based films were manufactured with different glycerol (GLY) percentages (from 0 to 50% w/w of CH) and anthocyanin-enriched fractions (from 0 to 5% of w/w CH) of acidified ethanol extract of Callistemon citrinus flowers (CCE). Callistemon citrinus is an ornamental plant known for its bioactive compounds endowed with health benefits. The hydrocolloid films showed promising mechanical properties. The 30% GLY + 5% CCE film achieved an elongation at break of 57.4%, comparable to the 50% GLY film while possessing enhanced tensile strength and Young's modulus. The CCE, rich in antioxidants, acted as a plasticizer, improving films' flexibility and manageability. The films exhibit hydrophilic characteristics with moisture content and uptake values reflecting their water-absorbing capacity, while films with 30% GLY and 5% CCE exhibit enhanced hydrophobicity. In addition, CCE characterization reveals significant polyphenol content (734.45 mg GAE/g), highlighting its antioxidant capacity. Moreover, CCE supplies remarkable antioxidant properties to the films. These findings suggest the potential of these bioplastics for industrial applications as a sustainable solution to traditional plastics and in reducing environmental impact while preventing oxidative reactions in packaged products.

Metal-organic frameworks-based moisture responsive essential oil hydrogel beads for fresh-cut pineapple preservation

The preservation of fresh-cut fruits and vegetables has attracted attention to the shelf-life reduction caused by high humidity. Herein, alginate/copper ions cross-linking, in-situ growth and self-assembly techniques of metal-organic frameworks (MOFs) were utilized to prepare a moisture responsive hydrogel bead (HKUST-1@ALG). As the multistage porous structure formation, tea tree essential oil (TTO) load capacity in hydrogel bead (TTO-HKUST-1@ALG) was increased from 6.1% to 21.6%. TTO-HKUST-1@ALG had excellent moisture response performance, and the release rates of TTO increased from 33.89% to 70.98% with moisture increasing from 45% to 95%. Besides, TTO-HKUST-1@ALG exhibited excellent antimicrobial, antioxidant capacity, and biocompatibility. During storage, TTO-HKUST-1@ALG effectively improved the cell membrane integrity by maintaining the balance of reactive oxygen species metabolism. The degradation of cell wall structure and tissue softening were delayed by inhibiting the cell wall-degrading enzymes activity. Briefly, TTO-HKUST-1@ALG improved the storage quality and extended shelf-life of fresh-cut pineapple, which was a promising preservative.

An insect lac blanket-mimetic and degradable shellac hydrogel/chitosan packaging film with controllable gas permeation for fresh-cut vegetables preservation

Fresh-cut products are extremely perishable due to the processing operations, and the atmosphere environment, especially CO2, O2 and H2O, could profoundly affect their shelf life. Herein, an insect "lac blanket"-mimetic and facile strategy was proposed for fresh-cut vegetables preservation, employing porous shellac hydrogel microparticles as gas "switches" in chitosan film to regulate CO2, O2 and H2O vapor permeability. Thus, the shellac hydrogel/chitosan hybrid film presented the controllable and wide range of gas permeability, compared with the chitosan film. The shellac-COOH nanoscale vesicles aggregated to form shellac hydrogel network via hydrophobic binding. The shellac hydrogel microparticles played a certain lubricating effect on the hybrid film casting solution. The hydrogen bond network between shellac hydrogel and chitosan contributed to the excellent mechanical properties of the hybrid film. The hybrid film also exhibited remarkable water-resistant, antifogging properties, optical transparency and degradability. The hybrid packaging films prepared through this strategy could adjust the internal gas (CO2, O2, H2O and ethylene) contents within the packages, and further exhibited admirable preservation performance on three fresh-cut vegetables with different respiratory metabolisms. This gas permeation-controlled strategy has great potential in fresh food preservation and various other applications that need a modified atmosphere.

Effect of polydimethylsiloxane on the structure and barrier properties of starch/PBAT composite films

This study aimed to investigate the effects of polydimethylsiloxane (PDMS) with a low surface energy on the structure and physicochemical properties of starch/poly (butylene adipate-co-terephthalate) (PBAT) blown films. The film's appearance was not significantly changed after the addition of PDMS. Compared with the films without PDMS, the films with PDMS displayed a smoother surface. A 2% w/w PDMS addition resulted in the maximum mechanical properties (8.10 MPa of strength, 211.00% of modulus) and surface hydrophobicity (87°) of the films. By contrast, the film with 3% w/w PDMS showed the lowest light transmittance, water vapor (2.73 × 10-11 g·cm·cm2·s-1·Pa-1) and oxygen permeability (9.73 × 10-13·cm3·cm·cm-2·s-1·Pa-1), owing to the improved tightness of the matrix, which increased the zigzag path for molecules to pass through. Films with higher PDMS contents effectively extended the shelf life of packaged bananas and shiitake mushrooms, benefiting from the outstanding and appropriate barrier properties, according to principal component analysis results. Findings supported that high-content starch/PBAT films containing PDMS had potential in the preservation of fresh agricultural products.

Odor Fingerprinting of Chitosan and Source Identification of Commercial Chitosan: HS-GC-IMS, Multivariate Statistical Analysis, and Tracing Path Study

Chitosan samples were prepared from the shells of marine animals (crab and shrimp) and the cell walls of fungi (agaricus bisporus and aspergillus niger). Fourier-transform infrared spectroscopy (FT-IR) was used to detect their molecular structures, while headspace-gas chromatography-ion mobility spectrometry (HS-GC-IMS) was employed to analyze their odor composition. A total of 220 volatile organic compounds (VOCs), including esters, ketones, aldehydes, etc., were identified as the odor fingerprinting components of chitosan for the first time. A principal component analysis (PCA) revealed that chitosan could be effectively identified and classified based on its characteristic VOCs. The sum of the first three principal components explained 87% of the total variance in original information. An orthogonal partial least squares discrimination analysis (OPLS-DA) model was established for tracing and source identification purposes, demonstrating excellent performance with fitting indices R2X = 0.866, R2Y = 0.996, Q2 = 0.989 for independent variable fitting and model prediction accuracy, respectively. By utilizing OPLS-DA modeling along with a heatmap-based tracing path study, it was found that 29 VOCs significantly contributed to marine chitosan at a significance level of VIP > 1.00 (p < 0.05), whereas another set of 20 VOCs specifically associated with fungi chitosan exhibited notable contributions to its odor profile. These findings present a novel method for identifying commercial chitosan sources, which can be applied to ensure biological safety in practical applications.

Highly flexible carbon nitride-polyethylene glycol-cellulose acetate film with photocatalytic antibacterial activity for fruit preservation

Cellulose acetate film, as a biodegradable and biomass-derived material, has great potential applications in food packaging. However, the poor mechanical and antibacterial properties limit its applications. Herein, a highly flexible carbon nitride-polyethylene glycol-cellulose acetate (CN-PEG-CA) film was successfully prepared by combining graphitic carbon nitride (g-C3N4) photocatalyst with cellulose acetate (CA). The g-C3N4 enables the film with antibacterial activity, as a green photocatalyst. PEG softens the rigid polymer CA and crosslinks CA, PEG, and g-C3N4 together by hydrogen bonding, as a flexible crosslinker. X-ray diffractometer (XRD), scanning electron microscope (SEM), and Fourier transform infrared spectrum (FT-IR) characterizations confirmed the successful preparation of the CN-PEG-CA film. The mechanical property tests demonstrated that adding PEG increased the elongation at break of the film by about 4 times. The composite film had high antibacterial activity, and the bactericidal rates on Escherichia coli and Staphylococcus aureus were 99.98 % and 99.89 %, respectively. It effectively extended the shelf life of strawberries to 96 h and effectively maintained the quality of strawberries during storage. After 96 h, the weight loss rate of strawberries packaged with 15 % CN-PEG-CA film was 21.83 %, vitamin C content was 45.47 %, titratable acidity content was 0.89 %, and color, hardness and total soluble solids were well maintained. And biocompatibility test results showed that the film was safe and nontoxic. From the ecological and economic point of view, the highly flexible and biodegradable films with efficient photocatalytic antibacterial activity synthesized in this paper have great potential in the field of food packaging.

Influence of chitin nanofibers and gallic acid on physical-chemical and biological performances of chitosan-based films

In this work, chitosan films loaded with gallic acid and different content of chitin nanofibers were prepared and subjected to different characterization techniques. The results showed that the inclusion of gallic acid to chitosan films caused moderate decrease in water vapor permeability (by 29 %) and increased tensile strength of films (by 169 %) in comparison to the neat chitosan films. Furthermore, it was found that the addition of chitin nanofibers up to 30 % into chitosan/gallic acid films additionally improved tensile strength (by 474 %) and reduced plasticity of films (by 171 %), when compared to the chitosan/gallic acid films. Increased concentration of chitin nanofibers in films reduced the overall water vapor permeability of films by 51 %. In addition, gallic acid and chitin nanofibers had synergic effect on high chitosan film's antioxidant and antifungal activity toward Botrytis cinerea (both above 95 %). Finally, chitosan/gallic acid/chitin nanofibers films reduced decay incidence of strawberries, increased total soluble solid content, and promoted high production of some polyphenols during cold storage, in comparison to the control chitosan films and uncoated strawberry samples. Hence, these results suggest that chitosan/gallic acid/chitin nanofibers can present eco-sustainable approach for preservation of strawberries, giving them additional nutritional value.

Gelatin/carboxymethylcellulose composite film combined with photodynamic antibacterial: New prospect for fruit preservation

Plastic packaging causes environmental pollution, and the development of simple and effective biodegradable active packaging remains a challenge. In this study, gelatin (G) and sodium carboxymethylcellulose (CMC) were used as film materials, with the addition of curcumin (Cur), a photosensitive substance, to investigate the changes in the physical and chemical properties of the film and its application in fruit preservation. The results demonstrated that Cur was compatible with the film. With the addition of Cur, the thickness of the film increased up to 1.3 times, while the moisture content was reduced to 12.10 %. The tensile strength (TS) and elongation at break (EAB) of the film can reach 8.84 MPa and 19.33 %, respectively. The photodynamic antibacterial experiment revealed that the film containing 0.5 % Cur exhibited the highest antibacterial rate, reaching 99.99 % against Staphylococcus aureus (S. aureus) and 95 % against Escherichia coli (E. coli). During storage, the grapes remained unspoiled for up to 9 days after being phototreated with the film and the microbial content of the skin was much lower than that of the control group. In addition, Cur provided antioxidant activity for the film, with a scavenging activity of 39.54 % against the 2,2-diphenyl-1-picrind radical (DPPH). Bananas exposed to the film-forming solution for a short period of time remained fresh for up to 6 days. During preservation, the weight of the treated bananas decreased more slowly than that of the control group. In addition, the activity of SOD on the 7th day was approximately 20 U/g higher than that of the control group, which helped to reduce oxidative stress during banana preservation. In summary, G-CMC/Cur film is an optional fruit-cling film that can be used in food packaging.

Electrospun Konjac Glucomannan/Polyvinyl Alcohol Long Polymeric Filaments Incorporated with Tea Polyphenols for Food Preservations

In this study, nanofiber films were prepared by electrospinning technology with polyvinyl alcohol (PVA) and konjac glucomannan (KGM) as raw materials. Tea polyphenols (TPs) were incorporated in the above matrix, which increased physicochemical (thermal and mechanical characteristics) and antibacterial properties of the nanofiber films. The release behavior of phenolic compounds from PVA/KGM-TPs nanofiber films was determined in different food simulants; antioxidant and antibacterial activity of the films were also evaluated. The results showed that the addition of KGM increased the physical and chemical properties of the films. The tensile strength (TS) and elongation at break (EB) increased from 5.40 ± 0.33 to 10.62 ± 0.34 and from 7.24 ± 0.32 to 18.10 ± 0.91, respectively. PVA/KGM-TPs nanofiber films performed controlled release of TPs, with final release of 49.17% in 3% acetic acid, 43.6% in 10% ethanol, and 59.42% in 95% ethanol. The nanofiber films showed good antioxidation properties, with the free radical scavenging rate increasing from 1.33% to 25.61%, and good antibacterial properties with inhibition zones against E. coli and S. aureus of 24.33 ± 0.47 mm and 34.33 ± 0.94 mm, respectively. In addition, the as-prepared films showed significant preservation performance for raw bananas at 25 °C.

Intelligent packaging based on chitosan/fucoidan incorporated with coleus grass (Plectranthus scutellarioides) leaves anthocyanins and its application in monitoring the spoilage of salmon (Salmo salar L.)

The innovation of this study was to develop a novel biodegradable intelligent packaging based on chitosan/fucoidan combined with different amounts (1, 3 and 5 wt% on chitosan basis) of coleus grass (Plectranthus scutellarioides) leaves anthocyanins (CGL) to monitor the spoilage of salmon (Salmo salar L.). The addition of fucoidan improved the barrier and mechanical properties of the chitosan films (CS) due to hydrogen bonds and intermolecular electrostatic interactions. Moreover, the addition of CGL not only improved the physical properties but also improved the biological activity of chitosan/fucoidan film (CF). The DPPH and ABTS radical scavenging activity of CF contained 5 wt% CGL was 1.83 and 1.75 times than CF, respectively. The inhibition zone size of CF films containing 5 wt% CGL (CF-5%CGL) was approximately 2.04 (Escherichia coli) and 2.16 (Staphylococcus aureus) times higher than that of CF. Moreover, CF-CGL displayed obvious color changes in different pH environments and is highly sensitive to ammonia gas. The CF-CGL has visible color changes during the monitoring of salmon spoilage and extended the shelf life of salmon. According to our findings, CF-CGL film might be employed as a possible intelligent packaging material for monitoring and preserving salmon in the future.

Functional, Physical, and Volatile Characterization of Chitosan/Starch Food Films Functionalized with Mango Leaf Extract

Active packaging is one of the currently thriving methods to preserve highly perishable foods. Nonetheless, the integration of active substances into the formulation of the packaging may alter their properties-particularly mass transfer properties-and therefore, the active compounds acting. Different formulations of chitosan (CH), starch (ST), and their blends (CH-ST), with the addition of mango leaf extract (MLE) have been polymerized by casting to evaluate their food preservation efficiency. A CH-ST blend with 3% MLE using 7.5 mL of the filmogenic solution proved to be the most effective formulation because of its high bioactivity (ca. 80% and 74% of inhibition growth of S. aureus and E. coli, respectively, and 40% antioxidant capacity). The formulation reduced the water solubility and water vapor permeability while increasing UV protection, properties that provide a better preservation of raspberry fruit after 13 days than the control. Moreover, a novel method of Headspace-Gas Chromatography-Ion Mobility Spectrometry to analyze the volatile profiles of the films is employed, to study the potential modification of the food in contact with the active film. These migrated compounds were shown to be closely related to both the mango extract additions and the film's formulation themselves, showing different fingerprints depending on the film.