Production, characterization, and antimicrobial activity of almond gum/polyvinyl alcohol/chitosan composite films containing thyme essential oil nanoemulsion for extending the shelf-life of chicken breast fillets

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

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

Chitosan/alginate/pectin biopolymer-based Nanoemulsions for improving the shelf life of refrigerated chicken breast

This study investigated the use of nanoemulsions and various polymer coatings to enhance the quality and shelf life of chicken breast. This comprehensive study explored the antibacterial activity of essential oils (EOs) against Escherichia coli and Staphylococcus aureus, as well as the characterization of nanoemulsions (Nes) and nanoemulsion-based coatings. The antimicrobial potential of EOs, such as cinnamon, tea tree, jojoba, thyme, and black cumin seed oil, was evaluated against microorganisms, and thyme oil exhibited the highest inhibitory effect, followed by cinnamon and tea tree oil by disk diffusion analysis. The MIC and MBC values of EOs were found between 0.16-2.5 mg/mL and 0.16-5 mg/mL, respectively, while thyme EO resulted in the lowest values showing its antimicrobial potential. Then, the essential oil nanoemulsions (EONe) and their coatings, formulated with thyme oil, alginate, chitosan, and pectin, were successfully characterized. Optical microscope observations confirmed the uniform distribution of droplets in all (EONe), while particle size analysis demonstrated multimodal droplet size distributions. The EONe-chitosan coating showed the highest efficacy in reducing cooking loss, while the EONe-chitosan, EONe-alginate, and EONe-pectin coatings displayed promising outcomes in preserving color stability. Microbial analysis revealed the significant inhibitory effects of the EONe-chitosan coating against mesophilic bacteria, psychrophilic bacteria, and yeasts, leading to an extended shelf life of chicken breast. These results suggest the potential application of thyme oil and NE-based coatings in various industries for antimicrobial activity and quality preservation.

Effect of clove essential oil nanoemulsion on physicochemical and antioxidant properties of chitosan film

This study evaluated the physicochemical and antioxidant properties of clove essential oil (0, 0.2, 0.4, 0.6, 0.8, 1.0 % v/v) nanoemulsion (CEON) loaded chitosan-based films. With the increasing concentrations of the CEON, the thickness, b* and ΔE values of the films increased significantly (P < 0.05), while L* and light transmission dropped noticeably (P < 0.05). The hydrogen bonds formed between the CEON and chitosan could be demonstrated through Fourier-transform infrared spectra, indicating their good compatibility and intermolecular interactions. Furthermore, the added CEON considerably reduced the crystallinity and resulted in a porous structure of the films, as observed through X-ray diffraction plots and scanning electron microscopy images, respectively. This eventually led to a drop in both tensile strength and moisture content of the films. Moreover, the antioxidant properties were significantly enhanced (P < 0.05) with the increase in the amount of clove essential oil (CEO) due to the encapsulation of CEO by the nanoemulsion. Films containing 0.6 % CEO had higher elongation at break, higher water contact angle, lower water solubility, lower water vapor permeability, and lower oxygen permeability than the other films; therefore, such films are promising for application in meat preservation.

Synergistic effects of thyme and oregano essential oil combinations for enhanced functional properties of sericin/pectin film

This work aimed to assess the synergistic antibacterial effects of thyme and oregano essential oils in various ratios (thyme:oregano; 10:0, 8:2, 6:4, 4:6, 2:8, 10:0). We hypothesized that the synergistic combination of thyme and oregano essential oils can be effectively incorporated into sericin/pectin film to enhance its functional properties. Among the combinations tested, the mixture of thyme/oregano essential oil (TOE) at an 8:2 ratio exhibited the most potent synergistic activity against P. aeruginosa and S. aureus, with fractional inhibitory concentration index (FICindex) of 0.9. In this combination, thymol constituting 51.83 % of TOE (8:2), was the predominant component. TOE at an 8:2 ratio was selected to incorporate into sericin/pectin film. Different concentrations of TOE (0.8 %, 1.2 % and 1.6 %) were applied to evaluate their impact on film properties compared to a film without essential oil (control). It was found that increasing TOE concentration (control; 0 %) to 1.6 % reduced film moisture content (from 21.53 % to 16.91 %), decreased yellowness (from 18.24 to 15.92), diminished gloss (from 63.79 to 11.18), lowered swelling index (from 1.24 to 0.98), and reduced tensile strength (from 9.70 to 4.14 MPa). However, the addition of TOE showed higher film total phenolic content (8.59-31.53 mg gallic acid/g dry sample) and increased antioxidant activity (0.99-3.68 μmol Trolox /g dry sample). Moreover, the film with 1.2 % and 1.6 % of thyme/oregano essential oil exhibited inhibitory effects against all tested bacteria. Therefore, the thyme/oregano essential oil combination can provide the desirable physicochemical properties of the sericin/pectin film, as well as its antibacterial and antioxidant activities, making it a promising alternative for food packaging material applications.

Investigating the effects of chitosan/ tragacanth gum/ polyvinyl alcohol composite coating incorporated with cinnamon essential oil nanoemulsion on safety and quality features of chicken breast fillets during storage in the refrigerator

The present study investigated the effects of composite coatings made of chitosan (CS), tragacanth gum (TG), and polyvinyl alcohol (PVA) containing cinnamon essential oil (CEO) on the shelf-life of refrigerated chicken breast fillets. The samples were treated with different coating dispersions, and coded as: T1 (distilled water as control), T2 (blank composite coating), and T3 (composite coating containing CEO). Results showed that incorporating CEO into CS/TG/PVA coatings could significantly increase the quality of chicken fillets. The obtained results showed that after 21 days, the total microbial population of lactic acid bacteria (LAB), psychrotrophic and mesophilic bacteria in T3 samples was less than T1 and T2 samples. In addition, the highest antioxidant activity (48.04 %) and total phenolic content (TPC) values (2.458 mg gallic acid /g), the best sensory characteristics and the lowest pH (5.73), total volatile basic nitrogen (TVB-N) (21.89 mg N/100 g), thiobarbituric acid reactive substances (TBARS) (1.678 mg malondialdehyde equivalent/kg) and percentage of cooking loss (30 %) were related to T3. Results disclosed that this composite coating is a promising technology to improve the shelf life of chicken fillets during storage.

Development of functional, sustainable pullulan-sodium alginate-based films by incorporating essential oil microemulsion for chilled pork preservation

Developing safe, eco-friendly, and functionally edible packaging materials has attracted global attention. Essential oils, can be incorporated into packaging materials as antioxidant and antibacterial agents. However, their high volatility and discontinuous film matrix issues may cause a rough film surface, limiting the application in food packaging. In this study, thyme essential oil microemulsion (TEO-M) was prepared and incorporated into a pullulan-sodium alginate (PS) film. The TEO-M incorporation endowed the PS film with antioxidant and UV protection properties. The antioxidant activities of the TEO-M-incorporated PS film were significantly better than those of the TEO-C (thyme essential oil coarse emulsion)-incorporated PS film. In comparison to TEO-C, the distribution of TEO-M in the film is more uniform. Lipid oxidation and the growth of microorganisms in chilled pork were inhibited by incorporating TEO-M at a concentration of 50 mg/mL in the PS film (PS-50M). After 10 days of storage at 4 °C, the total viable count (TVC) of chilled pork preserved in the PS-50M material was significantly reduced compared to the control group (P < 0.05). This study shows that incorporating TEO-M in the PS film provides a method for applying essential oils in food packaging, which may have great potential in the food industry.

Production of PVA-chitosan films using green synthesized ZnO NPs enriched with dragon fruit extract envisaging food packaging applications

In this work, the PVA-chitosan composite packaging films doped with biomass-fabricated zinc oxide nanoparticles (ZnO NPs) and dragon fruit waste extract (DFE) were developed for potential use in food packaging applications. ZnO NPs were synthesized using a sustainable method employing C. sinensis waste extract as a reducing agent. Chitosan and PVA were blended in a specific ratio (1: 1 w/w) to obtain a film-forming solution, into which the ZnO NPs and dragon fruit waste extract were incorporated. The resulting solution was cast into films, which were characterized using various analytical techniques. Mechanical properties, water solubility, and thermal stability of the films were also evaluated. The results demonstrated that the incorporation of green ZnO NPs and dragon fruit waste extract enhanced the mechanical strength and thermal stability of the films while reducing water vapor permeability. Moreover, the films exhibited biocidal and excellent 2,2-diphenyl-1-picrylhydrazyl (DPPH) scavenging properties, indicating their use in the food packaging sector. The production of these films offers a practical approach to produce bioactive food packaging materials. The use of plant extract and waste material as reducing agents can reduce the overall cost of production while providing added benefits, such as antioxidant and antibacterial properties.

Antimicrobial Activity of Essential Oils in Vapor Phase In Vitro and Its Application in Combination with Lactic Acid to Improve Chicken Breast Shelf Life

The effect of essential oils (EOs) incorporated in their vapor phase combined with lactic acid immersion pretreatment was studied on fresh refrigerated chicken breast shelf life. Among the several EOs assayed, the in vitro results obtained from the vapor diffusion test allowed mustard, oregano, and garlic EOs to be selected due to their higher antimicrobial activity. In addition, it was possible to determine the EO minimum inhibitory concentrations against Pseudomonas aeruginosa and Escherichia coli and to identify EO binary mixtures showing synergistic or additive effects. Based on the obtained results, a ternary mixture constituted by 0.073, 0.292, and 0.146 µL/mL of headspace of mustard, oregano, and garlic, respectively, was proposed for its application to chicken breasts. The ternary mixture inhibitory action was confirmed in vitro against P. aeruginosa and E. coli. Furthermore, the presence of numerous compounds with recognized antimicrobial and antioxidant activity was found in its volatile phase through gas chromatography. When applying an EO mixture in its vapor phase in combination with 1.0% v/v of lactic acid immersion pretreatment on refrigerated chicken breast, a decrease in mesophilic microorganisms' growth rate as well as in lipid oxidation was observed. Moreover, in a preliminary sensory test, the treated chicken breast was found to be acceptable to consumers and showed no significant differences compared to untreated chicken. In conclusion, the combined use of lactic acid immersion and EOs in their vapor phase was an effective alternative to increase chicken breast shelf life.

The effect of chitosan coating combined with cold plasma on the quality and safety of pistachio during storage

Pistachios are one of the most important agricultural and export products of Iran. Fresh pistachio fruit has soft skin, is highly perishable, and therefore has a short life after harvesting, which has made traders and consumers have a great desire to increase the shelf life of this product. For this purpose, in this study, the effect of different concentrations of chitosan as an edible coating (0.5 and 1.5% w/v) and the duration of cold plasma treatment (60 and 120 s) were investigated during 180 days of pistachio storage. The effect of treatments on the shelf life of pistachio fruit was evaluated by determining moisture content, color components, peroxide value, total mold and yeast, hardness, aflatoxin content, and sensory evaluations. The results showed that the treatment with 1.5% chitosan coating and 120 s of cold plasma treatment preserved the hardness of the pistachio and the color indices in the best way (p < .05). Also, this treatment had the minimum number of peroxide, aflatoxin, and mold and yeast counts during the storage time. The treatments with chitosan coating and under plasma application did not cause any unpleasant odor or taste during the storage time. In conclusion, according to the results of this research, it was determined that the simultaneous use of chitosan coating and cold plasma treatment can potentially be used as a new approach for commercial applications and the export of fresh pistachios.

Chitosan Coating Functionalized with Flaxseed Oil and Green Tea Extract as a Bio-Based Solution for Beef Preservation

Ecological and safe packaging solutions arise as pivotal points in the development of an integrated system for sustainable meat production. The aim of this study was to assess the effect of a combined chitosan (Ch) + green tea extract (GTE) + essential oil (thyme oil, TO; flaxseed oil, FO; or oregano oil, OO) coating on the safety and quality of vacuum-packaged beef during storage at 4 °C. An optimized bio-based coating formulation was selected (2% Ch + 2% GTE + 0.1% FO) to be applied to three fresh beef cuts (shoulder, Sh; knuckle, Kn; Striploin, St) based on its pH (5.8 ± 0.1), contact angle (22.3 ± 0.4°) and rheological parameters (viscosity = 0.05 Pa.s at shear rate > 20 s^-1). Shelf-life analysis showed that the Ch-GTE-FO coating delayed lipid oxidation and reduced total viable counts (TVC) and Enterobacteriaceae growth compared with uncoated beef samples over five days. In addition, Ch-GTE-FO coating decreased total color changes of beef samples (e.g., ∆E* = 9.84 and 3.94, for non-coated and coated Kn samples, respectively) for up to five days. The original textural parameters (hardness, adhesiveness and springiness) of beef cuts were maintained during storage when Ch-GTE-FO coating was applied. Based on the physicochemical and microbial characterization results, the combination of the Ch-GTE-FO coating developed was effective in preserving the quality of fresh beef cuts during refrigerated storage along with vacuum packaging.

Effects of grape seed oil nanoemulsion on physicochemical and antibacterial properties of gelatin‑sodium alginate film blends

The present study aimed to evaluate the impact of incorporating grape seed oil (GSO) nanoemulsion (NE) at varying concentrations into the film matrix on the physicochemical and antimicrobial properties of the resulting films. In this study, ultrasonic treatment was used to prepare GSO-NE, and different levels (2, 4, and 6 %) of nanoemulsioned GSO were incorporated into gelatin (Ge)/sodium alginate (SA)-based films to produce films with improved physical and antibacterial properties. The results revealed that incorporation of GSO-NE at 6 % concentration decreased the tensile strength (TS) and puncture force (PF) significantly (p < 0.05). The whiteness index (WI) of the films decreased from 63.4 to 47.79, while the total color change (ΔE) increased significantly (p < 0.05) with the increase in GSO-NE concentration. Thermogravimetric analysis (TGA) results showed that GSO-NE at different concentrations had improved the thermal stability of Ge/SA-based films. The incorporation of GSO-NE into the films led to the formation of a slightly porous structure. The incorporation of GSO-NE at 4 and 6 % concentrations decreased the water vapor permeability (WVP), moisture content (MC) %, and water solubility (WS) % significantly (p < 0.05). All composite films exhibited hydrophobic surfaces with contact angles θ > 90°. Ge/SA/GSO-NE films were found to be effective against both Gram-positive and Gram-negative bacteria. The prepared active films containing GSO-NE had a high potential for preventing food spoilage in food packaging.