The reduce of water vapor permeability of polysaccharide-based films in food packaging: A comprehensive review

Carboxymethyl cellulose-chitosan edible films for food packaging: A review of recent advances

Polysaccharide-based edible films have been widely developed as food packaging materials in response to the rising environmental concerns caused by the extensive use of plastic packaging. In recent years, the integration of carboxymethyl cellulose (CMC) and chitosan (CS) for a binary edible film has received considerable interest because this binary edible film can retain the advantages of both constituents (e.g., the great oxygen barrier ability of CMC and moderate antimicrobial activity of CS) while mitigating their respective disadvantages (e.g., the low water resistance of CMC and poor mechanical strength of CS). This review aims to present the latest advancements in CMC-CS edible films. The preparation methods and properties of CMC-CS edible films are comprehensively introduced. Potential additives and technologies utilized to enhance the properties are discussed. The applications of CMC-CS edible films on food products are summarized. Literature shows that the current preparation methods for CMC-CS edible film are solvent-casting (main) and thermo-mechanical methods. The CMC-CS binary films have superior properties compared to films made from a single constituent. Moreover, some properties, such as physical strength, antibacterial ability, and antioxidant activity, can be greatly enhanced via the incorporation of some bioactive substances (e.g. essential oils and nanomaterials). To date, several applications of CMC-CS edible films in vegetables, fruits, dry foods, dairy products, and meats have been studied. Overall, CMC-CS edible films are highly promising as food packaging materials.

The impacts of freeze-drying-induced stresses on the quality of meat and aquatic products: Mechanisms and potential solutions to acquire high-quality products

Freeze-drying is a preservation method known for its effectiveness in dehydrating food products while minimizing their deterioration. However, protein denaturation and oxidation during freezing and drying can degrade the quality of meat and aquatic products. Therefore, finding the strategies to ensure the dried products' sensory, functional, and nutritional attributes is crucial. This study aimed to summarize protein denaturation mechanisms and overall quality changes in meat and aquatic products during freezing and drying, while also exploring methods for quality control. Different freeze-drying conditions result in varying levels of oxidation and functionality in meat and aquatic products, leading to changes in quality, such as altered fatty and amino acid compositions, protein digestibility, and sensory attributes. To obtain high-quality dried products by freeze-drying, several parameters should be considered, including sample type, freezing and drying temperatures, moisture content, pulverization effects, and storage conditions.

Preparation and functional characterization of pullulan-sodium alginate composite film enhanced with ultrasound-assisted clove essential oil Nanoemulsions for effective preservation of cherries and mushrooms

Clove essential oil (CEO) exhibited potent antibacterial efficacy and are obtained from Eugenia caryophyllata tree flower buds. Herein, CEO nanoemulsions were prepared using various concentrations of casein protein treated with ultrasound for different time interval. The study demonstrated that CEO nanoemulsions with 5% casein protein subjected to ultrasound for 10 min displayed the most minimal particle size. The pullulan‑sodium alginate film incorporated with nanoemulsions treated with ultrasound exhibited enhanced physico-mechanical characteristics. Based on the structural analysis, the application of ultrasonic treatment improved intermolecular compatibility and organized molecular structure by strengthening hydrogen bonds. Furthermore, the composite film displayed remarkable efficacy against E. coli and S. aureus as well as longer retention of essential oils. The use of the developed films to protect cherry fruits and mushrooms produced promising results, emphasizing their potential in food packaging applications.

Characteristics of corn starch/polyvinyl alcohol composite film with improved flexibility and UV shielding ability by novel approach combining chemical cross-linking and physical blending

With the aim of effectively improving the performance of bio-friendly food packaging and circumventing the hazards associated with petroleum-based plastic food packaging, composite films of corn starch and polyvinyl alcohol were prepared using a new method that involved chemical cross-linking of glutaraldehyde and blending with cinnamon essential oil nanoemulsion (CNE). Glutaraldehyde and CNE enhance the film's network structure by chemical bonding and hydrogen bonding, respectively. This results in improved surface smoothness, mechanical properties, and UV shielding ability of the film. However, the films' surface hydrophilicity increased as a result of CNE, which is harmful for food preservation in high humidity. Overall, glutaraldehyde and CNE have a synergistic effect on some of the properties of the film which is mainly attributed to the films' structure improvement. The films have great potential for preparing flexible and UV-shielding films and offer new ideas for developing biodegradable films.

Enhancement of chitosan-based film physicochemical and storage properties by interaction with proanthocyanidin and natural deep eutectic solvent

Deep eutectic solvent (DES) has been recognized as a promising plasticizer for the preparation of biodegradable food packaging films. In addition, DES-plasticized chitosan (CS) films could also serve as a favorable carrier for loading active components. In this work, a ternary composite film was fabricated by plasticizing chitosan with DES and the active ingredient proanthocyanidin (PA) was used as a cross-linking agent. The incorporation of PAs significantly enhanced the toughness, elasticity, and hydrophobicity of the ternary CS-DES-PA composite films. It achieved antioxidant and bacteriostatic functions. In particular, the ternary CS-DES-PA composite films had a thickness of 0.16 ± 0.01 μm, a tensile strength of 2.63 ± 0.48 MPa, and an elongation about 73.22 %. They also have improved water resistance, UV blocking, with a high-water contact angle of 88.4° and a low water swelling of 5 % on the surface of the film. Meanwhile, the PAs in the film could slow down the browning of litchi fruits. This ternary blended film (CS-DES-PA) achieves better compatibility of the active ingredient in the film-forming substrate. It also provides a green and biodegradable packaging material for food packaging.

Glutaraldehyde crosslinked ternary carboxymethylcellulose/polyvinyl alcohol/polyethyleneimine film with enhanced mechanical properties, water resistance, antibacterial activity, and UV-shielding ability without any UV absorbents

Despite the plethora of methods reported for fabricating ultraviolet (UV) shielding films using various UV absorbers to date, it remains a major challenge for the development of novel UV shielding films that simultaneously exhibit excellent transparency. In this work, a novel composite film (GA-x-CMC/PVA/PEI) is fabricated by integrating anionic carboxymethylcellulose (CMC), cationic polyethyleneimine (PEI), and polyvinyl alcohol (PVA) via electrostatic and hydrogen bond interactions and further cross-linking with glutaraldehyde (GA). Herein, PVA expands hydrogen bonding networks, reduces film haze, and enhances its mechanical strength. GA acts as a crosslinker in producing Schiff bases with PEI and acetals with CMC and PVA. The synthesized GA-x-CMC/PVA/PEI composite film possesses a notable amount of unsaturated -CH=N- bonds of Schiff base, resulting from the condensation of PEI and GA, which exhibit superior shielding efficiency against both UV-A and UV-B rays while maintaining exceptional transparency, visibility, and simultaneously enhancing mechanical properties and thermal stability. Notably, increasing the content of PEI leads to almost complete shielding of the entire UV spectrum (<400 nm) due to the increasing of the number of -CH=N- unsaturated bonds. Furthermore, the obtained film without any UV-shielding additives has exceptional mechanical properties, hydrophobicity, and antibacterial properties, rendering it a wide application prospect.

Chemically tailored graphite oxide nanoparticles for improving material properties of canola protein-based films

Canola protein obtained from canola meal, a byproduct of the canola industry, is an economical biopolymer with promising film-forming properties. It has significant potential for use as a food packaging material, though it possesses some functional limitations that need improvement. Incorporating nanomaterials is an option to enhance functional properties. This study aims to produce canola protein films by integrating GO exfoliated at several oxidation times and weight ratios to optimize mechanical, thermal, and barrier properties. Oxidation alters the C/O ratio and adds functional groups that bond with the amino/carboxyl groups of protein, enhancing the film properties. Significant improvement was obtained in GO at 60 and 120 min oxidation time and 3% addition level. Tensile strength and elastic modulus increased 200% and 481.72%, respectively, compared to control. Control films showed a 37.57 × 10-3 cm3m/m2/day/Pa oxygen permeability, and it was significantly reduced to 5.65 × 10-3 cm3m/m2/day/Pa representing a 665% reduction.

A multifunctional biogenic films and coatings from synergistic aqueous dispersion of wood-derived suberin and cellulose nanofibers

Here, biogenic and multifunctional active food coatings and packaging with UV shielding and antimicrobial properties were structured from the aqueous dispersion of an industrial byproduct, suberin, which was stabilized with amphiphilic cellulose nanofibers (CNF). The dual-functioning CNF, synthesized in a deep eutectic solvent, functioned as an efficient suberin dispersant and reinforcing agent in the packaging design. The nanofibrillar percolation network of CNF provided a steric hindrance against the coalescence of the suberin particles. The low CNF dosage of 0.5 wt% resulted in dispersion with optimal viscosity (208.70 Pa.s), enhanced stability (instability index of <0.001), and reduced particle size (9.37 ± 2.43 μm). The dispersion of suberin and CNF was further converted into self-standing films with superior UV-blocking capability, good thermal stability, improved hydrophobicity (increase in water contact angle from 61° ± 0.15 to 83° ± 5.11), and antimicrobial properties against gram-negative bacteria. Finally, the synergistic bicomponent dispersions were demonstrated as fruit coatings for bananas and packaging for strawberries to promote their self-life. The coatings and packaging considerably mitigated fruit deterioration and improved their freshness by preventing moisture loss and microbial attack. This sustainable approach is expected to pave the way toward advanced, biogenic, and active food packaging based on widely available bioresources.

Preparation of Complex Polysaccharide Gels with Zanthoxylum bungeanum Essential Oil and Their Application in Fish Preservation

In this study, novel functional ZEO-complex gels were prepared using sodium alginate, inulin, grape seed extract (GSE), and Zanthoxylum bungeanum essential oil (ZEO) as the primary raw materials. The effect of the addition of inulin, GSE, and ZEO on water vapor permeability (WVP), tensile strength (TS), and elongation at break (EAB) of ZEO-complex polysaccharide gels was investigated. A comprehensive score (Y) for evaluating the characteristics of ZEO-complex polysaccharide gels was established by principal component analysis. MATLAB analysis and box-Behnken design describe each factor's four-dimensional and three-dimensional interactions. It was found that Y could reach the maximum value when the ZEO addition was at a moderate level (C = 2%). The optimum preparation process of ZEO-complex polysaccharide gels was as follows: the addition of inulin was at 0.84%, the addition of GSE was at 0.04%, and the addition of ZEO was at 2.0785%; in this way, the Y of ZEO-complex polysaccharide gels reached the maximum (0.82276). Optical scanning and X-ray diffraction tests confirmed that the prepared ZEO-complex gels have a smooth and continuous microstructure, good water insulation, and mechanical properties. The storage test results show that ZEO-complex polysaccharide gels could play a significant role in the storage and fresh-keeping of grass carp, and the physicochemical properties of complex polysaccharide gels were improved by adding ZEO. In addition, according to the correlation of fish index changes during storage, adding ZEO in complex polysaccharide gels was closely correlated with the changes in fish TBARS and TVB-N oxidation decay indices. In conclusion, the ZEO-complex polysaccharide gels prepared in this study had excellent water insulation, mechanical properties, and outstanding fresh-keeping effects on grass carp.

Materials based on biodegradable polymers chitosan/gelatin: a review of potential applications

Increased mass manufacturing and the pervasive use of plastics in many facets of daily life have had detrimental effects on the environment. As a result, these worries heighten the possibility of climate change due to the carbon dioxide emissions from burning conventional, non-biodegradable polymers. Accordingly, biodegradable gelatin and chitosan polymers are being created as a sustainable substitute for non-biodegradable polymeric materials in various applications. Chitosan is the only naturally occurring cationic alkaline polysaccharide, a well-known edible polymer derived from chitin. The biological activities of chitosan, such as its antioxidant, anticancer, and antimicrobial qualities, have recently piqued the interest of researchers. Similarly, gelatin is a naturally occurring polymer derived from the hydrolytic breakdown of collagen protein and offers various medicinal advantages owing to its unique amino acid composition. In this review, we present an overview of recent studies focusing on applying chitosan and gelatin polymers in various fields. These include using gelatin and chitosan as food packaging, antioxidants and antimicrobial properties, properties encapsulating biologically active substances, tissue engineering, microencapsulation technology, water treatment, and drug delivery. This review emphasizes the significance of investigating sustainable options for non-biodegradable plastics. It showcases the diverse uses of gelatin and chitosan polymers in tackling environmental issues and driving progress across different industries.

The urchin-like gold nanoparticles/poly(ε-caprolactone)/chitosan electrospun nanofibers for antibacterial active packaging

Inspired by the natural antimicrobial effect of the topographical features of insect wings, this study prepared urchin-like gold nanoparticles (UGNPs) and deposited them on poly(ε-caprolactone) (PCL)/chitosan (P/C) electrospun nanofiber film to strengthen antibacterial activities of this active packaging. Results showed that L-Dopa was a suitable reducing agent to prepare UGNPs, and the spine length of UGNPs increased from 21.23 to 35.83 nm as the molar ratio of L-Dopa:HAuCl4 increased from 1 to 3. As the nanofiber film was immersed in the nanoparticle solution for a longer time, the UGNP content in P/C nanofibers increased. As the spine length of UGNPs and depositing UGNP content increased, the inhibition rate against S. aureus and E. coli. of P/C nanofiber film increased. In addition, P/C nanofiber film deposited with UGNPs also exhibited good thermal stability, hydrophilicity, mechanical strength, and water vapor permeability, exhibiting its potential as an antibacterial active packaging.

Electrospun Photodynamic Antibacterial Konjac Glucomannan/Polyvinylpyrrolidone Nanofibers Incorporated with Lignin-Zinc Oxide Nanoparticles and Curcumin for Food Packaging

Due to the growing concerns surrounding microbial contamination and food safety, there has been a surge of interest in fabricating novel food packaging with highly efficient antibacterial activity. Herein, we describe novel photodynamic antibacterial konjac glucomannan (KGM)/polyvinylpyrrolidone (PVP) nanofibers incorporated with lignin-zinc oxide composite nanoparticles (L-ZnONPs) and curcumin (Cur) via electrospinning technology. The resulting KGM/PVP/Cur/L-ZnONPs nanofibers exhibited favorable hydrophobic properties (water contact angle: 118.1°), thermal stability, and flexibility (elongation at break: 241.9%). Notably, the inclusion of L-ZnONPs and Cur endowed the nanofibers with remarkable antioxidant (ABTS radical scavenging activity: 98.1%) and photodynamic antimicrobial properties, demonstrating enhanced inhibitory effect against both Staphylococcus aureus (inhibition: 12.4 mm) and Escherichia coli (12.1 mm). As a proof-of-concept study, we evaluated the feasibility of applying nanofibers to fresh strawberries, and the findings demonstrated that our nanofibers could delay strawberry spoilage and inhibit microbial growth. This photodynamic antimicrobial approach holds promise for design of highly efficient antibacterial food packaging, thereby contributing to enhanced food safety and quality assurance.

Recent progress on Pickering emulsion stabilized essential oil added biopolymer-based film for food packaging applications: A review

Nowadays food safety and protection are a growing concern for food producers and food industry. The stability of food-grade materials is key in food processing and shelf life. Pickering emulsions (PEs) have gained significant attention in food regimes owing to their stability enhancement of food specimens. PE can be developed by high and low-energy methods. The use of PE in the food sector is completely safe as it uses solid biodegradable particles to stabilize the oil in water and it also acts as an excellent carrier of essential oils (EOs). EOs are useful functional ingredients, the inclusion of EOs in the packaging film or coating formulation significantly helps in the improvement of the shelf life of the packed food item. The highly volatile nature, limited solubility and ease of oxidation in light of EOs restricts their direct use in packaging. In this context, the use of PEs of EOs is suitable to overcome most of the challenges, Therefore, recently there have been many papers published on PEs of EOs including active packaging film and coatings and the obtained results are promising. The current review amalgamates these studies to inform about the chemistry of PEs followed by types of stabilizers, factors affecting the stability and different high and low-energy manufacturing methods. Finally, the review summarizes the recent advancement in PEs-added packaging film and their application in the enhancement of shelf life of food.

Schiff base linkage of citral to zinc-casein hydrolysate chelates for preparing starch-based active films against L. monocytogenes on ready-to-eat foods

Listeria monocytogenes (L. monocytogenes) is a foodborne pathogen often found in ready-to-eat (RTE) foods, posing significant threats to human health. In this study, an active film based on cross-linking via Schiff base and electrostatic interaction to inactivate L. monocytogenes on RTE foods was constructed. Zinc-casein hydrolysate chelates (Zn-HCas) was prepared and blended with cationic starch (CSt) to form the substrates of the film. Then, Citral (CI) with excellent antibacterial properties was added to enhance the biological and packaging properties of the film through covalent cross-linking (Schiff base). Based on the zinc ion-activated metalloproteinases produced by L. monocytogenes, the cross-linked film could be disrupted and the release of CI was accelerated. The variation in color, FTIR, and amino group content proved that Schiff base reaction had taken place. Enhanced mechanical properties, barrier properties, thermal stability and antimicrobial activity against L. monocytogenes (exceed 99.99 %) were obtained from the CI/Zn-HCas/CSt film. The application on RTE cheese results demonstrated that the cross-linked film could be employed in active packaging field with the ability in maintaining the original chroma and texture properties of RTE cheese. In summary, the prepared cross-linked film could be used as an active packaging against L. monocytogenes contamination with great potential.

Fabrication, characterization, and application of pea protein-based edible film enhanced by oregano essential oil (OEO) micro- or nano-emulsion

Pea protein isolate (PPI)-based active films were prepared by incorporating 0.5 %, 1.0 %, or 2.0 % of oregano essential oil (OEO), either in the form of micro-emulsion (MOEO) or nano-emulsion (NOEO). The particle size and polydispersity index of OEO droplets were 2755.00 nm and 0.63 for MOEO, and 256.30 nm and 0.20 for NOEO. The surface and cross-sectional SEM results revealed the presence of holes and internal pores within the film upon the addition of OEO. The molecular interaction between PPI and OEO was confirmed by FTIR. The addition of OEO significantly increased film thickness, decreased water contact angle, and imparted a more yellow color. At a low concentration (0.5 %), the addition of OEO significantly improved the water vapor barrier and mechanical properties of the film. However, at higher concentrations, these film properties were significantly weakened. Additionally, the film antimicrobial properties were assessed after OEO addition. In vitro inhibition zone results indicated that a 2.0 % addition of OEO significantly suppressed the growth of three Salmonella strains [Salmonella Typhimurium (ATCC14028), Salmonella Infantis 94-1, and Salmonella Enteritidis PT-30]. Application of pea protein-based film with 2.0 % OEO on chicken breast demonstrated significant reduction in microbial count. Our results further showed that reducing the particle size of OEO from micrometer-scale to nanometer-scale in the PPI film matrix did not significantly alter film properties or antimicrobial activities. The study demonstrated that the antibacterial film based on pea protein and OEO is an innovative food packing material for prohibiting bacteria growth on poultry products.

Sodium alginate/carboxymethyl cellulose films embedded with liposomes encapsulated green tea extract: characterization, controlled release, application

To maintain the freshness of the fruit during storage, sodium alginate/carboxymethyl cellulose films embedded with pH-senstive liposomes encapsulated green tea extract were developed (SA/CMC/TP-Lip). An orthogonal design was used to optimise the preparation of TP-Lip and SA/CMC/TP-Lip was prepared through response surface. The stability of TP-Lip structure was measured. The morphology of SA/CMC/TP-Lip was characterised by SEM, and the mechanical properties and oxidation resistance of films were measured. Special attention was paid to the pH sensitivity of TP-Lip and the improvement of film properties. The zeta potential and encapsulation rate of TP-Lip were -45.85 ± 2.13 mV and 61.45 ± 0.23%. The average release rate of TP encapsulated into TP-Lip at pH 3 was 41.08%, an increase of 23.07% over pH 6 during 12 h. SEM and FTIR showed that TP-Lip was structurally stable and had good compatibility with SA/CMC. Tensile strength was increased by 30.55% and DPPH radical scavenging capacity was increased by 7.16% with the addition of TP-Lip. SA/CMC/TP-Lip is applied to blueberries to reduce their weight loss and improve the loss of freshness of blueberries during storage. Thus, SA/CMC/TP-Lip could provide a new way to extend active packaging materials and maintain fruit freshness during storage.