Preparation and functional properties of fish gelatin–chitosan blend edible films

Optimization of the extraction of duckweed protein and its application as an antioxidant composite membrane in blueberry preservation

In this paper, response surface methodology (RSM) was used to optimize the extraction process of proteins from duckweed and the protein extraction rate was increased to 24.11 ± 0.04 %. The duckweed protein extract (DP) was mixed with sodium carboxymethyl cellulose (CMC) and glycerol to prepare DP/CMC antioxidant membranes with different additions (0.5 % ∼ 2.5 %), and 2.0 % DP/CMC antioxidant membranes were used in blueberry preservation experiments. The results showed that the moisture permeability of DP/CMC antioxidant membrane was significantly reduced, the thermal stability was significantly improved, and the antioxidant property was significantly higher than that of CMC membrane (p < 0.05). The lowest oxygen content in the 2.0 % DP/CMC membrane package compared to PE and CMC membranes may be due to the synergistic effect of aerobic respiration of blueberries and oxidation of antioxidants in the membrane, under which the loss of antioxidants in the blueberries was lowest and the quality of blueberries was effectively maintained. In this study, for the first time, antioxidant membranes with significant freshness preservation effects were prepared using duckweed protein extract (DP), demonstrating its great potential as an active packaging material for food preservation, and opening up a new development direction for the application of DP.

Green synthesis of silver nanoparticles using persimmon polysaccharides for enhanced polysaccharide-based film performance

Herein, the polysaccharide-based film was prepared by using persimmon polysaccharides extraction (PPE) and sodium alginate (SA) with the synthesized silver nanoparticles (AgNPs). Firstly, PPE was used as reducing and stabilizing agents for the green synthesis of PPE-AgNPs for the first time. The synthesized AgNPs had face-centered-cubic crystal structure with an average particle size of 55.88 nm. Also, the synthesized AgNPs solution exhibited superior dispersion with yellow-brown, and showed excellent antimicrobial activity (p < 0.05). Then, with incorporating AgNPs, the SA-PPE-AgNPs film showed excellent performance, the tensile strength (TS) and elongation at break (EAB) reached 18.24 MPa and 21.94 %, the water vapor permeability (WVP) decreased to 4.91 × 10-11 g·m-1·s-1 Pa-1, and significantly improved UV-vis barrier property. Moreover, the SA-PPE-AgNPs film showed excellent antibacterial activities (p < 0.05) against Escherichia coli, Staphylococcus aureus, Saccharomyces cerevisiae and Aspergillus niger, with the highest antibacterial activity against Escherichia coli (inhibition zone diameter for 16.92 ± 0.14 mm). Preservation tests on sugar oranges showed that the SA-PPE-AgNPs coating treatment maintained the good appearance and color, slowed down the loss of weight (8.34 %), firmness (8.58 N), titratable acid (decreased by 30.23 %) and total soluble solids content (decreased by 10.46 %), and kept the stability of pH (4.26) and Vitamin C (Vc) (decreased by 17.51 %) during the storage period. In summary, SA-PPE-AgNPs film was an effective method for maintaining fruit freshness instead of the traditional films.

Sustainable UV absorbing bio-plastic films by valorisation of humins and chitosan

Humins, an inevitable bio-refinery waste by-product of sugar dehydration have been efficiently utilized for the first time for developing biodegradable thin films for UV shielding. The films were prepared from chitosan, and humins, a novel combination, aiming towards simultaneous utilization of marine and bio-refinery waste, rendering simple, effective, robust UV absorbing films. The structure-activity relationship of these films were elucidated with the help of different analytical techniques like X-ray diffraction, Fourier transform infrared spectroscopy, Thermogravimetric analysis, UV-vis spectroscopy, Atomic force microscopy, Scanning electron microscopy, Tensile testing, Contact angle measurements and water absorption studies. Intrinsic biodegradability was studied using fungi i.e. Aspergillus niger. Different feedstocks (corncob, rice husk, glucose and xylose) were explored for generating humins. Amongst them, humins derived from xylose were utilized for the preparation of the bio-plastic films of chitosan. The results revealed that, addition of 5.0 % humins was observed to be an optimum concentration yielding films with excellent UV absorption, mechanical properties, and biodegradability. The current work is in perfect alignment with sustainability and green chemistry as it ameliorates waste valorization (lignocellulosic and marine altogether). Further, its innovation stems from the first-hand use of humins for UV absorption, novel combination of biopolymers, use of green raw materials.

In situ synthesis of HKUST-1 on copper-ammonia fiber for preparation of quaternary-ammonium chitosan based active packaging with sustained-release cinnamaldehyde

Cinnamaldehyde (CIN) is gaining interest as a highly effective natural antimicrobial agent to extend the shelf life of fruits. However, its inherent instability limits further applications. In this work, a new strategy for the synthesis of HKUST-1 to encapsulate CINs by in situ growth method using copper-ammonia fiber as precursors is proposed. Subsequently, combining it with chitosan quaternary ammonium salt (CQAS) to formulate chitosan quaternary ammonium salt/copper-ammonia fiber@HKUST-1/cinnamaldehyde (CCAHC) packaging film. Based on copper-ammonia fiber to prepared HKUST-1, on the one hand, it has excellent compatibility with CQAS and improves the mechanical properties of the film. On the other hand, its porous structure also encapsulates CIN and significantly improves the stability of CIN (203h). Benefiting from the sustained release of CIN and Cu2+ from HKUST-1, CCAHC film not only exhibited long-lasting antimicrobial activity (12 days, 95 %), which was effective in prolonging the shelf life of strawberries, but also excellent antioxidant properties (20 h, 84 %), which maintained the good appearance of fresh-cut apples (over 14 h). Moreover, CCAHC films exhibited the great degradability in the soli, which promised it becoming a green packaging material. Therefore, this work provides an innovative method for designing CIN encapsulation and preparing bioactive packaging films.

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Research background

Nowadays, there is a growing interest in active packaging with the addition of natural extracts due to safety concerns and consumer preferences. Physalis angulata is a medicinal and edible species of the Solanaceae family and is rich in phenolic compounds. Phenolic compounds, the secondary metabolites, are synthesised and stored in all plant tissues. They can be used as plasticizers or fillers to improve the interfacial interaction between the two biopolymers and prevent the transfer of moisture and gas from the food product and extend the shelf life to some degree.

Experimental approach

The effect of a three-layer (P/G/B) film based on polylactic acid (P), gelatine (G) and polybutylene adipate-co-terephthalate (B) incorporated or not with Physalis leaf extract (PLE) on the quality changes of fish meat powder (sample) stored at 27-30 °C (30 days) was investigated in comparison with control (uncovered), polyethylene (PE), polylactic acid, polybutylene adipate-co-terephthalate and gelatine films. The samples were sealed in a cylindrical bottle covered with the prepared films. The storage properties such as moisture content, pH, peroxide value (PV), thiobarbituric acid reactive substances (TBARS), total volatile basic nitrogen (TVB-N), changes in colour, sensory properties and volatile compounds of samples packed with the developed films were analysed.

Results and conclusions

The moisture content was lower in the sample covered with the P/G/B-PLE-7 % film throughout the storage period. However, the sample covered with PE film had the highest PV (p<0.05). TBARS, TVB-N and volatile compounds decreased in the sample covered with P/G/B-PLE-7 % on day 30 of storage. The incorporation of Physalis leaf extract into the three-layer film improved the properties of the film and extended the shelf life of fish meat powder. Thus, the addition of Physalis leaf extract to the three-layer film could serve as a biodegradable active packaging and be a promising substitute for commercial plastic films.

Novelty and scientific contribution

This is the first report on the study of chemical changes of fish meat powder covered with a three-layer (P/G/B) film incorporated with Physalis leaf extract. This will lead to a better understanding of the role of the three-layer (P/G/B) film containing Physalis leaf extract on the extension of shelf life of fish meat powder.

Characterization and antibacterial activity of cellulose extracted from Washingtonia robusta and Phoenix dactylifera L. impregnated with eugenol: Promising wound dressing

This paper aimed to valorize two varieties of date palm mesh, Washingtonia robusta (S1) and Phoenix Dactylifera L. (S2) by extracting their fibrous cellulose structures for potential application in wound dressings. The extracted fibrous dressings were analyzed by using Fourier Transforms Infrareded (FTIR), X-ray diffraction (XRD), and Scanning Electron Microscopy (SEM). Additionally, mechanical properties, water absorption, and antimicrobial activity were analyzed. The results showed that S2 contained significantly higher fiber content (37.21 %) compared to S1 (12.63 %). FTIR analysis confirmed successful cellulose extraction from both palm varieties. SEM images showed that S1 fibers had a smooth-surface with smaller pores, contributing to a higher absorption capacity of 1289 ± 93 %. Therefore, S2 exhibited rougher-surfaced fibers, which enhanced its mechanical properties, as demonstrated by stress-strain tensile tests, and Young's modulus. Notably, S2 revealed superior mechanical strength compared to S1 fiber dressings. Water absorption for S2 was calculated at 509 ± 93 %. Both S1 and S2 exhibited high crystalline index (61.17 % and 62.88 %), with crystalline size of 3.54 nm for S1 and 10.03 nm for S2. Finally, Eugenol-enriched fibers showed significant activity against E. coli (3.8 mm and 2.3 mm), S. aureus (4.00 mm and 2.05 mm), and S. epidermidis (2.7 mm and 1.6 mm) for S1 and S2, respectively, suggesting their potential as effective new wound dressing materials.

Photo-responsive Cu-tannic acid nanoparticle-mediated antibacterial film for efficient preservation of strawberries

The existing films used for fruit preservation suffer from insufficient preservation abilities. This study introduces Cu-tannic acid (Cu-TA) nanoparticles, synthesized from tannic acid (TA) and Cu2+, to enhance food packaging properties. Integrated into a chitosan-gelatin (CG) matrix, the resultant Cu-TA nanocomposite films exhibit superior antibacterial efficacy and killing rates of Escherichia coli and Staphylococcus aureus more than 99 %, and double the shelf life of strawberries, underscoring the exceptional freshness preservation capabilities of film. Additionally, the tensile strength of the Cu-TA nanocomposite films increased by 1.75 times, the DPPH radical scavenging percentage increased from 29.4 % to 68.4 %, and the water vapor permeability (WVP) decreased by about 60 % compared to the pure CG films. Comprehensive cytotoxicity and migration assessments confirm the safety of film, paving the way for their application in food packaging. The excellent performance of the Cu-TA nanocomposite films positions them as a formidable solution for protecting perishable food items.

Enhancement of Biopolymer Film Properties Using Spermidine, Zinc Oxide, and Graphene Oxide Nanoparticles: A Study of Physical, Thermal, and Mechanical Characteristics

One of the main limitations of biopolymers compared to petroleum-based polymers is their weak mechanical and physical properties. Recent improvements focused on surmounting these constraints by integrating nanoparticles into biopolymer films to improve their efficacy. This study aimed to improve the properties of gelatin-chitosan-based biopolymer layers using zinc oxide (ZnO) and graphene oxide (GO) nanoparticles combined with spermidine to enhance their mechanical, physical, and thermal properties. The results show that adding ZnO and GO nanoparticles increased the tensile strength of the layers from 9.203 MPa to 17.787 MPa in films containing graphene oxide and zinc oxide, although the elongation at break decreased. The incorporation of nanoparticles reduced the water vapor permeability from 0.164 to 0.149 (g.m-2.24 h-1). Moreover, the transparency of the layers ranged from 72.67% to 86.17%, decreasing with higher nanoparticle concentrations. The use of nanoparticles enhanced the light-blocking characteristics of the films, making them appropriate for the preservation of light-sensitive food items. The thermal properties improved with an increase in the melting temperature (Tm) up to 115.5 °C and enhanced the thermal stability in the nanoparticle-containing samples. FTIR analysis confirmed the successful integration of all components within the films. In general, the combination of gelatin and chitosan, along with ZnO, GO, and spermidine, significantly enhanced the properties of the layers, making them stronger and more suitable for biodegradable packaging applications.

Self-Assembled Hydrogel Based on (Bio)polyelectrolyte Complex of Chitosan-Gelatin: Effect of Composition on Physicochemical Properties

Taking into account the trends in the field of green chemistry and the desire to use natural materials in biomedical applications, (bio)polyelectrolyte complexes ((bio)PECs) based on a mixture of chitosan and gelatin seem to be relevant systems. Using the approach of self-assembly from the dispersion of the coacervate phase of a (bio)PEC at different ratios of ionized functional groups of chitosan and gelatin (z), hydrogels with increased resistance to mechanical deformations and resorption in liquid media were obtained in this work in comparison to a hydrogel from gelatin. It was found that at z ≥ 1 a four-fold increase in the elastic modulus of the hydrogel occurred in comparison to a hydrogel based on gelatin. It was shown that hydrogels at z ≈ 1 had an increased sorption capacity and water sorption rate, as well as increased resistance to the in vitro model environment of phosphate-buffered saline (PBS) solution containing lysozyme at 37 °C. It was also shown that in PBS and simulated gastric fluid (SGF) solutions, the effect of the polyelectrolyte swelling of the hydrogels was significantly suppressed; however, at z ≥ 1, the (bio)PEC hydrogels had increased stability compared to the samples at z < 1 and based on gelatin.

The Effect of Cellulose Nanocrystals on the Molecular Organization, Thermomechanical, and Shape Memory Properties of Gelatin-Matrix Composite Films

Gelatin is a natural hydrocolloid with excellent film-forming properties, high processability, and tremendous potential in the field of edible coatings and food packaging. However, its reinforcing by materials such as cellulose nanocrystals (CNC) is often necessary to improve its mechanical behavior, including shape memory properties. Since the interaction between these polymers is complex and its mechanism still remains unclear, this work aimed to study the effect of low concentrations of CNC (2, 6, and 10 weight%) on the molecular organization, thermomechanical, and shape memory properties in mammalian gelatin-based composite films at low moisture content (~10 weight% dry base). The results showed that the presence of CNCs (with type I and type II crystals) interfered with the formation of the gelatin triple helix, with a decrease from 21.7% crystallinity to 12% in samples with 10% CNC but increasing the overall crystallinity (from 21.7% to 22.6% in samples with 10% CNC), which produced a decrease in the water monolayer in the composites. These changes in crystallinity also impacted significantly their mechanical properties, with higher E' values (from 1 × 104 to 1.3 × 104 Pa at 20 °C) and improved thermal stability at higher CNC content. Additionally, the evaluation of their shape memory properties indicated that while molecular interactions between the two components occur, CNCs negatively impacted the magnitude and kinetics of the shape recovery of the composites (more particularly at 10 weight% CNC, reducing shape recovery from 90% to 70%) by reducing the netting point associated with the lower crystallinity of the gelatin. We believe that our results contribute in elucidating the interactions of gelatin-CNC composites at various structural levels and highlights that even though CNC acts as a reinforcement material on gelatin matrices, their interaction are complex and do not imply synergism in their properties. Further investigation is, however, needed to understand CNC-gelatin interfacial interactions with the aim of modulating their interactions depending on their desired application.

Changes in the properties of the corn starch glycerol film in a time-dependent manner during gelatinization

This study aimed to investigate the fundamental properties, solubility, mechanical properties, barrier performance, and microstructural features of films composed of corn starch and glycerol. Changes in the microstructure were analyzed to understand how they relate to the physical and chemical properties of these films. Specifically, we found that increasing the gelatinization time decreased the film thickness, solubility, water vapor permeability, and maximum degradation temperature and increased the water content. A gradual increase in the water contact angle of the corn starch-glycerol films was observed with increasing gelatinization time. This trend is likely due to the disruptive effect of gelatinization on the crystalline and amorphous structures inherent in corn starch, resulting in reduced film crystallinity, degree of order (DO) and degree of double helix (DD).

Gelatin-chitosan interactions in edible films and coatings doped with plant extracts for biopreservation of fresh tuna fish products: A review

The preservation of tuna fish products, which are extremely perishable seafood items, is a substantial challenge due to their instantaneous spoilage caused by microbial development and oxidative degradation. The current review explores the potential of employing chitosan-gelatin-based edible films and coatings, which are enriched with plant extracts, as a sustainable method to prolong the shelf life of tuna fish products. The article provides a comprehensive overview of the physicochemical properties of chitosan and gelatin, emphasizing the molecular interactions that underpin the formation and functionality of these biopolymer-based films and coatings. The synergistic effects of combining chitosan and gelatin are explored, particularly in terms of improving the mechanical strength, barrier properties, and bioactivity of the films. Furthermore, the application of botanical extracts, which include high levels of antioxidants and antibacterial compounds, is being investigated in terms of their capacity to augment the protective characteristics of the films. The study also emphasizes current advancements in utilizing these composite films and coatings for tuna fish products, with a specific focus on their effectiveness in preventing microbiological spoilage, decreasing lipid oxidation, and maintaining sensory qualities throughout storage. Moreover, the current investigation explores the molecular interactions associated with chitosan-gelatin packaging systems enriched with plant extracts, offering valuable insights for improving the design of edible films and coatings and suggesting future research directions to enhance their effectiveness in seafood preservation. Ultimately, the review underscores the potential of chitosan-gelatin-based films and coatings as a promising, eco-friendly alternative to conventional packaging methods, contributing to the sustainability of the seafood industry.

Fabrication and characterization of carvacrol encapsulated gelatin/chitosan composite nanofiber membrane as active packaging material

In this study, carvacrol was effectively encapsulated in gelatin/chitosan composite nanofiber membrane using the electrospinning method with the help of the cationic surfactant cetyltrimethylammonium bromide (CTAB). The effects of CTAB (0.0%, 1.0%, w/w) and bioactive carvacrol (0.0%, 1.0%, 3.0%, 5.0%, 7.0%, 10.0%, w/w) on the structural, physicomechanical, antibacterial, and antioxidant characteristics of the nanofiber membranes were investigated. The results demonstrated that the antibacterial and antioxidant characteristics of the gelatin/chitosan composite nanofiber membrane (GC) and GC-CAR membrane (with the addition of 1.0% carvacrol) were unsatisfactory. As carvacrol and CTAB were both added, the elongation at break, antibacterial, and antioxidant properties of the nanofiber membranes significantly improved (p < 0.05), while the water vapor permeability (WVP) significantly decreased (p < 0.05). When the added amount of carvacrol was 5.0% (w/w), the nanofiber membrane (GC-CAR5-CTAB) exhibited the best antioxidant and antibacterial performance. Finally, the GC-CAR5-CTAB membrane was applied to the preservation of strawberries and Erjingtiao chilies, and their shelf life was effectively extended. The above results indicate that the nanofiber membrane prepared in this study has great potential for application in food-active packaging.

Preparation of citric acid cross-linked chitosan quaternary phosphonium/polyvinyl alcohol composite film and its application in strawberry preservation

Chitosan quaternary phosphine salts (NPCS) were synthesized with enhanced antimicrobial properties using a two-step method. Composite films (CNSP) were prepared by incorporating NPCS and polyvinyl alcohol (PVA) as the base material, citric acid as the crosslinker and functional additive, exhibiting antibacterial and UV-blocking properties. The composite film showed a maximum tensile strength of 20.4 MPa, an elongation at break of 677%, and a UV light barrier transmittance of 70%. Application of these composite membranes in preserving strawberries demonstrated effectiveness in maintaining freshness by preventing water loss, inhibiting microbial growth, and extending shelf life. In addition, the composite film demonstrated biosafety. These results indicate that CNSP composite films holds significant promise for safe and sustainable food packaging applications.

Insights into the effect of carboxylated cellulose nanocrystals on mechanical and barrier properties of gelatin films for flexible packaging applications

In this study, gelatin/carboxylated cellulose nanocrystal (cCNC) bionanocomposite films were developed as an eco-friendly alternative to non-biodegradable flexible plastic packaging. Cellulose nanocrystals were modified by 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO)-mediated oxidation (cCNC) to strategically interact with amino groups present in the gelatin macromolecular backbone. Gelatin/cCNC bionanocomposite films (0.5-6.0 wt% cCNC) obtained by solution casting were transparent to visible light while displayed high UV-blocking properties. The chemical compatibility between gelatin and cCNC was deepened by electrostatic COO-/NH3+ interactions, as detected by FTIR spectroscopy and morphologically indicated by scanning electron microscopy (SEM). Accordingly, Young's modulus and tensile strength of films were largely increased by 80 and 64 %, respectively, specifically near the cCNC percolation threshold (4 wt%), whereas the water vapor permeability (WVP) was reduced by 52 % at the optimum 6.0 wt% cCNC content in relation to the non-reinforced gelatin matrix (0.10 vs. 0.18 g H2O mm m-2 h-1 kPa-1). The oxygen transmission rates (OTR) of the gelatin/cCNC bionanocomposites were < 0.01 cm3 m-2 day-1, making them technically competitive to most promising biopolymers like polycaprolactone (PCL) and poly(lactic acid) (PLA). This study reveals how TEMPO-oxidized cellulose nanocrystals can broaden the performance of biodegradable gelatin films for use in packaging. The gelatin/cCNC bionanocomposites also represent an effective approach for designing newly sustainability-inspired flexible materials from the surface modification of nanocelluloses targeting specific interactions with protein structures.

Development of ultra-thin poly(L-lactic acid)-based films integrating toughness, barrier properties, and gas selectivity: Towards gas-permeation controllable green food packaging

High costs and low performance have constrained the application of bio-based materials in food packaging. Herein, a series of ultra-thin poly(L-lactic acid-iconic acid N-diol) (P(LA-NI)) copolymer films were developed using a "one-step" polycondensation process with integrated toughness, barrier properties, gas selectivity, and quality control features. The massive branched structure and gg conformers in P(LA-NI) act as "internal chain expansion" and "internal plasticization". Meanwhile, P(LA-NI) contains numerous polar groups and unique nanoscale microphase structures to realize excellent CO2, O2 barrier, CO2/O2 selectivity, anti-fogging, and UV shielding functions. The atmosphere within the package spontaneously achieves the desirable low O2 and high CO2 levels when packaging button mushrooms with high respiratory metabolism. Eventually, the shelf life of button mushrooms reached 24 days, >3-fold extended. This PLLA-based film meets "dual carbon" and "food safety" goals and has vast potential for fresh food preservation.

Production and performance evaluation of chitosan/collagen/honey nanofibrous membranes for wound dressing applications

Persistent bacterial infections are the leading risk factor that complicates the healing of chronic wounds. In this work, we formulate mixtures of polyvinyl alcohol (P), chitosan (CH), collagen (C), and honey (H) to produce nanofibrous membranes with healing properties. The honey effect at concentrations of 0 % (PCH and PCHC), 5 % (PCHC-5H), 10 % (PCHC-10H), and 15 % (PCHC-15H) on the physicochemical, antibacterial, and biological properties of the developed nanofibers was investigated. Morphological analysis by SEM demonstrated that PCH and PCHC nanofibers had a uniform and homogeneous distribution on their surfaces. However, the increase in honey content increased the fiber diameter (118.11-420.10) and drastically reduced the porosity of the membranes (15.79-92.62 nm). The addition of honey reduces the water vapor transmission rate (WVTR) and the adsorption properties of the membranes. Mechanical tests revealed that nanofibers were more flexible and elastic when honey was added, specifically the PCHC-15H nanofibers with the lowest modulus of elasticity (15 MPa) and the highest elongation at break (220 %). Also, honey significantly improved the antibacterial efficiency of the nanofibers, mainly PCHC-15H nanofibers, which presented the best bacterial reduction rates against Staphylococcus aureus (59.84 %), Pseudomonas aeruginosa (47.27 %), Escherichia coli (65.07 %), and Listeria monocytogenes (49.58 %). In vitro tests with cell cultures suggest that nanofibers were not cytotoxic and exhibited excellent biocompatibility with human fibroblasts (HFb) and keratinocytes (HaCaT), since all treatments showed higher or similar cell viability as opposed to the cell control. Based on the findings, PVA-chitosan-collagen-honey nanofibrous membranes have promise as an antibacterial dressing substitute.

Influence of Crosslinking Concentration on the Properties of Biodegradable Modified Cassava Starch-Based Films for Packaging Applications

Chitosan/modified cassava starch/curcumin (CS/S/Cur) films with a crosslinker were developed via the solvent casting technique for the application of food packaging. The effects of citric acid (CA) as a natural crosslinker were assessed at different concentrations (0-10.0%, w/w, on a dry base on CS and S content). To measure the most favorable film, chemical structure and physical, mechanical, and thermal properties were investigated. Successful crosslinking between CS and S was seen clearly in the Fourier Transform Infrared (FTIR) spectra. The properties of the water resistance of the CS/S/Cur films crosslinked with CA were enhanced when compared to those without CA. Furthermore, it was found that the addition of CA crosslinking would improve the mechanical properties of composite films to some extent. It had been reported that the CA crosslinking level of 7.5 wt% of CS/S/Cur film demonstrated high performance in terms of physical properties. The tensile strength of the crosslinked film increased from 8 ± 1 MPa to 12 ± 1 MPa with the increasing content of CA, while water vapor permeability (WVP), swelling degree (SD), and water solubility (WS) decreased. An effective antioxidant scavenging activity of the CS/S/Cur film decreased with an increase in CA concentrations. This study provides an effective pathway for the development of active films based on polysaccharide-based film for food packaging applications.

Insights into recent innovations in barrier resistance of edible films for food packaging applications

The utilization of biopolymer-based food packaging holds significant promise in aligning with sustainability goals and enhancing food safety by offering a renewable, biodegradable, and safer alternative to traditional synthetic polymers. However, these biopolymer-derived films often exhibit poor barrier and mechanical properties, potentially limiting their commercial viability. Desirable barrier properties, such as moisture and oxygen resistance, are critical for preserving and maintaining the quality of packaged food products. This review comprehensively explores different traditional and advance methodologies employed to access the barrier properties of edible films. Additionally, this review thoroughly examines various approaches aimed at enhancing the barrier properties of edible films, such as the fabrication of multilayer films, the selection of biopolymers for composite films, as well as the integration of plasticizers, crosslinkers, hydrophobic agents, and nanocomposites. Moreover, the influence of process conditions, such as preparation techniques, homogenization, drying conditions, and rheological behavior, on the barrier properties of edible films has been discussed. The review provides valuable insights and knowledge for researchers and industry professionals to advance the use of biopolymer-based packaging materials and contribute to a more sustainable and food-safe future.

Natural blackcurrant extract contained gelatin hydrogel with photothermal and antioxidant properties for infected burn wound healing

Burns represent a prevalent global health concern and are particularly susceptible to bacterial infections. Severe infections may lead to serious complications, posing a life-threatening risk. Near-infrared (NIR)-assisted photothermal antibacterial combined with antioxidant hydrogel has shown significant potential in the healing of infected wounds. However, existing photothermal agents are typically metal-based, complicated to synthesize, or pose biosafety hazards. In this study, we utilized plant-derived blackcurrant extract (B) as a natural source for both photothermal and antioxidant properties. By incorporating B into a G-O hydrogel crosslinked through Schiff base reaction between gelatin (G) and oxidized pullulan (O), the resulting G-O-B hydrogel exhibited good injectability and biocompatibility along with robust photothermal and antioxidant activities. Upon NIR irradiation, the controlled temperature (around 45-50 °C) generated by the G-O-B hydrogel resulted in rapid (10 min) and efficient killing of Staphylococcus aureus (99 %), Escherichia coli (98 %), and Pseudomonas aeruginosa (82 %). Furthermore, the G-O-B0.5 hydrogel containing 0.5 % blackcurrant extract promoted collagen deposition, angiogenesis, and accelerated burn wound closure conclusively, demonstrating that this well-designed and extract-contained hydrogel dressing holds immense potential for enhancing the healing process of bacterial-infected burn wounds.

Developing active and intelligent biodegradable packaging from food waste and byproducts: A review of sources, properties, film production methods, and their application in food preservation

Food waste and byproducts (FWBP) are a global issue impacting economies, resources, and health. Recycling and utilizing these wastes, due to processing and economic constraints, face various challenges. However, valuable components in food waste inspire efficient solutions like active intelligent packaging. Though research on this is booming, its material selectivity, effectiveness, and commercial viability require further analysis. This paper categorizes FWBP and explores their potential for producing packaging from both animal and plant perspectives. In addition, the preparation/fabrication methods of these films/coatings have also been summarized comprehensively, focusing on the advantages and disadvantages of these methods and their commercial adaptability. Finally, the functions of these films/coatings and their ultimate performance in protecting food (meat, dairy products, fruits, and vegetables) are also reviewed systematically. FWBP provide a variety of methods for the application of edible films, including being made into coatings, films, and fibers for food preservation, or extracting active substances directly or indirectly from them (in the form of encapsulation) and adding them to packaging to endow them with functions such as barrier, antibacterial, antioxidant, and pH response. In addition, the casting method is the most commonly used method for producing edible films, but more film production methods (extrusion, electrospinning, 3D printing) need to be tried to make up for the shortcomings of the current methods. Finally, researchers need to conduct more in-depth research on various active compounds from FWBP to achieve better application effects and commercial adaptability.

Active Fish Gelatin/Chitosan Blend Film Incorporated with Guava Leaf Powder Carbon Dots: Properties, Release and Antioxidant Activity

Active packaging is an innovative approach to prolonge the shelf-life of food products while ensuring their quality and safety. Carbon dots (CDs) from biomass as active fillers for biopolymer films have been introduced to improve their bioactivities as well as properties. Gelatin/chitosan (G/C) blend films containing active guava leaf powder carbon dots (GL-CDs) at various levels (0-3%, w/w) were prepared by the solvent casting method and characterized. Thickness of the control increased from 0.033 to 0.041 mm when 3% GL-CDs were added (G/C-CD-3%). Young's modulus of the resulting films increased (485.67-759.00 MPa), whereas the tensile strength (26.92-17.77 MPa) and elongation at break decreased (14.89-5.48%) as the GL-CDs' level upsurged (p < 0.05). Water vapor barrier property and water contact angle of the film were enhanced when incorporated with GL-CDs (p < 0.05). GL-CDs had a negligible impact on film microstructure, while GL-CDs interacted with gelatin or chitosan, as determined by FTIR. The release of GL-CDs from blend films was more pronounced in water than in alcoholic solutions (10-95% ethanol). The addition of GL-CDs improved the UV light barrier properties and antioxidant activities of the resultant films in a dose-dependent manner. Thus, GL-CD-added gelatin/chitosan blend films with antioxidant activities could be employed as potential active packaging for the food industry.

Sodium alginate films incorporated with Lepidium sativum (Garden cress) extract as a novel method to enhancement the oxidative stability of edible oil

This study addresses the growing interest in bio-based active food packaging by infusing Lepidium sativum (Garden cress) seeds extract (GRCE) into sodium alginate (SALG) films at varying concentrations (1, 3, and 5 %). The GRCE extract revealed six phenolic compounds, with gallic and chlorogenic acids being prominent, showcasing substantial total phenolic content (TPC) of 139.36 μg GAE/mg and total flavonoid content (TFC) of 26.46 μg RE/mg. The integration into SALG films significantly increased TPC, reaching 30.73 mg GAE/g in the film with 5 % GRCE. This enhancement extended to DPPH and ABTS activities, with notable rises to 66.47 and 70.12 %, respectively. Physical properties, including tensile strength, thickness, solubility, and moisture content, were positively affected. A reduction in water vapor permeability (WVP) was reported in the film enriched with 5 % GRCE (1.389 × 10-10 g H2O/m s p.a.). FT-IR analysis revealed bands indicating GRCE's physical interaction with the SALG matrix, with thermal stability of the films decreasing upon GRCE integration. SALG/GRCE5 effectively lowered the peroxide value (PV) of sunflower oil after four weeks at 50 °C compared to the control, with direct film-oil contact enhancing this reduction. Similar trends were observed in the K232 and K270 values.

A tear-free and edible dehydrated vegetables packaging film with enhanced mechanical and barrier properties from soluble soybean polysaccharide blending carboxylated nanocellulose

The aim of the study was to develop soybean polysaccharide (SSPS) -carboxylated nanocellulose (CNC) blending films with enhanced mechanical and barrier properties to be used as a tear-free and edible packaging materials. The films were formed by casting method, with CNC as the strengthening unit and glycerol as the plasticizer. The effect of CNC on structural and physical performances of the SSPS-CNC films were studied. SEM indicated that the film will stratify with excess CNC (10 %), but the film remains intact and compact. Incorporation of CNC into SSPS films did not change peak position in the XRD pattern significantly. Hydrogen bonds among SSPS, glycerol and CNC were indicated by the FTIR spectra. The compounding of CNC greatly lessened the light transmittance and hydrophilicity (CA increased from 55.42° to 70.67°), but perfected the barrier (WVP decreased from 3.595 × 10-10 to 2.593 × 10-10 g m-1 s-1 Pa-1) and mechanical properties (TS improved from 0.806 to 1.317 MPa). The results of packaging dehydrated vegetable indicated that the SSPS-8CNC film can effectively inhibit the packaged cabbage absorption water vapor. As a consequence, SSPS film perfected by CNC is hopeful to pack dehydrated vegetables in instant foods.

Enhancement of mechanical and barrier properties of chitosan-based bionanocomposites films reinforced with eggshell-derived hydroxyapatite nanoparticles

In this study, Hydroxyapatite nanoparticles (HANPs), derived from eggshell waste, were employed to reinforce chitosan biopolymer-based films through the solvent-casting method. The impact of varying HANPs content (1%, 3%, 5%, and 10 wt %) in bionanocomposites was investigated. The influence of HANPs addition on the final film properties was comprehensively analyzed using Thermogravimetric Analysis (TGA), Differential Scanning Calorimetry (DSC), Dynamic Mechanical Analysis (DMA), mechanical (tensile) testing, and Water Vapor Permeability (WVP). The morphological aspects of bionanocomposites and the dispersion of nanoparticles within the matrix were studied using Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), and X-ray Diffraction (XRD). The structural changes in the films were probed using Fourier-Transform Infrared Spectroscopy (FTIR) and X-ray Photoelectron Spectroscopy (XPS) techniques. Results indicated that the addition of 1% and 3% of HANPs exhibited a higher glass transition temperature and improved thermal stability in bionanocomposites. Films with 3% HANPs content exhibited a notable increase in tensile strength, showing a 61.54% increase, while films with 1% HANPs content displayed a 52% reduction in WVP compared to pristine chitosan films. These findings underscore the significant potential of chitosan-hydroxyapatite bionanocomposite films for applications in food packaging applications.

Optimization of an edible film formulation by incorporating carrageenan and red wine lees into fish gelatin film matrix

The study aimed to use response surface methodology (RSM) to create and understand a novel edible film made from fish gelatin (FG). This film includes wine lees (WL) and carrageenan (CAR). The concentrations of WL (0, 1, 2, and 3 %) and CAR (0, 1, and 3 %) were considered independent variables. The process variable combinations for the optimal response functions were 1.926 % WL and 3 % CAR, forming soft and rigid films with low tensile strength (TS) and high elongation at break (EAB%). Based on the evaluation of each response, FG film had the highest TS value, FG/CAR(3 %) film had the maximum EAB, and FG/WL (3 %)/CAR (3 %) film had the lowest vapor permeability (WVP) and the highest opacity (OP). The incorporation of WL considerably improved the functional properties of these films, enabling strong antioxidant activity and high phenolic content. Characterization of the films with analytical techniques: Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and X-ray diffraction (XRD) analysis demonstrated a considerable interaction between WL and FG, indicating a high level of compatibility between the two substances. Our data suggest that the formulation of edible films can be adjusted to fit the specific requirements of the design.

Preparation, physicochemical characterization and swelling properties of composite hydrogel microparticles based on gelatin and pectins with different structure

Composite hydrogel microparticles based on pectins with different structures (callus culture pectin (SVC) and apple pectin (AU)) and gelatin were developed. Hydrogel microparticles were formed by the ionotropic gelation and electrostatic interaction of COO- groups of pectin and NH3+ groups of gelatin, which was confirmed by FTIR spectroscopy. The addition of gelatin to pectin-based gel formulations resulted in a decrease in gel strength, whereas increasing gelatin concentration enhanced this effect. The microparticle gel strength increased in proportion to the increase in the pectin concentration. The DSC and TGA analyzes showed that pectin-gelatin gels had the higher thermal stability than individual pectins. The gel strength, Ca2+ content and thermal stability of the microparticles based on gelatin and SVC pectin with a lower degree of methylesterification (DM) (14.8 %) were higher compared to that of microparticles based on gelatin and AU pectin with a higher DM (40 %). An increase in the SVC concentration, Ca2+ content and gel strength of SVC-gelatin microparticles led to a decrease in the swelling degree in simulated gastrointestinal fluids. The addition of 0.5 % gelatin to gels based on AU pectin resulted in increased stability of the microparticles in gastrointestinal fluids, while the microparticles from AU without gelatin were destroyed.

Effect of emulsifiers on the properties of corn starch films incorporated with Zanthoxylum bungeanum essential oil

The use of natural and safe ingredients in green food packaging material is a hot research topic. This study investigated the effect of different emulsifiers on starch film properties. Three types of emulsifiers, including Tween 80 as a small-molecule surfactant, sodium caseinate (CAS), whey protein isolate (WPI), and gelatin (GE) as macromolecule emulsifiers, whey protein isolate fibril (WPIF) as a particle emulsifier, were utilized to prepare Zanthoxylum bungeanum essential oil (ZBO) emulsions. The mechanical, physical, thermal, antibacterial properties, microstructure and essential oil release of starch films were investigated. CAS-ZBO nanoemulsion exhibited the smallest particle size of 198.6 ± 2.2 nm. The film properties changed with different emulsifiers. CAS-ZBO film showed the highest tensile strength value. CAS-ZBO and WPIF-ZBO films exhibited lower water vapor permeability than Tween-ZBO. CAS-ZBO film showed good dispersion of essential oil, the slowest release rate of essential oils in all food simulants, and the best antibacterial effect against Staphylococcus aureus and Listeria monocytogenes. The films composed of CAS-ZBO nanoemulsion, corn starch, and glycerol are considered more suitable for food packaging. This work indicated that natural macromolecule emulsifiers of CAS and WPIF are expected to be used in green food packaging material to offer better film properties.

Revolutionizing single-use food packaging: a comprehensive review of heat-sealable, water-soluble, and edible pouches, sachets, bags, or packets

Edible food packaging has emerged as a critical focal point in the discourse on sustainability, prompting the development of innovative solutions, notably in the realm of edible pouches. Often denoted as sachets, bags, or packets, these distinct designs have garnered attention owing to their water-soluble and heat-sealable attributes, tailored explicitly for single-use applications encompassing oils, instant or dry foods, and analogous products. While extant literature extensively addresses diverse facets of edible films, this review addresses a conspicuous void by presenting a consolidated and specialized overview dedicated to the intricate domain of edible pouches. Through a meticulous synthesis of current research, we aim to illuminate the trajectory of advancements made thus far, delving into critical aspects, including materials, production techniques, functional attributes, consumer perceptions, and regulatory considerations. By furnishing a comprehensive perspective on the potential, challenges, and opportunities inherent in edible pouches, our overarching aim is to stimulate collaborative endeavors in research, innovation, and exploration. In doing so, we aspire to catalyze the broader adoption of sustainable packaging solutions tailored to the exigencies of single-use applications.

Application of a Chitosan-based Active Packaging Film Prepared with Cell-free Supernatant of Lacticaseibacillus paracasei ALAC-4 in Mongolian Cheese Preservation

Fungal spoilage of food is a worldwide concern prompting the development of many antimicrobial agents and applications. In this study, the cell-free supernatant (CFS) of Lacticaseibacillus paracasei ALAC-4 had a significant inhibition effect on fungi. The CFS with antifungal activities were combined with chitosan (CS) matrix to prepare an active packaging CS-CFS films by using a solvent casting method and used for the packaging of Mongolian cheese for 15 days during storage at 4 ± 1℃. The optimized formulation of the film were 1.25% (w/v) chitosan, 1.75% (w/v) gelatin, 0.3% (v/v) glycerol, and 9.6% (w/v) CFS. It was found that CS-CFS films exhibited strong antifungal activities against molds and yeasts, especially Candida albicans, and also had excellent mechanical properties. Additionally, FTIR spectroscopy indicated that hydrogen bonds between the CFS and CS formed, and there was a smooth surface, compact cross-section observed in SEM morphologies of CS-CFS films. Furthermore, CS-CFS film also displayed a strong antifungal effect against molds and yeasts on cheese surface. These results suggest that the chitosan-based CS-CFS film has a promising application for Mongolian cheese and food preservation.

Packaging films based on biopolymers from seafood processing wastes: Preparation, properties, and their applications for shelf-life extension of seafoods-A comprehensive review

Biopolymers derived from seafood processing byproducts are used to prepare active and biodegradable films as the packaging of food products. These films possess bioactivities to enhance the shelf life of packed foods by proactively releasing antimicrobial/antioxidative agents into the foods and providing sufficient barrier properties. Seafood processing byproducts are an eminent source of valuable compounds, including biopolymers and bioactive compounds. These biopolymers, including collagen, gelatin, chitosan, and muscle proteins, could be used to prepare robust and sustainable food packaging with some antimicrobial agents or antioxidants, for example, plant extracts rich in polyphenols or essential oils. These active packaging are not only biodegradable but also prevent the deterioration of packed foods caused by spoilage microorganisms as well as chemical deterioration. Seafood discards have a promising benefit for the development of environmentally friendly food packaging systems via the appropriate preparation methods or techniques. Therefore, the green packaging from seafood leftover can be better exploited and replace the synthetic counterpart.

Characterization of chitosan-gelatin cryogel templates developed by chemical crosslinking and oxidation resistance of camellia oil cryogel-templated oleogels

In this study, chitosan-gelatin conjugates were prepared by chemical crosslinking of tannic acid. The cryogel templates were developed through freeze-drying and immersed in camellia oil to construct cryogel-templated oleogels. Chemical crosslinking resulted in apparent colour changes and improved emulsion-related/rheological properties on conjugates. The cryogel templates with different formulas exhibited different microstructures with high porosities (over 96 %), and crosslinked samples might have higher hydrogen bonding strength. Tannic acid crosslinking also led to enhanced thermal stabilities and mechanical properties. Cryogel templates could reach a considerable oil absorption capacity of up to 29.26 g/g and prevent oil from leaking effectively. The obtained oleogels with high tannic acid content possessed outstanding antioxidant abilities. After 8 days of rapid oxidation at 40 °C, Oleogels with a high degree of crosslinking owned the lowest POV and TBARS values (39.74 nmol/kg, and 24.40 μg/g, respectively). This study indicates that the involvement of chemical crosslinking would favor the preparation and the application potential of cryogel-templated oleogels, and the tannic acid in the composite biopolymer systems could act as both the crosslinking agent and the antioxidant.

Physicochemical and functional characterization of gelatin edible film incorporated with fucoidan isolated from Sargassum tenerrimum

Biodegradable films were created with fish gelatin and fucoidan extracted from Sargassum tenerrimum using 30% glycerol as a plasticizer. The gelatin films were incorporated with fucoidan (2.5%, 5%, 7.5%, and 10%), respectively. Results presented that the average thickness of films ranged from 0.12 to 0.147 mm. Tensile strength (TS) was decreased from 29.27 to 3.46 MPa by adding the fucoidan except for the gelatin/fucoidan 10% (5.35 MPa) sample. The results showed that the physical characteristics (the contact angle (Ɵ), water solubility, opacity, and moisture content) of the films significantly changed depending on different fucoidan concentrations. FTIR and SEM analysis confirmed the interaction of fucoidan with gelatin in the composite film. Furthermore, adding 10% fucoidan showed high DPPH radical scavenging activity (65%) than other treatments. Therefore, incorporation of fucoidan extracted from brown algae (Sargassum tenerrimum) with fish gelatin films improved thermal stability, anti-oxidative, and antibacterial characteristics in addition to enhanced mechanical and protective properties, to be used as a bioactive edible film in the food packaging industry.

Gelatin Improves the Performance of Oregano Essential Oil Nanoparticle Composite Films-Application to the Preservation of Mullet

In this study, the addition of oregano oil chitosan nanoparticles (OEO-CSNPs) was conducted to enhance the comprehensive properties of gelatin films (GA), and the optimal addition ratio of nanoparticles was determined for its application in the preservation of mullet. Oregano oil chitosan nanoparticles were organically combined with gelatin at different concentrations (0%, 2%, 4%, 6% and 8%) to obtain oregano oil-chitosan nanoparticle-GA-based composite films (G/OEO-CSNPs), and thereafter G/OEO-CSNPs were characterized and investigated for their preservative effects on mullet. Subsequent analysis revealed that OEO-CSNPs were uniformly dispersed in the GA matrix, and that G/OEO-CSNPs had significantly improved mechanical ability, UV-visible light blocking performance and thermal stability. Furthermore, the nanoparticles exhibited excellent antioxidant and antibacterial properties, and they improved the films' suitability as edible packaging. The attributes of the G/OEO-CSNPs were optimized, the films had the strongest radical scavenging and lowest water solubility, and electron microscopy also showed nanoparticle penetration into the polymer when the concentration of OEO-CSNPs was 6% (thickness = 0.092 ± 0.001, TS = 47.62 ± 0.37, E = 4.06 ± 0.17, water solubility = 48.00 ± 1.11). Furthermore, the GA-based composite film containing 6% OEO-CSNPs was able to inhibit microbial growth, slow fat decomposition and protein oxidation, reduce endogenous enzyme activity, and delay the spoilage of mullet during the refrigeration process, all of which indicate its excellent potential for meat preservation application.

Chitosan Based Biodegradable Composite for Antibacterial Food Packaging Application

A recent focus on the development of biobased polymer packaging films has come about in response to the environmental hazards caused by petroleum-based, nonbiodegradable packaging materials. Among biopolymers, chitosan is one of the most popular due to its biocompatibility, biodegradability, antibacterial properties, and ease of use. Due to its ability to inhibit gram-negative and gram-positive bacteria, yeast, and foodborne filamentous fungi, chitosan is a suitable biopolymer for developing food packaging. However, more than the chitosan is required for active packaging. In this review, we summarize chitosan composites which show active packaging and improves food storage condition and extends its shelf life. Active compounds such as essential oils and phenolic compounds with chitosan are reviewed. Moreover, composites with polysaccharides and various nanoparticles are also summarized. This review provides valuable information for selecting a composite that enhances shelf life and other functional qualities when embedding chitosan. Furthermore, this report will provide directions for the development of novel biodegradable food packaging materials.

Development of Edible Composite Film from Fish Gelatin-Pectin Incorporated with Lemongrass Essential Oil and Its Application in Chicken Meat

One of the greatest challenges encountered by the food industry is the loss of quality of food products during storage, especially perishable foods such as chicken breast, which eventually adds to the waste. Edible films are known as a potential alternative to maintain food quality and also improve shelf life by delaying the microbial spoilage and providing moisture and gas barrier properties. Developments in edible films from biopolymer composites such as fish gelatin, pectin and essential oils have great potential and promising results in enhancing the shelf life of food products. This study was conducted to determine the effect of adding pectin and lemongrass essential oil on the properties of gelatin film and its application to preserve the quality of chicken breast. In this study, the fish skin gelatin and pectin were used with various compositions (100:0; 75:25; 50:50%), with and without the addition of lemongrass essential oil to develop edible films by a casting method. The results showed that the fish gelatin-pectin with the addition of essential oils caused a significant influence on several physicochemical properties such as the thickness, transmittance, transparency, water content, tensile strength, elongation at break and also antioxidant activity (p < 0.05). The antibacterial activity evaluation showed that edible film from a biocomposite of gelatin-pectin (75:25 and 50:50) with the addition of essential oil had an inhibitory effect on Salmonella. The biocomposite of the edible film made from gelatin-pectin and the addition of lemongrass essential oil have the potential to be developed as a food packaging material, especially for perishable food. Based on the result of the application of edible film to chicken breast, it also could maintain the quality of chicken breast during storage.

Mechanical Properties of Protein-Based Food Packaging Materials

The quality and safety of food products greatly depend on the physiochemical properties of the food packaging material. There is an increasing trend in the utilization of protein-based biopolymers for the preparation of edible films and coating due to their film-forming properties. Various studies have reported the preparation of protein-based edible films with desirable mechanical and barrier properties. The mechanical attributes of the protein-based food packaging materials can be enhanced by incorporating various components in the film composition such as plasticizers, surfactants, crosslinkers, and various bioactive compounds, including antimicrobial and antioxidant compounds. This review article summarizes the recent updates and perspective on the mechanical attributes such as Tensile Strength (TS), Elongation at Break (EAB), and Young’s Modulus (YM) of edible films based on different proteins from plants and animal sources. Moreover, the effects of composite materials such as other biopolymers, bioactive compounds, essential oils, and plasticizers on the mechanical properties of protein-based edible films are also discussed.

Gelatin/carboxymethyl cellulose edible films: modification of physical properties by different hydrocolloids and application in beef preservation in combination with shallot waste powder

In this work, a gelatin/carboxymethyl cellulose (CMC) base formulation was first modified by using different hydrocolloids like oxidized starch (1404), hydroxypropyl starch (1440), locust bean gum, xanthan gum, and guar gum. The properties of modified films were characterized using SEM, FT-IR, XRD and TGA-DSC before selecting of best-modified film for further development with shallot waste powder. SEM images showed that the rough or heterogeneous surface of the base was changed to more even and smooth depending on the hydrocolloids used while FTIR results demonstrated that a new NCO functional group non-existent in the base formulation was found for most of the modified films, implying that the modification led to the formation of this functional group. Compared to other hydrocolloids, the addition of guar gum into the gelatin/CMC base has improved its properties such as better color appearance, higher stability, and less weight loss during thermal degradation, and had minimal effect on the structure of resulting films. Subsequently, the incorporation of spray-dried shallot peel powder into gelatin/CMC/guar gum was conducted to investigate the applicability of edible films in the preservation of raw beef. Antibacterial activity assays revealed that the films can inhibit and kill both Gram-positive and Gram-negative bacteria as well as fungi. It is noteworthy that the addition of 0.5% shallot powder not only effectively decelerated the microbial growth but also destroyed E. coli during 11 days of storage (2.8 log CFU g-1) and the bacterial count was even lower than that of uncoated raw beef on day 0 (3.3 log CFU g-1).

Enhancement of water barrier and antimicrobial properties of chitosan/gelatin films by hydrophobic deep eutectic solvent

Biodegradable chitosan/gelatin (CS/GEL) films have attracted attention as food packaging, but the poor water sensitivity and functional limitations of these films should be addressed. In this study, the hydrophobic deep eutectic solvent (DES, 0-15 %) consisting of thymol and octanoic acid was used to improve the water resistance and antibacterial performance of the CS/GEL composite films. FTIR and SEM analyses revealed a strong interaction between the CS/GEL matrix and DES. The films blended with DES showed increased water contact angle values and thermal stability. Furthermore, the addition of DES resulted in a significant increase in the elasticity and decrease water vapor transmission rate (WVTR). The CS/GEL films blended with 9% DES showed a 38.5% decrease in WVTR compared to those without DES. Additionally, the DES-containing film displayed good antibacterial activity against Staphylococcus aureus and Escherichia coli. Overall, the CS/GEL-DES composite films are expected to contribute an improvement to food packaging.

A comprehensive approach to chitosan-gelatine edible coating with β-cyclodextrin/lemongrass essential oil inclusion complex - Characterization and food application

Biopolymer-based films present an ideal matrix for the incorporation of active substances such as antimicrobial agents, giving active packaging a framework of green chemistry and a step forward in food packaging technology. The chitosan-gelatine active coating has been prepared using lemongrass oil as an antimicrobial compound applying a different approach. Instead of surfactants, to achieve compatibilization of compounds, β-cyclodextrin was used to encapsulate lemongrass oil. The antimicrobial effect was assessed using the dip-coating method on freshly harvested cherry tomatoes artificially contaminated by Penicillium aurantiogriseum during 20 days of cold storage. According to the evaluation of the antimicrobial effect of coating formulation on cherry tomato samples, which was mathematically assessed by predictive kinetic models and digital imaging, the applied coating formulation was found to be very effective since the development of fungal contamination for active-coated samples was observed for 20 days.

Inhibition of Chitosan Ice Coating on the Quality Deterioration of Quick-Frozen Fish Balls during Repeated Freeze-Thaw Cycles

Chitosan ice coating's properties and its inhibitory effect on the quality deterioration of quick-frozen fish balls during repeated freeze-thaw cycles were investigated. When the chitosan (CH) coating concentration increased, the viscosity and ice coating rate increased, while water vapor permeability (WVP), water solubility, and transmittance decreased, and 1.5% CH was regarded as the excellent coating to apply to freeze-thaw quick-frozen fish balls. As the freeze-thaw cycles increased, the frost production, total volatile base nitrogen (TVB-N) values, and free water content of all of the samples increased significantly (p < 0.05), and the whiteness values, textural properties, and water-holding capacity (WHC) decreased. Freeze-thaw cycles expanded the aperture between the muscle fibers and the occurrence of crystallization and recrystallization between cells increased, damaging the original intact tissue structure, which were confirmed by SEM and optical microscopy. Compared with the untreated ones, the frost production, free water, and TVB-N of the samples with 1.5% CH decreased during 1, 3, 5, and 7 cycles, and were reduced by 23.80%, 32.21%, 30.33%, and 52.10% by the 7th cycle. The WHC and texture properties showed an increasing trend during the freeze-thaw cycles. Therefore, the chitosan ice coating effectively inhibited the quality deterioration by reducing water loss, the occurrence of ice crystallization and recrystallization, and the pores of the samples.

Preparation and characterization of active Cirish fructans-fish gelatin film: Physicochemical, antioxidant, and antimicrobial properties

This study was aimed to evaluate the film-forming ability and characterization of ultrasonically extracted Cirish fructans (CF) and CF-cold-water fish gelatin (G) composite films. The film-forming solutions were prepared at different levels (CF100-0G, CF75-G25, CF50-G50, CF25-G75, and CF0-G100) and the corresponding data were analyzed based on one-way analysis of variance. The results indicated that CF addition led to an impressive increase in composite films thickness (69.38-86.45 μm), moisture content (16.05%-27.8%), surface hydrophobicity, tensile strength (5.73-17.89 MPa), elongation at break (0.83%-1.66%), Young's modulus (77.12-88.15 MPa), and Tg (38.83-47.4°C) which CF75-G25 had the highest values. Meanwhile, the solubility (77.12%-88.15%), WVP (1.89-2.86 × 10-10gm-1 s-1 Pa-1), and oxygen permeability (1.53-3.26 × 1014 cm3 m-1 s-1 Pa-1) of the composite films decreased. The FTIR spectra indicated the protein-polysaccharide interactions and revealed that the secondary structure of gelatin was shifted from triple-helix structure (1661 cm-1) toward α-helix structure (1650-1657 cm-1) when CF was incorporated. The microstructure observations indicated that unlike gelatin film, CF film exhibited the smooth and uniform surface without cracks and phase separation. It was found that CF films had high total phenolic content (6.73 mg GEA g-1) and showed DPPH radical scavenging activity (67.86%). On the other hand, it showed inherent antimicrobial activity against both gram-positive and gram-negative bacteria. The results indicated that CF and CF-cold fish gelatin have great potential as active films with improved physical, mechanical, and barrier properties.

Production and characterization of biodegradable bi-layer films from poly(lactic) acid and zein

Recently, packaging industry has turned to biodegradable packaging, and poly(lactic acid) has become the most remarkable polymer. However, the high oxygen permeability of PLA films significantly limits their use. Therefore, this study, it was aimed to improve the oxygen barrier properties of PLA films without adversely affecting the mechanical and water vapor barrier properties. Biodegradable PLA-Zein bi-layer films were produced by changing PLA and zein thickness. Transparent and UV barrier bi-layer films were obtained. Mechanical properties of PLA films were improved by the production of bi-layer films. Water vapor permeability of bi-layer films increased whereas the permeance decreased with zein coating of PLA. Multi-criteria decision hierarchy was used to select the best bi-layer films based on mechanical, permeance, and opacity results. Oxygen barrier properties of PLA film significantly improved by zein coating, and hydrophobicity of PLA film was not affected by zein coating. The crystallization and melting temperatures of films decreased when compared to PLA films, supporting the mechanical results. Homogeneous, non-porous, and smooth film surface was obtained and zein layer was in good compatibility with PLA layer. These results suggest that zein coatings could be used to decrease oxygen permeability of PLA films without negatively affecting other properties.

Using celluloses in different geometries to reinforce collagen-based composites: Effect of cellulose concentration

Cellulose is frequently used to strengthen biocomposite films, but few literature systematically deliberates the effects of concentration of celluloses in different geometries on the reinforcement of these composites. Here we prepared three types of celluloses, including rod-like cellulose nanocrystalline (CNC), long-chain cellulose nanofiber (CNF) and microscopic cellulosic fines (CF). The effect of concentration of the three celluloses was examined on the barrier properties to water and light, thermostability, microstructure, and mechanical properties of collagen (COL) films. The addition of celluloses increased the watertightness and thermostability of composite films. Besides, FTIR showed a increased hydrogen bonding for COL/CNF and COL/CNC composite films, but decrease for COL/CF composites. As the concentration of CF and CNF increased, the strength of composites improved. The TS for COL/CNF (124 MPa) and COL/CF composites (113 MPa) were largely increased, compared with that of collagen ones (90 MPa). Considering the factors of crystallinity, hydrogen bonding, and interfacial tortuosity, COL/CNF composites possessed better mechanical behaviors than that of COL/CF and COL/CNC composites. Furthermore, Halpin-Kardos and Ouali models well predicted the modulus of COL/CNF composites when CNF was below and above percolation threshold (2.7 wt%), respectively.

Polysaccharides for Biodegradable Packaging Materials: Past, Present, and Future (Brief Review)

The ecological problems emerging due to accumulation of non-biodegradable plastics are becoming more and more urgent. This problem can be solved by the development of biodegradable materials which will replace the non-biodegradable ones. Among numerous approaches in this field, there is one proposing the use of polysaccharide-based materials. These polymers are biodegradable, non-toxic, and obtained from renewable resources. This review opens discussion about the application of polysaccharides for the creation of biodegradable packaging materials. There are numerous investigations developing new formulations using cross-linking of polymers, mixing with inorganic (metals, metal oxides, clays) and organic (dyes, essential oils, extracts) compounds. The main emphasis in the present work is made on development of the polymer blends consisting of cellulose, starch, chitin, chitosan, pectin, alginate, carrageenan with some synthetic polymers, polymers of natural origin, and essential oils.

Development and characterization of active packaging films based on chitosan, plasticizer, and quercetin for repassed oil storage

Novel chitosan (Ch) films containing choline chloride and citric acid mixture as plasticizer (deep eutectic solvent, DES) and different amounts of quercetin (QUE) as antioxidant additive were prepared. Physicochemical and mechanical characteristics of the developed Ch/DES/QUE films were studied using FTIR, SEM, and AFM techniques. FTIR spectra revealed the possible interactions between all the components. The surface of the films was dense and rough. The addition of quercetin caused an increase in the tensile strength (TS) and Young's modulus, but significantly decreased the elongation at break. The films containing quercetin showed improved antioxidant activity in relation to Ch/DES film. Finally, the oxidation phenomena of rapeseed oils with and without chitosan films were evaluated as amounts of primary and secondary oxidation products and total oxidation index. The addition of Ch/DES films with quercetin to oil samples successfully retarded secondary lipid oxidation processes and improved its antioxidant activity under the accelerated storage condition.