Enhanced functional properties of nanocomposite film incorporated with EGCG-loaded dialdehyde glucomannan/gelatin matrix for food packaging

Progress of research on aroma absorption mechanism and aroma fixation pathway of jasmine green tea

This overview summarizes the latest research progress on the aroma absorption mechanism and aroma fixation pathway of jasmine green tea, and discusses in depth the aroma absorption mechanism of green tea, the aroma release mechanism of jasmine flowers, as well as the absorption and fixation mechanism of the aroma components of jasmine green tea in the process of scenting, to provide a theoretical basis for the improvement of the quality of jasmine green tea and the innovation of processing technology. It was found that the aroma absorption mechanism of jasmine green tea is mainly associated with both physical and chemical adsorption, aroma release in jasmine involves the phenylpropanoid/benzoin biosynthetic pathway, β-glycosidase enzymes interpreting putative glycosidic groups, and heat shock proteins (HSPs) as molecular chaperones to prevent stress damage in postharvest flowers due to high temperatures and to promote the release of aroma components, and so forth. The preparation of aroma-protein nano-complexes, heat stress microcapsules, and the spraying of polymeric substances - β-cyclodextrin are three examples of aroma-fixing pathways. This overview also summarizes the problems and future development trends of the current research and proposes the method of loading benzyl acetate, the main aroma component of jasmine, through konjac glucomannan (KGM)-based gel to solve the problem of volatile aroma and difficult-to-fix aroma, which provides a reference for the sustainable development of the jasmine green tea industry. © 2024 Society of Chemical Industry.

Sacrificial hydrogen bonds enhance the performance of covalently crosslinked composite films derived from soy protein isolate and dialdehyde starch

Soy protein films have the advantage of being eco-friendly and renewable, but their practical applications are hindered by the mechanical properties. The exceptional tensile strength and fracture toughness of natural silk stem from sacrificial hydrogen bonds it contains that effectively dissipates energy. In this study, we draw inspiration from silk's structural principles to create biodegradable films based on soy protein isolate (SPI). Notably, composite films containing sodium lignosulfonate (LS) demonstrate exceptional strain at break (up to 153%) due to the augmentation of reversible hydrogen bonding, contrasted to films with the addition of solely dialdehyde starch (DAS). The enhancement of tensile strength is realized through a combination of Schiff base cross-linking and sacrificial hydrogen bonding. Furthermore, the incorporation of LS markedly improves the films' ultraviolet (UV) blocking capabilities and hydrophobicity. This innovative design strategy holds great promise for advancing the production of eco-friendly SPI-based films that combine strength and toughness.

Konjac glucomannan films incorporated pectin-stabilized Mandarin oil emulsions: Structure, properties, and application in fruit preservation

To enhance the water-resistance and antibacterial properties of KGM films, mandarin oil (MO), was directly emulsified by pectin and then dispersed to the KGM matrix. The effect of MO concentration (0, 0.5, 1.0, 1.5, and 2 wt%) on the performance of the film-forming emulsions as well as the emulsion films was investigated. The results revealed that pectin could encapsulate and protect MO, and KGM as film matrix could further contributed to the high stability of the film-forming emulsions. The FT-IR, XRD, and SEM suggested that MO stabilized by pectin was uniformly distributed in the KGM matrix. The compatibility and good interaction between KGM and pectin contributed to highly dense and compact structure. Furthermore, increasing the concentration of MO effectively improved water-resistance, oxygen barrier, and antimicrobial activity of the KGM based films. The 1.5 wt% MO loaded KGM film had the highest tensile strength (72.22 MPa) and water contact angle (θ = 95.73°), reduced the WVP and oxygen permeability by about 25.8 % and 32.8 times, respectively, prolonged the shelf life of strawberries for 8 days. As demonstrated, the 1.5 wt% MO-loaded KGM film has considerable potential for high-performance natural biodegradable active films to ensure food safety and reduce environmental impacts.

Robust construction of konjac glucomannan/polylactic acid nanofibrous films incorporated with carvacrol via microfluidic blow spinning for food packaging

In recent years, the application of biopolymer-based nanofibers prepared via microfluidic blow spinning (MBS) for food packaging has continuously increased due to their advantages of biocompatibility, biodegradability, and safety. However, the poor spinnability, undesirable water barrier capacity, and loss of antibacterial and antioxidant properties of biopolymer-based nanofibers strictly restrict their real-world applications. In this work, carvacrol (CV) incorporated konjac glucomannan (KGM)/polylactic acid (PLA) nanofibrous films (KP-CV) were produced by MBS. The FTIR spectra and XRD analysis revealed the hydrogen bonding interactions among CV, PLA, and KGM, thus significantly improving the TS of KP-CV nanofibrous films from 0.23 to 1.27 MPa with increased content of CV from 0 % to 5 %. Besides, KP-CV nanofibrous films showed improved thermal stability, excellent hydrophobicity (WCA: 128.19°, WVP: 1.02 g mm/m2 h kPa), and sustained release of CV combined with good antioxidant activities (DPPH radical scavenging activity: 77.51 ± 1.57 %), and antibacterial properties against S. aureus (inhibition zone: 26.33 mm) and E. coli (inhibition zone: 22.67 mm). Therefore, as prepared KP-CV nanofibrous films can be potentially applied as packaging materials for the extended shelf life of cherry tomatoes.

Pickering nanoemulsion loaded with eugenol contributed to the improvement of konjac glucomannan film performance

Konjac glucomannan (KGM) is becoming a very potential food packaging material due to its good film-forming properties and stability. However, KGM film has several shortcomings such as low mechanical strength, strong water absorption, and poor self-antibacterial performance, which limits its application. Therefore, in order to enhance the mechanical and functional properties of KGM film, this study prepared Pickering nanoemulsion loaded with eugenol and added it to the KGM matrix to explore the improvement effect of Pickering nanoemulsion on KGM film properties. Compared to pure KGM film and eugenol directly added film, the mechanical strength of Pickering-KGM film was significantly improved due to the establishment of ample hydrogen bonding interactions between the β-cyclodextrin inclusion complex system and KGM. Pickering-KGM film had significant antioxidant capacity than pure KGM film and eugenol directly added KGM film (eugenol-KGM film) (~3.21 times better than KGM film, ~0.51 times better than eugenol-KGM film). In terms of antibacterial activity, Pickering-KGM film had good inhibitory effect on Escherichia coli, Staphylococcus aureus, and Candida albicans, and raspberry preservation experiment showed that the shelf life of the Pickering-KGM film could be extended to about 6 days. To sum up, this study developed a novel means to improve the film performance and provide a new insight for the development and application of food packaging film.

An antibacterial packaging film based on amylose starch with quaternary ammonium salt chitosan and its application for meat preservation

A new generation of food packaging films is gradually replacing traditional plastic packaging films because of their biodegradability, safety, and some functional properties such as anti-bacterial and oxidant resistance. In the present work, an antibacterial packing film based on amylose starch and 2-hydroxypropyl-trimethylammonium chloride chitosan (HTCC) was prepared for meat preservation. The interfacial bonding mechanism between amylose, HTCC, and glutaraldehyde (GA) was determined experimentally and through molecular dynamics (MD) simulation. The macromolecular chains of amylose starch and HTCC became entangled via inter-molecular H-bonds and then cross-linked with GA via the Schiff base reaction. The interaction of amylose starch and HTCC improved the mechanical properties of the amylose films. Compared with the amylose films, the tensile strength and elongation at break of the optimal HTCC/amylose films reached to 16.13 MPa (an increase of 206.65 %) and 53.86 % (an increase of 109.49 %). The HTCC/amylose films were found to provide obvious bacteriostatic performance, a relatively low cytotoxicity, the lower transmittance in the UV region, and thus the ability to enhance the preservation of fresh meat. These excellent characteristics therefore suggest that HTCC/amylose films might be promising candidates for application in antibacterial food packaging films.

Physicochemical properties and pork preservation effects of lotus seed drill core powder starch-based active packaging films

Lotus seed drill core powder starch (LCPS)-based active packaging films incorporated with cellulose nanocrystals (CNC) and grapefruit essential oil-corn nanostarch Pickering emulsion (ECPE) were characterized, and their pork preservation effects were investigated in this study. In contrast with corn, potato and rice starches, LCPS showed higher amylose content, elliptical and circular shape with more uniform size distribution. Furthermore, LCPS film exhibited lower light transmittance, stronger tensile strength, and smaller elongation at break compared to the other starch films. Then, the LCPS film containing 4 % CNC and 9 % ECPE was fabricated which had stronger mechanical properties, lower water vapor permeability and oxygen transmission rate, and denser network structure. FTIR and XRD analyses also confirmed that CNC and ECPE were successfully implanted into the LCPS matrix without damaging the crystalline structure of LCPS. Herein, the LCPS/CNC/ECPE film exerted potential antibacterial activity against Escherichia coli and Staphylococcus aureus. Besides, packaging with this composite film significantly preserved the pork during cold storage via decreasing its juice loss rate, pH value, total number of colonies, total volatile base nitrogen and thiobarbituric acid reactive substance values. The present study will provide a theoretical basis for the application of LCPS as new biodegradable active films.

Preparation and characterization of chitosan/dialdehyde carboxymethyl cellulose composite film loaded with cinnamaldehyde@zein nanoparticles for active food packaging

In this study, zein-loaded cinnamaldehyde (Cin@ZN) nanoparticles were incorporated into Chitosan (CS)/dialdehyde carboxymethyl cellulose (DCMC) matrix to fabricate the active food packaging materials possessing outstanding antioxidant and antibacterial properties. The research investigated how varying levels of Cin@ZN nanoparticles affected the morphology, microstructure, physicochemical properties of CS/DCMC composite films. The inclusion of Cin@ZN could significantly improve the mechanical strength, reduce the water vapor and oxygen permeability of CS/DCMC composite films and endow films with UV-light blocking properties. It's worth noting that the antibacterial and antioxidant capacities of CS/DCMC films had an astonishing enhancement with Cin@ZN blending, in which ABTS scavenging ratio of the composite films (100 mg) with different Cin@ZN contents reached >90 %. Furthermore, CS/DCMC/Cin@ZN 35 % composite film has the ability to efficiently protect strawberries from microbial damage and decelerate the spoilage rate of strawberries under ambient condition. Consequently, the CS/DCMC/Cin@ZN composite film can be applied as packaging material to extend the lifespan of fruits.

Effect of polysaccharide concentration on heat-induced Tremella fuciformis polysaccharide-soy protein isolation gels: Gel properties and interactions

The formation of a single soybean protein isolate (SPI) gel is limited by the processing conditions, and has the disadvantages of poor gel property, and it is usually necessary to add other biomacromolecules to improve its property. In this study, we investigated the effects of polysaccharide concentration on gel properties and interaction mechanisms of Tremella fuciformis polysaccharide (TFP)-SPI complexes. It was found that (1) the rheological properties, texture properties, water-holding properties, and thermal stability of TFP-SPI composite gels were improved with the addition of TFP (0.25-2.0 %, w/v) in a concentration-dependent manner; (2) hydrogen bond, the electrostatic interaction, hydrophobic interaction, and disulfide bond in the gel system increased with the increase of TFP concentration; (3) the electrostatic and hydrophobic interactions played an important role in the formation of the TFP-SPI composite gel while hydrogen bond formation was the least contributor to the binary composite gel network. Overall, TFP is not only a critical health food but also a promising structural component for improving the gel properties of SPI.

Eggshell waste act as multifunctional fillers overcoming the restrictions of starch-based films

Starch has great potential to replace petroleum-based plastics in food packaging applications. However, starch films often exhibit poor mechanical and barrier properties, and are vulnerable to moisture and bacterial contamination. This study proved that the incorporation of eggshell powder (ES) enhanced the hydrogen bonding in starch-based films significantly, which contributed to improved tensile strength, Young's modulus, and water resistance of the films. The performance of ES-incorporated films could be optimized by adjusting the size, concentration, and surface property of ES in the film matrix. Notably, adsorbing epigallocatechin gallate (EGCG) on the surface of porous ES contributed to enhanced dispersibility of the fillers in the film matrix, which increased the tortuous path of light, water vapor, and oxygen have to take through the films, resulting in increased UV screening performance, water vapor and oxygen barrier property of the films by 60 %, 7.2 %, and 27.9 %, respectively. Meanwhile, loading EGCG in ES also enable superior antibacterial activity of the final films. This study suggests that eggshell fillers offer a sustainable means of improving the functional performance of starch-based films, which may increase their application as packaging materials in the food industry.

Preparation and characterization of egg white protein film incorporated with epigallocatechin gallate and its application on pork preservation

The aim of this study was to develop the composite films with antioxidant and biodegradable activity based on egg white protein (EWP) and epigallocatechin gallate (EGCG). Water susceptibility, light transmittance, microstructure and antioxidant properties of the composite films without and with EGCG were fully characterized. It was noted that the addition of EGCG might decrease the moisture content, water solubility and swelling capacity. SEM micrographs revealed that discontinuous blocks and rough surfaces were caused by increasing concentration of EGCG, whereas compact and homogeneous particles appeared when the concentration of EGCG reached to 80 μmol/L. Moreover, the biodegradability of the composite films was demonstrated by the soil degradation properties that they can be almost completely degraded within ten days. Experimental results on the application in chilled fresh pork showed that the EWP-based films could play an antioxidant role when incorporated with EGCG, indicating their great potential for food packaging.

Konjac glucomannan/carboxymethyl chitosan film embedding gliadin/casein nanoparticles for grape preservation

Constructing biopolymer-based packaging films with fantastic water resistance and mechanical properties for food preservation is highly desirable and challenging. In this work, Gliadin/Casein nanoparticles (GCNPs) were prepared by pH-driven method and embedded into konjac glucomannan/carboxymethyl chitosan (KC) film matrix to improve the water resistance and mechanical properties of KC film. Gliadin and Casein showed good compatibility and co-assembled to form compact GCNPs clusters through hydrogen bonding and hydrophobic interaction verified by FT-IR spectroscopy, and fluorescence spectroscopy. The particle size and zeta potential of GCNPs was 269.7 nm and -7.6 mV, respectively. The effect of GCNPs on the mechanics, water barrier, thermal stability, and UV-shielding of KC-GCNPs film was investigated. SEM images revealed that GCNPs uniformly distributed into KC film matrix and significantly improved the mechanics (tensile strength: 75.6 MPa, elongation at breaking: 36.7 %), water barrier ability (water contact angle: 91.3°, water vapor permeability: 0.994 g mm/m2 day kPa, water solubility: 52.0 %), thermal stability and UV blocking property of KC-GCNPs film. Furthermore, KC-GCNPs film could also be applied to extend the shelf life of grapes. This paper demonstrated the great potential of GCNPs as functional nanofillers in enhancing the physicochemical properties of KC film.

Development of chitosan/konjac glucomannan/tragacanth gum tri-layer food packaging films incorporated with tannic acid and ε-polylysine based on mussel-inspired strategy

Constructing biodegradable food packaging with good mechanics, gas barrier and antibacterial properties to maintain food quality is still challenge. In this work, mussel-inspired bio-interface emerged as a tool for constructing functional multilayer films. Konjac glucomannan (KGM) and tragacanth gum (TG) with physical entangled network are introduced in the core layer. Cationic polypeptide ε-polylysine (ε-PLL) and chitosan (CS) producing cationic-π interaction with adjacent aromatic residues in tannic acid (TA) are introduced in the two-sided outer layer. The triple-layer film mimics the mussel adhesive bio-interface, where cationic residues in outer layers interact with negatively charged TG in the core layer. Furthermore, a series of physical tests showed excellent performance of triple-layer film with great mechanical properties (tensile strength (TS): 21.4 MPa, elongation at break (EAB): 7.9 %), UV-shielding (almost 0 % UV transmittance), thermal stability, water, and oxygen barrier (oxygen permeability (OP): 1.14 × 10^-3 g/m s Pa and water vapor permeability (WVP): 2.15 g mm/m² day kPa). In addition, the triple-layer film demonstrated advanced degradability, antimicrobial functions, and presented good moisture-proof performance for crackers, which can be potentially applied as dry food packaging.

Natural and biocompatible dressing unit based on tea carbon dots modified core-shell electrospun fiber for diabetic wound disinfection and healing

Wound infection and healing in patients with diabetes is one of the complex problems in trauma treatment. Therefore, designing and preparing an advanced dressing membrane for treating the wounds of such patients is essential. In this study, a zein film with biological tea carbon dots (TCDs) and calcium peroxide (CaO₂) as the main components for promoting diabetic wound healing was prepared by an electrospinning technique, which combines the advantages of natural degradability and biosafety. CaO₂ is a biocompatible material with a microsphere structure that reacts with water to release hydrogen peroxide and calcium ions. TCDs with a small diameter were doped in the membrane to mitigate its properties while improving the antibacterial and healing effects of the membrane. TCDs/CaO₂ was mixed with ethyl cellulose-modified zein (ZE) to prepare the dressing membrane. The antibacterial properties, biocompatibility and wound-healing properties of the composite membrane were investigated by antibacterial experiment, cell experiment and a full-thickness skin defect. TCDs/CaO₂ @ZE exhibited significant anti-inflammatory and wound healing-promoting properties in diabetic rats, without any cytotoxicity. This study is meaningful in developing a natural and biocompatible dressing membrane for diabetic wound healing, which shows a promising application in wound disinfection and recovery in patients with chronic diseases.

Characterizations of konjac glucomannan/curdlan edible coatings and the preservation effect on cherry tomatoes

In this study, konjac glucomannan (KGM) and curdlan were used to fabricate composite coating (KC). The coating solutions were investigated using a rheological method, and the coatings were characterized by water solubility tests, water vapor permeability (WVP), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and thermogravimetric analysis (TGA). The preservation effect of KC coating on cherry tomatoes stored at room temperature was determined. Results indicated that the curdlan addition can adjust the hydrophilicity/hydrophobicity of KGM coatings. Curdlan addition enhanced intermolecular entanglement and film-forming property. Increasing curdlan content in KC coatings significantly decreased the moisture content, dissolution and swelling ratio, and WVP. The KGM-curdlan composites behaved as high-performance coatings with good compatibility and uniformity. The K₃C₂ coating showed the best uniformity, water barrier, and thermal stability. The application of K₃C₂ coating significantly reduced the weight loss, decay loss, and delayed the decreases of firmness, soluble solids, total acid, and VC contents of cherry tomatoes. The KGM/curdlan edible coatings have promising potential for prolonging the shelf life of cherry tomatoes and applications in fruits preservation in the future.

Structure, Merits, Gel Formation, Gel Preparation and Functions of Konjac Glucomannan and Its Application in Aquatic Food Preservation

Konjac glucomannan (KGM) is a natural polysaccharide extracted from konjac tubers that has a topological structure composed of glucose and mannose. KGM can be used as a gel carrier to load active molecules in food preservation. The three-dimensional gel network structure based on KGM provides good protection for the loaded active molecules and allows for sustained release, thus enhancing the antioxidant and antimicrobial activities of these molecules. KGM loaded with various active molecules has been used in aquatic foods preservation, with great potential for different food preservation applications. This review summarizes recent advances in KGM, including: (i) structural characterization, (ii) the formation mechanism, (iii) preparation methods, (iv) functional properties and (v) the preservation of aquatic food.

Stable O/W emulsions and oleogels with amphiphilic konjac glucomannan network: preparation, characterization, and application

BACKGROUND

The stabilization of oil-in-water (O/W) emulsions has long been explored. Assembly of polymer networks is an effective method for stabilizing O/W emulsions. Konjac glucomannan (KGM) is a plant polysaccharide and the network of KGM gel is a good candidate for stabilizing O/W emulsions based on its high viscosity and thickening properties. However, natural KGM has strong hydrophilicity and is not able to offer interfacial activity. Octenyl succinic anhydride (OSA) is a hydrophobic molecule, which is widely used as thickener and stabilizer in food emulsions. In this work, the amphiphilic biopolymer (OSA-KGM) was fabricated by modifying the KGM with OSA. Furthermore, OSA-KGM biopolymer was used to prepare O/W emulsions, which were then freeze-dried and used to prepare oleogels as fat substitute for bakery products.

RESULTS

OSA-KGM had advanced hydrophobicity with water contact angle 81.13° and adsorption behavior at the oil-water interface, with interfacial tension decreasing from 18.52 to 13.57 mN m^-1 within 1 h. The emulsification of OSA-KGM remarkably improved the stability of emulsions without phase separation during storage for 31 days. Oleogels with OSA-KGM showed good thixotropic and structure recovery properties (approximately 100%) and low oil loss (from 69.5% to 50.4%). Cakes made from oleogels had a softer texture than cakes made from peanut oil and margarine.

CONCLUSION

Amphiphilic biopolymer OSA-KGM shows advanced interfacial activity and hydrophobicity. This paper provides an insight into preparing stable O/W emulsions with a new biopolymer and oleogels potentially applied as fat substitute in bakery products. © 2022 Society of Chemical Industry.

Potential Application of Luteolin as an Active Antibacterial Composition in the Development of Hand Sanitizer Products

Antibacterial hand sanitizers could play a prominent role in slowing down the spread and infection of hand bacterial pathogens; luteolin (LUT) is potentially useful as an antibacterial component. Therefore, this study elucidated the antibacterial mechanism of LUT against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) and developed an antibacterial hand sanitizer. The results showed that LUT had excellent antibacterial activity against both E. coli (minimum inhibitory concentration (MIC) = 312.5 μg/mL, minimal bactericidal concentration (MBC) = 625 μg/mL), and S. aureus (MIC = 312.5 μg/mL, MBC = 625 μg/mL). Furthermore, LUT induced cell dysfunction in E. coli and S. aureus, changed membrane permeability, and promoted the leakage of cellular contents. Confocal laser scanning microscopy (CLSM) and scanning electron microscopy (SEM) analysis showed that LUT treatment affected cell structure and disrupted cell membrane integrity. The Fourier transform infrared analysis (FTIR) also confirmed that the LUT acted on the cell membranes of both E. coli and S. aureus. Overall, the application of LUT in hand sanitizer had better inhibition effects. Therefore, this study could provide insight into expanding the application of LUT in the hand sanitizer markets.

Bio-Nanocomposite Based on Edible Gelatin Film as Active Packaging from Clarias gariepinus Fish Skin with the Addition of Cellulose Nanocrystalline and Nanopropolis

This study develops bio-nano composite gelatin-based edible film (NEF) by combining nanogelatin, cellulose nanocrystal (CNC), and nanopropolis (NP) fillers to improve the resulting film characteristics. The NEF was characterized in terms of thickness, swelling, pH, water content, solubility, vapor and oxygen permeability, mechanical properties, heat resistance, morphology, transparency, and color. The results showed that the thickness and swelling increased significantly, whilst the pH did not significantly differ in each treatment. The water content and the water solubility also showed no significant changes with loadings of both fillers. At the same time, vapor and oxygen permeability decreased with addition of the fillers but were not significantly affected by the loading amounts. The heat resistance properties increased with the filler addition. Tensile strength and Young’s modulus increased for the films loaded with >3% CNC. The elongation at break showed a significant difference together with transparency and color change. The greater the CNC concentration and NP loading were, the darker the resulting transparency and the color of the NEF. Overall results show a considerable improvement in the properties of the resulting NEFs with the incorporation of CNC and NP fillers.

Chitosan films with tunable droplet size of Pickering emulsions stabilized by amphiphilic konjac glucomannan network

In this work, chitosan (CS) emulsion films were prepared with grapefruit essential oil (GEO) Pickering emulsions (OGEOs) stabilized by amphiphilic octenyl succinic anhydride (OSA) konjac glucomannan (OSA-KGM) network. The droplet size of emulsion was regulated by altering oil content in OGEOs (10 %, 20 %, 30 % and 40 %, w/w). The structural and physicochemical properties of CS films with tunable emulsion droplets (OGEOs) were investigated. The droplet size of OGEOs increased with the increasing content of GEO. FT-IR revealed that the formation of CS-OGEOs films was attributed to hydrogen bonding. CS-OGEOs films with large droplets presented smoother surface, enhanced water resistance, UV-shielding property, mechanical properties, but increased water vapor permeability (WVP) compared with CS-OGEOs films with small droplets. In addition, CS-OGEOs films with large droplets also presented compact film structure, controlled release of GEO, high efficiency of DPPH free radical scavenging and antibacterial activity. To sum up, incorporation of emulsion droplets was a good strategy for improving the structural and physicochemical properties of CS films.

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

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

Development of pH-responsive konjac glucomannan/pullulan films incorporated with acai berry extract to monitor fish freshness

In this work, konjac glucomannan (KGM)-based film reinforced with pullulan (PL) and acai berry extract (ABE) was developed by solvent casting method. The as-prepared films performed pH-sensitive properties, which can be potentially applied for fish freshness detection. Rheology, Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), scanning electron microscopy (SEM) were used to characterize chemical structure and morphology of ABE-loaded KGM/PL (KP) films (KP-ABE). FT-IR spectrum indicated that hydrogen bond dominated the formation of KP-ABE films. Adding PL contributed to enhanced mechanical properties of KGM film with increased tensile strength (TS) from 21.25 to 50.27 MPa and elongation at break (EAB) from 10.64 to 19.19 %. Incorporating ABE upgraded flexibility, UV-shielding, thermostability, water barrier (decreased Water vapor permeability (WVP) from 2.07 to 1.67 g·mm/m²·day kPa), antioxidant, and antibacterial ability of KP films, but weakened TS. In addition, KP-ABE films can reflect fish freshness in real time through color variability. Therefore, KP-ABE films exhibited potential applications in intelligent food packaging materials.

Development of antimicrobial oxidized cellulose film for active food packaging

Foodborne diseases caused by bacteria have aroused ongoing concerns for food safety. Most existing packaging plastics bring pollution and potential toxicity. Here antimicrobial dialdehyde cellophane (DACP) was developed by periodate oxidation. The structure, mechanical properties, optical properties, and barrier properties of DACP were characterized. The antimicrobial activity of DACP against four Gram-positive bacteria was studied. The packaging effect of DACP for food with high water content was evaluated, including strawberry and tofu. The antimicrobial activity of DACP improved with increased aldehyde content. Compared with the polyethylene film and cellophane, our DACP exhibited excellent antimicrobial effect and extended the shelf life of food significantly, which shows promising prospects in food packaging.

Structural characterization and antibacterial properties of konjac glucomannan/soluble green tea powder blend films for food packaging

Antimicrobial activity is a promising property for food packaging which could prolong the shelf life of food products. In this paper, the physicochemical and antimicrobial properties of konjac glucomannan (KGM)/soluble green tea powder (SGTP) edible films were firstly prepared and analyzed through light barrier properties, Fourier transform infrared spectroscopy (FT-IR), tensile strength (TS), X-ray diffraction (XRD), thermogravimetric analysis and scanning electron microscope (SEM). The results showed that appropriate addition of SGTP could improve the TS of composite films. With the increase of SGTP content, the transmittance of the films in the ultraviolet region decreased obviously, and the thermal stability was improved in a SGTP dependent manner. KGM/SGTP films present a fairly smooth and flat surface without any fracture when 0.5% SGTP was provided. The bacteriostatic test showed that the bacteriostatic performance of the composite films against Staphylococcus aureus and Escherichia coli was also significantly enhanced. When 1% SGTP was provided, the zones of inhibition for Escherichia coli and Staphyloccocus aureus reached to 13.45 ± 0.94 mm and 13.76 ± 0.92 mm, respectively. Overall, the KGM/SGTP films showed great potential as bioactive packaging materials to extend food shelf life.

Application of Gelatin in Food Packaging: A Review

Owing to the increasing environmental concerns and requirements for high-quality foods, edible films and coatings (based on proteins, polysaccharides, natural phenolic active substances, etc.) are being developed as effective alternatives to traditional plastic packaging. Gelatin is extracted from collagen. It is an ideal material for food packaging due to its versatile advantages such as low price, polymerization, biodegradability, good antibacterial and antioxidant properties, etc. However, gelatin film exists poor waterproof and mechanical properties, which limit its developments and applications in food packaging. Previous studies show that pure gelatin can be modified by adding active ingredients and incorporating them with bio-polymers to improve its mechanical properties, aiming to achieve the desirable effect of preservation. This review mainly shows the preparation and molding ways of gelatin-based edible films and the applications of gelatin modified with other biopolymers. Furthermore, this review provides the latest advances in gelatin-based biodegradable packaging and food applications that exhibit outstanding advantages in food preservation.

Multilayer Films Based on Poly(lactic acid)/Gelatin Supplemented with Cellulose Nanocrystals and Antioxidant Extract from Almond Shell By-Product and Its Application on Hass Avocado Preservation

In this work, poly(lactic acid) (PLA)/gelatin/PLA multilayer films supplemented with cellulose nanocrystals and antioxidant extract from almond shell (AS) by-products were developed by solvent casting technique for active food packaging. The almond shell antioxidant extract (ASE) was obtained by microwave-assisted extraction, while cellulose nanocrystals (CNCs) were extracted from AS by a sequential process of alkalization, acetylation and acid hydrolysis. Four formulations were obtained by adding 0 (control), 6 wt.% of ASE (FG/ASE), 4.5 wt.% of CNCs (FG/CNC) and 6 wt.% + 4.5 wt.% of ASE + CNCs, respectively, (FG/ASE + CNC) into fish gelatin (FG). PLA/FG/PLA multilayer films were prepared by stacking two outer PLA layers into a middle FG film. A surface modification of PLA by air atmospheric plasma treatment was optimized before multilayer development to improve PLA adhesion. Complete characterization of the multilayers underlined the FG/ASE + CNC formulation as a promising active reinforced packaging system for food preservation, with low values of transparency, lightness and whiteness index. A good adhesion and homogeneity of the multilayer system was obtained by SEM, and they also demonstrated low oxygen permeability (40.87 ± 5.20 cm³ mm m^-2 day) and solubility (39.19 ± 0.16%) values, while mechanical properties were comparable with commercial plastic films. The developed multilayer films were applied to Hass avocado preservation. The initial degradation temperature (T_ini), DSC parameters and in vitro antioxidant capacity of the films were in accordance with the low peroxide and anisidine values obtained from avocado pulp after packaging for 14 days at 4 °C. The developed PLA/FG/PLA films supplemented with 6 wt.% ASE+ 4.5 wt.% CNCs may be potential bioactive packaging systems for fat food preservation.

Polysaccharide-Based Nanocomposites for Food Packaging Applications

The article presents a review of the literature on the use of polysaccharide bionanocomposites in the context of their potential use as food packaging materials. Composites of this type consist of at least two phases, of which the outer phase is a polysaccharide, and the inner phase (dispersed phase) is an enhancing agent with a particle size of 1-100 nm in at least one dimension. The literature review was carried out using data from the Web of Science database using VosViewer, free software for scientometric analysis. Source analysis concluded that polysaccharides such as chitosan, cellulose, and starch are widely used in food packaging applications, as are reinforcing agents such as silver nanoparticles and cellulose nanostructures (e.g., cellulose nanocrystals and nanocellulose). The addition of reinforcing agents improves the thermal and mechanical stability of the polysaccharide films and nanocomposites. Here we highlighted the nanocomposites containing silver nanoparticles, which exhibited antimicrobial properties. Finally, it can be concluded that polysaccharide-based nanocomposites have sufficient properties to be tested as food packaging materials in a wide spectrum of applications.

Integrating Antioxidant Functionality into Polymer Materials: Fundamentals, Strategies, and Applications

While antioxidants are widely known as natural components of healthy food and drinks or as additives to commercial polymer materials to prevent their degradation, recent years have seen increasing interest in enhancing the antioxidant functionality of newly developed polymer materials and coatings. This paper provides a critical overview and comparative analysis of multiple ways of integrating antioxidants within diverse polymer materials, including bulk films, electrospun fibers, and self-assembled coatings. Polyphenolic antioxidant moieties with varied molecular architecture are in the focus of this Review, because of their abundance, nontoxic nature, and potent antioxidant activity. Polymer materials with integrated polyphenolic functionality offer opportunities and challenges that span from the fundamentals to their applications. In addition to the traditional blending of antioxidants with polymer materials, developments in surface grafting and assembly via noncovalent interaction for controlling localization versus migration of antioxidant molecules are discussed. The versatile chemistry of polyphenolic antioxidants offers numerous possibilities for programmed inclusion of these molecules in polymer materials using not only van der Waals interactions or covalent tethering to polymers, but also via their hydrogen-bonding assembly with neutral molecules. An understanding and rational use of interactions of polyphenol moieties with surrounding molecules can enable precise control of concentration and retention versus delivery rate of antioxidants in polymer materials that are critical in food packaging, biomedical, and environmental applications.

Biodegradable Packaging Materials from Animal Processing Co-Products and Wastes: An Overview

Biodegradable polymers are non-toxic, environmentally friendly biopolymers with considerable mechanical and barrier properties that can be degraded in industrial or home composting conditions. These biopolymers can be generated from sustainable natural sources or from the agricultural and animal processing co-products and wastes. Animals processing co-products are low value, underutilized, non-meat components that are generally generated from meat processing or slaughterhouse such as hide, blood, some offal etc. These are often converted into low-value products such as animal feed or in some cases disposed of as waste. Collagen, gelatin, keratin, myofibrillar proteins, and chitosan are the major value-added biopolymers obtained from the processing of animal's products. While these have many applications in food and pharmaceutical industries, a significant amount is underutilized and therefore hold potential for use in the generation of bioplastics. This review summarizes the research progress on the utilization of meat processing co-products to fabricate biodegradable polymers with the main focus on food industry applications. In addition, the factors affecting the application of biodegradable polymers in the packaging sector, their current industrial status, and regulations are also discussed.

Advanced properties of gelatin film by incorporating modified kappa-carrageenan and zein nanoparticles for active food packaging

Recently, the improvement of gelatin-based films for usage in food packaging has attracted more attention owing to their non-toxicity, biodegradability, availability, and renewability. In the current study, the improved gelatin-based films were produced using covalent interaction through dialdehyde kappa-carrageenan (DAK-car) and thymol-loaded zein nanoparticle content. The influences of DAK-car into the matrix of gelatin films (GEL) on the structural, total soluble matter (TSM), moisture content (MC), and water vapor permeability (WVP), and mechanical properties were investigated. After the formation of covalent crosslinking amongst the amino groups of GEL and the dialdehyde groups of DAK-car with the blending ratio of 1:2 (GEL 4% w/v): (DAK-car 1% w/v), a remarkably (p < 0.05) reduction was saw in TSM, MC, and WVP of film. The tensile strength of this film (72.26 ± 0.3 MPa) was ~20-fold higher compared with pure GEL film. It should also be noted that the presence of zein nanoparticles (ZNPs) did not have a notably effect on improving the attributes of gelatin-based film. However, the presence of thymol in concentrations of 0.25 and 0.5 mg/mL showed acceptable antioxidant and antimicrobial activities. As a result, GEL/DAK-car with blending ratio of 1:2 containing thymol-loaded ZNPs films demonstrated the valuable potential for application in active food packaging.

Synergistic effect of silane cross-linker (APTEOS) on PVA/gelatin blend films for packaging applications

The objective of this work is to fabricate hydrogel films which are biodegradable and also fit for packaging applications. The hydrogel films were prepared by the reaction of polyvinyl alcohol and gelatin with and without 3-aminopropyltriethoxysilane (APTEOS) cross-linker. The hydrogel films were then characterized by FTIR spectroscopy, degree of swelling, TGA, SEM analysis and mechanical testing. The FTIR spectra of the hydrogel films confirmed the presence of both polymers and hydrogen bonding between them. TGA analysis confirmed the increase in thermal stability with the increase of cross-linker amount. SEM analysis confirmed the increase in uniformity of structure with the increase of cross-linker amount. The increase in cross-linker amount resulted in decrease of degree of swelling and increase of tensile strength. The biodegradability of hydrogel films was evaluated by performing soil burial test and found to be decreased with the increase of cross-linker amount. In order to balance the tensile strength and biodegradability, the optimum amount of cross-linker was determined which resulted in the formation of the best performing film. Finally, our best performing film was compared with other hydrogel films reported in the literature. Hence, the hydrogel films cross-linked with APTEOS are biodegradable, having high tensile strength and suitable for packaging purpose.

Preparation of pH-sensitive food packaging film based on konjac glucomannan and hydroxypropyl methyl cellulose incorporated with mulberry extract

A pH-sensitive food packaging film was prepared based on konjac glucomannan (KGM) and hydroxypropyl methyl cellulose (HPMC) incorporated with mulberry extracts² (MBE). FT-IR and XRD analysis revealed that there are good molecular interactions among the three components. The incorporation of MBE into KGM and HPMC (KH) films can significantly improve the mechanical properties and UV resistance. Notably, the KH-MBE-20% film almost completely blocked UV light in the range of 200-600 nm. The best antioxidant and antibacterial properties were obtained when the addition of MBE in the composite film was 20%. In addition, KH-MBE film has good responsiveness to buffers with pH range from 2 to 12. In visual monitoring experiments using the film on fresh fish, the color of the KH-MBE film changed from purple to gray to yellow as the freshness of the fish decreased, and the KH-MBE-20% film had the best color stability. Therefore, intelligent packaging of KH-MBE film has potential applications in real-time monitoring of fish freshness.

Degradable Gelatin-Based Supramolecular Coating for Green Paper Sizing

Developing a paper sizing agent to meet the requirements of low cost, high quality of the paper, and environmental sustainability is significant but remains a challenge. Herein, a novel degradable gelatin-based coating emulsion for paper surface sizing was developed by a simple one-step polymerization and blending process. Poly(methacrylic acid) (PMAA) was first introduced to a gelatin solution to form gelatin-PMAA emulsion (G-PMAA) through the formation of hydrogen bonds between PMAA and gelatin. The addition of PMAA endowed gelatin with the increased hydrophobicity and the decreased upper critical solution temperature. Then, a relatively small amount of the flexible poly(butyl acrylate) (PBA), which imparted the toughness of the formed film, was blended with the G-PMAA emulsion to form G-PMAA/PBA emulsion. The G-PMAA/PBA emulsion with a high gelatin content of 0.2 g/mL was in the sol state at room temperature, which facilitated the application of the G-PMAA/PBA emulsion. The corrugated papers sized by G-PMAA/PBA emulsion exhibited excellent mechanical properties and water resistance.