A smart film incorporating anthocyanins and tea polyphenols into sodium carboxymethyl cellulose/polyvinyl alcohol for application in mirror carp

Supramolecular deep eutectic solvents as green media for efficient extraction of tea polyphenols and its application in bio-active film

Ultrasonic-assisted supramolecular deep eutectic solvents (SUPRADESs) extraction of active ingredients from plants is a novel green extraction method. In this study, a series of SUPRADESs combined with cyclodextrins (CDs) and organic acids or polyols were synthesized and used to extract the tea polyphenols (TP). SUPRADESs, consisting of Hydroxypropyl-β-cyclodextrin (HP-β-CD) and L-lactic acid (LA) with a mass ratio of 1:5, contributed to achieving the maximum extraction efficiency of TP. Then, the extraction rate was optimized by different experimental conditions, and the optimal extraction yield of TP was (111.36 ± 2.31 mg/g). Then, the biofilms were successfully prepared using HP-β-CD/LA extract as a plasticizer for polyvinyl alcohol and chitosan. Furthermore, the antioxidant activity of extract and film containing TP was determined using biochemical kits. Finally, the synthesis process of HP-β-CD/LA and the TP extraction were investigated using molecular simulation. The findings indicate that enhanced TP yield could be attributed to an increase in non-covalent bonds between HP-β-CD and TP through the assistance of LA.

Anthocyanin modified by chondroitin sulphate and tannic acid improved the quality-indicating properties of gelatin-based intelligent film

A highly pH-responsive gelatin film incorporating purple cabbage anthocyanin (PCA) and chondroitin sulphate (CS)/tannic acid (TA) was developed. Co-pigmentation of PCA via CS/TA improved its photothermal stability and visibility of color change in gelatin film. The morphological and structural properties of CS-PCA and TA-PCA films revealed that a more stable network was formed as new hydrogen bonds were generated by the co-pigmentation. Meanwhile, the co-pigmentation improved film's mechanical and hydrophobic properties, expressed as higher tensile strength (16.65 and 17.97 Mpa) and lower water vapor permeability (1.45 and 1.41) in CS-PCA and TA-PCA films, compared to PCA film. CS-PCA and TA-PCA films showed distinct color transitions for chilled fish fillets during storage. Total color difference (ΔE) of CS-PCA and TA-PCA films correlated well with the deterioration indexes of total volatile base nitrogen (TVB-N). All the results provided a novel pH-sensitive intelligent packaging strategy by co-pigmenting CS/TA with PCA for freshness monitoring.

Starch-pectin smart tag containing purple carrot peel anthocyanins as a potential indicator of analogous meat freshness

Smart films of starch/pectin and purple carrot peel (PCP) containing anthocyanins were developed, characterized, and used as pH-responsive tags to monitor plant-based chicken analogous. This study innovates by incorporating PCP in the film solution both as an extract and as a powder, and the resulting tags were applied to a plant-based food. PCP powder <100-mesh was directly incorporated into the film-forming suspension. For powder >100-mesh, two extracts were tested: an aqueous solution and a 1 % NADES solution added to the film-forming suspension. Quantification of PCP anthocyanins by HPLC showed a higher extraction under acidic conditions (1664 mg C3G equivalents 100 g-1). Films with PCP presented greater light protection. Films with 15 % and 25 % PCP and those with added extract showed better tensile strength (3.0-3.6 MPa), elongation at break (16-20 %) and a water contact angle of 52°. All films responded to pH variations (1 to 14) and ammonia vapor and showed ΔE* values >5. After 3 days, films used as smart tags monitoring chicken analogous presented noticeable color differences for PCPNADES (55 ± 8) and 15%PCP (40 ± 1). PCP showed strong potential as a pigmenting agent in films, especially as an aqueous extract with NADES for use as pH-responsive tags in chicken analogous.

3D printing cassava starch-ovalbumin intelligent labels: Co-pigmentation effects of gallic acid on anthocyanins

Anthocyanins are often chosen as signal converters of intelligent labels. However, they are degraded by high-temperature oxidation in the process of intelligent label preparation. The color fading seriously affects the sensitivity of color development. In this study, a green 3D printing intelligent label preparation technique was developed, in which gallic acid (GA) was added to a blueberry anthocyanin (BA) solution to enhance the color of the co-pigment to ensure the color sensitivity. The combined effect of GA-BA reduced the fade rate of the anthocyanins from 35.13 % to 26.44 % at 90 °C. The printing ink has shear-thinning viscosity characteristics and yield stresses in the range of 500-600 MPa for high-quality printing. Structural analysis revealed that GA-BA co-pigmentation enhanced the interaction between ovalbumin and cassava starch. In addition, the method of 3D printing to prepare labels was conducive to solving the problem of waste in traditional labeling process. The results of freshness testing of sea shrimp proved that labels can be applied to fresh boxes to reflect the freshness of food. We provide a method for enhancing the color of 3D-printed smart ink to prepare intelligent labels with reproducible and customizable batch shapes.

Development of carboxymethyl cellulose/starch films enriched with ZnO-NPs and anthocyanins for antimicrobial and pH-indicating food packaging

Active packaging, which can monitor food freshness and extend the shelf life, has gained significant attention in recent years. This study aims to develop a novel carboxymethyl cellulose (CMC)/starch/anthocyanins/ZnO active films with enhanced properties and specific functionalities. Scanning electron microscopy (SEM) and X-ray diffraction (XRD) revealed that the addition of anthocyanins and nano-ZnO particles (ZnO-NPs) led to heterogeneous microstructures and a slight decrease in the crystallinity. Fourier transform infrared spectroscopy (FTIR) indicated that there were no chemical interactions among film components. Active films containing ZnO-NPs exhibited improved ductility, as well as enhanced light barrier and water resistance properties. Notably, a shift from hydrophilic to hydrophobic behavior of the films was observed with high ZnO-NP content, as evidenced by a significant increase in the water contact angle (from 63.44° to 114.22°). Furthermore, the presence of only 1 % ZnO-NPs resulted in efficient inhibition of Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) growth. Moreover, active films containing both anthocyanins and ZnO-NPs were highly sensitive to pH changes in buffer solutions (pH 2-11). Based on the results, a recommended film formulation for future active packaging applications is a 80:20 CMC/starch blend with 3 % ZnO-NPs and 0.1 g anthocyanins.

Intelligent Packaging Systems with Anthocyanin: Influence of Different Polymers and Storage Conditions

With the aim of meeting the growing demand for safe food, intelligent packaging has emerged, which monitors the conditions of the food and informs the consumer about its quality directly at the time of purchase. Among intelligent packaging options, colorimetric indicator films, which change color in response to changes in the food, such as the release of volatile compounds, have been widely studied. Among them, pH indicator films composed of dyes sensitive to small variations in the pH value of the food surface have received greater attention in recent years. Anthocyanins, which are natural pigments, have stood out as one of the most commonly used sources of dyes in the production of these indicator films. In this context, the present review aims to present an updated overview of research employing anthocyanins in indicator films, including their stability under different storage conditions, the influence of different polymers used in their production, and alternative techniques for maintaining stability.

A double-sided coating paper antibacterial indicator card based on polyvinyl alcohol/sodium carboxymethyl cellulose-anthocyanins and chitosan-halloysite nanotubes loaded essential oil to monitor fish freshness

This study developed a multifunctional paper-based freshness antibacterial indicator card by dual-sided coating on conventional filter paper. The indicator coating was composed of anthocyanins from purple cabbage, and polyvinyl alcohol and sodium carboxymethyl cellulose as substrates while the antibacterial coating contained halloysite nanotubes for loaded thyme essential oil and chitosan. FT-IR, XRD, and SEM analyses revealed that the components were well-mixed, and the paper was tightly bound to the coatings through hydrogen bonds. Additionally, the coating effectively filled the porous fiber gaps in the paper, significantly enhancing the mechanical properties of the paper. The tensile strength of the coated paper was enhanced from 14.28 MPa to a range of 42.25-47.71 MPa, and the bending resistance was increased from 0.35 N·mm to a range of 1.72-1.99 N·mm compared to the uncoated paper. The addition of anthocyanins provided excellent sensitivity to pH and ammonia for the indicator card. Furthermore, the coating including halloysite nanotubes for loaded thyme essential oil exhibited antimicrobial resistance against Escherichia coli and Staphylococcus aureus. When used on fresh carp, the antibacterial indicator card not only indicated the freshness of the carp but also extended the best before date of the fish meat by 1-2 days. The indicator exhibited the most pronounced color transformation and optimal freshness indication performance when the mass fraction of anthocyanins was 2 %.

Intelligent double-layer film based on gellan gum/modified anthocyanin/curcumin/sodium alginate/zinc oxide for monitoring shrimp freshness

In this study, intelligent double-layer films were prepared using modified black rice anthocyanin (MBRA)-curcumin (CUR)-gellan gum (GG) as the inner indicator layer and sodium alginate (ALG)‑zinc oxide (ZnO) as the outer antimicrobial layer. The bilayer films were successfully prepared, as revealed by scanning electron microscopy, Fourier-transform infrared spectroscopy, and X-ray diffraction measurements. The mechanical characteristics, moisture content, and water vapor resistance of GG-MBRA/CUR1@ALG-ZnO, GG-MBRA/CUR2@ALG-ZnO, and GG-MBRA/CUR3@ALG-ZnO films showed significant enhancement compared to GG-MBRA/CUR3 and ALG-ZnO films. The bilayer films exhibited excellent pH responsiveness and reacted effectively to ammonia. The outer layer significantly improved the antioxidant and antibacterial properties of the inner layer. When the films were applied to shrimp, it was found that the double-layer films not only monitored the freshness of the shrimp in real-time but also were influential in extending the shelf life of the shrimp by about 1 d. Therefore, the double-layer film demonstrated potential as a smart packaging material for real-time monitoring of meat product freshness.

Preparation and characterization of ternary polysaccharide hydrogels based on carboxymethyl cellulose, carboxymethyl chitosan, and carboxymethyl β-cyclodextrin

A series of ternary polysaccharide hydrogels were facile prepared by incorporating carboxymethyl cellulose (CMC) into the carboxymethyl chitosan/carboxymethyl β-cyclodextrin (CMCS/CMCD) complex solution based on multiple physical interactions. Structure properties of the CMC/CMCS/CMCD hydrogels were revealed by FTIR, XRD, SEM, and TG. The rheological and texture properties, temperature/pH-response behaviors, biocompatablity, and antimicrobial activity of the hydrogels were determined in detail. These results showed that the existence of electron force and hydrogen bond among three components leading to formation of the hydrogels, displaying good mechanical characteristic, stable solid-like rheological properties, controllable swelling and degradation behaviors, and excellent biocompatibility. Additionally, the swelling kinetics can be well described by the Schott's pseudo second order model. Moreover, the hydrogels loaded with cinnamic acid (CA) exhibited good antimicrobial activity against both Staphylococcus aureus and Escherichia coli, and the antimicrobial activity was related to the composition of the prepared hydrogels. The novel ternary polysaccharide hydrogels may have good application prospects in food and bio-medicine.

Polyvinyl alcohol/kappa-carrageenan-based package film with simultaneous incorporation of ferric ion and polyphenols from Capsicum annuum leaves for fruit shelf-life extension

Bio-based food packaging materials have elicited growing interests due to their great degradability, high safety and active biofunctions. In this work, by simultaneously introducing the polyphenolic extracts from Capsicum annuum leaves and ferric ion (Fe3+) into the Polyvinyl alcohol/kappa-carrageenan (PVA/κ-carrageenan)-based film-forming matrix, an active package film was developed, with the purpose to improve the food shelf life. The experimental results indicated that the existence of Fe3+ can not only improve the mechanical properties owing to the multiple dynamic coordinated interactions, but also endow the composite films with excellent fire-retardancy. Moreover, the composite films could display excellent UV resistant performance, water vapor/oxygen gas barrier properties and antioxidant activities with the corporation of polyphenols. In particular, the highest DPPH and ABTS radical scavenging capacities for composite film (PC-PLP7 sample) were evaluated to be 82.5 % and 91.1 %, respectively. Higher polyphenol concentration is favorable to the bio-functions of the materials. Benefitting from these features, this novel kind of films with a dense and steady micro-structure could be further applicated in fruit preservations, where the ripening bananas were ensured with the high storage quality. This integration as a prospective food packaging material provides an economic and eco-friendly approach to excavate the high added-values of biomass.

Development of CO2-sensitive antimicrobial bilayer films based on gellan gum and sodium alginate/sodium carboxymethyl cellulose and its application in strawberries

To effectively extend the shelf life of fruits meanwhile facilitating consumers to judge their freshness, in this work, a double-layer multifunctional film combining CO2 sensitivity and antibacterial properties was successfully prepared by adding methyl red (MR), bromothymol blue (BTB) into gellan gum (GG) as the sensing inner layer, and doping tannic acid (TA) into sodium alginate with sodium carboxymethyl cellulose (CMC) as the antimicrobial outer layer, which was applied to the freshness indication of strawberries. Microscopic morphology and spectral analysis demonstrated that the bi-layer films were fabricated successfully. The mechanical characteristics, thermal stability, water vapor resistance, and antibacterial capabilities of the bilayer films improved as TA concentration rose. They exhibited noticeable color changes at pH = 2-10 and different concentrations of CO2. Application of the prepared films to strawberries revealed that the GG-MB@SC-6%TA film performed most favorably under 4 °C storage conditions, not only monitoring strawberry freshness but also retaining high soluble solids and titratable acidity, resulting in a slight decrease in hardness and weight loss. Therefore, taking into account all of the physical-functional characteristics, the GG-MB@6%TA film has a broad application prospect for intelligent food packaging.

Study on preservation and monitoring effect of sodium alginate-konjac glucomannan films loaded with tea polyphenols and Lycium ruthenicum anthocyanins

To investigate the efficacy of sodium alginate-konjac glucomannan (SA-KGM) films with anthocyanins (LRA) and tea polyphenols (TP) in meat, beef and grass carp were selected as representative meat products for preservation and freshness monitoring experiments at 4 °C. Concurrently, storage experiments of the films were conducted in this controlled environment. The results of the storage experiment showed that the films delayed meat spoilage by 2-4 days, nearly doubling the preservation time compared to the blank control. Additionally, the film exhibited significant capability to monitor the spoilage process of beef and grass carp. It was revealed by curve fitting analysis that there was a significant correlation between the color change of the film and the spoilage index of the meat. Throughout the storage experiment with the film, it was observed that moisture significantly influenced the microstructure and bonding situation of the films, thereby impacting their mechanical and barrier properties. However, the films were still able to maintain satisfactory physicochemical properties in general. The above findings were crucial in guiding the promotion of the film within the food preservation industry.

Effects of freeze-thaw cycles on in-vitro digestive properties of myofibrillar protein in mirror carp (Cyprinus carpio L.), based on protein degradation, oxidation, and structural properties

The in-vitro digestive properties of myofibrillar protein (MP) in mirror carp (Cyprinus carpio L.) after freeze-thaw (F-T) cycles were analyzed in terms of the relationship between protein degradation, oxidation, and structural properties. The F-T samples exhibited a significant increase in glucosidase activity, N-acetyl-β-d-glucosidase activity, total protease activity, and non-protein nitrogen content. α-aminoadipate semialdehyde and γ-glutamate semialdehyde contents increased by 23.17% and 123.12%, respectively. Furthermore, 53.97% decrease in the total nitrogen content and changes in the content of different soluble proteins were observed. X-ray diffraction intensity, thermal stability, free amine content, hydrolysis degree, and digestibility of the MP samples decreased, and the 2θ angle and zeta potential were reversed. Besides, changes in the amide band wavenumbers were also detected. Therefore, the protein structure was unfolded and aggregates were formed through degradation and oxidation induced by the F-T cycles, ultimately making the in-vitro digestion of MP difficult.

Pressurized liquid extraction of bioactive compounds from grape peel and application in pH-sensing carboxymethyl cellulose films: A promising material to monitor the freshness of pork and milk

This study produced pH-sensing carboxymethyl cellulose (CMC) films functionalized with bioactive compounds obtained by pressurized liquid extraction (PLE) of grape peel to monitor the freshness of pork and milk. A semi-continuous PLE was conducted using hydroethanolic solution (70:30, v/v) at a flow rate of 5 mL/min, 15 MPa, and 60 °C. The films were produced by the casting technique using CMC (2.5 %, w/v), glycerol (1 %, v/v), and functionalized with 10, 30, and 50 % (v/v) grape peel extract. From the results obtained, LC-MS/MS revealed that PLE extracted twenty-seven phenolic compounds. The main phenolic compounds were kaempferol-3-glucoside (367.23 ± 25.88 µg/mL), prunin (270.23 ± 3.62 µg/mL), p-coumaric acid (236.43 ± 26.02 µg/mL), and procyanidin B1 (117.17 ± 7.29 µg/mL). The CMC films presented suitable color and mechanical properties for food packaging applications. The addition of grape peel extract promoted the pH-sensing property, showing the sensitivity of anthocyanins to pH changes. The films functionalized with grape peel extract presented good release control of bioactive compounds, making them suitable for food packaging applications. When applied to monitor the freshness of pork and milk, the films exhibited remarkable color changes associated with the pH of the food during storage. In conclusion, PLE is a sustainable approach to obtaining bioactive compounds from the grape peel, which can be applied in the formulation of pH-sensing films as a promising sustainable material to monitor food freshness during storage.

A novel curdlan/methyl cellulose/walnut green husk polyphenol edible composite film for walnut packaging

In this study, polyphenols were extracted from walnut green husk, an agricultural waste, and were incorporated into curdlan (CD) and methyl cellulose (MC) to create a novel edible composite film. For structural character, the film matrix was tightly bound primarily by non-covalent bonds and the addition of walnut green husk polyphenols (WGHP) significantly reduced the surface roughness of the composite film. For mechanical properties, the addition of WGHP improve the flexibility of films, and it significantly improved the barrier ability of ultraviolet rays and water-vapor. Furthermore, the incorporation of WGHP to the CD-MC film resulted in enhanced antioxidant and antibacterial effects, which effectively retards lipid oxidation in fried walnuts. Consequently, the fabricated CD-MC-WGHP composite film bears immense potential for use in food preservation applications, particularly in extending the shelf life of fried walnuts.

Host-Guest Chemosensor Ensembles based on Water-Soluble Sulfonated Calix[n]arenes and a Pyranoflavylium Dye for the Optical Detection of Biogenic Amines

Biogenic amines (BAs) are biologically active nitrogen-containing compounds formed during the food spoilage process and are often related as key markers of food quality, safety, and freshness. Because their presence in foods at high levels can cause significant health problems, researchers have been focused on developing novel strategies and methods for early detection and capture of these analytes. Herein, water-soluble sulfonated calix[n]arene macrocycles (SC4, SC6, and SC8) and a pH-sensitive dye (4'-hydroxy-10-methylpyranoflavylium) were investigated as host-guest systems for BA sensing. The hosts were able to bind the flavylium cation of the dye with association constants of 103 to 104 M-1. The dye complexation also allowed tuning its pKa from 6.72 (free) toward high values: 7.68 (SC4), 7.79 (SC6), and 8.45 (SC8). These data were crucial to optimize the host-guest complexes as optical sensing systems for putrescine/tyramine (pH 7.2-7.6), yielding a colorimetric redshift from yellow to red. The BA sensing was also demonstrated by fluorescence quenching for the calix[n]arene/dye complexes and fluorescence recovery after the addition of BAs. 1H NMR spectroscopy was used to demonstrate the interaction mode, confirming an encapsulation-driven mechanism. Overall, these host-guest systems demonstrated great potential for the detection of BAs, one of the main key markers of food spoilage.

Fabrication of ammonia and acetic acid-responsive intelligent films based on grape skin anthocyanin via adjusting the pH of film-forming solution

pH-responsive intelligent films for food freshness monitoring have attracted great attentions recently. In this study, several intelligent films based on chitosan (CS), polyvinyl alcohol (PVA), and grape skin anthocyanin (GSA) were prepared, and the effect of film-forming solution pH on the properties of intelligent films was investigated. The results of SEM, FTIR, XRD and TGA displayed that the hydrogen bond between CS and GSA was strong at strong acidic conditions (2.0-2.5), and it weakened at weak acidic conditions (3.0-4.5). Meanwhile, the hydrogen bond between PVA and GSA was negligible under strong acidic conditions, and it appeared under weak acidic conditions. Consequently, the films fabricated under weak acidic conditions displayed lower water solubility, lower water vapor permeability, and higher elongation at break. The tensile strength of films increased firstly and subsequently decreased with pH increasing, reaching a maximum value of 31.44 MPa at pH 3.5. Additionally, the films prepared at pH 2.5 and 4.0 showed the best color responsiveness to ammonia and acetic acid, respectively. Overall, the intelligent films prepared under variant pH have the potential to realize the goal of monitoring the freshness of different types of food, thereby expanding the application subject of anthocyanins-based intelligent films.

Intelligent active films of sodium alginate and konjac glucomannan mixed by Lycium ruthenicum anthocyanins and tea polyphenols for milk preservation and freshness monitoring

To achieve real-time monitoring of food freshness, a pH-responsive film based on sodium alginate-konjac glucomannan loaded with Lycium ruthenicum anthocyanins (LRA) was prepared, with the addition of tea polyphenols (TP) to enhance the stability of LRA. The surface structure of the films was observed by AFM. The results of FTIR and molecular docking simulation showed that LRA and TP were bound to polysaccharide by hydrogen bonds. The mechanical properties, barrier properties, and antioxidant/antibacterial properties of the films were significantly improved and the films showed obvious color response to pH. Notably, the AFM images showed TP and LRA could lead to more severe damage to the bacterial structure. The results of molecular docking simulation suggested that TP and LRA could act on different components of the bacterial cell wall, indicating their synergistic mechanism in antimicrobial activity. Moreover, the stability of LRA was improved due to the interactions of TP and polysaccharides with LRA. The aggregates formed by TP and LRA were clearly observed by AFM. Finally, the film showed excellent preservation and freshness monitoring effect in milk. In conclusion, TP-LRA-SA-KGM intelligent film exhibited excellent performance and represented a promising novel food packaging material with potential applications.

Preparation and characterization of smart indicator films based on gellan gum/modified black rice anthocyanin/curcumin for improving the stability of natural anthocyanins

In order to improve the stability of natural anthocyanins in intelligent packaging materials, this work first modified black rice anthocyanins (BRA) by acylation with acetic acid, then modified the acylated BRA by co-coloring with different ratios of curcumin (CUR), and finally added the mixed indicator to gellan gum (GG) to develop intelligent packaging films with good stability. The UV spectroscopy results showed that acetic acid had successfully modified the BRA, while the thermal, photostability and pH stability of the modified black rice anthocyanin (MBRA) were significantly enhanced. The indicators of BRA, MBRA and MBRA mixed with CUR showed excellent pH sensitivity in different buffer solutions. The SEM, FT-IR and XRD results indicated apparent crystalline aggregates on the surface of the films added with a high concentration of CUR. Compared with GG-BRA film, GG-MBRA film improved all properties except for antioxidant performance. Notably, the GG-MBRA/CUR series composite films exhibited significant improvements over the GG-BRA and GG-MBRA films in terms of optical characteristics, mechanical properties, water vapor barrier, oxidation resistance, and color stability; meanwhile, all films exhibited excellent pH sensitivity. Considering all the properties of the films, GG-MBRA/CUR3 film has tremendous potential as a smart indicator film for improving freshness accuracy.

Preparation and activity of sodium carboxymethyl cellulose (CMC-Na) and Metarhizium rileyi ZHKUMR1 composite membrane

Improving the adhesion capability of Metarhizium rileyi ZHKUMR1 on leaves enabled by the combination with Carboxymethyl Cellulose (CMCNa) materials is feasible to improve the utilization rate of Metarhizium rileyi. Herein, the CMC-Na-ZHKUMR1 membrane was prepared by simply mixing Carboxymethyl Cellulose (CMCNa) with Metarhizium rileyi. Through compatibility test, it was found that the inhibition rates of spore germination and mycelial growth of ZHKUMR1 were only 1.51 % and 3.13 % when the concentration of Carboxymethyl Cellulose (CMCNa) was 0.5 %. By adding 2 % of Carboxymethyl Cellulose (CMCNa) under UV irradiation for 30 min, the protective rate of spore germination of ZHKUMR1 was up to ~12.44 %, where the wettability on corn leaves was achieved and the retention of ZHKUMR1 spores on corn leaves was increased. After indoor activity determination, it was found that after 3 min of simulated rain washing, the lethal rate of corn leaves pretreated with CMC-Na-ZHKUMR1 on the 2nd instar larvae of Spodoptera frugiperda was 46.67 %, which was much higher than that of ZHKUMR1 spore suspension alone. This work clearly showed that Carboxymethyl Cellulose (CMCNa) effectively improved the field application effect of Metarhizium rileyi ZHKUMR1, and this strategy provided guidance for improving the field efficacy of Metarhizium rileyi ZHKUMR1.

Recent Advances in Functional Cellulose-based Films with Antimicrobial and Antioxidant Properties for Food Packaging

The packaging of food plays a crucial role in food preservation worldwide. However, traditional packaging systems are passive layers with weak efficiency in protecting the food quality. Therefore, packaged foods are gradually spoiled due to the oxidation and growth of microorganisms. Additionally, most of the commercial packaging films are made of petroleum-based materials which raise environmental concerns. Accordingly, the development of eco-friendly natural-derived active packaging systems has increased the attention of scientists. Cellulose as the most abundant polysaccharide on earth with high biocompatibility, no toxicity, and high biodegradability has extensively been applied for the fabrication of packaging films. However, neat cellulose-based films lack antioxidant and antimicrobial activities. Therefore, neat cellulose-based films are passive films with weak food preservation performance. Active films have been developed by incorporating antioxidants and antimicrobial agents into the films. In this review, we have explored the latest research on the fabrication of antimicrobial/antioxidant cellulose-based active packaging films by incorporating natural extracts, natural polyphenols, nanoparticles, and microparticles into the cellulose-based film formulations. We categorized these types of packaging films into two main groups: (i) blend films which are obtained by mixing solutions of cellulose with other soluble antimicrobial/antioxidant agents such as natural extracts and polyphenols; and (ii) composite films which are fabricated by dispersing antimicrobial/antioxidant nano- or microfillers into the cellulose solution. The effect of these additives on the antioxidant and antimicrobial properties of the films has been explained. Additionally, the changes in the other properties of the films such as hydrophilicity, water evaporation rate, and mechanical properties have also been briefly addressed.

Simultaneously realizing enhancement of sensitivity for freshness monitoring and multinomial properties of carrageenan/konjac glucomannan/blueberry anthocyanin-based intelligent film by diatomite

Here, highly sensitive blueberry anthocyanin (BBA)-induced intelligent indicating films were fabricated by incorporating a novel composite ingredient, diatomite (DA), into a matrix of konjac glucomannan (KGM), carrageenan (CAR) and BBA. We systematically investigated the effects of introducing DA and BBA on the structure, physical properties, colorimetric response, and practical application of the KGM/CAR film. Our findings revealed that the DA particles and BBA were well-distributed in the KGM/CAR matrix through hydrogen bonding interactions. This distribution significantly improved tensile strength, surface hydrophobicity, thermal stability, and barrier properties of the KGM/CAR film. Notably, the KGM/CAR-based intelligent film loaded with 6 % DA exhibited the most optimal properties. Furthermore, DA exhibited a hierarchical porous structure, enabling the KGM/CAR film to detect volatile amines with heightened sensitivity. When applied to monitor shrimp spoilage in transparent plastic packaging, the color of the composite film underwent remarkable changes from bright pink to bluish violet. These color changes correlated well with the total volatile basic nitrogen (TVB-N) and pH changes in the shrimp, as determined by standard laboratory procedures. Our work presents a promising approach to the development of high-performance and intelligent food packaging materials. These materials hold great potential for practical applications in the field of food packaging.

Attempt to identify antimicrobial Tridax procumbens (TP) mechanical properties using experimental work coupled with FEM model for biomedical applications

Medicinal plants play a prodigious role in the wound-healing process. Tridax procumbens (TP) has been proven to show strong antimicrobial activity against Staphylococcus aureus and could heal skin infections. Identifying mechanical properties of TP in his solid state and mixed with carboxymethylcellulose (CMC) have never been studied before. In this study, fresh TP liquid extracts blended with carboxymethylcellulose (CMC) biofilm were developed through the solution casting method. The casted film was tested for tensile strength through the Universal Tensile Tester (UTT), and the results were compared with the Finite Element Numerical Model (FEM) through the FEM code developed on the ANSYS solver. The experimental mean tensile test results for pure CMC were found as follows: tensile stress at the maximum of 15.31 MPa, modulus of elasticity of 7,24 GPa, the density of 1,62 g/cm3, and Poisson's ratio of 0.22. The experimental mean tensile test results for pure CMC/TP 50% were as follows: tensile stress at the maximum of 26.2 MPa, modulus of elasticity of 2.092 GPa, and density of 1.276 g/cm3. After several iterations, the following results were found for pure TP: modulus of elasticity of 0.225 GPa, a density of 0.93 g/cm3, and Poisson's ratio of 0.4 through FEM using inverse method technique. The experimental results were compared with the FEM solutions, which were found to be very close to the experimental results. The TP/CMC bio-membrane could be applied as a good wound dressing in biomedical applications. Mechanical properties found in this paper can contribute to the valorization of TP usage in several medical curing films applications.

Novel “all-in-one” multifunctional gelatin-based film for beef freshness maintaining and monitoring

In this study, a novel multifunctional food packaging was developed by incorporating alizarin (AL) and oregano essential oil Pickering emulsion (OEOP) into a gelatin film matrix. The incorporation of OEOP and alizarin improved the UV-vis resistance property of the film, blocking almost all UV-vis light (decreasing 71.80% to 0.06% at 400 nm). The elongation-at-break (EBA) was 4.02 times of that of gelatin film, indicating the improved mechanical properties of the films. This film showed a significant color change from yellow to purple in the pH range of 3-11 and a considerable sensitivity to ammonia vapor within 4 min, which was attributed to the deprotonation of the alizarin molecule. The film's antioxidant and dynamic antimicrobial capacity was significantly improved owing to the sustained release effect of OEOP. Furthermore, the multifunctional film effectively slowed down the beef spoilage rate and provided real-time visual monitoring of freshness through color changes. Additionally, the color change of the beef quality was linked to the RGB values of the film through a smartphone APP. Overall, this work broadens the possibilities of applications in the food packaging industry for multifunctional food packaging film with preservation and monitoring functions.

Carboxymethyl cellulose/poly(vinyl alcohol) blended films reinforced by buckypapers of carbon nanotubes and 2D material (MoS2): Enhancing mechanical strength, toughness, and barrier properties

Plastic waste is one cause of climate change. To solve this problem, packaging films are increasingly produced from biodegradable polymers. Eco-friendly carboxymethyl cellulose and its blends have been developed for such a solution. Herein, a unique strategy is demonstrated to improve the mechanical and barrier properties of carboxymethyl cellulose/poly(vinyl alcohol) (CMC/PVA) blended films for the packaging of nonfood dried products. The blended films were impregnated with buckypapers containing different combinations of multiwalled carbon nanotubes, two-dimensional molybdenum disulfide (2D MoS₂) nanoplatelets, and helical carbon nanotubes (HCNTs). Compared to the blend, the polymer composite films exhibit significant increases in tensile strength (~105 %, from 25.53 to 52.41 MPa), Young's modulus (~297 %, from 155.48 to 617.48 MPa), and toughness (~46 %, from 6.69 to 9.75 MJ m^-3). Polymer composite films containing HCNTs in buckypapers offer the highest toughness. For barrier properties, the polymer composite films are opaque. The water vapor transmission rate of the blended films decreases (~52 %, from 13.09 to 6.25 g h^-1 m^-2). Moreover, the maximum thermal-degradation temperature of the blend rises from 296 to 301 °C, especially for the polymer composite films with buckypapers containing MoS₂ nanosheets that contribute to the barrier effect for both water vapor and thermal-decomposition gas molecules.