Preparation and characterization of active and intelligent packaging films based on cassava starch and anthocyanins from Lycium ruthenicum Murr

Development of seaweed-derived polysaccharide/cellulose nanocrystal-based antifogging labels loaded with alizarin for monitoring aquatic products' freshness

Intelligent freshness indicator labels have attracted great interest for their massive potential in monitoring the freshness of aquatic products over the years. However, there is still a challenge where fogging on the labels during dramatic temperature changes affects the reading of freshness. At the same time, the freshness indicator labels need high mechanical strength to resist collision damage during transportation and storage. Herein, an antifogging freshness indicator label was developed based on seaweed extracts and alizarin. Firstly, soluble polysaccharides and insoluble components were extracted from Gelidium amansii, and cellulose nanocrystal (CNC) was further prepared from the insoluble components by sulfuric acid hydrolysis. Subsequently, a polysaccharide-based film was fabricated using soluble polysaccharides as the matrix materials and CNC as the reinforcement agent. Antifogging experiments showed that the hydrophilic composite films presented good antifogging performance. After loading with alizarin, the composite indicator label exhibited both antifogging and freshness-indicating properties for the salmon sample. The work provided a new idea for developing freshness indicator labels suitable for low-temperature transportation and storage.

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.

Development of curcumin-containing polyvinyl alcohol/chitosan active/intelligent films for preservation and monitoring of Schizothorax prenanti fillets freshness

Active/intelligent films for the preservation and monitoring of Schizothorax prenanti fillets freshness were prepared by combining curcumin (CUR) with polyvinyl alcohol/chitosan (PVA/CS) matrix. SEM images showed that the CUR with a maximum content of 1.5 % (w/w) was evenly distributed in the composite matrix. The addition of CUR did not affect the chemical structure of PVA/CS matrix, as confirmed by FTIR investigation. When 1.5 % (w/w) CUR was added, the water vapor barrier property, tensile strength and antioxidant activity of the composite film were the best, which were 5.38 ± 0.25 × 10-11 g/m·s·Pa, 62.05 ± 1.68 MPa and 85.50 ± 3.63 %, respectively. Water solubility of PVA/CS/CUR-1.5 % film was reduced by approximately 27 % compared to PVA/CS film. After adding CUR, the antibacterial properties of the composite film increased significantly. Although the addition of CUR reduced the biodegradability of PVA/CS film, the PVA/CS/CUR-1.5 % film degraded >60 % within 5 weeks. By measuring pH, weight loss, total volatile base‑nitrogen (TVB-N), thiobarbituric acid reactive substances (TBARS), and total viable counts (TVC), the preservation effect of the composite films on the fish freshness was evaluated. The fish shelf life treated by PVA/CS/CUR-1.5 % film expanded from 3-6 days to 12-15 days at 4 °C. In addition, when PVA/CS/CUR-1.5 % film was used to monitor the fish freshness, it exhibited clear color fluctuations, from yellow to orange and to red, corresponding to first-grade freshness, second-grade freshness, and rottenness of the fish, respectively. As a result, the films can be successfully used for Schizothorax prenanti fillets preservation and deterioration monitoring.

Novel oxidation indicator films based on natural pigments and corn starch/carboxymethyl cellulose

The existing oil oxidation detection methods are unsuitable for consumers to identify oil oxidation in a domestic setting. This study aims to develop indicator films detecting the degree of lipid oxidation with the naked eye. Purple sweet potato pigment (PSP) was chosen as a color indicator due to its response to hydrogen peroxide. The novel oxidation indicator films were prepared using corn starch, carboxymethyl cellulose (CMC), and varying concentrations of PSP. Fourier transform infrared spectroscopy spectra and scanning electron microscopy analysis confirmed the successful dispersion of PSP in the films. Thermal stability, light resistance, ultraviolet light resistance, mechanical resistance, and flexibility of films containing PSP were improved, enhancing the potential application in detecting oxidized substances. All the films exhibited noticeable color changes when exposed to different concentrations of hydrogen peroxide. These differences were more pronounced with higher levels of PSP. When these films were used to determine the degree of lipid oxidation, the ∆E value of the CS-PSP-0.25 % film showed a linear relationship (R2 = 0.929) with the peroxide value, unlike other films. Therefore, it is reliable to infer the peroxide value of edible oil by observing the color of the films, which helps customers avoid consuming expired oils.

Development and characterization of a new potato starch/watermelon peel pectin composite film loaded with TiO2 nanoparticles and microencapsulated Lycium barbarum leaf flavonoids and its use in the Tan mutton packaging

Reinforced edible film with active nanoparticles has been in increasing demand as a new technology to improve the quality and extend the shelf-life of muscle foods. The study aimed to fabricate and characterize a novel potato starch (Pst)/watermelon peel pectin (Wpp) composite film with the microencapsulated Lycium barbarum leaf flavonoids (MLF) and nano-TiO2 (Pst/Wpp/MLF/TiO2) and further apply the film in Tan mutton preservation. The moisture content, thickness and water vapor permeability (WVP) of the composite film were relatively increased with increasing the percentage of MLF, while nano-TiO2 had slight influence on the thickness, but leaded to a significantly decreased the moisture content and WVP. Also, the SEM images showed that the roughness and porosity were created on the film surface by adding MLF and nano-TiO2. FTIR revealed electrostatic and hydrogen bond interactions between the components in the film system. Meanwhile, MLF and nano-TiO2 effectively enhanced the mechanical strength, UV-barrier, controlled-release, thermal stability, antimicrobial and antioxidation properties of the Pst/Wpp film. Also, the composite film containing MLF and nano-TiO2 significantly inhibited the growth of microorganisms and chemical deterioration of mutton samples, which suggested that such film has potential as a prospective active packaging for preserving Tan mutton.

Development and application of intelligent packaging films based on guar gum, polyvinyl alcohol and hyacinth bean (Lablab purpureus (L.) sweet) anthocyanins

The pH-response color-changeable films were prepared by adding different contents (1 %, 2 % and 3 %) of hyacinth bean anthocyanins (HBA) into guar gum/polyvinyl alcohol blend matrix. The structural characterization and optical, barrier, mechanical, thermal, antioxidant and color-changeable properties of the films were determined. The films were applied to monitor the freshness of chilled shrimp and pork. Results showed that HBA were pH-dependent color-changeable pigments that endowed the films with purple color. 2 % and 3 % of HBA improved the uniformity and compactness of the films by forming hydrogen bonds with film matrix. The barrier ability of the films against UV-vis light, water vapor and oxygen was significantly elevated by 2 % and 3 % of HBA. The mechanical, thermal and antioxidant properties of the films were improved by HBA. The films containing HBA were much sensitive to pH variation and ammonia vapor, presenting obvious color changes (purple→green→yellow-green). The films containing HBA showed good color stability when stored at 4 °C for 30 days. Moreover, the film containing 2 % HBA showed color changes (purple→green) when the chilled shrimp and pork decayed. The results suggested that the film containing 2 % HBA was suitable to monitor the freshness of meat products in intelligent packaging field.

Colorimetric pH indicators based on well-defined amylose and amylopectin matrices enriched with anthocyanins from red cabbage

This study aimed to prepare a novel colorimetric indicator film from virtually pure (99 %) amylose (AM) and anthocyanins extracted from red cabbage (RCA). The AM used was a unique engineered bulk material extracted from transgenic barley grains. Films produced by solution casting were compared to normal barely starch (NB) and pure barley amylopectin (AP), with amylose contents of 30 % and 0 %, respectively. The pH-indicator films were produced by incorporation of RCA into the different starch support matrices with different amylose contents. Barrier, thermal, and mechanical properties, photo degradation stability, and release behavior data revealed that RCA interact differently through the glucan matrices. Microstructural observations showed that RCA were evenly dispersed in the glucan matrix, and AM+RCA indicator films showed high UV-barrier and mechanical performance over normal starch. FTIR revealed that RCA was properly affected by the AM matrix. Moreover, the AM+RCA films showed sensitive color changes in the pH range (2-11) and a predominant Fickian diffusion release mechanism for RCA. This study provides for the first time data regarding AM films with RCA and their promising potential for application as support matrices in responsive food and other industrial biodegradable packaging materials.

A bibliometrics visualization analysis of active packaging system for food packaging

This bibliometric study includes publications on the use of active packaging in food packaging from 2000 to 2021. The number of research related to this study tends to increase annually with an annual growth rate of 23.76%, totaling 857 articles. In this study it was found that the most influential countries in the field of Active Packaging are Spain, China, and Brazil. Moreover, the International Journal of Biological Macromolecules and Nerín are the most prolific journal and author in scientific publications, respectively. Active packaging, food packaging, and antimicrobial are often used based on the total link strength out of the 1,775 keywords. The keyword analysis based on time found new terms that are being studied by many researchers, namely, bioplastics as environmentally friendly packaging, based on polysaccharides and nanoparticles, which have the potential to be developed or collaborated for breakthroughs. Therefore, the use of active packaging shows a promising trend for the packaging industry in the future.

Xanthoceras sorbifolia Husk Extract Incorporation for the Improvement in Physical and Antioxidant Properties of Soy Protein Isolate Films

With the increasing awareness of ecological and environmental protection, the research on eco-friendly materials has experienced a considerable increase. The objective of our study was to explore a novel soy protein isolate (SPI) film functionalized with antioxidants extracted from Xanthoceras sorbifolia husk (XSHE) as bio-based active packaging films. The films were evaluated in light of their structure, physical machinery, and antioxidant performance using advanced characterization techniques. The FTIR and microscopy results revealed the hydrogen-bond interaction between the SPI and XSHE and their good compatibility, which contributed to the improvement in various properties of the composite films, such as tensile strength (TS), UV blocking, and the water barrier property. As the XSHE content increased to 5%, the TS of the films dramatically increased up to 7.37 MPa with 47.7% and the water vapor permeability decreased to 1.13 × 10-10 g m m-2 s-1 Pa-1 with 22.1%. Meanwhile, the introduction of XSHE caused further improvement in the antioxidant capacity of films, and the release of active agents from films was faster and higher in 10% ethanol than it was in a 50% ethanol food simulant. Overall, SPI-based films functionalized with XSHE demonstrated promising potential applications in food packaging.

Formulation Study on Edible Film from Waste Grape and Red Cabbage

(1) Background: Recent research on the valorization of agro-industrial waste has attempted to obtain new products. Grape residue is a waste product used in the grape wine industry that is rich in anthocyanins, as well as leaves and waste parts from red cabbage processing. Anthocyanins, thanks to their various functionalities, can be recovered and used as active and intelligent agents in food packaging. Anthocyanins have antioxidant properties that help to prevent cardiovascular disease. (2) Methods: In this study, the process of extracting waste was studied using solvent and supercritical CO₂ extraction. The obtained anthocyanins were used in starch-based food film formulations. Several formulations were studied using rheometric techniques and the effect of adding anthocyanins on optimal film formulation was investigated. (3) Results: Solvent extractions resulted in a maximum extraction yield. The extracts obtained were used for the preparation of coating and edible films, optimized in the formulation. (4) Conclusions: The addition of anthocyanins to films resulted in increased sample structuring and mechanical properties that are valid for applications, like dipping using coverage methods. The packaging is also attractive and pH-sensitive.

Lycium ruthenicum Murr. anthocyanins inhibit hyperproliferation of synovial fibroblasts from rheumatoid patients and the mechanism study powered by network pharmacology

BACKGROUND

Rheumatoid arthritis (RA), is a typical autoimmune disease affecting nearly 1% of the world's population. The dysfunctional hyperproliferation of synovial fibroblast (SF) in articular cartilage of RA patients is considered as the essential etiology. Traditional chemotherapeutic agents for RA treatment are imperfect for their high cost and unpredictable side-effects. L. ruthenicum anthocyanins (LRAC) is a natural product that of potential for therapeutic application against RA.

METHODS

LRAC was characterized by UPLC-MS/MS. Bioinformatics analyses based on network pharmacology were applied to predict the potential targets of LRAC, and to select DEGs (differentially expressed genes) caused by RA pathogenesis from GSE77298. Interactions between LRAC and the predicted targets were evaluated by molecular docking. Effects of LRAC on SFs from RA patients were examined by in vitro assays, which were analyzed by flow cytometry and western blotting (WB).

RESULTS

LRAC was able to inhibit the abnormal proliferation and aggressive invasion of SFs from RA patients. LRAC was mainly constituted by petunidin (82.7%), with small amount of delphinidin (12.9%) and malvidin (4.4%) in terms of anthocyanidin. Bioinformatics analyses showed that in 3738 RA-related DEGs, 58 of them were collectively targeted by delphinidin, malvidin and delphinidin. AR, CDK2, CHEK1, HIF1A, CXCR4, MMP2 and MMP9, the seven hub genes constructed a central network mediating the signal transduction. Molecular docking confirmed the high affinities between the LRAC ligands and the protein receptors encoded by the hub genes. The in vitro assays validated that LRAC repressed the growth of RASF by cell cycle arresting and cell invasion paralyzing (c-Myc/p21/CDK2), initiating cell apoptosis (HIF-1α/CXCR4/Bax/Bcl-2), and inducing pyroptosis via ROS-dependent pathway (NOX4/ROS/NLRP3/IL-1β/Caspase-1).

CONCLUSION

LRAC can selectively inhibit the proliferation of RASFs, without side-effecting immunosuppression that usually occurred for RA treatment using MTX (methotrexate). These findings demonstrate the potential application of LRAC as a phytomedicine for RA treatment, and provide a valid approach for exploring natural remedies against autoimmune diseases.

Composite films of sodium alginate and konjac glucomannan incorporated with tea polyphenols for food preservation

At present, food waste has become a serious issue and the use of petroleum-based food packaging films has resulted in a series of potential hazards. Therefore, more attention has been focused on the development of new food packaging materials. The polysaccharide-based composite film loaded with active substances considered to be an excellent preservative material. A novel packaging film based on sodium alginate and konjac glucomannan (SA-KGM) blended with tea polyphenols (TP) was prepared in the present study. The excellent microstructure of films was shown by atomic force microscopy (AFM). It was indicated by FTIR spectra that the components could interact with each other through hydrogen bonds, which was also confirmed by molecular docking simulation. Meanwhile, the mechanical properties, barrier property, oxidation property, antibacterial activity, and stability of the structure of the TP-SA-KGM film were significantly improved. The AFM images and results of molecular docking simulation indicated that TP could affect the cell wall of bacteria by acting with peptidoglycan. Finally, the film showed excellent preservation effects in both beef and apples, which suggested that TP-SA-KGM film could be a novel bioactive packaging material with wide application potential in food preservation.

Development and characterization of a new active and intelligent packaging system based on soluble soybean polysaccharide-Malva sylvestris extract

This work aimed to develop an active and intelligent film based on soluble soybean polysaccharide (SSPS)/Malva sylvestris extract (MSE) to extend the shelf life of foodstuff and detect indirectly the food spoilage. The influence of MSE content on physico-mechanical properties, biological activity, and pH sensitivity of the SSPS-based films was examined. When the MSE concentration increased from 0 to 6% (w/w), water solubility and water vapor permeability of the films decreased (p ˂ 0.05). Clear antioxidant and antibacterial capacities were observed for SSPS films incorporated with different concentrations of MSE. SSPS/MSE films could sense the pH variation in a pH range of 7 to 8. SSPS/MSE film was used to detect the spoilage of shrimp and showed a pH-sensitive highly distinctive color variation from grey to dark green as the shrimp's quality altered. Overall, SSPS/MSE film can be introduced as a promising candidate for application as active and intelligent packaging.

Loquat seed starch - Emerging source of non-conventional starch: Structure, properties, and novel applications

Recently, non-conventional sources of starch have attracted attention due to their potential to provide cost-effective alternatives to traditional starch. Among non-conventional starches, loquat (Eriobotrya japonica) seed starch is an emerging source of starch consisting of the amount of starch (nearly 20 %). Due to its unique structure, functional properties, and novel applications, it could be utilized as a potential ingredient. Interestingly, this starch has similar properties as commercial starches including high amylose content, small granule size, and high viscosity and heat stability, making it an attractive option for various food applications. Therefore, this review mainly covers the fundamental understanding of the valorization of loquat seeds by extracting the starch using different isolation methods, with preferable structural, morphological, and functional properties. Different isolation and modification methods (wet milling, acid, neutral and alkaline) are effectively used to obtain higher amounts of starch are revealed. Moreover, insight into various analytical techniques including scanning electron microscopy, differential scanning calorimetry, and X-ray diffraction used to characterize the molecular structure of the starch are discussed. In addition, the effect of shear rate and temperature on rheological attributes with solubility index, swelling power, and color is revealed. Besides, this starch contains bioactive compounds that have shown a positive impact on the enhancement of the shelf-life of the fruits. Overall, loquat seed starches have the potential to provide sustainable and cost-effective alternatives to traditional starch sources and can lead to novel applications in the food industry. Further research is needed to optimize processing techniques and develop value-added products that can be produced at a large scale. However, there is relatively limited published scientific evidence on the structural and morphological characteristics of loquat seed starch. Thus, in this review, we focused on different isolation techniques of loquat seed starch, its structural and functional characteristics, along with potential applications.

Development of intelligent and active potato starch films based on purple corn cob extract and molle essential oil

The present study aims to develop of an active and "intelligent" film that uses potato starch as a polymeric matrix, anthocyanins from purple corn cob as a natural dye, and molle essential oil as an antibacterial compound. The color of anthocyanin solutions is pH-dependent, and the developed films shows a visual color change from red to brown after immersion in solutions with pH values ranging from 2 to 12. SEM and FTIR analyses suggested that anthocyanins have favorable dispersibility and good compatibility with the starch-glycerol matrix. The study found that both anthocyanins and molle essential oil significantly enhanced the ultraviolet-visible light barrier performance; moreover, tensile strength, elongation at break, and elastic modulus reached values of 3.21 MPa, 62.16 %, and 12.87 MPa, respectively. The biodegradation rate in vegetal compost also accelerated during the three-week period, achieving a weight loss of 95 %. Moreover, the film presented an inhibition halo for Escherichia coli, indicating its antibacterial activity. The results suggest that the developed film has the potential to be used as food-packaging material.

Nanofibrous composite membranes based on chitosan-nano zinc oxide and curcumin for Kyoho grapes preservation

Nanofibrous composite membranes consisting of polyvinyl alcohol (PVA), sodium alginate (SA), chitosan-nano zinc oxide nanoparticles (CS-Nano-ZnO) and curcumin (Cur) were prepared by ultrasonic processing and electrospinning. When the ultrasonic power was set to 100 W, the prepared CS-Nano-ZnO had a minimum size (404.67 ± 42.35 nm) and a generally uniform particle size distribution (PDI = 0.32 ± 0.10). The composite fiber membrane with Cur: CS-Nano-ZnO mass ratio of 5:5 exhibited the best water vapor permeability, strain and stress. Furthermore, the inhibitory rates against Escherichia coli and Staphylococcus aureus were 91.93 ± 2.07 % and 93.00 ± 0.83 %, respectively. The Kyoho grape fresh-keeping trial revealed that grape berries wrapped with composite fiber membrane still maintained good quality and a higher rate of good fruit (60.25 ± 1.46 %) after 12 days of storage. The shelf life of grape was extended by at least 4 days. Thus, nanofibrous composite membranes based on CS-Nano-ZnO and Cur was expected to be used as an active material for food packaging.

Progress and Prospective of the Industrial Development and Applications of Eco-Friendly Colorants: An Insight into Environmental Impact and Sustainability Issues

Color is the prime feature directly associated with the consumer's attraction and choice of their food. The flavor, safety, and nutritional value of any food product are directly associated with the food color. Natural and synthetic colorants (dyes and pigments) have diversified applications in various sectors such as food, feed, pharmaceutical, textiles, cosmetics, and others. Concerning the food industry, different types of natural and synthetic colorants are available in the market. Synthetic food colorants have gained popularity as they are highly stable and cheaply available. Consumers worldwide prefer delightful foodstuffs but are more concerned about the safety of the food. After its disposal, the colloidal particles present in the synthetic colorants do not allow sunlight to penetrate aquatic bodies. This causes a foul smell and turbidity formation and gives a bad appearance. Furthermore, different studies carried out previously have presented the toxicological, carcinogenic effects, hypersensitivity reactions, and behavioral changes linked to the usage of synthetic colorants. Natural food colorings, however, have nutraceutical qualities that are valuable to human health such as curcumin extracted from turmeric and beta-carotene extracted from carrots. In addition, natural colorants have beneficial properties such as excellent antioxidant properties, antimutagenic, anti-inflammatory, antineoplastic, and antiarthritic effects. This review summarizes the sources of natural and synthetic colorants, their production rate, demand, extraction, and characterization of food colorants, their industrial applications, environmental impact, challenges in the sustainable utilization of natural colorants, and their prospects.

Sensing materials for fresh food quality deterioration measurement: a review of research progress and application in supply chain

Fresh food are consumed in large quantities worldwide. During the supply chain, microbial growth in fresh food can lead to the production of a number of metabolites, which make food highly susceptible to spoilage and contamination. The quality of fresh food changes in terms of smell, tenderness, color and texture, which causes a decrease in freshness and consumers acceptance. Therefore, the quality monitoring of fresh food has become an essential part in the supply chain. As traditional analysis methods are highly specialized, expensive and have a small scope of application, which cannot be applied to the supply chain to realize real-time monitoring. Recently, sensing materials have received a lot of attention from researchers due to the low price, high sensitivity and high speed. However, the progress of research on sensing materials has not been critically evaluated. The study examines the progress of research in the application of sensing materials for fresh food quality monitoring. Meanwhile, indicator compounds for spoilage of fresh food are analyzed. Moreover, some suggestions for future research directions are given.

A double-layer smart film based on gellan gum/modified anthocyanin and sodium carboxymethyl cellulose/starch/Nisin for application in chicken breast

In order to overcome this challenge of poor stability of natural anthocyanins in intelligent packaging materials, roselle anthocyanin (RA) was first modified by acetic acid, and then a double-layer smart indication antimicrobial film was developed using modified roselle anthocyanin (MRA)-gellan gum (GG) as the inner layer and sodium carboxymethyl cellulose (CMC)-starch (ST)-Nisin as the outer layer. UV spectra revealed that acetic acid was successfully grafted onto RA, which dramatically improved their thermal stability, antioxidant capabilities, photostability, and pH stability. The bilayer films were successfully prepared, as revealed by scanning electron microscopy, Fourier-transform infrared spectroscopy, and X-ray diffraction measurements. In comparison to GG-MRA and CMC-ST-Nisin films, the water content, water solubility, mechanical characteristics, water vapor barrier, oxygen barrier, and hydrophobicity of GG-MRA@CMC-ST-Nisin films were significantly enhanced. The presence of the outer layer films significantly enhanced the UV-vis light barrier, opacity, antioxidant and antibacterial properties of the inner layer films. When the films were applied to chicken breast, it was found that the indicator films not only monitored the freshness of the chicken in real-time but also that the GG-MRA film and the double-layer film were effective in extending the shelf life of the chicken by 1 and 2 days, respectively, compared to the control group.

Characterization of Cassava Starch Extruded Sheets Incorporated with Tucumã Oil Microparticles

The application of biopolymers and feasible technologies to obtain sheets is crucial for the large-scale production of food packages and for reducing plastic pollution. Additionally, the inclusion of additives in sheets can affect and improve their properties. This work aimed to incorporate tucumã oil (TO) and TO microparticles produced by spray drying (SD), spray chilling (SC), and their combination (SDC) into extruded cassava starch sheets and to evaluate the effect of such addition on their physical, optical, and mechanical properties. Gum Arabic and vegetable fat were used as wall materials for SD and SC/SDC, respectively. The sheets enriched with tucumã oil (FO) and the microparticles produced by SD, SC and SDC (FSD, FSC, and FSDC, respectively) presented yellow color (hue angle around 90°) and higher opacity (11.6–25.3%) when compared to the control (6.3%). All sheets showed high thickness (1.3–1.8 mm), and the additives reduced the water solubility of the materials (from 27.11% in the control to 24.67–25.54% in enriched samples). The presence of large SDC particles, as evidenced by Scanning Electron Microscopy (SEM), caused discontinuity of the sheet structure and decreased mechanical strength of the FSDC. One may conclude that potential active packages were obtained by extrusion of cassava starch sheets added with pure and encapsulated TO.

Novel color stability and colorimetry-enhanced intelligent CO2 indicators by metal complexation of anthocyanins for monitoring chicken freshness

This study aims to improve the color stability of anthocyanins and develop a CO2-sensitive indicator based on black goji anthocyanin (BGA) extract. Although the BGA extracts showed distinct color changes, such as red-purple-blue, their intrinsic color diminished after 24 h. A metal complexation method was used for the high color stability of BGA. BGA extracts were chelated with various concentrations of Al3+ [0 - 20% (w/w)]. It showed high color stability and strong intensity in a dose-dependent manner. A CO2-sensitive indicator sachet was developed using hydroxypropyl methylcellulose hydrogel, based on 5% (w/w) Al3+-BGA complexes. The indicator was applied to the chicken breast and detected its spoilage after 3 days with its changing color to greyish blue, due to the microbial growth to 7.00 log CFU/g. These results demonstrated the possibility of chelated anthocyanin complexes as indicating dyes and the ability to monitor the food quality changes through noticeable color changes.

A comprehensive review of intelligent packaging for fruits and vegetables: Target responders, classification, applications, and future challenges

Post-harvest fruits and vegetables are extremely susceptible to dramatic and accelerated quality deterioration deriving from their metabolism and adverse environmental influences. Given their vigorous physiological metabolism, monitoring means are lacking due to the extent that unnecessary waste and damage are caused. Numerous intelligent packaging studies have been hitherto carried out to investigate their potential for fruit and vegetable quality monitoring. This state-of-the-art overview begins with recent advances in target metabolites for intelligent packaging of fruits and vegetables. Subsequently, the mechanisms of action between metabolites and packaging materials are presented. In particular, the exact categorization and function of intelligent packaging of fruits and vegetables, are all extensively and comprehensively described. In addition, for the sake of further research in this field, the obstacles that impede the scaling up and commercialization of intelligent packaging for fruits and vegetables are also explored, to present valuable references.

Colorimetric and antioxidant films based on biodegradable polymers and black nightshade (Solanum nigrum L.) extract for visually monitoring Cyclina sinensis freshness

In this study, colorimetric and antioxidant films were developed by using cassava starch (CS), κ-carrageenan (KC) and black nightshade fruit anthocyanins (BNA), and their physical and functional properties were investigated. We found BNA presented significant color changes in different pH solutions. And incorporation of BNA significantly increased the tensile strength, water vapor permeability, UV-vis light barrier property, pH-sensitivity and antioxidant activity of CS-KC film. Results of structural characterization indicated that H-bonds were formed between CS, KC and BNA in films and the film compactness was significantly improved by BNA incorporation. Results of the rheological property assay showed the films had high apparent viscosity with an obvious shear-thinning behavior. When applied to monitoring the quality change of Cyclina sinensis, CS-KC-BNA films exhibited significant color changes with the degradation process of C. sinensis qualities. Our results suggested CS-KC-BNA films could be utilized in smart packaging in food industry.

Antioxidant and ammonia-sensitive films based on starch, κ-carrageenan and Oxalis triangularis extract as visual indicator of beef meat spoilage

In this study, we first investigated the rheological property of sweet potato starch (SPS), κ-carrageenan (KC) and Oxalis triangularis extract (OTE) blends and found that the blends exhibited high apparent viscosity with an apparent shear thinning behavior. And then films based on SPS, KC and OTE were developed and their structural and functional properties were studied. The physico-chemical test results showed that OTE exhibited different colors in solutions with different pH values and the incorporation with OTE and KC could significantly increase the thickness, water vapor permeability, light barrier ability, tensile strength and elongation at break as well as the pH- and ammonia-sensitive properties of the SPS film. The structural property test results showed that some intermolecular interactions between OTE and SPS/KC occurred in SPS-KC-OTE films. Finally, the functional properties of SPS-KC-OTE films were examined and SPS-KC-OTE films showed significant DPPH radical scavenging activity as well as a visible color change in response to changes in beef meat freshness. Our results suggested that the SPS-KC-OTE films could be used as an active and intelligent food packaging material in food industry.

Development of active and intelligent pH food packaging composite films incorporated with litchi shell extract as an indicator

The anthocyanin-rich litchi shell extract (LE) was mixed with the matrix to prepare active/intelligent food packaging composite films. The microstructure and properties of composite films were characterized. The results showed that the composite films incorporated with LE had texture-oriented layered, compact, uniform cross-sections. The composite films with LE showed different degrees of red. The composite films had similar water vapor transmission rates (1.62-1.65 × 10^-12 g·cm/cm²·Pa·s). However, gelatin/chitosan/polyvinyl alcohol/litchi shell extract (Gel/Csa/PVA/LE) film had better UV blocking rates (0-20 %), the best tensile strength (18.6 MPa) and elongation at break (116%). When the composite films monitored for fish freshness at 4 °C (10 d) and 25 °C (3 d), the Gel/Csa/PVA/LE film had the pH sensitivity to show an obvious color change at 25 °C, 1th day. The results suggested that the Gel/Csa/PVA/LE film could be applied to intelligent food packaging film to indicate the freshness of fish.

Cassava starch films for food packaging: Trends over the last decade and future research

Cassava starch is one of the most available and cost-effective biopolymers. This work aimed to apply a bibliometric methodology to identify the most impactful scientific data on cassava starch and its residues for food packaging in the last ten years. As a result, an increasing interest in this subject has been observed, mainly in the past five years. Among the 85 selected scientific publications, Brazil and China have been leading the research on starch-based films, accounting for 39 % of the total. The International Journal of Biological Macromolecules was the main scientific source of information. Besides cassava starch, 41.18 % of these studies added other biopolymers, 5.88 % added synthetic polymers, and 4.71 % added a combination of both. Studies analyzed suggested that different modifications in starch can improve films' mechanical and barrier properties. In addition, 52.94 % of articles evaluated the film's bioactivity. Still, only 37.65 % assessed the performance of those films as food packaging, suggesting that more studies should be conducted on assessing the potential of these alternative packages. Future research should consider scale-up methods for film production, including cost analysis, assessment life cycle, and the impact on the safety and quality of a broader range of foods.

Preparation and characterization of antioxidant and pH-sensitive films based on arrowhead (Sagittaria sagittifolia) starch, κ-carrageenan and black chokeberry (Aronia melanocarpa) extract for monitoring spoilage of chicken wings

In this study, we firstly developed an antioxidant and pH-sensitive film based on arrowhead starch (AS), κ-carrageenan (KC) and black chokeberry extract (BCE) and its physical and structural properties were investigated. We found BCE showed different colors in different pH solutions and incorporation with KC and BCE could significantly decrease light transmittance, increase thickness, elongation at break and pH-sensitive property of AS film. The results of structural property assay indicated that there were some intermolecular interactions between BCE and AS/KC in AS-KC-BCE films. Secondly, we investigated the rheological property of AS, AS-KC and AS-KC-BCE suspensions and found the suspensions showed an obvious shear-thinning behavior with high apparent viscosity. Finally, the functional properties of AS-KC-BCE films were investigated and AS-KC-BCE films showed strong scavenging activity on DPPH free radical and presented visible colour changes in response to the changes of the chicken wing qualities. The results suggest that AS-KC-BCE films can be used in active and intelligent packaging of food industry.

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

Multifunctional food packaging films were developed based on polyvinyl alcohol (PVA), sodium carboxymethyl cellulose (CMC), tea polyphenol (TP) and black carrot anthocyanin (CA). Results of Zeta potential, scanning electron microscopy, Fourier transform infrared spectroscopy and X-ray diffraction showed that CA enhanced the stability of the particle dispersion system through hydrogen bonding and electrostatic interactions, promoted the compatibility between TP and PVA-CMC (PC) substrates, and enhanced the binding between the components of the films. Because of the interaction of TP and CA, PC-TP-CA films had better water resistance and water vapor barrier properties, thermal stability, antioxidant and antimicrobial properties. PC-CA and PC-TP-CA films exhibited excellent UV-blocking properties. They also showed distinct color responsiveness in the pH range of 2-13, significant sensitivity to ammonia vapor in a short period of time and excellent color stability over 20 days of storage under different conditions. When the film was applied to fish, it was found that PC-TP-CA film could extend the shelf life of fish by 1-2 days and successfully monitor the freshness of the fish in real-time. Considering all the physical and functional properties, the non-toxic and biodegradable PC-TP-CA film has excellent potential as a new multifunctional food packaging material in the future.

Edible films/coatings containing bioactive ingredients with micro/nano encapsulation: A comprehensive review of their fabrications, formulas, multifunctionality and applications in food packaging

Due to the consumer's pursuit of safe, nontoxic and nutritious foods, edible and/or biodegradable materials have stood out in food packaging and preservation. In this context, the preparation and application of micro/nano encapsulated active ingredients (M/N-E-BAIs) represent a step toward reinforcing the properties of sustainable and controllable food packaging, particularly for the successful incorporation of new substances and functionalities into traditional edible films/coatings. This review, from the preparation of M/N-E-BAIs, the fabrication of edible film/coating containing M/N-E-BAIs to their characterization of multifunction and the application in food, makes a systematic summary and in-depth discussion. Food-grade polymers can encapsulate bioactive ingredients (BAIs) by chemical, physicochemical and mechanical methods, thereby forming M/N-E-BAIs with suitable sustained-release and unique biological activities. Furthermore, M/N-E-BAIs is incorporated into biopolymer substrates by solvent casting, 3D printing or electrostatic spinning to obtain novel edible films/coatings. This advanced packaging material exhibits superior physicochemical and functional properties over traditional food films/coatings. Besides, their applications in foods as active and intelligent packaging can improve food quality, prolong shelf life and monitor food corruption. Even so, there are still many challenges and limitations in formulation, preparation and application of this new packaging technology that need to be addressed in the future.

On-package indicator films based on natural pigments and polysaccharides for monitoring food quality: a review

Deterioration of food quality and freshness is mainly due to microbial growth and enzyme activity. Chilled fresh food, especially meat and seafood, as well as pasteurized products, rapidly lose quality and freshness during packing, distribution and storage. Real-time food quality monitoring using on-package indicator films can help consumers make informed purchasing decisions. Interest in the use of intelligent packaging systems for monitoring safety and food quality has increased in recent years. Polysaccharide-based films can be developed into on-package indicator films due to their excellent film-forming properties and biodegradability. Another important component is the use of colorants with visible color changes at various pH levels. Currently, natural pigments are receiving increased attention because of their safety and environmental friendliness. This review highlights the recent findings regarding the role of natural pigments, the effects of incorporating natural pigments and polysaccharides on properties of indicator film, current application and limitations of on-package indicator films based on polysaccharides in some foods, problems and improvement of physical properties and color conversion of indicator film containing natural pigments, and development of polysaccharide-based pH-responsive films. © 2022 Society of Chemical Industry.

Biodegradable Active Packaging Material Containing Grape Seed Ethanol Extract and Corn Starch/κ-Carrageenan Composite Film

An active film composed of corn starch/κ-carrageenan and ethanolic grape seed extract (0, 1, 3, and 5 wt% of GSE on corn starch basis) were successfully prepared using the solvent casting technique. The effects of the different concentrations of ethanolic grape seed extract (GSE) on the physicochemical properties, antioxidant properties, and antibacterial properties of CS/κC films were analyzed. The results showed that the addition of GSE inhibited the recrystallization of starch in the composite film. The glass transition temperature of composite film is 121.65 °C. With the addition of GSE, the surface roughness of the composite film increased, and the cross-section displayed a stratification phenomenon. Meanwhile, when GSE was added to the composite film, the tensile strength of the composite film decreased (3.50 ± 0.27 MPa), the elongation at break increased (36.87 ± 2.08%), and the WVP increased (1.58 ± 0.03 g mm/m2·d· kPa). With the increase of the concentration of GSE in the composite film, the a* value and b* value of the composite film increase, the L* value decreases, and the opacity increases. The lipid oxidation test proved that the composite films containing 1% GSE has a significant inhibitory effect on the oxidation of lard (p < 0.05). The above results indicate that the GSE can be used as a food-grade packaging material and has a good application prospect in the food industry.

Preparation and application of a colorimetric film based on sodium alginate/sodium carboxymethyl cellulose incorporated with rose anthocyanins

To monitor the freshness of Penaeus vannamei during storage, a colorimetric film based on sodium alginate/sodium carboxymethyl cellulose incorporated with rose anthocyanins extract (RAE) was prepared. The results showed that the incorporation of RAE increased moisture content, water vapor permeability, and water contact angle of the colorimetric film. FTIR, XRD spectra, and SEM demonstrated that RAE had good compatibility with the film-forming substrate. The colorimetric film presented obvious color variation in the pH range of 2.0-12.0 and was sensitive to volatile ammonia. The colorimetric film exhibited a visual color change from pink to pale yellow to yellowish green during the storage of Penaeus vannamei at 4 °C. Significant correlations were observed between the color change of colorimetric film (ΔE) and the pH value or TVB-N content of Penaeus vannamei (p < 0.05). Therefore, the colorimetric film shows great application potential to monitor the freshness of shrimp as intelligent packaging.

Development of Shrimp Freshness Indicating Films by Embedding Anthocyanins-Rich Rhododendron simsii Flower Extract in Locust Bean Gum/Polyvinyl Alcohol Matrix

Freshness indicating films containing anthocyanins are one type of smart packaging technology. Anthocyanins in the films can show visual color changes when food spoilage occurs, thereby indicating the freshness degree of food in real-time. Rhododendron simsii is a landscape plant with attractive flowers that are abundant in anthocyanins. In this study, smart packaging films were prepared by embedding 2% and 4% R. simsii flower anthocyanins (RA) in locust bean gum- (LBG) and polyvinyl alcohol- (PVA) based matrices. The micro-structure, barrier, mechanical, thermal, antioxidant, and color-changeable properties of the films were determined. The potential application of the films in indicating the freshness of shrimp at 4 °C was also investigated. Results showed that the RA interacted with the LBG/PVA matrices through hydrogen bonds, which significantly improved the barrier, mechanical, thermal, antioxidant, pH-sensitive, and ammonia-sensitive properties of the films. Meanwhile, the performance of the films was remarkably influenced by the content of the RA. The film containing 4% RA had the highest light blocking ability, tensile strength (38.32 MPa), elongation at break (58.18%), and antioxidant activity, and also showed the lowest water vapor permeability (22.10 × 10^-11 g m^-1 s^-1 Pa^-1) and oxygen permeability (0.36 cm³ mm m^-2 day^-1 atm^-1). The films containing 2% and 4% RA could effectively change their colors when the level of total volatile basic nitrogen in the shrimp exceeded the safe value, which demonstrated the suitability of the films for indicating the freshness degree of shrimp.

Cassava Starch Films with Anthocyanins and Betalains from Agroindustrial by-Products: Their Use for Intelligent Label Development

The development of biodegradable packaging materials has become a widely addressed topic in recent years. Microparticles generated from Brassica oleracea var. capitata f. rubra (red cabbage, RC) and Beta vulgaris L. var. conditiva (beetroot, BR) which contained anthocyanins or betalains, were included in the formulation of edible films based on cassava starch (CS) giving origin to films CSRC, CSBR, or CSBC (mixture of both particles). The inclusion of the filler determined an increase in the stress at rupture from 0.8 MPa (CS) to 1.2 MPa (CSRC) or 1.0 MPa (CSBC), of the contact angle from 2.6° to 13.8° (CSBR) or 19.6° (CSBC). The use of these films for developing a smart label for hake packaging and the study of the TBV-N content, the microbiological characteristics of the muscle, and the color changes of the label with time, allowed us to conclude that the films CSRC and CSBC would be suitable for sensing the deterioration of packaged and chilled hake and that the color change of the label CSBC was completely consistent with fish muscle deterioration. As the microparticles can be obtained from by-products of the production and industrialization of plant tissues, the composite films and the smart labels developed can contribute not only to the development of safe food but also to the addition of value to those residues and to environmental protection.

Development of an Indicator Film Based on Cassava Starch-Chitosan Incorporated with Red Dragon Fruit Peel Anthocyanin Extract

The increase in new technology and consumer demand for healthy and safe food has led to the development of smart packaging to help consumers understand food conditions in real time. The incorporation of red dragon fruit peel anthocyanin into cassava starch and chitosan films was used in this study as a color indicator to monitor food conditions. This indicator film was generated using the solvent-casting method. The mechanical, morphological, and physicochemical characterizations of the film were studied, and food freshness monitoring was carried out. The results showed that adding red dragon fruit peel anthocyanin increased up to 94.44% of the antioxidant activity. It also improved its flexibility, indicated by the lowest tensile strength (3.89 ± 0.15 MPa) and Young's modulus (0.14 ± 0.01 MPa) and the highest elongation at break (27.62 ± 0.57%). The indicator film was sensitive to pH, which was indicated by its color change from red to yellow as pH increased. The color of the film also changed when it was used to test the freshness of packaged shrimp at both room and chiller temperatures. According to the results, the indicator film based on cassava starch-chitosan incorporated with red dragon fruit peel anthocyanin showed its potential as a smart packaging material.

Colorimetric Indicators Based on Anthocyanin Polymer Composites: A Review

This review explores the colorimetric indicators based on anthocyanin polymer composites fabricated in the last decade, in order to provide a comprehensive overview of their morphological and compositional characteristics and their efficacy in their various application fields. Notably, the structural properties of the developed materials and the effect on their performance will be thoroughly and critically discussed in order to highlight their important role. Finally, yet importantly, the current challenges and the future perspectives of the use of anthocyanins as components of colorimetric indicator platforms will be highlighted, in order to stimulate the exploration of new anthocyanin sources and the in-depth investigation of all the possibilities that they can offer. This can pave the way for the development of high-end materials and the expansion of their use to new application fields.