Accurately intelligent film made from sodium carboxymethyl starch/κ-carrageenan reinforced by mulberry anthocyanins as an indicator

Carrageenan-based sustainable biomaterials for intelligent food packaging: A review

This article explores the use of carrageenan-based biomaterials in developing sustainable and efficient intelligent food packaging solutions. The research in this field has seen a notable surge, evident from >1000 entries in databases such as Web of Science, PubMed and Science Direct between 2018 and 2023. Various film preparation techniques are explored, including solvent casting, layer-by-layer (LbL) assembly, and electrospinning. Solvent casting is commonly used to incorporate active compounds, while LbL assembly and electrospinning are favored for enhancing mechanical properties and solubility. Carrageenan's film-forming characteristics enable the production of transparent films, ideal for indicator films that facilitate visual inspection for color changes indicative of pH variations, crucial for detecting food spoilage. Surface properties can be modified using additives like plant extracts to regulate moisture interaction, affecting shelf life and food safety. These materials' antioxidant and antimicrobial attributes are highlighted, demonstrating their efficacy against pathogens such as E. coli.

High-performance carboxymethyl starch/PVA based intelligent packaging films engineered with Cu-Trp nanocrystal as functional compatibilizer

A spindle-like Cu-based framework (Cu-Trp, Trp = L-Tryptophan) nanocrystal with ammonia-responsiveness was fabricated via simple aqueous solution approach, and it was subsequently explored as a functional compatibilizer of carboxymethyl starch/polyvinyl alcohol (CMS/PVA) blend toward constructing high-performance intelligent packaging films. The results showed that incorporation of Cu-Trp nanocrystal into CMS/PVA blend resulted in significant promotions regarding to the compatibility, mechanical strength (42.92 MPa), UV-blocking (with UV transmittance of only 2.4%), and water vapor barrier effectiveness of the blend film. Besides, the constructed CMS/PVA/Cu-Trp nanocomposite film exhibited superb long-term color stability, favorable antibacterial capacity (over 98.0%) toward both E. coli and S. aureus bacteria, as well as color change ability under ammonia environment. Importantly, the application trial confirmed that the CMS/PVA/Cu-Trp nanocomposite film is capable of visually monitoring shrimp spoilage during storage. These results implied that the CMS/PVA/Cu-Trp nanocomposite film holds tremendous potential as an intelligent active packaging material.

An effective preserving strategy for strawberries by constructing pectin/starch coatings reinforced with functionalized eggshell fillers

Food waste occurs frequently worldwide, though hunger and malnutrition issues have received global attention. Short-term spoilage of perishable foods causes a significant proportion of food waste. Developing simple, green, and low-cost strategies to preserve the freshness of perishable foods is important to address this issue and improving food safety. By using strawberries as the model perishable fruit, this study reported a pectin/carboxy methyl starch sodium (PC) based coating using epigallocatechin gallate-loaded eggshell powder (ES@EGCG) as the functional fillers. In comparison to PC coating, the PC-ES@EGCG coating displayed much-enhanced performance, such as enhanced mechanical (2 folds) and barrier (water vapor & oxygen) properties. This composite coating reduced the weight loss of strawberries from over 60% to around 30% after 7-day storage. Coated strawberries exhibit better freshness retention, which achieves the purpose of preserving strawberries during storage. This study provided a cost-effective and eco-friendly coating strategy for reducing food waste.

A biodegradable pH-response packaging film with blueberry extract: Blown-extrusion fabrication, multifunctional activity, and kinetic investigation

This work proposed a novel strategy for manufacturing biodegradable pH-response packaging. Briefly, to minimize the amount and thermal processing times of blueberry extract (BE), ethanol-dissolved BE (≤ 3‰ w/w) was sprayed onto the starch/poly(butylene adipate-co-terephthalate) (PBAT) pellets before extrusion blowing. BE was well-integrated into the matrix, forming uniformly colored films. The films with BE exhibited superior mechanical (7.85 MPa of strength, 606.53% of elongation) and enhanced barrier capabilities against ultraviolet light, moisture, and gas. Additionally, they exhibited good antioxidant capacity (68.69%), antibacterial activity (72.40%), and maintained color stability. The film with 3‰ w/w BE presented excellent color responsiveness (ΔE⁎ ≥ 15) in the alkaline range, and successfully monitored the spoilage of shrimp. The pigments in the film had the maximum migration degree (≥ 70%) and rate in 50% ethanol simulation, following a first-order kinetic behavior dominated by Fickian diffusion. Findings supported the application of this strategy in the fabrication of starch/PBAT/BE films for pH-response intelligent packaging.

pH-triggered bilayer film based on carboxymethyl cellulose/zein/Eudragit L100 with purple cabbage anthocyanin for monitoring pork freshness

A novel pH-triggered bilayer film was composed of zein (Z), carboxymethylcellulose (CMC), Eudragit L100 (L100), and purple cabbage anthocyanin (PCA), followed by casting for monitoring pork freshness during storage at 4 °C and 25 °C. This bilayer film was employed to encapsulate anthocyanins, preventing anthocyanins oxidation and photodegradation. Additionally, under pH 6, this film ruptures and releases anthocyanins, inducing a sudden color change in the indicator film, significantly reducing errors in freshness indications. Notably, the ZCLP8% film had excellent stability and pH response properties. The performance of the ZCLP8% film in monitoring pork freshness was evaluated. When the concentration of pork TVB-N reached 15.59 mg/100 g (pH = 6.35), the bilayer film was ruptured, and the release rate of PCA was 85.52 %, which was a significant change in the color of the bilayer film compared with that at pH = 5. Therefore, this work addresses the limitation that anthocyanin-based intelligent films are subject to judgment errors when applied, opening new possibilities for food freshness differentiation monitoring.

Intelligent films based on dual-modified starch and microencapsulated Aronia melanocarpa anthocyanins: Functionality, stability and application

This study aims to enhance the physical properties and color stability of anthocyanin-based intelligent starch films. Three dual-modified starches, namely crosslinked-oxidized starch (COS), acetylated distarch phosphate (ADSP), and hydroxypropyl distarch phosphate (HDSP), were utilized as film matrices. Aronia melanocarpa anthocyanins were incorporated through three different pre-treatments (free, spray-drying microencapsulation, and freeze-drying microencapsulation) to assess the prepared films' functionality, stability, and applicability. The results indicate that the ADSP film exhibited an approximately two-fold increase in elongation at break (EAB) compared to native starch film. Specifically, the ADSP film's water contact angle (WCA) reached 90°, demonstrating excellent flexibility and hydrophobicity. Scanning electron microscopy (SEM) revealed stronger interactions between anthocyanins and the film matrix after microencapsulation. Furthermore, after 30 days of exposure to 37 °C heat and light radiation, the freeze-dried anthocyanin-based intelligent film (FDA film) exhibited minimal fading, displaying the highest stability among the tested films. Notably, during beef freshness monitoring, the intelligent films underwent significant color changes as the beef deteriorated. In conclusion, the developed FDA film, with its outstanding stability and responsive pH characteristics, holds immense potential as a novel packaging material for food applications.

Facilitating safe and sustained submucosal lift through an endoscopically injectable shear-thinning carboxymethyl starch sodium hydrogel

Traditional submucosal filling materials frequently show insufficient lifting height and duration during clinical procedures. Here, the anionic polysaccharide polymer sodium carboxymethyl starch and cationic Laponite to prepare a hydrogel with excellent shear-thinning ability through physical cross-linking, so that it can achieve continuous improvement of the mucosal cushion through endoscopic injection. The results showed that the hydrogel (56.54 kPa) had a lower injection pressure compared to MucoUp (68.56 kPa). The height of submucosal lifting height produced by hydrogel was higher than MucoUp, and the height maintenance ability after 2 h was 3.20 times that of MucoUp. At the same time, the hydrogel also showed satisfactory degradability and biosafety, completely degrading within 200 h. The hemolysis rate is as low as 0.76 %, and the cell survival rate > 80 %. Subcutaneous implantation experiments confirmed that the hydrogel showed no obvious systemic toxicity. Animal experiments clearly demonstrated the in vivo feasibility of using hydrogels for submucosal uplift. Furthermore, successful endoscopic submucosal dissection was executed on a live pig stomach, affirming the capacity of hydrogel to safely and effectively facilitate submucosal dissection and mitigate adverse events, such as bleeding. These results indicate that shear-thinning hydrogels have a wide range applications as submucosal injection materials.

Preparation and characterization of intelligent and active bi-layer film based on carrageenan/pectin for monitoring freshness of salmon

This work aimed to develop and characterize a novel bi-layer film (BIF) for monitoring the freshness of salmon. The indicator layer consists of carrageenan (Car), pectin (PEC) and purple sweet potato anthocyanin (PSPA), and the antibacterial layer consists of Car and magnolol (Mag). The results showed that the Car/Mag2 had the optimal water resistance: the static water contact angle of 80.36 ± 0.92 °, moisture content of 31.38 ± 0.86 %, swelling degree of 92.96 ± 0.46 %, and water solubility of 40.08 ± 1.17 %, and showed excellent antibacterial properties against E. coli and S. aureus with antibacterial rate of 86.13 % ± 0.10 % and 97.53 % ± 0.02 %, respectively. Then BIFs with different PSPA concentration were tested. The morphology, mechanical and water vapor properties (WVP) of the BIFs were studied, and its application in salmon preservation was evaluated. The mechanical properties and WVP test results showed that the BIF0.2 had the optimal Tensile strength (TS) and WVP values. The BIFs showed distinguishable color changes between the pH ranges of 3-10. The shelf life of salmon packaged by BIF0.2 was prolonged by 2 days. Moreover, the BIF0.2 was able to effectively monitor salmon freshness. In conclusion, the BIF has great potential for monitoring salmon meat freshness.

The preparation of edible water-soluble films comprising κ-carrageenan/carboxymethyl starch/gum ghatti and their application in instant coffee powder packaging

This study successfully prepared an edible packaging film that rapidly dissolves in water by utilizing a combination of κ-carrageenan, carboxymethyl starch, and gum ghatti. We investigated the influence of these three materials on the microstructure and physical properties of the film, as well as the impact of the film's dissolution on the stability of beverages. SEM, FTIR, and XRD analyses revealed that the κ-carrageenan, carboxymethyl starch, and gum ghatti primarily interacted through hydrogen bonding, resulting in a more uniform and dense film structure. Surface hydrophilicity and swelling tests indicated an increased presence of hydrophilic groups in the composite film. The inclusion of carboxymethyl starch and gum ghatti significantly improves the film's physical properties, resulting in a notable reduction in water solubility time, an increase in elongation at break from 19.5 % to 26.0 %, a rise in the contact angle from 49.1° to 67.0°, and a decrease in water vapor permeability from 7.5 × 10-10 to 6.2 × 10-10 g/m·s·Pa. Furthermore, coffee packaging bags made from this composite film dissolved entirely in hot water in just 40 s. Dissolving these bags significantly improved the stability of instant coffee, reducing centrifugal sedimentation from 3.8 % to 1.7 %. This study highlights the substantial potential of the κ-carrageenan/carboxymethyl starch/gum ghatti composite film as a packaging material for solid beverages.

Nanocomposite Films of Babassu Coconut Mesocarp and Green ZnO Nanoparticles for Application in Antimicrobial Food Packaging

In this work, novel nanocomposite films based on babassu coconut mesocarp and zinc oxide nanoparticles (ZnO NPs), synthesized by a green route, were produced for application as food packaging films. The films were prepared using the casting method containing different contents of ZnO NPs (0 wt%, 0.1 wt%, 0.5 wt%, and 1.0 wt%). The films were characterized by Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), instrumental color analysis, and optical properties. The water vapor permeability (WVP) and tensile strength of films were also determined. The antimicrobial activity of the films against cooked turkey ham samples contaminated with Staphylococcus aureus was investigated. The results showed that incorporating ZnO NPs into babassu mesocarp matrices influenced the structure of the biopolymer chains and the color of the films. The BM/ZnO-0.5 film (0.5 wt% ZnO NPs) showed better thermal, mechanical, and WVP properties. Furthermore, the synergistic effect of babassu mesocarp and ZnO NPs in the BM/ZnO-0.5 film improved the antimicrobial properties of the material, reducing the microbial count of S. aureus in cooked turkey ham samples stored under refrigeration for 7 days. Thus, the films produced in this study showed promising antimicrobial packaging materials for processed foods.

Colorimetric indicator films based on carboxymethyl cellulose and anthocyanins as a visual indicator for shrimp freshness tracking

This study aimed to evaluate the response efficiency of colorimetric indicator films based on carboxymethyl cellulose (CMC) incorporated with different anthocyanins [Karanda alone (CMC/AK), butterfly pea alone (CMC/AB), and a mixture of anthocyanins from Karanda and butterfly pea (CMC/AK75/AB25)] for tracking shrimp freshness during storage at different temperatures and times (4 °C for 8 days and 25 °C for 30 h). The mathematical models were also applied to predict their freshness and shelf life. The CMC/AK75/AB25 indicator film was the most sensitive and clearly changed color, which could be distinguished by the naked eye. Color changes indicated the shrimp deterioration processes: dark purple (fresh), purplish gray or gray (semi-fresh), and olive green or brown (spoilage). During shrimp storage at temperatures of 4 and 25 °C, the pH reached 7.52 and 8.14, TVB-N 35.98 and 72.72 mg/100 g, and TVC 5.75 and 7.88 log CFU/g, respectively, indicating shrimp had completely deteriorated. Furthermore, there was a positive correlation between the ΔE value of the indicator film and both TVB-N and TVC. These findings suggest that the CMC/AK75/AB25 indicator film could serve as a real-time visual indicator for tracking shrimp freshness and could enhance the guarantee of shrimp safety.

Development of pH-responsive intelligent films based on κ-carrageenan/straw lignin and anthocyanin from Padus virginiana peel for real-time monitoring of chicken

A series of intelligent films with pH-responsive properties were prepared using Padus virginiana peel extract (PVE) as a smart response factor, κ-carrageenan (κC) as a matrix, and complexed with rice straw lignin (SL). Following the addition of 5 mL PVE at a concentration of 430.99 mg/L, tensile strength and elongation at break of the films increased to a maximum value of 21.25 ± 0.75 MPa and 24.04 ± 0.69 %, respectively. The water vapour permeability of the films decreased with increasing PVE addition, and the minimum value was 5.85 ± 0.09 × 10-11 g m-1 s-1 Pa-1. All the films had favourable thermal stability, transparency, haze and antioxidant properties. PVE-containing films all exhibited excellent pH and ammonia response properties. The higher the humidity of the environment, the faster the ammonia response, and the films were capable of rapid discoloration at 75 % relative humidity. κC/SL-PVE5 can be used to monitor the freshness of chicken breast meat. When the total volatile basic nitrogen of chicken breast meat was increased to 14.27 mg/100 g, κC/SL-PVE5 changed from pink to greyish-yellow. In conclusion, κC/SL-PVE intelligent films hold great promise for real-time monitoring of meat freshness.

Chitosan/zein-based sustained-release composite films: Fabrication, physicochemical properties and release kinetics of tea polyphenols from polymer matrix

This study investigated the properties of chitosan/zein/tea polyphenols (C/Z/T) films and analyzed the release kinetics of tea polyphenols (TP) in various food simulants to enhance the sustainability and functionality of food packaging. The results revealed that TP addition enhanced the hydrophilicity, opacity and mechanical properties of film, and improved the compatibility between film matrix. 1.5 % TP film showed the lowest lightness (76.4) and the highest chroma (29.1), while 2 % TP film had the highest hue angle (1.5). However, the excessive TP (above 1 % concentration) led to a decrease in compatibility and mechanical properties of film. The TP concentration (2 %) resulted in the highest swelling degree in aqueous (750.6 %), alcoholic (451.1 %), and fatty (6.4 %) food simulants. The cumulative release of TP decreased to 16.32 %, 47.13 %, and 5.87 % with the increase of TP load in the aqueous, alcoholic, and fatty food simulants, respectively. The Peleg model best described TP release kinetics. The 2 % TP-loaded film showed the highest DPPH (97.13 %) and ABTS (97.86 %) free radical scavenging activity. The results showed TP release influenced by many factors and obeyed Fick's law of diffusion. This study offered valuable insights and theoretical support for the practical application of active films.

Enhanced stability and bioavailability of mulberry anthocyanins through the development of sodium caseinate-konjac glucomannan nanoparticles

This study was carried out to improve the stability of anthocyanins (ACNs) by developing MA-SC-KGM nanoparticles using a self-assembly method that involved the combination of sodium caseinate (SC) and konjac glucomannan (KGM) with mulberry anthocyanin extract (MA). Atomic force microscopy (AFM) analysis showed SC encapsulated MA successfully. Multispectral techniques demonstrated the presence of hydrogen bonds and hydrophobic interactions in the nanoparticles. MA-SC-KGM ternary mixture improved storage stability, color stability and anthocyanin retention better compared to the MA-SC binary mixture. Notably, MA-SC-KGM nanoparticles significantly inhibited the thermal degradation of ACNs, improved pH stability, and showed stability and a slow-release effect in gastrointestinal digestion experiments. In addition, MA-SC-KGM nanoparticles were effective in scavenging DPPH· and ABTS+ free radicals, with enhanced stability and antioxidant capacity even during the heating process. This study successfully developed a novel MA-SC-KGM protein-polysaccharide composite material that effectively stabilized natural ACNs, expanding the application of ACNs in various industries.

Recent Progress of Carrageenan-Based Composite Films in Active and Intelligent Food Packaging Applications

Recently, as concerns about petrochemical-derived polymers increase, interest in biopolymer-based materials is increasing. Undoubtedly, biopolymers are a better alternative to solve the problem of synthetic polymer-based plastics for packaging purposes. There are various types of biopolymers in nature, and mostly polysaccharides are used in this regard. Carrageenan is a hydrophilic polysaccharide extracted from red algae and has recently attracted great interest in the development of food packaging films. Carrageenan is known for its excellent film-forming properties, high compatibility and good carrier properties. Carrageenan is readily available and low cost, making it a good candidate as a polymer matrix base material for active and intelligent food packaging films. The carrageenan-based packaging film lacks mechanical, barrier, and functional properties. Thus, the physical and functional properties of carrageenan-based films can be enhanced by blending this biopolymer with functional compounds and nanofillers. Various types of bioactive ingredients, such as nanoparticles, natural extracts, colorants, and essential oils, have been incorporated into the carrageenan-based film. Carrageenan-based functional packaging film was found to be useful for extending the shelf life of packaged foods and tracking spoilage. Recently, there has been plenty of research work published on the potential of carrageenan-based packaging film. Therefore, this review discusses recent advances in carrageenan-based films for applications in food packaging. The preparation and properties of carrageenan-based packaging films were discussed, as well as their application in real-time food packaging. The latest discussion on the potential of carrageenan as an alternative to traditionally used synthetic plastics may be helpful for further research in this field.

A novel anthocyanin indicator film with rosmarinic acid copigmentation having enhanced stability and pH indicator ability for monitoring pork freshness

BACKGROUND

Anthocyanin-based pH-sensing films have been widely fabricated for potential application in monitoring food freshness. However, the color fading of anthocyanins limits their application for the food industry due to their low stability. In addition, the color sensitivity and pH indicator ability of anthocyanin-based films currently available are not satisfied and need to be improved.

RESULTS

Chitosan/xanthan gum (CX)-based colorimetric films with addition of purple cabbage anthocyanin (PAN) and different amounts of rosmarinic acid (RA) were fabricated. RA copigmentation in chitosan/xanthan gum-purple cabbage anthocyanin-rosmarinic acid (CX-P-RA) films significantly improved the stability and pH response sensitivity of PAN, and the combined copigmentation of RA and xanthan gum exhibited an additive effect. The addition of RA significantly improved the tensile strength and elongation at break, thermal stability, antioxidant and antibacterial activities of CX-P-RA films. Moreover, addition of RA enhanced the pH sensitivity and colorimetry of CX-P-RA films, which exhibited a good response to different pH values. CX-P-RA2 film was tested to monitor the freshness of pork. It showed visible color changes during the storage of pork. In addition, the ∆E of CX-P-RA2 film was highly correlated with changes in total volatile basic nitrogen in pork (R2  = 0.951).

CONCLUSION

These results indicated that CX-P-RA2 film can be used as a pH-sensing indicator with good stability and high sensitivity for real-time monitoring of pork freshness. © 2023 Society of Chemical Industry.

Functional pH-Sensitive Film Containing Purple Sweet Potato Anthocyanins for Pork Freshness Monitoring and Cherry Preservation

An antioxidative and pH-sensitive multifunctional film, incorporating anthocyanin-rich purple sweet potato extract (PPE) was fabricated from polyvinyl alcohol (PVA) and sodium alginate (SA)/sodium carboxymethyl cellulose (CMC-Na). The film was composed of 6:4 PVA:SA/CMC-Na (mass ratio, SA:CMC-Na at 1:1) with added PPE, and changed color with changes in pH, and also had useful UV-blocking, antioxidant, mechanical, and water vapor barrier properties, which enable its use as a food coating film. In addition, the incorporation of 300 mg PPE increased the biodegradability of the film in soil from 52.47 ± 1.12% to 64.29 ± 1.75% at 17 days. The pH sensitivity of the film enabled its successful use for the evaluation of pork freshness. Cherries coated with the film had an extended shelf life from 3-4 to 7-9 days, during storage at 25 °C. Consequently, the multifunctional film can be applied to packaging for real-time pH/freshness monitoring and for effectively preserving the freshness of meat and fruit.

κ-Carrageenan/poly(vinyl alcohol) functionalized films with gallic acid and stabilized with metallic ions

Given the environmental issues caused by the extensive use of conventional petroleum-based packaging, this work proposes functional films based on commercial κ-carrageenan (κc), poly(vinyl alcohol) (PVA), and gallic acid (GA) prepared by the "casting" method. Metallic ions in the κc composition stabilized the films, supporting processability and suitable mechanical properties. However, the incorporated GA amount (6.25 and 10 wt%) in the films created from an aqueous κc solution at 3.0 % wt/v (κc3) prevented crystalline domains in the resulting materials. The κc3/GA6.25 and κc3/GA10 films had less tensile strength (8.50 ± 0.61 and 10.28 ± 0.65 MPa) and high elongation at break (2.36 ± 0.16 and 1.19 ± 0.17 %) compared to the other samples, respectively. Low κc contents (κc2.5/GA6.25 and κc2.5/GA10) promoted stiff films and less permeability to water vapor (5.36 ± 0.51 and 3.76 ± 0.02 [×10-12 g(Pa × m × s)-1], respectively. The κc/GA weight ratio also influenced the film wettability, indicating water contact angles (WCAs) between 55 and 74°. The surface wettability implies a low oil permeability and high water swelling capacity of up to 1600 %. The κc/GA also played an essential role in the film's antimicrobial action against Staphylococcus aureus and Escherichia coli. Thus, the κc3/GA10 film showed suitable physical, chemical, and biological properties, having the potential to be applied as food coatings.

Preparation, characterization and application of pH-responsive smart film based on chitosan/zein and red radish anthocyanin

This research was aimed at developing a novel pH-responsive smart film made of chitosan, zein and red radish anthocyanin (RRA). The morphology, interaction, crystallization, thermal stability, physiochemical properties and pH sensitivity of films were analyzed. The smart film was applied to monitor the freshness of mushroom (Agaricus bisporus). The results of morphology (SEM) and spectrum (FT-IR and XRD) indicated that the incorporation of RRA could enhance the interaction between polymer matrix. The addition of RRA had no significant effect on the thermal stability of films. The chitosan/zein/red radish anthocyanin (C/Z/R) films exhibited higher tensile strength, Young's modulus, hydrophobicity, antioxidant activity and lower elongation at break. The C/Z/R films had stronger water vapor and gas barrier capacity. The C/Z/R films showed a pH-sensitive color variation from red (pH 2) to green (pH 12) and good reversibility under alkaline and acidic environment. The prepared smart film could be successfully used for the quality monitoring of mushroom.

Preparation of a Dual-Functional Active Film Based on Bilayer Hydrogel and Red Cabbage Anthocyanin for Maintaining and Monitoring Pork Freshness

In this study, a composite film was created with the dual goal of prolonging pork shelf life and showing freshness. Hydrogel materials as solid base films were selected from gelatin (G), sodium alginate (SA) and carboxymethyl cellulose (CMC) based on their antioxidant activity, water vapor permeability, mechanical properties, as well as their stability, antimicrobial activity, and freshness, which indicates effectiveness when combined with anthocyanins. Furthermore, the effects of several concentrations of red cabbage anthocyanin (R) (3%, 6%, 12%, and 24%) on freshness indicators and bacteriostasis were investigated. The antimicrobial activity of the composite films was evaluated against Escherichia coli, Bacillus subtilis, and Staphylococcus aureus. Likewise, the freshness indicates effectiveness was evaluated for NH3. Considering the mechanical properties, antibacterial ability, freshness indicator effect, and stability of the composite film, CS film combined with 12% R was selected to prepare a dual-functional intelligent film for pork freshness indicator and preservation. By thoroughly investigating the effect of composite film on pork conservation and combining with it KNN, the discriminative model of pork freshness grade was established and the recognition rate of the prediction set was up to 93.3%. These results indicated that CSR film can be used for the creation of active food packaging materials.

Preparation and characterization of corn starch-based antimicrobial indicator films containing purple corncob anthocyanin and tangerine peel essential oil for monitoring pork freshness

A novel antibacterial indicator film was prepared by mixing corn starch with tangerine peel essential oil (TEO) Pickering emulsion emulsified by ultrasonic and esterified modified starch (UDSt), and then incorporated with purple corncob anthocyanin (PCA), which was used to monitor the freshness of pork. The results showed that the UDSt can effectively stabilize the TEO emulsion. PCA showed obvious color changes at different pH. With the increase of pH, the color of film changed from red to yellow, and its response to volatile ammonia changed from pink to cyan, showing better response ability. The loading of TEO conferred the film excellent bacteriostatic ability against E. coli and S. aureus. The film also had good ability of light blocking and free radical scavenging. In the process of pork deterioration, the antibacterial indicator film changed from pink to yellow, which was closely related to pork quality and had a good linear indicator correlation. The addition of TEO reduced the release of PCA in the antibacterial indicator film and helped to maintain the functional properties of the film. This type of antibacterial indicator film had considerable application potential in indicating food freshness.

Development of antioxidant and smart NH3 -sensing packaging film by incorporating bilirubin into κ-carrageenan matrix

BACKGROUND

Active and smart food packaging based on natural polymers and pH-sensitive dyes as indicators has attracted widespread attention. In the present study, an antioxidant and amine-response color indicator film was developed by incorporating bilirubin (BIL) into the κ-carrageenan (Carr) matrix.

RESULTS

It was found that the introduction of BIL had no effect on the crystal/chemical structure, water sensitivity and mechanical performance of the Carr-based films. However, the barrier properties to light and the thermal stability were significantly improved after the addition BIL. The Carr/BIL composite films exhibited excellent 1,1-diphenyl-2-picryl-hydrazyl (i.e. DPPH)/2,2'-azino-bis-(3-ethylbenzothiazoline-6-sulfonic acid) (i.e. ABTS) free radical scavenging abilities and color responsiveness to different concentrations of ammonia. The application assay reflected that the Carr/BIL0.0075 film was effective in delaying the oxidative deterioration of shrimp during storage and realizing the color response of its freshness through the change of b* value.

CONCLUSION

Active and smart packaging films were successfully prepared by incorporating different contents of BIL into the Carr matrix. The present study helps to further encourage the design and development of a multi-functional packaging material. © 2023 Society of Chemical Industry.

Ammonia-sensitive cellulose acetate-based films incorporated with Co-BIT microcrystals for smart packaging application

Nowadays, there is an increasing demand for smart packaging materials capable of effectively monitoring the food freshness. In this study, new Co-based MOF (Co-BIT) microcrystals with ammonia-sensitivity and antibacterial function were constructed and then loaded within cellulose acetate (CA) matrix to create smart active packaging materials. The influences of Co-BIT loading upon structure, physical, and functional properties of the CA films were then thoroughly explored. It was observed that microcrystalline Co-BIT was uniformly integrated inside CA matrix, which caused significant promotions in mechanical strength (from 24.12 to 39.76 MPa), water barrier (from 9.32 × 10^-6 to 2.73 × 10^-6 g/m·h·Pa) and ultraviolet light protection performances of CA film. Additionally, the created CA/Co-BIT films displayed striking antibacterial efficacy (>95.0 % for both Escherichia coli and Staphylococcus aureus), favorable ammonia-sensitivity function as well as color stability. Finally, the CA/Co-BIT films were successfully applied for indicating the spoilage of shrimp through discernible color changes. These findings suggest that Co-BIT loaded CA composite films have great potential for use as smart active packaging.

Fabricating a visibly colorimetric film via self-releasing of anthocyanins from distributed mulberry pomace particles in hydrophilic sodium carboxymethyl starch-based matrix to monitor meat freshness

A highly distinguishable indicator film was developed based on sodium carboxymethyl starch, κ-carrageenan, carboxylated cellulose nanocrystals and mulberry pomace particles (MPPs). As the content of MPPs increased from 0 % to 6 %, the tensile strength decreased from 11.71 MPa to 5.20 MPa, the elongation at break increased from 26.84 % to 43.76 %, respectively, and the haze increased from 34.12 % to 52.10 %. The films accurately exhibit a color change from purple to blue-green under alkaline conditions. The enhanced haze improved the visible resolution of the films during the color-changing process. The films with the size of 7.50 mm × 7.50 mm and 10.0 mm × 10.0 mm exhibited obvious color changes when the total volatile basic nitrogen reached 14.60 mg/100 g and 19.04 mg/100 g, respectively, which accurately indicated the quality of pork and fish. This study will offer a simplified path to improve both accurate sensitivity and distinguishability for smart films.

Application of biodegradable colorimetric films based on purple tomatoes anthocyanins loaded chitosan and polyvinyl alcohol in pork meat

A series of biodegradable colorimetric films were prepared by using chitosan and polyvinyl alcohol as matrix, in which, the weight ratio of chitosan: Polyvinyl alcohol was 100: 0, 80: 20, 50: 50, 20: 80, or 0: 100, with addition of 10% (w/w, relative to chitosan) anthocyanins extracted from purple tomatoes (purple tomatoes anthocyanin) as pigment. The aim of this study was to observe the effect of weight ratio (chitosan: Polyvinyl alcohol) on the mechanical properties, contact angle, swelling rate, pH sensitivity, antioxidant properties of chitosan-polyvinyl alcohol/purple tomatoes anthocyanins films, and the antibacterial activity of films produced for pork packaging. In addition, the films as a smart colorimetric indicator for monitoring the freshness of pork was investigated. The results showed that as the ratio of chitosan to polyvinyl alcohol decreases, the elongation at break, hydrophilicity, and swelling rate of the films increased especially from 16.5% to 174.2% for elongation at break and 93.0° to 53.8° for water contact angle, however, the tensile strength decreased from 67.3 to 24.7 MPa. With decreasing of chitosan: Polyvinyl alcohol, the antibacterial activity on pork was decreased, and the antioxidant properties of films increased first then decreased. Fourier transform infrared spectroscopy indicated there were interactions among chitosan, polyvinyl alcohol, and purple tomatoes anthocyanins. The color response of films was depended on pH, as well as the immersion time. The longer immersion resulted in a more pronounced color change. The color changed from purplish red (pH 2-4) to green (pH 5-10) to yellow (pH 10-12). In monitoring the freshness of pork, the film showed a nice visual color change, indicating a potential application in smart packaging. These bio-based materials may be useful alternatives to synthetic plastics for food applications such as active and smart packaging, thereby improving the environmental friendliness and sustainability of the food supply.

Sodium alginate/carboxymethyl starch/κ-carrageenan enteric soft capsule: Processing, characterization, and rupture time evaluation

Although gelatin has good characteristics in preparing soft capsules, its noticeable shortcomings force researchers to further develop substitutes for gelatin soft capsules. In this paper, sodium alginate (SA), carboxymethyl starch (CMS) and κ-carrageenan (κ-C) were used as matrix materials, and the formula of the co-blended solution was screened through rheological method. In addition, films of the different blends were characterized by thermogravimetry analysis, SEM, FTIR, X-ray, water contact angle and mechanical properties. The results showed that κ-C had strong interaction with CMS and SA and the mechanical properties of capsule shell were greatly improved by the addition of κ-C. When the ratio of CMS/SA/κ-C was 2:0.5:1.5, the microstructure of the film was more dense and uniform. In addition, this formula had the best mechanical properties and adhesion properties, and was more suitable for the production of soft capsules. Finally, a novel plant soft capsule was successfully prepared by dropping method, and its appearance and rupture properties met the requirements of enteric soft capsules. In simulated intestinal juice, the soft capsule was almost completely degraded within 15 min, and it was superior to the gelatin soft capsule. Therefore, this study provides an alternative formula for preparing enteric soft capsules.

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.

The properties of pH-responsive gelatin-based intelligent film as affected by ultrasound power and purple cabbage anthocyanin dose

A pH-sensitive intelligent film was prepared using gelatin as base substrate and purple cabbage anthocyanins (PCA) as indicator with the aid of ultrasound. Fourier transforms infrared and X-ray diffraction analysis showed that 600 W ultrasound brought changes to characteristic bands of gelatin and PCA, and flattened diffraction peak around 2θ = 20°. Film prepared with 600 W ultrasound exhibited high tensile strength and elongation at break and showed high transition temperature and surface hydrophobicity by differential scanning calorimetry and contact angle analysis. The incorporation of <0.35 % PCA had no effect on mechanical properties of films, but it improved the antioxidative activity. Films with 0.14 %, 0.21 % and 0.28 % PCA suggested pronounced color difference at pH 5-8, in accordance with the sharp ΔE difference. Films with 0.28 % PCA was applied for monitoring chilled-stored fish quality. It showed visible color change from pink to atrovirens during storage. The difference of ΔE at various days was ≥5 and ΔE highly correlated with total volatile basic nitrogen. Therefore, gelatin along with PCA under appropriate ultrasound treatment could prepare intelligent film to preserve and monitor the quality of chilled-stored fish.

Novel ammonia-responsive carboxymethyl cellulose/Co-MOF multifunctional films for real-time visual monitoring of seafood freshness

Nowadays, ammonia-responsive biopolymer-based intelligent active films are of great interest for their huge potential in maintaining and monitoring the freshness of seafood. However, it is still a challenge to create biopolymer-based intelligent active films with favorable color stability, antibacterial and visual freshness indication functions. Herein, cobalt-based metal-organic framework (Co-MOF) nanosheets with ammonia-sensitive and antibacterial functions were successfully synthesized and then embedded into carboxymethyl cellulose (CMC) matrix to develop high performance and multifunctional CMC-based intelligent active films. The influence of Co-MOF addition on the structure, physical and functional characters of CMC film was comprehensively studied. The results showed that the Co-MOF nanofillers were homogeneously embedded within the CMC matrix, bringing about remarkable promotion on tensile strength (from 45.3 to 62.2 MPa), toughness (from 0.7 to 2.3 MJ/m³), water barrier and UV-blocking performance of CMC film. Notably, the obtained CMC/Co-MOF nanocomposite films also presented excellent long-term color stability, antibacterial activity (with the bacteriostatic efficiency of 99.6 % and 99.3 % against Escherichia coli and Staphylococcus aureus), and ammonia-sensitive discoloration performance. Finally, the CMC/Co-MOF nanocomposite films were successfully applied for real-time visual monitoring of shrimp freshness. The above results demonstrate that the CMC/Co-MOF nanocomposite films possess huge potential applications in intelligent active packaging.

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.

Developing strong and tough cellulose acetate/ZIF67 intelligent active films for shrimp freshness monitoring

There is a growing demand for the development of intelligent active packaging films to maintain and monitor the freshness of meat food. Herein, nano Co-based MOF (ZIF67) with ammonia-sensitive and antimicrobial functions was successfully synthesized and then integrated into cellulose acetate (CA) matrix to prepare intelligent active films. The impacts of ZIF67 incorporation on the structure, physical and functional characteristics of CA film were fully investigated. The results demonstrated that the ZIF67 nanofillers were evenly dispersed in CA matrix, resulting in remarkable improvement on tensile strength, toughness, thermal stability, UV barrier, hydrophobicity and water vapor barrier ability of CA film. Furthermore, the prepared CA/ZIF67 films exhibited superb antimicrobial and ammonia-sensitive functions. The CA/ZIF67 intelligent films turned their color from blue at beginning to brown during progressive spoilage of shrimp. These results revealed that the CA/ZIF67 films with excellent antimicrobial and ammonia-sensitive functions could be applied in intelligent active food packaging.

High-Stability Bi-Layer Films Incorporated with Liposomes @Anthocyanin/Carrageenan/Agar for Shrimp Freshness Monitoring

High-stability bi-layer films were prepared by incorporating anthocyanin-loaded liposomes into carrageenan and agar (A-CBAL) for non-destructive shrimp freshness monitoring. The encapsulation efficiency of the anthocyanin-loaded liposomes increased from 36.06% to 46.99% with an increasing ratio of lecithin. The water vapor transmission (WVP) of the A-CBAL films, with a value of 2.32 × 10^-7 g · m^-1 · h^-1 · pa^-1, was lower than that of the film with free anthocyanins (A-CBA). The exudation rate of the A-CBA film reached 100% at pH 7 and pH 9 after 50 min, while the A-CBAL films slowed down to a value lower than 45%. The encapsulation of anthocyanins slightly decreased the ammonia sensitivity. Finally, the bi-layer films with liposomes successfully monitored shrimp freshness with visible color changes to the naked eye. These results indicated that films with anthocyanin-loaded liposomes have potential applications in high-humidity environments.

A novel anthocyanin electrospun film by caffeic acid co-pigmentation for real-time fish freshness monitoring

In recent years, the use of intelligent and efficient food freshness indicators (FFIs) for monitoring food freshness has been studied widely. In this work, we employed polyacrylonitrile as polymer, blueberry anthocyanins as an indicator, and caffeic acid as a co-pigment and fabricated a novel colorimetric sensing film for real-time monitoring the freshness of fish. The total volatile basic nitrogen (TVB-N) level is one of the potential indicators to evaluate meat freshness. Visual observation confirmed that the polyacrylonitrile-anthocyanin-caffeic acid film changed from pink to light purple, and then to dark purple providing a good indication of spoilage, which correlated well with the TVB-N content and pH values in fish. It is because the volatile ammonia combined with water to form NH₃·H₂O, and then NH₃·H₂O is hydrolyzed to form OH^- and NH₄⁺. The change of the polyacrylonitrile-anthocyanin film was caused by OH^-. Compared with the polyacrylonitrile-anthocyanin film without caffeic acid, the addition of the caffeic acid film had enhanced significantly ammonia responsiveness with a total color difference value of 29.897. And it was also observed that caffeic acid obviously improved the storage stability of the film. This study provided a reference for detecting food freshness using co-pigmentation and electrospinning encapsulation technology in combination.

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 Facile Strategy for Development of pH-Sensing Indicator Films Based on Red Cabbage Puree and Polyvinyl Alcohol for Monitoring Fish Freshness

This study aimed to develop a novel pH-sensing biopolymer film based on red cabbage puree (RCP) incorporated with polyvinyl alcohol (PVA), which was utilized for monitoring fish freshness during storage at 25 °C. A homogenized RCP suspension with a mean particle size of 12.86 ± 0.03 μm and a total anthocyanin concentration of 292.17 ± 2.65 mg/L was directly used as a film-forming substance and anthocyanin source to blend with PVA, showing visual changes in color and ultraviolet-visible spectra within a pH of 2–12. Rheological and microstructural studies certified the strong interactions and good compatibility between the RCP and PVA, resulting in better mechanical properties and water resistance of the composite film than those of a pure RCP film, but without affecting its pH sensitivity. When used for fish freshness monitoring at 25 °C, the developed RCP/PVA film presented visible color differences from purple to yellow, which corresponded to the spoilage threshold of the total volatile basic nitrogen and the total viable count in fish samples. The study highlights that anthocyanin-rich purees of fruits and vegetables, in this case red cabbage puree, can be fully utilized to develop eco-friendly pH-sensing indicator films for intelligent food packaging.

Recent advances in carrageenan-based films for food packaging applications

In order to solve the increasingly serious environmental problems caused by plastic-based packaging, carrageenan-based films are drawing much attentions in food packaging applications, due to low cost, biodegradability, compatibility, and film-forming property. The purpose of this article is to present a comprehensive review of recent developments in carrageenan-based films, including fabrication strategies, physical and chemical properties and novel food packaging applications. Carrageenan can be extracted from red algae mainly by hydrolysis, ultrasonic-assisted and microwave-assisted extraction, and the combination of multiple extraction methods will be future trends in carrageenan extraction methods. Carrageenan can form homogeneous film-forming solutions and fabricate films mainly by direct coating, solvent casting and electrospinning, and mechanism of film formation was discussed in detail. Due to the inherent limitations of the pure carrageenan film, physical and chemical properties of carrageenan films were enhanced by incorporation with other compounds. Therefore, carrageenan-based films can be widely used for extending the shelf life of food and monitoring the food freshness by inhibiting microbial growth, reducing moisture loss and the respiration, etc. This article will provide useful guidelines for further research on carrageenan-based films.

Intelligent pH-sensing film based on polyvinyl alcohol/cellulose nanocrystal with purple cabbage anthocyanins for visually monitoring shrimp freshness

We aimed to prepare a new pH-sensing film based on the immobilization of purple cabbage anthocyanins (PCA) into Polyvinyl alcohol (PVA) reinforced by cellulose nanocrystals (CNC). FT-IR, XRD and TGA were used to assess the intermolecular interactions and thermo-stability of films. The addition of CNC and PCA resulted in an enhancement in UV-vis barrier, mechanical properties and moisture resistance. Inclusion of PCA imparted intelligent properties to the films. PCA-loaded films displayed strong visually detectable colorimetric responses to pH (2-13) and volatile ammonia. When applied to monitor shrimp freshness at 4 °C, PVA/CNC films containing 0.6 % PCA exhibited conspicuous color fluctuations from purple to gray blue upon deterioration. As a result, PVA/CNC-PCA colorimetric films were considered as intelligent packaging labels with significant mechanical, water vapor barrier properties and pH-sensing qualities for visual quality evaluation of fresh seafood products.

Fabrication of intelligent/active films based on chitosan/polyvinyl alcohol matrices containing Jacaranda cuspidifolia anthocyanin for real-time monitoring of fish freshness

The present work describes the natural anthocyanin from Jacaranda cuspidifolia (JC) flower immobilized within a biopolymer matrix composed of chitosan (CS) and polyvinyl alcohol (PVA) gave novel intelligent/active packaging films (CPC). We introduced microwave irradiation to prepare polymeric composite films noticed faster mixing of the polymers and extract take place than the conventional method. The prepared composite films are characterized by various analytical and spectroscopic techniques. The smooth SEM images demonstrated CS/PVA matrix miscibility and compatibility with anthocyanin for the film formation. The addition of anthocyanin to the CS/PVA films significantly reduced UV-Vis light transmission, while causing a slight decrease in the films transparency. An increased anthocyanin concentration on polymer films showed improved oxygen permeability (77.09 %), moisture retention capacity (11.64 %), and water vapor transmission rate (43.10 %) substantially. Additionally, the prepared CPC smart films exhibited strong antioxidant (97.92 %) as well as antibacterial activities against common foodborne pathogens such as S. aureus, and E. coli. Furthermore, the prepared smart films demonstrated pink color in acidic, while grey to yellowish in basic solvent. Further, the color response of the freshness label was consistent with the spoilage Total Volatile Basic-Nitrogen (TVB-N) content determined in the fish samples with varied time period. The CPC smart films also showed promising application in terms of monitoring freshness of the fish fillets at room temperature. The obtained results suggested that, the prepared CPC smart films have potential to be used as quality indicator in the marine food packaging system.

Development of halochromic indicator film based on arrowroot starch/iota-carrageenan using Kyoho skin extract to monitor shrimp freshness

Increasing trends in food safety awareness drive consumer demands for fresher healthier diets and has led to the development of low-cost pH-sensitive indicator films to evaluate deterioration levels in fresh foods. Arrowroot starch/iota-carrageenan-based films were combined with 10, 30, 50% Kyoho skin extract (KSE) to produce indicator films with halochromic abilities. The KSE indicator films were characterized based on their physico-mechanical, functional, and crystallinity properties; thermal stability; and their pH-dependent color changes in in situ anthocyanin-based monitoring of shrimp freshness. All KSE indicator films displayed compact structure under scanning electron microscope analysis and increased tensile strength, exhibited UV-vis barrier ability, and presented low water wettability. Moreover, FTIR signaled strong hydrogen bond interactions among polymers and KSE that strengthened peak crystallinity in XRD analysis and lowered weight loss at melting temperature, which indicated thermal stability of the indicator films. Furthermore, pH-sensitivity of the indicator films integrated with natural KSE anthocyanin demonstrated color changes from purple to red under acidic conditions, purple to green in an ammonium environment, and yellow appeared in high alkaline conditions. Finally, this study demonstrated the food packaging and halochromic capacity of biopolymer-based pH-sensitivity of the KSE indicator films in real-time monitoring of shrimp at room storage temperatures.

Active edible films with plant extracts: a updated review of their types, preparations, reinforcing properties, and applications in muscle foods packaging and preservation

Currently, edible films have been increasingly explored to solve muscle food spoilage during storage, especially through the incorporation of plant extracts to develop edible packaging materials. Natural polymers matrices with plant extracts are befitting for fabricating edible films by casting methods. In the films system, the structure and physicochemical properties were strengthened via chemical interactions between active molecules in plant extracts and the reactive groups in the polymer chain. The antibacterial and antioxidant properties were dramatically reinforced through both physical and chemical actions of the plant extracts. Additionally, edible films imbedded with color-rich plant extracts could be considered as potential sensitive indicators to monitor the spoilage degree of muscle foods in response to change in gas or temperature. Furthermore, these films could increase sensory acceptability, improve quality and prolong the shelf life of muscle foods. In this article, the types, preparation methods and reinforcing properties of the edible films with plant extracts were discussed. Also, the applications of these films were summarized on quality maintenance and shelf-life extension and intelligent monitoring in muscle foods. Finally, a novel technology for film preparation achieving high-stability and sustained release of active compounds will become an underlying trend for application in muscle food packaging.