Carrageenan/agar-based functional film integrated with zinc sulfide nanoparticles and Pickering emulsion of tea tree essential oil for active packaging applications

Physicochemical properties of active films of rose essential oil produced using soy protein isolate-polyphenol conjugates for cherry tomato preservation

Soy protein isolate (SPI)-polyphenol conjugates were produced by grafting SPI individually with curcumin, naringenin, and catechin. The resulting conjugates showed better emulsifying properties and were used to develop active films containing rose essential oil. The effect of conjugation on the physicochemical and mechanical properties of these emulsion-based films was evaluated. The results showed that the barrier and mechanical properties of the films were improved when the SPI-polyphenol conjugates were used to emulsify the essential oil; in particular, the SPI-curcumin conjugate showed significant improvement. The improvements on the water vapor and oxygen barrier properties in the films were attributed to the formation of compact structure. Emulsion-based films stabilized by SPI-polyphenol conjugates showed antioxidant and antibacterial activities. They also demonstrated an ability to extend the shelf life of cherry tomatoes, as indicated by better preservation of weight, firmness, and ascorbic acid content.

Metal-organic frameworks-based moisture responsive essential oil hydrogel beads for fresh-cut pineapple preservation

The preservation of fresh-cut fruits and vegetables has attracted attention to the shelf-life reduction caused by high humidity. Herein, alginate/copper ions cross-linking, in-situ growth and self-assembly techniques of metal-organic frameworks (MOFs) were utilized to prepare a moisture responsive hydrogel bead (HKUST-1@ALG). As the multistage porous structure formation, tea tree essential oil (TTO) load capacity in hydrogel bead (TTO-HKUST-1@ALG) was increased from 6.1% to 21.6%. TTO-HKUST-1@ALG had excellent moisture response performance, and the release rates of TTO increased from 33.89% to 70.98% with moisture increasing from 45% to 95%. Besides, TTO-HKUST-1@ALG exhibited excellent antimicrobial, antioxidant capacity, and biocompatibility. During storage, TTO-HKUST-1@ALG effectively improved the cell membrane integrity by maintaining the balance of reactive oxygen species metabolism. The degradation of cell wall structure and tissue softening were delayed by inhibiting the cell wall-degrading enzymes activity. Briefly, TTO-HKUST-1@ALG improved the storage quality and extended shelf-life of fresh-cut pineapple, which was a promising preservative.

Development of smart colorimetric indicators for tracking kimchi freshness by loading aronia extract in agar, κ-carrageenan, and cellulose nanofiber films

Color indicator films incorporating aronia extract powder (AEP) and biopolymers like agar, carrageenan, and cellulose nanofiber (CNF) were developed to monitor kimchi freshness. AEP-containing films showed strong UV-barrier properties, and reduced light transmittance by 99.12 % for agar, 98.86 % for carrageenan, and 98.67 % for CNF-based films. All AEP-films exhibited high sensitivity to pH changes and vapor exposure to ammonia and acetic acid. Color change notably influenced by the polymer type, particularly evident with ammonia vapor exposure, especially in the AEP/carrageenan film. The chemical structure and thermal stability of the biopolymers remained unchanged after AEP-addition. Tensile strength increased by 24.2 % for AEP/CNF but decreased by 19.4 % for AEP/agar and 24.3 % for AEP/carrageenan films. AEP-containing films displayed strong antioxidant activity, with 99 % free radical scavenging in ABTS and ~ 80 % in DPPH assays. Alkalized AEP-indicator films were more effective in detecting color changes during kimchi packaging tests. Among the labels, alkalized AEP/agar film showed the most obvious color change from green-gray (fresh kimchi, pH 5.5, acidity 0.48 %) to pale brown (optimal fermentation, pH 4.6, acidity 0.70 %), and pale violet-brown (over-fermented, pH 3.80, acidity 1.35 %). Alkalized AEP-indicator films offer promising real-time detection of packed fermented foods like kimchi.

Recent progress on Pickering emulsion stabilized essential oil added biopolymer-based film for food packaging applications: A review

Nowadays food safety and protection are a growing concern for food producers and food industry. The stability of food-grade materials is key in food processing and shelf life. Pickering emulsions (PEs) have gained significant attention in food regimes owing to their stability enhancement of food specimens. PE can be developed by high and low-energy methods. The use of PE in the food sector is completely safe as it uses solid biodegradable particles to stabilize the oil in water and it also acts as an excellent carrier of essential oils (EOs). EOs are useful functional ingredients, the inclusion of EOs in the packaging film or coating formulation significantly helps in the improvement of the shelf life of the packed food item. The highly volatile nature, limited solubility and ease of oxidation in light of EOs restricts their direct use in packaging. In this context, the use of PEs of EOs is suitable to overcome most of the challenges, Therefore, recently there have been many papers published on PEs of EOs including active packaging film and coatings and the obtained results are promising. The current review amalgamates these studies to inform about the chemistry of PEs followed by types of stabilizers, factors affecting the stability and different high and low-energy manufacturing methods. Finally, the review summarizes the recent advancement in PEs-added packaging film and their application in the enhancement of shelf life of food.

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.

Development and characterization of active poly (3-hydroxybutyrate) based composites with grapeseed oil and MgO nanoparticles for shelf-life extension of white button mushrooms (Agaricus bisporus)

Poly (3-hydroxybutyrate) (PHB) is undoubtedly a potential substitute for petroleum-based non-biodegradable food packaging materials due to its renewability, high crystallinity, biocompatibility, and biodegradability. Nonetheless, PHB exhibits certain shortcomings, including low flexibility, moderate gas barrier properties, and negligible antimicrobial and antioxidant activities, which limit its direct application in food packaging. Loading essential oils can increase flexibility and induce antimicrobial and antioxidant activities in biopolymers but at the cost of reduced tensile strength. In contrast, nanofiller reinforcement can increase the tensile strength and barrier properties of such biopolymers. Therefore, to harness the synergistic effects of essential oil and nanofiller, PHB-based films incorporated with 5 wt% grapeseed oil (GS) and varying concentrations (0.1-1 wt%) of MgO nanoparticles (MgO NPs) were prepared in this study following simple sonication-assisted solution casting technique. Physicochemical, tensile, microstructural, optical, barrier, antimicrobial, and antioxidant properties were then evaluated for the prepared composite films. FESEM analysis of the PHB-based films with 5 wt% GS and 0.7 wt% MgO NPs (PHB/5GS/0.7MgO) confirmed its compact morphology without any aggregates, pores, or phase separation. In comparison with pristine PHB, the PHB/5GS/0.7MgO films demonstrated higher tensile strength (by 1.4-fold) and flexibility (by 30-fold), along with 79 and 90 % reduction in water vapor and oxygen transmission, respectively. In addition, PHB/5GS/0.7MgO showed good UV-blocking properties, 65.25 ± 0.98 % antioxidant activity, and completely inhibited the growth of Staphylococcus aureus and Escherichia coli. Moreover, PHB/5GS/0.7MgO films proved beneficial effects in terms of extending the shelf-life of white button mushrooms up to 6 days at ambient room conditions.

Enhancement of a hybrid colorimetric film incorporating Origanum compactum essential oil as antibacterial and monitor chicken breast and shrimp freshness

Recently, intelligent packaging has combined several functions, including monitoring and preserving food freshness in real-time. This study was developed a hybrid film (active/ colorimetric) based on AM/CPC/9%SFW as a carrier of Origanum compactum essential oil (OC) in various concentrations (0%, 1%, 1.25%, and 1.5% v/v). The film's emulsions showed homogeneity regarding particle size, polydispersity index, and ζ -potential. Hybrid films' morphological, mechanical, water and light barrier, thermal, and antioxidant properties were enhanced with an increased OC. Interestingly, all films rapidly responded to pH/NH3 and reflected different colors. In the hybrid films, an inhibition effect against gram-positive (Staphylococcus aureus) and gram-negative (Escherichia coli) bacteria and OC (1.5%) film exhibited a large inhibition zone attained diameters of 37.33 and 15.67 mm, respectively, in the disc diffusion test. Outstanding, AM/CPC/9%SFW/1.5 %OC film displayed the ability to preserve and monitor chicken breast and shrimp freshness to 33 and 21 h, respectively, during storage at 25 °C.

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.

Application of chitosan and other biopolymers based edible coatings containing essential oils as green and innovative strategy for preservation of perishable food products: A review

Deterioration of perishable foods due to fungal contamination and lipid peroxidation are the most threatened concern to food industry. Different chemical preservatives have been used to overcome these constrains; however their repetitive use has been cautioned owing to their negative impact after consumption. Therefore, attention has been paid to essential oils (EOs) because of their natural origin and proven antifungal and antioxidant activities. Many EO-based formulations have been in use but their industrial-scale application is still limited, possibly due to its poor solubility, vulnerability towards oxidation, and aroma effect on treated foods. In this sense, active food packaging using biopolymers could be considered as promising approach. The biopolymers can enhance the stability and effectiveness of EOs through controlled release, thus minimizes the deterioration of foods caused by fungal pathogens and oxidation without compromising their sensory properties. This review gives a concise appraisal on latest advances in active food packaging, particularly developed from natural polymers (chitosan, cellulose, cyclodextrins etc.), characteristics of biopolymers, and current status of EOs. Then, different packaging and their effectiveness against fungal pathogens, lipid-oxidation, and sensory properties with recent previous works has been discussed. Finally, effort was made to highlights their safety and commercialization aspects towards market solutions.

Constructing a biodegradable carrageenan based food packaging film according to the synergistic strategies between peppermint essential oil and thymol

The research and development trend of food packaging is changing from synthetic polymers to eco-friendly materials such as polysaccharides and other hydrocolloids, aiming to solve the problem of pollution from plastic wastes. In this work, a biodegradable food packaging noted KC/PT film was constructed using konjac glucomannan (KGM)/carrageenan (CAR) composite as the matrix and peppermint essential oil (PO)/thymol (THY) with synergistic effect as the reinforcements. The KC/PT film showed great mechanical properties, UV-blocking activity, increased water contact angle and reduced water vapor permeability. Due to the synergistic effect between PO and THY, the KC/PT film showed excellent antioxidant performance and antibacterial behavior against Escherichia coli ATCC 25922, Listeria monocytogenes ATCC 19115 and Staphylococcus aureus ATCC 6538. The antibacterial mechanism was further illustrated. The prepared KC/PT film, as a unique packaging film, not only successfully extended the shelf life of strawberry to 16 days at 4 °C, but also well expressed its environmental friendliness that it could nearly degrade after 47 days in natural soil conditions. Most importantly, the film exhibited good stability in terms of mechanical properties, antioxidant activity and antibacterial performances after 4 months storage. Therefore, the film the KC/PT film has great potentials in the field of food packaging area.

Development of a novel 1-octen-3-ol-loaded agar/curdlan hydrogel for inhibiting peach fruit diseases

Our previous study found that 1-octen-3-ol fumigation treatment could effectively induce the resistance of peach fruit diseases. However, 1-octen-3-ol is a liquid fumigant, which is not conducive to storage and application. Herein, the gel of 1 % agar compound with 1 % curdlan was used as a novel material for covering 1-octen-3-ol. The interaction of agar and curdlan was promoted by adding 1-octen-3-ol, leading to a higher thermostability compared to single-component antibacterial gels. Moreover, 1-octen-3-ol resulted in changes in the internal structure and mechanical properties of gel to form a pore-like structure, which is beneficial to the retention and release of 1-octen-3-ol. Additionally, the 2 % agar gel containing 1-octen-3-ol had the best inhibitory effect on the mycelial growth of Monilinia fructicola and Rhizopus stolonifer in vitro, and the compound hydrogel of 1 % agar and 1 % curdlan with 1-octen-3-ol could most effectively inhibit brown rot and soft rot caused by these two pathogens in vivo. Overall, the data indicated that the novel 1-octen-3-ol-loaded agar/curdlan hydrogels could effectively retain and release 1-octen-3-ol, and induce the resistance of peach fruit diseases.

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.

Films Based on Biopolymers Incorporated with Active Compounds Encapsulated in Emulsions: Properties and Potential Applications-A Review

The rising consumer demand for safer, healthier, and fresher-like food has led to the emergence of new concepts in food packaging. In addition, the growing concern about environmental issues has increased the search for materials derived from non-petroleum sources and biodegradable options. Thus, active films based on biopolymers loaded with natural active compounds have great potential to be used as food packaging. However, several lipophilic active compounds are difficult to incorporate into aqueous film-forming solutions based on polysaccharides or proteins, and the hydrophilic active compounds require protection against oxidation. One way to incorporate these active compounds into film matrices is to encapsulate them in emulsions, such as microemulsions, nanoemulsions, Pickering emulsions, or double emulsions. However, emulsion characteristics can influence the properties of active films, such as mechanical, barrier, and optical properties. This review addresses the advantages of using emulsions to encapsulate active compounds before their incorporation into biopolymeric matrices, the main characteristics of these emulsions (emulsion type, droplet size, and emulsifier nature), and their influence on active film properties. Furthermore, we review the recent applications of the emulsion-charged active films in food systems.

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.

Exploring the Potential of Seaweed Derivatives for the Development of Biodegradable Plastics: A Comparative Study

Biodegradable films made from biopolymer materials have the potential to replace conventional plastics, which can reduce waste disposal problems. This study aims to explore the potential of different seaweed derivate films consisting of 2% (w/w) of kappaphycus alverezi (KA), kappa carrageenan (KC), refined carrageenan (RC) and semi-refined carrageenan (SRC) as bio-based materials with 0.9% (w/w) glycerol (G), and reinforced with different concentrations of cellulose nanofibers (CNFs) derived from palm waste. A characterization of the glycerol-plasticized seaweed derivatives containing 0, 5, 10, and 15% (v/w) cellulose nanofiber is carried out. The CNFs were studied based on their mechanical, physical and thermal properties including mechanical properties, thickness, moisture content, opacity, water solubility, water vapor permeability and thermal stability. The hydrogen bonding was determined using the DFT calculation generated by Gauss view software version 9.6. The KA + G + 10%CNF film exhibited a surface with slight cracks, roughness, and larger lumps and dents, resulting in inferior mechanical properties (18.50 Mpa), making it unsuitable for biofilm production. The KC + G + 10%CNF film exhibited mechanical properties 24.97 Mpa and water vapor permeability of 1.42311 × 10^-11 g s^-1 m^-1 Pa^-1. The RC/G/10%CNF film displayed the highest TS (48.23 MPa) and water vapor permeability (1.4168 × 10^-11 g s^-1 m^-1 Pa^-1), but it also had higher solubility in water (66%). In contrast, the SRC + G + 10%CNF film demonstrated excellent mechanical properties (45.98 MPa), low water solubility (42.59%), low water vapor permeability (1.3719 × 10^-11 g s^-1 m^-1 Pa^-1), and a high decomposition temperature (250.62 °C) compared to KA, KC and RC. These attributes develop films suitable for various applications, including food packaging with enhanced properties and stability.

Facile modification of nanochitin in aqueous media for stabilizing tea tree oil based Pickering emulsion with prolonged antibacterial performance

Nanochitins have been explored for preparing Pickering Emulsions, however its application is restricted by its simplex disperse nature. It was hypothesized that zwitterionic nanochitins should be capable of stabilizing oil/water (O/W) interfaces in wider pH range. Furthermore, the control of their size, disperse nature and self-assembly performance suggest the formulation of tunable emulsions. Zwitterionic nanochitins were prepared via Schiff base reaction. A systematic study was performed analyzing the disperse nature, fibril morphology, surface characteristic of modified nanochitins. Oil-in-Water Pickering Emulsions stabilized by modified nanochitins were formulated and emulsion stability was analyzed as function of concentration, pH and self-assembly property and further applied for prolonged antibacterial applications. Comparing freshly prepared nanochitins, neutral/alkaline stably dispersed nanochitins can be prepared while maintaining fibril characteristics such as fibril size, crystallinity, thermal stability and so on. Better suspension stability of modified nanochitins under alkaline conditon together with the self assembly performance resulting from amino groups and carboxyl groups benefit the enhanced emulsion stability under nanochitins concentreation of 0.2 %. Encapsulation of tea tree oil in Pickering Emulsions prolongs the diffusion rate oil in the aqueous environment, thus resulting prolongs its antibacterial performance against E. coli and B. subtilis.

Fortification of polysaccharide-based packaging films and coatings with essential oils: A review of their preparation and use in meat preservation

As the demand for botanical food additives and eco-friendly food packaging materials grows, the use of essential oils, edible biodegradable films and coatings are becoming more popular in packaging. In this review, we discussed the recent research trends in the use of natural essential oils, as well as polysaccharide-based coatings and films: from the composition of the substrates to preparing formulations for the production of film-forming technologies. Our review emphasized the functional properties of polysaccharide-based edible films that contain plant essential oils. The interactions between essential oils and other ingredients in edible films and coatings including polysaccharides, lipids, and proteins were discussed along with effects on film physical properties, essential oil release, their active role in meat preservation. We presented the opportunities and challenges related to edible films and coatings including essential oils to increase their industrial value and inform the development of edible biodegradable packaging, bio-based functional materials, and innovative food preservation technologies.

Development of fish gelatin/carrageenan/zein bio-nanocomposite active-films incorporated with turmeric essential oil and their application in chicken meat preservation

Gelatin/carrageenan (Ge/Car) active packaging films incorporated with turmeric essential oil (TEO) encapsulated in zein nanoparticles (ZNP) were developed. The efficacy of these active packaging films and their antimicrobial properties were also investigated to ensure their practical application. Three different types of nanocomposite films (Ge/Car, Ge/Car/TEO, and Ge/Car/ZNP) were prepared. The characterization of the films was elucidated using Fourier transform infrared (FTIR), X-ray diffraction analyses (XRD), and scanning electron microscope (SEM). Physicochemical and mechanical properties of the films were enhanced, owing to the application of TEO-containing nanocomposites. Supercritical-CO₂ extracted TEO showed excellent biological activities, alongside GC-MS analysis identified that TEO contained 33 bioactive compounds where the major constituent was Zingiberene. ZNP proved an excellent carrier of TEO. The nanocomposite film sustainably released TEO, improving the shelf life of the chicken meat by reducing bacterial colonies from 3.08 log CFU/g to 2.81 log CFU/g after 14 days incubation against Salmonella enterica compared with 6.66 log CFU/g observed in the control film. The overall results of this study suggest that the nanocomposite active film is an excellent candidate for food packaging to ensure a better world.

Recent Developments and Formulations for Hydrophobic Modification of Carrageenan Bionanocomposites

Versatility of the anionic algal polysaccharide carrageenan has long been discussed and explored, especially for their affinity towards water molecules. While this feature is advantageous in certain applications such as water remediation, wound healing, etc., the usefulness of this biopolymer is extremely limited when it comes to applications such as food packaging. Scientists around the globe are carrying out research works on venturing diverse methods to integrate a hydrophobic nature into these polysaccharides without compromising their other functionalities. Considering these foregoing studies, this review was designed to have an in-depth understanding of diverse methods and techniques adopted for tuning the hydrophobic nature of carrageenan-based bionanocomposites, both via surface alterations or by changes made to their chemical structure and attached functional groups. This review article mainly focused on how the hydrophobicity of carrageenan bionanocomposites varied as a function of the type and refinement of carrageenan, and with the incorporation of additives including plasticisers, nanofillers, bioactive agents, etc. Incorporation of nanofillers such as polysaccharide-based nanoparticles, nanoclays, bioceramic and mineral based nanoparticles, carbon dots and nanotubes, metal oxide nanoparticles, etc., along with their synergistic effects in hybrid bionanocomposites are also dealt with in this comprehensive review article.

A visual bi-layer sensor based on Agar/TiO2/butterfly bean flower anthocyanin/κ-carrageenan with photostability for monitoring Penaeus chinensis freshness

Visual indicator bi-layer films were manufactured incorporating κ-carrageenan, butterfly pea flower anthocyanin, varying Nano‑titanium dioxide (TiO₂) content and agar for Penaeus chinensis (Chinese white shrimp) freshness detection. The κ-carrageenan-anthocyanin (CA) layer served as indicator, while the TiO₂-agar (TA) layer functioned as the protective layer to improve the photostability of film. The bi-layer structure was characterized by scanning electron microscopy (SEM). The TA2-CA film had the best tensile strength with a value of 17.8 MPa and the lowest water vapor permeability (WVP) value of bi-layer films was 2.98 × 10^-7 g.m^-1.h^-1.pa^-1. The bi-layer film protected anthocyanin against exudation when immersed in aqueous solution of varying pH. The TiO₂ particles filled the pores of the protective layer, increasing the opacity from 1.61 up to 4.49 significantly improving the photostability with a consequent slight color change under illumination of UV/visible light. Under UV irradiation, the TA2-CA film had no significant color change with a ΔE value of 4.23. Finally, the TA2-CA films showed an obvious color change from blue to yellow green in the early stages of Penaeus chinensis putrefaction (≤48 h) then the color change and Penaeus chinensis freshness were well correlated (R² = 0.8739).

Efficient Utilization of Tea Resources through Encapsulation: Dual Perspectives from Core Material to Wall Material

With the high production and consumption of tea around the world, efficient utilization of tea byproducts (tea pruning, tea residues after production, and drinking) is the focus of improving the economy of the tea industry. This review comprehensively discusses the efficient utilization of tea resources by encapsulation from the dual perspectives of core material and wall material. The core material is mainly tea polyphenols, followed by tea oils. The encapsulation system for tea polyphenols includes microcapsules, nanoparticles, emulsions, gels, conjugates, metal-organic frameworks, liposomes, and nanofibers. In addition, it is also diversified for the encapsulation of tea oils. Tea resources as wall materials refer to tea saponins, tea polyphenols, tea proteins, and tea polysaccharides. The application of the tea-based delivery system widely involves functionally fortified food, meat preservation, film, medical treatment, wastewater treatment, and plant protection. In the future, the coencapsulation of tea resources as core materials and other functional ingredients, the precise targeting of these tea resources, and the wide application of tea resources in wall materials need to be focused on. In conclusion, the described technofunctional properties and future research challenges in this review should be followed.

Biopolymer Food Packaging Films Incorporated with Essential Oils

Petroleum-based packaging materials are typically nonbiodegradable, which leads to significant adverse environmental and health issues. Therefore, developing novel efficient, biodegradable, and nontoxic food packaging film materials has attracted increasing attention from researchers. Due to significant research and advanced technology, synthetic additives in packaging materials are progressively replaced with natural substances such as essential oils (EOs). EOs demonstrate favorable antioxidant and antibacterial properties, which would be an economical and effective alternative to synthetic additives. This review summarized the possible antioxidant and antimicrobial mechanisms of various EOs. We analyzed the properties and performance of food packaging films based on various biopolymers incorporated with EOs. The progress in intelligent packaging materials has been discussed as a prospect of food packaging materials. Finally, the current challenges regarding the practical application of EOs-containing biopolymer films in food packaging and areas of future research have been summarized.

Fabrication of multifunctional materials based on chitosan/gelatin incorporating curcumin-clove oil emulsion for meat freshness monitoring and shelf-life extension

A new multifunctional film with active and intelligent effects was developed by incorporating curcumin-clove oil emulsion into natural materials. The basic properties, functional characteristics, and pH/NH₃-sensitivity of films were investigated, and then these films were applied to extend shelf-life and monitor freshness of meat. Curcumin solution and emulsion illustrated significant color variations at different pH values. The incorporation of emulsion improved the UV-vis barrier and water resistance properties of films, which blocked most of UV-light and its water contact angle reached 100.03°. Meanwhile, the films had stronger mechanical strength and higher thermal stability, with elongation at break reaching 79.18 % and the maximum degradation temperature rising to 316 °C. Moreover, emulsion made films have a slow-release effect on clove oil, which not only enhanced the antioxidant property but also significantly improved their antibacterial activity. Additionally, the multifunctional films presented a significant color response to acidic/alkaline environments over a short time interval and could be easily identified by naked eyes. Finally, the films effectively extended the shelf-life of fresh meat by 3 days at 4 °C and visually monitored freshness through color changes in real-time. This knowledge provides insights and ideas for the development of novel food packaging with both active and intelligent functions.

Cellulose-Based Light-Management Films with Improved Properties Directly Fabricated from Green Tea

Tea polyphenols are a phenolic bioactive compound extracted from tea leaves and have been widely used as additives to prepare functional materials used in packaging, adsorption and energy fields. Nevertheless, tea polyphenols should be extracted first from the leaves before use, leading to energy consumption and the waste of tea. Therefore, completely and directly utilizing the tea leaf to fabricate novel composite materials is more attractive and meaningful. Herein, semi-transparent green-tea-based all-biomass light-management films with improved strength, a tunable haze (60–80%) and UV-shielding properties (24.23% for UVA and 4.45% for UVB) were directly manufactured from green tea by adding high-degree polymerization wood pulps to form entanglement networks. Additionally, the green-tea-based composite films can be produced on a large scale by adding green tea solution units to the existing continuous production process of pure cellulose films. Thus, a facile and feasible approach was proposed to realize the valorization of green tea by preparing green-tea-based all-biomass light-management films that have great prospects in flexible devices and energy-efficient buildings.

Recent advances in metal sulfide nanoparticle-added bionanocomposite films for food packaging applications

Metal sulfide nanoparticles have recently attracted much attention due to their unique physical and functional properties. Metal sulfide nanoparticles used as optoelectronic and biomedical materials in the past decades are promising for making functional nanocomposite films due to their low toxicity and strong antibacterial activity. Recently, copper sulfide and zinc sulfide nanomaterials have been used to produce food packaging films for active packaging. Metal sulfide nanoparticles added as nanofillers are attracting attention in packaging applications due to their excellent potential to improve mechanical, barrier properties, and antibacterial activity. This review covers the fabrication process and important applications of metal sulfide nanoparticles. The development of metal sulfides reinforcing mainly copper sulfide and zinc sulfide nanomaterials as multifunctional nanofillers in bio-based films for active packaging applications has been comprehensively reviewed. As the recognition of metal sulfide nanoparticles as a functional filler increases, the development and application potential of active packaging films using them is expected to increase.

Progress in the Application of Food-Grade Emulsions

The detailed investigation of food-grade emulsions, which possess considerable structural and functional advantages, remains ongoing to enhance our understanding of these dispersion systems and to expand their application scope. This work reviews the applications of food-grade emulsions on the dispersed phase, interface structure, and macroscopic scales; further, it discusses the corresponding factors of influence, the selection and design of food dispersion systems, and the expansion of their application scope. Specifically, applications on the dispersed-phase scale mainly include delivery by soft matter carriers and auxiliary extraction/separation, while applications on the scale of the interface structure involve biphasic systems for enzymatic catalysis and systems that can influence substance digestion/absorption, washing, and disinfection. Future research on these scales should therefore focus on surface-active substances, real interface structure compositions, and the design of interface layers with antioxidant properties. By contrast, applications on the macroscopic scale mainly include the design of soft materials for structured food, in addition to various material applications and other emerging uses. In this case, future research should focus on the interactions between emulsion systems and food ingredients, the effects of food process engineering, safety, nutrition, and metabolism. Considering the ongoing research in this field, we believe that this review will be useful for researchers aiming to explore the applications of food-grade emulsions.

The Improved Properties of Carboxymethyl Bacterial Cellulose Films with Thickening and Plasticizing

This study aims to improve the thermal stability and mechanical properties of carboxymethyl bacterial cellulose (CMBC) composite films. Experiments were conducted by preparing bacterial cellulose (BC) into CMBC, then parametrically mixing sodium alginate/starch/xanthan gum/gelatin and glycerin/sorbitol/PEG 400/PEG 6000 with CMBC to form the film. Scanning electron microscopy, X-ray diffractometry, infrared spectroscopy, mechanical tests, and thermogravimetric analysis showed that the composite films had better mechanical properties and thermal stability with the addition of 1.5% CMBC (% v/v), 1% sodium alginate, and 0.4% glycerin. Tensile strength was 38.13 MPa, the elongation at break was 13.4%, the kinematic viscosity of the film solution was 257.3 mm²/s, the opacity was 4.76 A/mm, the water vapor permeability was 11.85%, and the pyrolysis residue was 45%. The potential causes for the differences in the performance of the composite films were discussed and compared, leading to the conclusion that CMBC/Sodium alginate (SA)/glycerin (GL) had the best thermal stability and mechanical properties.

Polysaccharides: Sources, Characteristics, Properties, and Their Application in Biodegradable Films

Biodegradable films emerge as alternative biomaterials to conventional packaging from fossil sources, which, in addition to offering protection and increasing the shelf life of food products, are ecologically sustainable. The materials mostly used in their formulation are based on natural polysaccharides, plasticizing agents, and bioactive components (e.g., antimicrobial agents or antioxidants). The formulation of biodegradable films from polysaccharides and various plasticizers represents an alternative for primary packaging that can be assigned to specific food products, which opens the possibility of having multiple options of biodegradable films for the same product. This review describes the main characteristics of the most abundant polysaccharides in nature and highlights their role in the formulation of biodegradable films. The compilation and discussion emphasize studies that report on the mechanical and barrier properties of biodegradable films when made from pure polysaccharides and when mixed with other polysaccharides and plasticizing agents.

Development and characterization of sodium alginate/tea tree essential oil nanoemulsion active film containing TiO2 nanoparticles for banana packaging

To improve the postharvest quality and reduce the anthracnose of bananas, the sodium alginate (SA)/tea tree essential oil nanoemulsion (TEON) based bilayer films incorporated with different contents of TiO₂ nanoparticles were fabricated in this work. The developed TEON presented satisfactory DPPH scavenging activity (65.5 ± 1.8%) and antifungal capability (90.5 ± 5.8%). The microscopy images of the cross-section of the films indicated that the bilayer films with well-cross-linked were developed successfully. Notably, the addition of a certain content of TiO₂ to SA greatly improved the UV blocking and water vapor and oxygen barrier properties of the developed film. However, the barrier property of the film was decreased when the TiO₂ content further increased to 4.0 mg/100 mg of SA. The retention of TEO under visible and UV light in the bilayer film was respectively prolonged to 24 days and 32 h when the addition of TiO₂ content was 2.0 mg/100 mg of SA. Finally, the postharvest quality and anthracnose of banana fruits were significantly improved by SA-TiO₂ + SA-TEON film-forming solution treatments. Results from the present work might open up new insights into the approaches of postharvest quality improvement of bananas.