Agar-based edible films for food packaging applications - A review

Advances in agar-based composites: A comprehensive review

This review article explores the developments and applications in agar-based composites (ABCs), emphasizing various constituents such as metals, clay/ceramic, graphene, and polymers across diversified fields like wastewater treatment, drug delivery, food packaging, the energy sector, biomedical engineering, bioplastics, agriculture, and cosmetics. The focus is on agar as a sustainable and versatile biodegradable polysaccharide, highlighting research that has advanced the technology of ABCs. A bibliometric analysis is conducted using the Web of Science database, covering publications from January 2020 to March 2024, processed through VOSviewer Software Version 1.6.2. This analysis assesses evolving trends and scopes in the literature, visualizing co-words and themes that underscore the growing importance and potential of ABCs in various applications. This review paper contributes by showcasing the existing state-of-the-art knowledge and motivating further development in this promising field.

Algal carbohydrates: Sources, biosynthetic pathway, production, and applications

Algae play a significant role in the global carbon cycle by utilizing photosynthesis to efficiently convert solar energy and atmospheric carbon dioxide into various chemical compounds, notably carbohydrates, pigments, lipids, and released oxygen, making them a unique sustainable cellular factory. Algae mostly consist of carbohydrates, which include a broad variety of structures that contribute to their distinct physical and chemical properties such as degree of polymerization, side chain, branching, degree of sulfation, hydrogen bond etc., these features play a crucial role in regulating many biological activity, nutritional and pharmaceutical properties. Algal carbohydrates have not received enough attention in spite of their distinctive structural traits linked to certain biological and physicochemical properties. Nevertheless, it is anticipated that there will be a significant increase in the near future due to increasing demand, sustainable source, biofuel generation and their bioactivity. This is facilitated by the abundance of easily accessible information on the structural data and distinctive characteristics of these biopolymers. This review delves into the different types of saccharides such as agar, alginate, fucoidan, carrageenan, ulvan, EPS and glucans synthesized by various macroalgal and microalgal systems, which include intracellular, extracellular and cell wall saccharides. Their structure, biosynthetic pathway, sources, production strategies and their applications in various field such as nutraceuticals, pharmaceuticals, biomedicine, food and feed, cosmetics, and bioenergy are also elaborately discussed. Algal polysaccharide has huge a scope for exploitation in future due to their application in food and pharmaceutical industry and it can become a huge source of capital and income.

Advances in biomaterials based food packaging systems: Current status and the way forward

World hunger is getting worse, while one-third of food produced around the globe is wasted and never consumed. It is vital to reduce food waste to promote the sustainability of food systems, and improved food packaging solutions can augment this effort. The utilization of biomaterials in smart food packaging not only enhances food preservation and safety but also aligns with current demands for eco-friendly technologies to mitigate the impacts of climate change. This review provides a comprehensive overview of the developments in the field of food packaging based on the innovative use of biomaterials. It emphasizes the potential use of biomaterials derived from nature including cellulose, chitosan, keratin, etc. for this purpose. Various smart food packaging technologies such as active and intelligent packaging are discussed in detail including scavenging additives, colour-changing environment indicators, sensors, RFID tags, etc. The article also delves into the utilization of edible films and coatings, nanoparticle fillers and 2D materials in food packaging systems. Furthermore, it outlines the challenges and opportunities in this dynamic domain, emphasizing the ongoing need for research and innovation to shape the future of sustainable and smart food packaging solutions to enhance and monitor the shelf-life of food products.

Removal of heavy metal ions (Pb2+, Cu2+, Cr3+, and Cd2+) from multimetal simulated wastewater using 3-aminopropyl triethoxysilane grafted agar porous cryogel

In this study, we have developed agar, a seaweed derived polysaccharide based green adsorbent for the removal of heavy metal ions (Pb2+, Cu2+, Cr3+ and Cd2+) from multimetal solution. Porous cryogels of agar grafted with 3-aminopropyl triethoxysilane (APTES) were prepared by freeze-drying. The adsorption capacity and selectivity of the optimized APTES-agar cryogel for heavy metal ions (Cu2+, Cr3+, Pb2+, Cd2+) were investigated in multimetal solutions. >95 % of all the cationic metal ions were removed from 400 mg/L multimetal metal solutions having equal concentrations of each metal at pH 5.5. The experimental adsorption capacities of Cr3+, Cu2+, Pb2+, and, Cd2+ were changed from 39.14, 39.0, 39.20, 37.93 mg/g, to 52.58, 52.70, 45.53, 31.10 mg/g, respectively, for the 400 mg/L and 800 mg/L multimetal solutions suggesting competitive adsorption of the metal ions for active sites. The competitive adsorption studies showed that Cd ions had lower affinity than other metal ions for active sites on APTES grafted agar surface, and adsorption followed in the order of Cu2+ ≈ Cr3+ > Pb2+ > Cd2+. The developed seaweed-derived agar-based porous adsorbent exhibits promise in the removal of several heavy metal ions from wastewater, and this approach would increase the use of natural polysaccharides that are sustainable.

Microbial Polysaccharides as Functional Components of Packaging and Drug Delivery Applications

This review examines microbial polysaccharides' properties relevant to their use in packaging and pharmaceutical applications. Microbial polysaccharides are produced by enzymes found in the cell walls of microbes. Xanthan gum, curdlan gum, pullulan, and bacterial cellulose are high-molecular-weight substances consisting of sugar residues linked by glycoside bonds. These polysaccharides have linear or highly branched molecular structures. Packaging based on microbial polysaccharides is readily biodegradable and can be considered as a renewable energy source with the potential to reduce environmental impact. In addition, microbial polysaccharides have antioxidant and prebiotic properties. The physico-chemical properties of microbial polysaccharide-based films, including tensile strength and elongation at break, are also evaluated. These materials' potential as multifunctional packaging solutions in the food industry is demonstrated. In addition, their possible use in medicine as a drug delivery system is also considered.

Seaweed as a Valuable and Sustainable Resource for Food Packaging Materials

Plastic food packaging causes massive pollution in the environment via resource extraction, gas emissions, and the enduring plastic waste accumulation. Hence, it is of crucial importance to discover sustainable alternatives in order to protect ecosystems and conserve precious resources. Recently, seaweed has been emerging as a promising sustainable solution to plastic pollution. Seaweed is a fast-growing marine plant that is abundant in tropical coastlines and requires minimal resources to cultivate. In addition, seaweed is rich in valuable polysaccharides such as alginate, fucoidan, carrageenan, agar, and ulva, which can be extracted and processed into biodegradable films, coatings, and wraps. This ability allows the creation of an alternative to plastic food packages that are completely biodegradable, made from renewable resources, and do not linger in landfills or oceans for centuries. In this context, this review discusses the main classification of seaweed, their production and abundance in the world, and provides a summary of seaweed-based materials developed in the last 2-5 years for potential usage in the food packaging sector.

Development of quaternized agar-based materials for the coronavirus inactivation

The COVID-19 pandemic has revealed weaknesses in healthcare systems and underscored the need for advanced antimicrobial materials. This study investigates the quaternization of agar, a seaweed-derived polysaccharide, and the development of electrospun membranes for air filtration in facemasks and biomedical applications. Using the betacoronavirus MHV-3 as a model, quaternized agar and membranes achieved a 90-99.99 % reduction in viral load, without associated cytotoxicity. The quaternization process reduced the viscosity of the solution from 1.19 ± 0.005 to 0.64 ± 0.005 Pa.s and consequently the electrospun fiber diameter ranged from 360 to 185 nm. Membranes synthesized based on polyvinyl alcohol and thermally cross-linked with citric acid exhibited lower water permeability. Avoiding organic solvents in the electrospinning technique ensured eco-friendly production. This approach offers a promising way to develop biocompatible and functional materials for healthcare and environmental applications.

Edible-algae base composite film containing gelatin for food packaging from macroalgae, Gracilaroid (Gracilaria fisheri)

BACKGROUND

Conventional petroleum-based packaging films cause severe environmental problems. In the present study, bio-edible film was introduced as being safe to replace petroleum-based polymers. A food application for edible sachets and a composite edible film (EF) from marine algae, Gracilaria fisheri (GF) extract, were proposed.

RESULTS

Carbohydrates were the most prevalent component in fresh GF fronds. Under neutral conditions comprising 90 °C for 40 min, the structure of the extract was determined by Fourier transform infrared to be a carrageenan-like polysaccharide. Glycerol was the best plasticizer for EF formation because it had the highest tensile strength (TS). The integration of gelatin into the algal composite film with gelatin (CFG) was validated to be significant. The best casting temperatures for 2 h were 70 and 100 °C among the four tested temperatures (25, 60, 70 and 100 °C). Temperatures did not result in any significant (P ≤ 0.05) differences in any character (color values, TS, water vapor permeability, oxygen transmission, thickness and water activity), except elongation at break. Visually, the CFG had a slightly yellow appearance. The best-to-worst order of film stability in the three tested solvents was oil, distilled water (DW) and ethanol. Its stability in ethanol (0-100%), temperature of DW (30-100 °C) and pH (3-7 in DW) demonstrated inverse relationships with the concentration or different conditions, except for pH 8-10 in DW. All treatments were significantly (P ≤ 0.05) different.

CONCLUSION

The novel material made from polysaccharides from algae, G. fisheri, was used to improve EF. The edible sachet application is plausible from the EF. © 2024 Society of Chemical Industry.

Reduction of oxidative rancidification of fungal melanin-coated films in pork lard preservation in trading

Storage of meat has always been challenging due to its deterioration caused by oxidative rancidity and microbial activity, especially in trading. The melanin-coated film acts as a potent antioxidant, prevents the oxidation of fatty acids, and neutralizes the reactive oxygen species (ROS) helping to withstand or perpetuate the oxidative stress of meat. This study emphasizes the production of fungal melanin extracted from Curvularia lunata and the preparation of two different melanin film combinations of gelatin/melanin and agar/melanin at 0.1% and 0.5% formulation for rancidity stability of coated pork lard. Interpretations revealed the delayed rancidity in both peroxide and acid values with 5.76% in 0.5% agar-coated melanin up to the 11th day which was supported by arithmetical analysis showing p < 0.05 are statistically significant. Further, upon testing the brine shrimp assay for melanin toxicity, 7% were in a mortal state at 1000 µg/mL concentration, considered zero lethality. This result implies that modified coatings, particularly when trading meats, that include fungal melanin can effectively prevent the oxidation of pork lard.

Seaweed-based biopolymers for food packaging: A sustainable approach for a cleaner tomorrow

With the increasing environmental and health consequences of uncontrolled plastic use, the scientific community is progressively gravitating toward biodegradable and ecofriendly packaging alternatives. Seaweed polysaccharides have attracted attention recently because of their biodegradability, nontoxicity, antioxidant properties, and superior film-forming ability. However, it has some limitations for packaging applications, such as low tensile strength, water solubility, and only modest antimicrobial properties. The incorporation of biopolymers, nanoparticles, or organic active ingredients enhances these characteristics. This review encapsulates the contemporary research landscape pivoting around the role of seaweed polysaccharides in the development of bioplastics, active packaging solutions, edible films, and protective coatings. A meticulous collation of existing literature dissects the myriad food application avenues for these marine biopolymers, emphasizing their multifaceted physical, mechanical, thermal, and functional attributes, including antimicrobial and antioxidant. A key facet of this review spotlights environmental ramifications by focusing on their biodegradability, reinforcing their potential as a beacon of sustainable innovation. This article delves into the prevalent challenges that stymie large-scale adoption and commercialization of seaweed-centric packaging, offering a comprehensive perspective on this burgeoning domain.

Wood inspired biobased nanocomposite films composed of xylans, lignosulfonates and cellulose nanofibers for active food packaging

The growing concerns on environmental pollution and sustainability have raised the interest on the development of functional biobased materials for different applications, including food packaging, as an alternative to the fossil resources-based counterparts, currently available in the market. In this work, functional wood inspired biopolymeric nanocomposite films were prepared by solvent casting of suspensions containing commercial beechwood xylans, cellulose nanofibers (CNF) and lignosulfonates (magnesium or sodium), in a proportion of 2:5:3 wt%, respectively. All films presented good homogeneity, translucency, and thermal stability up to 153 °C. The incorporation of CNF into the xylan/lignosulfonates matrix provided good mechanical properties to the films (Young's modulus between 1.08 and 3.79 GPa and tensile strength between 12.75 and 14.02 MPa). The presence of lignosulfonates imparted the films with antioxidant capacity (DPPH radical scavenging activity from 71.6 to 82.4 %) and UV barrier properties (transmittance ≤19.1 % (200-400 nm)). Moreover, the films obtained are able to successfully delay the browning of packaged fruit stored over 7 days at 4 °C. Overall, the obtained results show the potential of using low-cost and eco-friendly resources for the development of sustainable active food packaging materials.

Chemically modified seaweed polysaccharides: Improved functional and biological properties and prospective in food applications

Seaweed polysaccharides are natural biomacromolecules with unique physicochemical properties (e.g., good gelling, emulsifying, and film-forming properties) and diverse biological activities (e.g., anticoagulant, antioxidant, immunoregulatory, and antitumor effects). Furthermore, they are nontoxic, biocompatible and biodegradable, and abundant in resources. Therefore, they have been widely utilized in food, cosmetics, and pharmaceutical industries. However, their properties and bioactivities sometimes are not satisfactory for some purposes. Modification of polysaccharides can impart the amphiphilicity and new functions to the biopolymers and change the structure and conformation, thus effectively improving their functional properties and biological activities so as to meet the requirement for targeted applications. This review outlined the modification methods of representative red algae polysaccharides (carrageenan and agar), brown algae polysaccharides (fucoidan, alginate, and laminaran), and green algae polysaccharides (ulvan) that have potential food applications, including etherification, esterification, degradation, sulfation, phosphorylation, selenylation, and so on. The improved functional properties and bioactivities of the modified seaweed polysaccharides and their potential food applications are also summarized.

Seaweed as Basis of Eco-Sustainable Plastic Materials: Focus on Alginate

Seaweed, a diverse and abundant marine resource, holds promise as a renewable feedstock for bioplastics due to its polysaccharide-rich composition. This review explores different methods for extracting and processing seaweed polysaccharides, focusing on the production of alginate plastic materials. Seaweed emerges as a promising solution, due to its abundance, minimal environmental impact, and diverse industrial applications, such as feed and food, plant and soil nutrition, nutraceutical hydrocolloids, personal care, and bioplastics. Various manufacturing techniques, such as solvent casting, injection moulding, and extrusion, are discussed for producing seaweed-based bioplastics. Alginate, obtained mainly from brown seaweed, is particularly known for its gel-forming properties and presents versatile applications in many sectors (food, pharmaceutical, agriculture). This review further examines the current state of the bioplastics market, highlighting the growing demand for sustainable alternatives to conventional plastics. The integration of seaweed-derived bioplastics into mainstream markets presents opportunities for reducing plastic pollution and promoting sustainability in material production.

Preparation and drug release performance of different gelation type polysaccharide/β-lactoglobulin fiber composite gels

Self-assembled protein fibers have attracted much attention in the fields of medicine and food because of their high aspect ratio, polymorphic structure and strong surface hydrophobicity. In this study, three different gelation types of polysaccharides/β-lactoglobulin fiber (Fblg) composite gels, including ionic alginate-Fblg gels, synergistic xanthan-Fblg gels, and double network agar-Fblg gels, were first prepared. The interactions between the polysaccharides and the Fblgs, the microstructure and mechanical properties of the composite gels were investigated using the light scattering, scanning electron microscopy, rheology and texture analysis in order to reveal their formation mechanisms. Then the loading and release properties of the water-soluble drug 5-fluorouracil (5-FU) and the hydrophobic drug curcumin (Cur) through these composite gels were further studied with release mechanisms determined by fitting different release models. It was found that the mechanical properties of the composite gels were determined by the mesh density of the three-dimensional networks formed inside the gels. The network structure and mechanical strength of the alginate-Fblg gels became weaker with the increase of Fblg content at pH 4 due to their attractive interaction which hindered the binding of Ca2+ to ALG, while the network and the strength of the alginate-Fblg gels didn't change much at pH 7 due to the repulsion between Alg and Fblg. The xanthan-Fblg gels formed lamellar structures with enhanced gel network and mechanical strength due to the hydrogen bonding and the electrostatic interaction with Fblg. The Agar-Fblg composite gel formed at 60 °C (above the gelation temperature of agar of 40 °C) had a denser double network structure and higher mechanical strength than that formed at 0 °C due to inhibition of diffusion of Ca2+ as salt bridges for Fblg. The hydrophilic drugs were loaded in the meshes of the composite gels and their release was determined by the structure of the composite gel networks, whereas the hydrophobic drugs were loaded by attaching to the Fblgs in the composite gels and their release was determined by the loading ability and strength of the gels. The study not only provided a new idea for the preparation and application of polysaccharide-protein fiber composite hydrogels, but also provided insights for improving the efficiency of drug carriers.

Granulation of Lithium-Ion Sieves Using Biopolymers: A Review

The high demand for lithium (Li) relates to clean, renewable storage devices and the advent of electric vehicles (EVs). The extraction of Li ions from aqueous media calls for efficient adsorbent materials with various characteristics, such as good adsorption capacity, good selectivity, easy isolation of the Li-loaded adsorbents, and good recovery of the adsorbed Li ions. The widespread use of metal-based adsorbent materials for Li ions extraction relates to various factors: (i) the ease of preparation via inexpensive and facile templation techniques, (ii) excellent selectivity for Li ions in a matrix, (iii) high recovery of the adsorbed ions, and (iv) good cycling performance of the adsorbents. However, the use of nano-sized metal-based Lithium-ion sieves (LISs) is limited due to challenges associated with isolating the loaded adsorbent material from the aqueous media. The adsorbent granulation process employing various binding agents (e.g., biopolymers, synthetic polymers, and inorganic materials) affords composite functional particles with modified morphological and surface properties that support easy isolation from the aqueous phase upon adsorption of Li ions. Biomaterials (e.g., chitosan, cellulose, alginate, and agar) are of particular interest because their structural diversity renders them amenable to coordination interactions with metal-based LISs to form three-dimensional bio-composite materials. The current review highlights recent progress in the use of biopolymer binding agents for the granulation of metal-based LISs, along with various crosslinking strategies employed to improve the mechanical stability of the granules. The study reviews the effects of granulation and crosslinking on adsorption capacity, selectivity, isolation, recovery, cycling performance, and the stability of the LISs. Adsorbent granulation using biopolymer binders has been reported to modify the uptake properties of the resulting composite materials to varying degrees in accordance with the surface and textural properties of the binding agent. The review further highlights the importance of granulation and crosslinking for improving the extraction process of Li ions from aqueous media. This review contributes to manifold areas related to industrial application of LISs, as follows: (1) to highlight recent progress in the granulation and crosslinking of metal-based adsorbents for Li ions recovery, (2) to highlight the advantages, challenges, and knowledge gaps of using biopolymer-based binders for granulation of LISs, and finally, (3) to catalyze further research interest into the use of biopolymer binders and various crosslinking strategies to engineer functional composite materials for application in Li extraction industry. Properly engineered extractants for Li ions are expected to offer various cost benefits in terms of capital expenditure, percent Li recovery, and reduced environmental footprint.

Antibacterial and Antifungal Activities of Cimbopogon winterianus and Origanum syriacum Extracts and Essential Oils against Uropathogenic Bacteria and Foodborne Fungal Isolates

This study focused on testing the antibacterial and antifungal activity of Origanum syriacum (O. syriacum) and Cimbopogon winterianus (C. winterianus) extracts and their essential oils (EOs). The bacteria were isolated from urine samples and identified by a VITEK assay, and the fungi were isolated from spoiled food samples and further identified by MALDI-TOF. The susceptibility of the microbial isolates was assessed by determining the bacteriostatic and bactericidal/fungicidal effects by the minimum inhibitory concentration (MIC) and minimum bactericidal/fungicidal concentration (MBC/MFC) broth microdilution assay and time-kill test. The antibiofilm activities were assessed by the antibiofilm screening assays. The bacterial isolates included three Gram-negative isolates (Escherichia coli, Klebsiella pneumonia, and Citrobacter freundii) and two Gram-positive isolates (Staphylococcus aureus and Streptococcus intermedius). The fungal isolates included Candida albicans and Aspergillus niger. The O. syriacum and C. winterianus extracts exhibited bacteriostatic and fungistatic activities (MIC 1.25-2.5 mg/mL for the bacterial isolates and 2.5-5 mg/mL for the fungal isolates). However, their EOs exhibited bactericidal (MBC 5-20%) and fungicidal (MFC 1.25-10%) activities, meaning that the EOs had a better antimicrobial potential than the extracts. The antibiofilm activities of the mentioned extracts and their EOs were relatively weak. The O. syriacum extract inhibited S. aureus, S. intermedius, and K. pneumonia biofilms at a concentration of 0.3125 mg/mL and C. albicans and A. niger biofilms at 0.625 mg/mL. No antibiofilm activity was recorded for C. winterianus extract. In addition, the packaging of grapes with C. winterianus extract preserved them for about 40 days. The results reflect the significant antimicrobial activity of O. syriacum and C. winterianus extracts and their EOs, thus suggesting their potential in food packaging and preservation.

Macroalgae Bioplastics: A Sustainable Shift to Mitigate the Ecological Impact of Petroleum-Based Plastics

The surge in global utilization of petroleum-based plastics, which notably heightened during the COVID-19 pandemic, has substantially increased its harm to ecosystems. Considering the escalating environmental impact, a pivotal shift towards bioplastics usage is imperative. Exploring and implementing bioplastics as a viable alternative could mitigate the ecological burden posed by traditional plastics. Macroalgae is a potential feedstock for the production of bioplastics due to its abundance, fast growth, and high cellulose and sugar content. Researchers have recently explored various methods for extracting and converting macroalgae into bioplastic. Some of the key challenges in the production of macroalgae bioplastics are the high costs of large-scale production and the need to optimize the extraction and conversion processes to obtain high-quality bioplastics. However, the potential benefits of using macroalgae for bioplastic production include reducing plastic waste and greenhouse gas emissions, using healthier materials in various life practices, and developing a promising area for future research and development. Also, bioplastic provides job opportunities in free enterprise and contributes to various applications such as packaging, medical devices, electronics, textiles, and cosmetics. The presented review aims to discuss the problem of petroleum-based plastic, bioplastic extraction from macroalgae, bioplastic properties, biodegradability, its various applications, and its production challenges.

Agarose biodegradation by deep-sea bacterium Vibrio natriegens WPAGA4 with the agarases through horizontal gene transfer

This study aimed to reveal the importance of horizontal gene transfer (HGT) for the agarose-degrading ability and the related degradation pathway of a deep-sea bacterium Vibrio natriegens WPAGA4, which was rarely reported in former works. A total of four agarases belonged to the GH50 family, including Aga3418, Aga3419, Aga3420, and Aga3472, were annotated and expressed in Escherichia coli cells. The agarose degradation products of Aga3418, Aga3420, and Aga3472 were neoagarobiose, while those of Aga3419 were neoagarobiose and neoagarotetraose. The RT-qPCR analysis showed that the expression level ratio of Aga3418, Aga3419, Aga3420, and Aga3472 was stable at about 1:1:1.5:2.5 during the degradation, which indicated the optimal expression level ratio of the agarases for agarose degradation by V. natriegens WPAGA4. Based on the genomic information, three of four agarases and other agarose-degrading related genes were in a genome island with a G + C content that was obviously lower than that of the whole genome of V. natriegens WPAGA4, indicating that these agarose-degrading genes were required through HGT. Our results demonstrated that the expression level ratio instead of the expression level itself of agarase genes was crucial for agarose degradation by V. natriegens WPAGA4, and HGT occurred in the deep-sea environment, thereby promoting the deep-sea carbon cycle and providing a reference for studying the evolution and transfer pathways of agar-related genes.

Incorporation of cellulose nanocrystals to improve the physicochemical and bioactive properties of pectin-konjac glucomannan composite films containing clove essential oil

This study aimed to investigate the effectiveness of cellulose nanocrystals (CNC) isolated from cotton in augmenting pectin (PEC)/konjac glucomannan (KGM) composite films containing clove essential oil (CEO) for food packaging application. The effects of CNC dosage on film properties were examined by analyzing the rheology of film-forming solutions and the mechanical, barrier, antimicrobial, and CEO-release properties of the films. Rheological and FTIR analysis revealed the enhanced interactions among the film components after CNC incorporation due to its high aspect ratio and abundant hydroxyl groups, which can also prevent CEO droplet aggregation, contributing to form a compact microstructure as confirmed by SEM and 3D surface topography observations. Consequently, the addition of CNC reinforced the polysaccharide matrix, increasing the tensile strength of the films and improving their barrier properties to water vapor. More importantly, antibacterial, controlled release and kinetic simulation experiments proved that the addition of CNC could further slow down the release rate of CEO, prolonging the antimicrobial properties of the films. PEC/KGM/CEO composite films with 15 wt% CNC was found to have relatively best comprehensive properties, which was also most effective in delaying deterioration of grape quality during the storage of 9 days at 25 °C.

Algal carbohydrate polymers: Catalytic innovations for sustainable development

Algal polysaccharides, harnessed for their catalytic potential, embody a compelling narrative in sustainable chemistry. This review explores the complex domains of algal carbohydrate-based catalysis, revealing its diverse trajectory. Starting with algal polysaccharide synthesis and characterization methods as catalysts, the investigation includes sophisticated techniques like NMR spectroscopy that provide deep insights into the structural variety of these materials. Algal polysaccharides undergo various preparation and modification techniques to enhance their catalytic activity such as immobilization. Homogeneous catalysis, revealing its significance in practical applications like crafting organic compounds and facilitating chemical transformations. Recent studies showcase how algal-derived catalysts prove to be remarkably versatile, showcasing their ability to customise reactions for specific substances. Heterogeneous catalysis, it highlights the significance of immobilization techniques, playing a central role in ensuring stability and the ability to reuse catalysts. The practical applications of heterogeneous algal catalysts in converting biomass and breaking down contaminants, supported by real-life case studies, emphasize their effectiveness. In sustainable chemistry, algal polysaccharides emerge as compelling catalysts, offering a unique intersection of eco-friendliness, structural diversity, and versatile catalytic properties. Tackling challenges such as dealing with complex structural variations, ensuring the stability of the catalyst, and addressing economic considerations calls for out-of-the-box and inventive solutions. Embracing the circular economy mindset not only assures sustainable catalyst design but also promotes efficient recycling practices. The use of algal carbohydrates in catalysis stands out as a source of optimism, paving the way for a future where chemistry aligns seamlessly with nature, guiding us toward a sustainable, eco-friendly, and thriving tomorrow. This review encapsulates-structural insights, catalytic applications, challenges, and future perspectives-invoking a call for collective commitment to catalyze a sustainable scientific revolution.

Effect of the pre-crosslinking of Ba2+ ions on wet spinning of agar fibers

Decreased coagulation bath concentration and difficult recovery are classical issues observed during the wet spinning of fibers. In this paper, a novel method was presented for preparing environment-friendly agar fibers using deionized water as the coagulation and stretch baths. The addition of Ba2+ into the spinning solution increased the crosslinking time and improved the performance of spinning solution. The results showed that the introduction of Ba2+ in the spinning solution increased the viscosity of the spinning solution. Particularly, when the concentration of BaCl2 in the spinning solution was 7 wt%, the viscosity increased to 39.29 Pa·s, which made the molecular chain arrangement of agar more compact and ordered and promoted the gelation transformation of the spinning solution, resulting in an increase in the gel temperature from 0.2 °C (Ba-0/agar) to 5.4 °C (Ba-7/agar). The spinning solution was more conducive to the formation of fibers in deionized water. In addition, the physical and chemical properties of agar fibers were characterized by X-ray diffraction, Fourier transform infrared spectroscopy, tensile testing, and scanning electron microscopy. The results showed that the use of deionized water as the coagulation bath can improve the color of fiber and solve the problem of fiber adhesion, whereas the mechanical strength of agar fibers with pre-cross-linking metal ions was also improved. For example, the breaking strength of Ba-7/agar/DIW was 0.73 cN/dtex while the breaking strength of Ba-0/agar/DIW was only 0.62 cN/dtex.

In vitro digestibility of proteins from red seaweeds: Impact of cell wall structure and processing methods

This study aimed to assess the nutritional quality and digestibility of proteins in two red seaweed species, Gelidium corneum and Gracilaropsis longissima, through the application of in vitro gastrointestinal digestions, and evaluate the impact of two consecutive processing steps, extrusion and compression moulding, to produce food snacks. The protein content in both seaweeds was approximately 16 %, being primarily located within the cell walls. Both species exhibited similar amino acid profiles, with aspartic and glutamic acid being most abundant. However, processing impacted their amino acid profiles, leading to a significant decrease in labile amino acids like lysine. Nevertheless, essential amino acids constituted 35-36 % of the total in the native seaweeds and their processed products. Although the protein digestibility in both seaweed species was relatively low (<60 %), processing, particularly extrusion, enhanced it by approximately 10 %. Interestingly, the effect of the different processing steps on the digestibility varied between the two species. This difference was mainly attributed to compositional and structural differences. G. corneum exhibited increased digestibility with each processing step, while G. longissima reached maximum digestibility after extrusion. Notably, changes in the amino acid profiles of the processed products affected adversely the protein nutritional quality, with lysine becoming the limiting amino acid. These findings provide the basis for developing strategies to enhance protein quality in these seaweed species, thereby facilitating high-quality food production with potential applications in the food industry.

Silver Nanoparticle-Loaded Titanium-Based Metal-Organic Framework for Promoting Antibacterial Performance by Synergistic Chemical-Photodynamic Therapy

The abuse of antibiotics leads to an increasing emergence of drug-resistant bacteria, which not only causes a waste of medical resources but also seriously endangers people's health and life safety. Therefore, it is highly desirable to develop an efficient antibacterial strategy to reduce the reliance on traditional antibiotics. Antibacterial photodynamic therapy (aPDT) is regarded as an intriguing antimicrobial method that is less likely to generate drug resistance, but its efficiency still needs to be further improved. Herein, a robust titanium-based metal-organic framework ACM-1 was adopted to support Ag nanoparticles (NPs) to obtain Ag NPs@ACM-1 for boosting antibacterial efficiency via synergistic chemical-photodynamic therapy. Apart from the intrinsic antibacterial nature, Ag NPs largely boost ROS production and thus improve aPDT efficacy. As a consequence, Ag NPs@ACM-1 shows excellent antibacterial activity under visible light illumination, and its minimum bactericidal concentrations (MBCs) against E. coli, S. aureus, and MRSA are as low as 39.1, 39.1, and 62.5 μg mL-1, respectively. Moreover, to expand the practicability of Ag NPs@ACM-1, two (a dense and a loose) Ag NPs@ACM-1 films were readily fabricated by simply dispersing Ag NPs@ACM-1 into heated aqueous solutions of edible agar and sequentially cooling through heating or freeze-drying, respectively. Notably, these two films are mechanically flexible and exhibit excellent antibacterial activities, and their antimicrobial performances can be well retained in their recyclable and remade films. As agar is nontoxic, degradable, inexpensive, and ecosustainable, the dense and loose Ag NPs@ACM-1 films are potent to serve as recyclable and degradable antibacterial plastics and antibacterial dressings, respectively.

Development of Eco-Friendly Biocomposite Films Based on Opuntia ficus-indica Cladodes Powder Blended with Gum Arabic and Xanthan Envisaging Food Packaging Applications

Currently, food packaging is facing a critical transition period and a major challenge: it must preserve the food products' quality and, at the same time, it must meet the current requirements of the circular economy and the fundamental principles of packaging materials eco-design. Our research presents the development of eco-friendly packaging films based on Opuntia ficus-indica cladodes (OFIC) as renewable resources. OFIC powder (OFICP)-agar, OFICP-agar-gum arabic (GA), and OFICP-agar-xanthan (XG) blend films were eco-friendlily prepared by a solution casting method. The films' properties were investigated by scanning electron microscope (SEM), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (X-RD), and differential scanning calorimeter (DSC). Water solubility and moisture content were also determined. Morphology, thickness, molecular interactions, miscibility, crystallinity, and thermal properties, were affected by adjusting the gums (GA and XG) content and glycerol in the blend films. Moisture content increased with increasing glycerol and XG content, and when 1.5 g of GA was added. Water solubility decreased when glycerol was added at 50% and increased with increasing GA and XG content. FTIR and XRD confirmed strong intermolecular interactions between the different blend film compounds, which were reflected in the shifting, appearance, and disappearance of FTIR bands and XRD peaks, indicating excellent miscibility. DSC results revealed a glass transition temperature (Tg) below room temperature for all prepared blend films, indicating that they are flexible and soft at room temperature. The results corroborated that the addition of glycerol at 30% and the GA to the OFICP increased the stability of the film, making it ideal for different food packaging applications.

Classification, gelation mechanism and applications of polysaccharide-based hydrocolloids in pasta products: A review

Polysaccharide-based hydrocolloids (PBHs) are a group of water-soluble polysaccharides with high molecular weight hydrophilic long-chain molecules, which are widely employed in food industry as thickeners, emulsifiers, gelling agents, and stabilizers. Pasta products are considered to be an important source of nutrition for humans, and PBHs show great potential in improving their quality and nutritional value. The hydration of PBHs to form viscous solutions or sols under specific processing conditions is a prerequisite for improving the stability of food systems. In this review, PBHs are classified in a novel way according to food processing conditions, and their gelation mechanisms are summarized. The application of PBHs in pasta products prepared under different processing methods (baking, steaming/cooking, frying, freezing) are reviewed, and the potential mechanism of PBHs in regulating pasta products quality is revealed from the interaction between PBHs and the main components of pasta products (protein, starch, and water). Finally, the safety of PBHs is critically explored, along with future perspectives. This review provides a scientific foundation for the development and specific application of PBHs in pasta products, and provides theoretical support for improving pasta product quality.

Seaweed polysaccharide nanocomposite films: A review

A million tonnes of plastic produced each year are disposed of after single use. Biodegradable polymers have become a promising material as an alternative to petroleum-based polymers. Utilising biodegradable polymers will promote environmental sustainability which has emerged with potential features and performances for various applications in different sectors. Seaweed-derived polysaccharides-based composites have been the focus of numerous studies due to the composites' renewability and sustainability for industries (food packaging and medical fields like tissue engineering and drug delivery). Due to their biocompatibility, abundance, and gelling ability, seaweed derivatives such as alginate, carrageenan, and agar are commonly used for this purpose. Seaweed has distinct film-forming characteristics, but its mechanical and water vapour barrier qualities are weak. Thus, modifications are necessary to enhance the seaweed properties. This review article summarises and discusses the effect of incorporating seaweed films with different types of nanoparticles on their mechanical, thermal, and water barrier properties.

Unveiling the Potential of Marine Biopolymers: Sources, Classification, and Diverse Food Applications

Environmental concerns regarding the usage of nonrenewable materials are driving up the demand for biodegradable marine biopolymers. Marine biopolymers are gaining increasing attention as sustainable alternatives in various industries, including the food sector. This review article aims to provide a comprehensive overview of marine biopolymers and their applications in the food industry. Marine sources are given attention as innovative resources for the production of sea-originated biopolymers, such as agar, alginate, chitin/chitosan, and carrageenan, which are safe, biodegradable, and are widely employed in a broad spectrum of industrial uses. This article begins by discussing the diverse source materials of marine biopolymers, which encompass biopolymers derived from seaweed and marine animals. It explores the unique characteristics and properties of these biopolymers, highlighting their potential for food applications. Furthermore, this review presents a classification of marine biopolymers, categorizing them based on their chemical composition and structural properties. This classification provides a framework for understanding the versatility and functionality of different marine biopolymers in food systems. This article also delves into the various food applications of marine biopolymers across different sectors, including meat, milk products, fruits, and vegetables. Thus, the motive of this review article is to offer a brief outline of (a) the source materials of marine biopolymers, which incorporates marine biopolymers derived from seaweed and marine animals, (b) a marine biopolymer classification, and (c) the various food applications in different food systems such as meat, milk products, fruits, and vegetables.

Algal Phycocolloids: Bioactivities and Pharmaceutical Applications

Seaweeds are abundant sources of diverse bioactive compounds with various properties and mechanisms of action. These compounds offer protective effects, high nutritional value, and numerous health benefits. Seaweeds are versatile natural sources of metabolites applicable in the production of healthy food, pharmaceuticals, cosmetics, and fertilizers. Their biological compounds make them promising sources for biotechnological applications. In nature, hydrocolloids are substances which form a gel in the presence of water. They are employed as gelling agents in food, coatings and dressings in pharmaceuticals, stabilizers in biotechnology, and ingredients in cosmetics. Seaweed hydrocolloids are identified in carrageenan, alginate, and agar. Carrageenan has gained significant attention in pharmaceutical formulations and exhibits diverse pharmaceutical properties. Incorporating carrageenan and natural polymers such as chitosan, starch, cellulose, chitin, and alginate. It holds promise for creating biodegradable materials with biomedical applications. Alginate, a natural polysaccharide, is highly valued for wound dressings due to its unique characteristics, including low toxicity, biodegradability, hydrogel formation, prevention of bacterial infections, and maintenance of a moist environment. Agar is widely used in the biomedical field. This review focuses on analysing the therapeutic applications of carrageenan, alginate, and agar based on research highlighting their potential in developing innovative drug delivery systems using seaweed phycocolloids.

Biopolymer-Based Sustainable Food Packaging Materials: Challenges, Solutions, and Applications

Biopolymer-based packaging materials have become of greater interest to the world due to their biodegradability, renewability, and biocompatibility. In recent years, numerous biopolymers-such as starch, chitosan, carrageenan, polylactic acid, etc.-have been investigated for their potential application in food packaging. Reinforcement agents such as nanofillers and active agents improve the properties of the biopolymers, making them suitable for active and intelligent packaging. Some of the packaging materials, e.g., cellulose, starch, polylactic acid, and polybutylene adipate terephthalate, are currently used in the packaging industry. The trend of using biopolymers in the packaging industry has increased immensely; therefore, many legislations have been approved by various organizations. This review article describes various challenges and possible solutions associated with food packaging materials. It covers a wide range of biopolymers used in food packaging and the limitations of using them in their pure form. Finally, a SWOT analysis is presented for biopolymers, and the future trends are discussed. Biopolymers are eco-friendly, biodegradable, nontoxic, renewable, and biocompatible alternatives to synthetic packaging materials. Research shows that biopolymer-based packaging materials are of great essence in combined form, and further studies are needed for them to be used as an alternative packaging material.

Algal nutraceuticals: A perspective on metabolic diversity, current food applications, and prospects in the field of metabolomics

The current consumers' demand for food naturalness is urging the search for new functional foods of natural origin with enhanced health-promoting properties. In this sense, algae constitute an underexplored biological source of nutraceuticals that can be used to fortify food products. Both marine macroalgae (or seaweeds) and microalgae exhibit a myriad of chemical constituents with associated features as a result of their primary and secondary metabolism. Thus, primary metabolites, especially polysaccharides and phycobiliproteins, present interesting properties to improve the rheological and nutritional properties of food matrices, whereas secondary metabolites, such as polyphenols and xanthophylls, may provide interesting bioactivities, including antioxidant or cytotoxic effects. Due to the interest in algae as a source of nutraceuticals by the food and related industries, novel strategies should be undertaken to add value to their derived functional components. As a result, metabolomics is considered a high throughput technology to get insight into the full metabolic profile of biological samples, and it opens a wide perspective in the study of algae metabolism, whose knowledge is still little explored. This review focuses on algae metabolism and its applications in the food industry, paying attention to the promising metabolomic approaches to be developed aiming at the functional characterization of these organisms.

Hydrophobic modified agar: Structural characterization and application in encapsulation and release of curcumin

In this study, three kinds of anhydrides with different structures were introduced into agar molecules to study the effects of varying degrees of substitution (DS) and anhydride structures on the physicochemical properties and curcumin (CUR) loading capacity. Increasing the carbon chain length and saturation of the anhydride affects the hydrophobic interaction and hydrogen bonding of the esterified agar, thereby changing the stable structure of the agar. Although the gel performance declined, the hydrophilic carboxyl group and the loose porous structure provide more binding sites for the adsorption of water molecules, hence providing excellent water retention (1700 %). Next, CUR was used as a hydrophobic active ingredient to study agar microspheres' drug encapsulation and in vitro release ability. Results showed that the excellent swelling and hydrophobic structure of esterified agar could promote the encapsulation of CUR (70.3 %). The release process is controlled by pH, and the release of CUR under weak alkaline conditions is significant, which can be explained by the pore structure, swelling characteristics, and carboxyl binding of agar. Therefore, this study shows the application potential of hydrogel microspheres in loading hydrophobic active ingredients and sustained release and provides the possibility for the application of agar in drug delivery systems.

Review on Propolis Applications in Food Preservation and Active Packaging

Propolis is a natural hive product collected by honeybees from different plants and trees. The collected resins are then mixed with bee wax and secretions. Propolis has a long history of use in traditional and alternative medicine. Propolis possesses recognized antimicrobial and antioxidant properties. Both properties are characteristics of food preservatives. Moreover, most propolis components, in particular flavonoids and phenolic acids, are natural constituents of food. Several studies suggest that propolis could find use as a natural food preservative. This review is focused on the potential application of propolis in the antimicrobial and antioxidant preservation of food and its possible application as new, safe, natural, and multifunctional material in food packaging. In addition, the possible influence of propolis and its used extracts on the sensory properties of food is also discussed.

A comprehensive approach to chitosan-gelatine edible coating with β-cyclodextrin/lemongrass essential oil inclusion complex - Characterization and food application

Biopolymer-based films present an ideal matrix for the incorporation of active substances such as antimicrobial agents, giving active packaging a framework of green chemistry and a step forward in food packaging technology. The chitosan-gelatine active coating has been prepared using lemongrass oil as an antimicrobial compound applying a different approach. Instead of surfactants, to achieve compatibilization of compounds, β-cyclodextrin was used to encapsulate lemongrass oil. The antimicrobial effect was assessed using the dip-coating method on freshly harvested cherry tomatoes artificially contaminated by Penicillium aurantiogriseum during 20 days of cold storage. According to the evaluation of the antimicrobial effect of coating formulation on cherry tomato samples, which was mathematically assessed by predictive kinetic models and digital imaging, the applied coating formulation was found to be very effective since the development of fungal contamination for active-coated samples was observed for 20 days.

Antimicrobial Poly (Lactic Acid)/Copper Nanocomposites for Food Packaging Materials

Composites based on polylactic acid (PLA) and copper for food packaging applications were obtained. Copper clusters were synthesized in polyethylene glycols 400 and 600, respectively, using ascorbic acid as a reducing agent, by reactive milling. Copper clusters were characterized by Scanning Electron Microscopy (SEM), Fourier Transform Infrared (FT-IR), and Ultraviolet-Visible (UV-VIS) spectroscopy. Copper/PLA composites containing Proviplast as plasticizer were characterized by FT-IR spectroscopy, mechanical tests, Differential Scanning Calorimetry (DSC), Thermogravimetric Analysis (TGA), absorption of the saline solution, contact angle, and antibacterial properties. It was observed that the concentration of Copper/PEG influenced the investigated properties. The mechanical properties of the samples decreased with the increasing of Copper/PEG concentration. We recorded the phase transformation temperatures and identified the exothermic or endothermic processes. The lowest absorption values were recorded in the case of the sample containing 1% Cu. The contact angle decreases with the increase in the concentration of the PEG 600-Cu mixture in the recipes. The increase in the content of Cu clusters favors the decrease in the temperature, taking place 15% wt mass losses. The obtained composites showed antibacterial properties for all tested strains. These materials could be used as alternative materials for obtaining biodegradable food packaging.

Characterization of a Galactose Oxidase from Fusarium odoratissimum and Its Application in the Modification of Agarose

A galactose oxidase gene, gao-5f, was cloned from Fusarium odoratissimum and successfully expressed in E. coli. The galactose oxidase GAO-5F belongs to the AA5 family and consists of 681 amino acids, with an estimated molecular weight of 72 kDa. GAO-5F exhibited maximum activity at 40 °C and pH 7.0 and showed no change in activity after 24 h incubation at 30 °C. Moreover, GAO-5F exhibited 40% of its maximum activity after 24 h incubation at 50 °C and 60% after 40 h incubation at pH 7.0. The measured thermostability of GAO-5F is superior to galactose oxidase's reported thermostability. The enzyme exhibited strict substrate specificity toward D-galactose and oligosaccharides/polysaccharides containing D-galactose. Further analysis demonstrated that GAO-5F specifically oxidized agarose to a polyaldehyde-based polymer, which could be used as a polyaldehyde to crosslink with gelatin to form edible packaging films. To our knowledge, this is the first report about the modification of agarose by galactose oxidase, and this result has laid a foundation for the further development of edible membranes using agarose.

Potato Starch-Based Film Incorporated with Tea Polyphenols and Its Application in Fruit Packaging

Effects of tea polyphenols (TP) on the physical properties, barrier properties and functionality of potato starch-based film were determined, while the interaction mechanism between TP and starch in film and the application of this film in fruit packaging were further evaluated. TP exhibited different effects on the physical properties of potato starch-based film, including thickness (0.083 to 0.087 mm), moisture content (9.27% to 9.68%), color (ΔE value: 5.41 to 10.55), light transmittance (51% to 62%), tensile properties and thermal properties, and improved its barrier properties, including water vapor permeability (9.68 to 11.84 × 10-11 g m-1 s-1 Pa-1),oxygen permeability (1.25 to 2.78 × 10-16 g m-1 s-1 Pa-1) and antioxidant activity. According to the determination of wide-angle X-ray diffraction, Fourier transform infrared and scanning electron microscope, TP could interact with starch chains via hydrogen bonds to form non-crystal complexes, thus affecting the cross-linking among starch chains and further changing the microstructure of film. Furthermore, film incorporated with TP could improve the storage quality (including weight and texture) of blueberries, and inhibit the enzymatic browning of fresh-cut bananas during storage. All present results suggested that tea polyphenols had potential to enhance the properties and function of potato starch-based film, and the film exhibited the application prospect in fruit packaging and preservation.

Chemical modifications in the structure of marine polysaccharide as serviceable food processing and preservation assistant: A review

Marine polysaccharides are a kind of natural polysaccharides which isolated and extracted from marine organisms. Now some marine polysaccharides, such as chitosan, sodium alginate and agar, have been proven to exhibit antibacterial, antioxidant functions and biocompatibility, which are often used to preserve food or improve the physicochemical properties of food. However, they still have the defects of unsatisfactory preservation effect and biological activity, which can be remedied by its modification. Chemical modification is the most effective of all modification methods. The advances in common chemical modification methods of chitosan, sodium alginate, agar and other marine polysaccharides and research progress of modified products in food processing and preservation were summarized, and the influence of additional reaction conditions on the existence of chemical modification sites of polysaccharides was discussed. The modification of functional groups in natural marine polysaccharides leads to the change of molecular structure, which can improve the physical, chemical and biological properties of marine polysaccharides. Chemically modified products have been used in various fields of food applications, such as food preservatives, food additives, food packaging, and food processing aids. In general, chemical modification has excellent potential for food processing and preservation, which can improve the function of marine polysaccharides.

Active Food Packaging Made of Biopolymer-Based Composites

Food packaging plays a vital role in protecting food products from environmental damage and preventing contamination from microorganisms. Conventional food packaging made of plastics produced from unrenewable fossil resources is hard to degrade and poses a negative impact on environmental sustainability. Natural biopolymers are attracting interest for reducing environmental problems to achieve a sustainable society, because of their abundance, biocompatibility, biodegradability, chemical stability, and non-toxicity. Active packaging systems composed of these biopolymers and biopolymer-based composites go beyond simply acting as a barrier to maintain food quality. This review provides a comprehensive overview of natural biopolymer materials used as matrices for food packaging. The antioxidant, water barrier, and oxygen barrier properties of these composites are compared and discussed. Furthermore, biopolymer-based composites integrated with antimicrobial agents-such as inorganic nanostructures and natural products-are reviewed, and the related mechanisms are discussed in terms of antimicrobial function. In summary, composites used for active food packaging systems can inhibit microbial growth and maintain food quality.

Swelling and Antimicrobial Activity Characterization of a GO-Reinforced Gelatin-Whey Hydrogel

Whey-based hydrogel samples with increasing concentrations of graphene oxide (GO) were studied, against a control sample (M), for swelling behavior in light of nuclear magnetic resonance (NMR) and mathematical models of the diffusion process and for antibacterial activity. Graphene oxide (GO) is an optimal filler for whey-based hydrogels, giving them improved mechanical and swelling properties at low concentrations. Crosslinking induces a certain stiffness of the hydrogels, which is why only the first part of the swelling process (<60%) follows the first-order model, while during the whole time interval, the swelling process follows the second-order diffusion model. The NMR relaxometry results are consistent with the swelling behavior of GO-reinforced whey−gelatin composite hydrogels, showing that higher GO concentrations induce a higher degree of cross-linking and, therefore, lower swelling capacity. Only hydrogel samples with higher GO concentrations demonstrated antibacterial activity.

Pectin/carbon quantum dots fluorescent film with ultraviolet blocking property through light conversion

Carbon quantum dots (CQDs) were synthesized using glucose as a carbon source through a hydrothermal method. CQDs showed negligible cytotoxicity to L929 cells even after prolonged exposure of 72 h. The addition of CQD did not affect the pectin film's mechanical properties, water contact angle, and thermal stability. However, the CQD-added composite film generates reactive oxygen species (ROS), providing high antibacterial activity against pathogenic bacteria (L. monocytogenes and E. coli) and antifungal activity against mold (Aspergillus flavus), where a 100% eradication of bacteria and fungi population was observed. Also, the addition of CQD strengthens the antioxidant activity of the composite films by 95%. Further, the CQD-added pectin film converted ultraviolet rays into blue light, which improved the film's UV protection properties. Therefore, the pectin/CQD film has a high potential for a light conversion active packaging film that may prevent the deterioration of high-fat foods.

Active Packaging for the Extended Shelf-Life of Meat: Perspectives from Consumption Habits, Market Requirements and Packaging Practices in China and New Zealand

Active packaging (AP) has been developed to improve the safety, quality and integrity of food, and minimise food waste, while its application in meat is scarce. This review aims to describe meat production and consumption culture in China and New Zealand to provide the context for packaging innovation requirements, focusing on the emerging opportunities for AP to be used for the improvement of the shelf-life of pre-rigor, aged, and frozen-thawed meat products. Sustainable polymers utilised in the manufacturing of AP, manufacturing techniques, the release mechanisms of actives, and legal and regulatory constraints are also discussed. Diverse market compositions and consumption cultures in China and New Zealand require different packaging solutions to extend the shelf-life of meat. AP containing antimicrobials, moisture regulating agents, and antioxidants may be used for pre-rigor, dry- and wet-aged products and in improving the quality and shelf-life of frozen-thawed meat. Further innovations using sustainably produced polymers for AP, along with incorporating active compounds of multiple functions for effectively improving meat quality and shelf-life are necessary. Challenges remain to resolve issues with scaling the technology to commercially relevant volumes as well as complying with the rigorous legal and regulatory constraints in various countries.

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.