Recent advances in polymer-metallic composites for food packaging applications

A review on bio-based polymer polylactic acid potential on sustainable food packaging

Poly(lactic acid) (PLA) stands as a compelling alternative to conventional plastic-based packaging, signifying a notable shift toward sustainable material utilization. This comprehensive analysis illuminates the manifold applications of PLA composites within the realm of the food industry, emphasizing its pivotal role in food packaging and preservation. Noteworthy attributes of PLA composites with phenolic active compounds (phenolic acid and aldehyde, terpenes, carotenoid, and so on) include robust antimicrobial and antioxidant properties, significantly enhancing its capability to bolster adherence to stringent food safety standards. The incorporation of microbial and synthetic biopolymers, polysaccharides, oligosaccharides, oils, proteins and peptides to PLA in packaging solutions arises from its inherent non-toxicity and outstanding mechanical as well as thermal resilience. Functioning as a proficient film producer, PLA constructs an ideal preservation environment by merging optical and permeability traits. Esteemed as a pioneer in environmentally mindful packaging, PLA diminishes ecological footprints owing to its innate biodegradability. Primarily, the adoption of PLA extends the shelf life of products and encourages an eco-centric approach, marking a significant stride toward the food industry's embrace of sustainable packaging methodologies.

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Green interconnected network structure of chitosan-microcrystalline cellulose-lignin biopolymer film for active packaging applications

As an excellent alternative to petroleum-based food packaging materials, a novel green hybrid composite film with an excellent interconnected network structure was successfully fabricated by integrating chitosan (chi), microcrystalline cellulose (MCC), and lignin nanoparticles (LNP), including the desired amount of plasticizer glycerol (gly). Overall, 36 combinations were developed and investigated for superior biocomposite film formation. Among the various concentration ratios, the 40:35:25 chi-MCC-gly film provided well-organized film formation, good physicochemical properties, mechanical stability, efficient water contact angle, reduced water solubility, and lower water vapor permeability (11.43 ± 0.55 × 10-11 g.m-1.s-1.Pa-1). The performance of the chi-MCC-gly film further enhanced by the homogeneous incorporation of ∼100 nm LNP. With 1 % LNP addition, the tensile strength of the film increased (28.09 MPa, 47.10 % increase) and the water vapor permeability reached a minimum of 11.43 × 10-11 g.m-1.s-1.Pa-1, which proved the impact of LNP in composite films. Moreover, the films showed excellent resistance to thermal shrinkage even at 100 °C and exhibited nearly 100 % UV blocking efficiency at higher LNP concentrations. Interestingly, the green composite films extended the shelf life of freshly cut cherry tomatoes to seven days without spoilage. Overall, the facile synthesis of strong, insoluble, UV-blocking, and thermally stable green composite films realized for food packaging applications.

AIEgen orthopalladated hybrid polymers for efficient inactivation of the total coliforms in urban wastewater

Monitorable AIE polymers with a bioactive pattern are employed in advanced biomedical applications such as functional coatings, theranostic probes, and implants. After the global COVID-19 pandemic, interest in developing surfaces with superior antimicrobial, antiproliferative, and antiviral activities dramatically increased. Many formulations for biocide surfaces are based on hybrid organic/inorganic materials. Palladium (II) complexes display relevant activity against common bacteria, even higher when compared to their uncoordinated ligands. This article reports the design and synthesis of two series of orthopalladated polymers obtained by grafting a cyclopalladated fragment on two different O, N chelating Schiff base polymers. Different grafting percentages were examined and compared for each organic polymer. The fluorescence emission in the solid state was explored on organic matrixes and grafted polymers. DFT analysis provided a rationale for the role of the coordination core. The antibacterial response of the two series of hybrid polymers was tested against the total coliform group of untreated urban wastewater, revealing excellent inactivation ability.

Capability of Copper Hydroxy Nitrate (Cu2(OH)3NO3) as an Additive to Develop Antibacterial Polymer Contact Surfaces: Potential for Food Packaging Applications

The globalization of the market, as well as the increasing world population, which require a higher demand for food products, pose a great challenge to ensure food safety and prevent food loss and waste. In this sense, active materials with antibacterial properties are an important alternative in the prolongation of shelf life and ensuring food safety. In this work, the ability of copper(II) hydroxy nitrate (CuHS) to obtain antibacterial films based on low density polyethylene (LDPE) and polylactic acid (PLA), was evaluated. The thermal properties of the composites, evaluated using thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC), showed that the concentrations of added CuHS do not particularly change these characteristics with respect to the neat polymer matrix films. The mechanical properties, determined using dynamic mechanical analysis (DMTA), indicate a small increase in the brittleness of the material in PLA-based composites. The antibacterial properties against Listeria monocytogenes and Salmonella enterica were evaluated using a surface contact test, and a bacterial reduction of at least 8 to 9 logarithmic units for the composites with 0.3% CuHS, both in LDPE and PLA and against both bacteria, were achieved. The reusability of the composite films after their first use demonstrated a higher stability against Listeria monocytogenes. The migration and cytotoxicity of the composites loaded with 0.3% CuHS was evaluated, demonstrating the safety of these materials, which reinforces their potential use in food packaging applications.

Polymer and Composite Materials in Two-Phase Passive Thermal Management Systems: A Review

The application of polymeric and composite materials in two-phase passive heat transfer devices is reviewed critically, with a focus on advantages and disadvantages of these materials in thermal management systems. Recent technology developments led to an increase of the power density in several applications including portable electronics, space and deployable systems, etc., which require high-performance and compact thermal management systems. In this context, passive two-phase systems are the most promising heat transfer devices to dissipate large heat fluxes without external power supply. Usually, heat transfer systems are built with metals due to their excellent thermal properties. However, there is an increasing interest in replacing metallic materials with polymers and composites that can offer cost-effectiveness, light weight and high mechanical flexibility. The present work reviews state-of the-art applications of polymers and composites in two-phase passive thermal management systems, with an analysis of their limitations and technical challenges.

Recent insights into metallic nanoparticles in shelf-life extension of agrifoods: Properties, green synthesis, and major applications

Nanotechnology emerged as a revolutionary technology in various fields of applied sciences, such as biomedical engineering and food technology. The pivotal roles of nanocompounds have been explored in various fields, such as food protection, preservation, and enhancement of shelf life. In this sequence, metallic nanoparticles (MNPs) are proven to be useful in developing products with antimicrobial activity and subsequently improve the shelf life of agrifoods. The major application of MNPs has been observed in the packaging industry due to the combining ability of biopolymers with MNPs. In recent years, various metal nanoparticles have been explored to formulate various active food packaging materials. However, the method of production and the need for risk evaluation are still a topic of discussion among researchers around the world. In general, MNPs are synthesized by various chemical and physical means, which may pose variable health risks. To overcome such issues, the green synthesis of MNPs using microbial and plant extracts has been proposed by various researchers. In this review, we aimed at exploring the green synthesis of MNPs, their properties and characterization, various ways of utilizing MNPs to extend their shelf life, and, most importantly, the risk associated with these along with their quality and safety considerations.

Cost-Effective Synthesis of Bacterial Cellulose and Its Applications in the Food and Environmental Sectors

Bacterial cellulose (BC), also termed bio-cellulose, has been recognized as a biomaterial of vital importance, thanks to its impressive structural features, diverse synthesis routes, high thermomechanical properties, and its ability to combine with multiple additives to form composites for a wide range of applications in diversified areas. Its purity, nontoxicity, and better physico-mechanical features than plant cellulose (PC) make it a better choice for biological applications. However, a major issue with the use of BC instead of PC for various applications is its high production costs, mainly caused by the use of expensive components in the chemically defined media, such as Hestrin–Schramm (HS) medium. Furthermore, the low yield of BC-producing bacteria indirectly accounts for the high cost of BC-based products. Over the last couple of decades, extensive efforts have been devoted to the exploration of low-cost carbon sources for BC production, besides identifying efficient bacterial strains as well as developing engineered strains, developing advanced reactors, and optimizing the culturing conditions for the high yield and productivity of BC, with the aim to minimize its production cost. Considering the applications, BC has attracted attention in highly diversified areas, such as medical, pharmaceutics, textile, cosmetics, food, environmental, and industrial sectors. This review is focused on overviewing the cost-effective synthesis routes for BC production, along with its noteworthy applications in the food and environmental sectors. We have made a comprehensive review of recent papers regarding the cost-effective production and applications of BC in the food and environmental sectors. This review provides the basic knowledge and understanding for cost-effective and scaleup of BC production by discussing the techno-economic analysis of BC production, BC market, and commercialization of BC products. It explores BC applications as food additives as its functionalization to minimize different environmental hazards, such as air contaminants and water pollutants.

Recent advances in biobased and biodegradable polymer nanocomposites, nanoparticles, and natural antioxidants for antibacterial and antioxidant food packaging applications

Inorganic nanoparticles (NPs) and natural antioxidant compounds are an emerging trend in the food industry. Incorporating these substances in biobased and biodegradable matrices as polysaccharides (e.g., starch, cellulose, and chitosan) and proteins has highlighted the potential in active food packaging applications due to more significant antimicrobial, antioxidant, UV blocking, oxygen scavenging, water vapor permeability effects, and low environmental impact. In recent years, the migration of metal NPs and metal oxides in food contact packaging and their toxicological potential have raised concerns about the safety of the nanomaterials. In this review, we provide a comprehensive overview of the main biobased and biodegradable polymer nanocomposites, inorganic NPs, natural antioxidants, and their potential use in active food packaging. The intrinsic properties of NPs and natural antioxidant actives in packaging materials are evaluated to extend shelf-life, safety, and food quality. Toxicological and safety aspects of inorganic NPs are highlighted to understand the current controversy on applying some nanomaterials in food packaging. The synergism of inorganic NPs and plant-derived natural antioxidant actives (e.g., vitamins, polyphenols, and carotenoids) and essential oils (EOs) potentiated the antibacterial and antioxidant properties of biodegradable nanocomposite films. Biodegradable packaging films based on green NPs-this is biosynthesized from plant extracts-showed suitable mechanical and barrier properties and had a lower environmental impact and offered efficient food protection. Furthermore, AgNPs and TiO₂ NPs released metal ions from packaging into contents insufficiently to cause harm to human cells, which could be helpful to understanding critical gaps and provide progress in the packaging field.

Application of natural extracts as active ingredient in biopolymer based packaging systems

Active packaging systems come under novel techniques and are creating demands in food packaging aspects. They are specially designed for food products where shelf life is a key driving factor. Their wide range of functionality preserves the color, texture, smell, and taste of the food item retaining their freshness and edibility for longer than any other methods available on market. An active ingredient in packaging systems enables efficient consumable quality which resulted in reduced complaints from consumers. However, techniques must be inexpensive and environment-friendly. The use of biodegradable packaging systems reinforced by exploiting natural compounds forms the latest trend to attract consumer demand in substituting synthetic preservatives in foods that can protect against food spoilage. Natural extracts have gained commercial importance in active packaging nowadays for the delivery of safe and high-quality foods that are being employed in both fresh and processed produce. Development and use of innovative active packaging systems in varied forms are expected to increase in the future for food safety, quality, and stability. The review overviews the beneficial effects of plant acquired components in modulating product quality in packaged form for commercial aspects in the market.

Rational Design and Characterisation of Novel Mono- and Bimetallic Antibacterial Linde Type A Zeolite Materials

The development of antimicrobial devices and surfaces requires the setup of suitable materials, able to store and release active principles. In this context, zeolites, which are microporous aluminosilicate minerals, hold great promise, since they are able to serve as a reservoir for metal-ions with antimicrobial properties. Here, we report on the preparation of Linde Type A zeolites, partially exchanged with combinations of metal-ions (Ag⁺, Cu²⁺, Zn²⁺) at different loadings (0.1–11.9 wt.%). We combine X-ray fluorescence, scanning electron microscopy, energy-dispersive X-ray spectroscopy, and X-ray diffraction to monitor the metal-ion contents, distribution, and conservation of the zeolite structure after exchange. Then, we evaluate their antimicrobial activity, using agar dilution and optical-density monitoring of Escherichia coli cultures. The results indicate that silver-loaded materials are at least 70-fold more active than the copper-, zinc-, and non-exchanged ones. Moreover, zeolites loaded with lower Ag⁺ concentrations remain active down to 0.1 wt.%, and their activities are directly proportional to the total Ag content. Sequential exchanges with two metal ions (Ag⁺ and either Cu²⁺, Zn²⁺) display synergetic or antagonist effects, depending on the quantity of the second metal. Altogether, this work shows that, by combining analytical and quantitative methods, it is possible to fine-tune the composition of bi-metal-exchanged zeolites, in order to maximise their antimicrobial potential, opening new ways for the development of next-generation composite zeolite-containing antimicrobial materials, with potential applications for the design of dental or bone implants, as well as biomedical devices and pharmaceutical products.

Recent advancement in improvement of properties of polysaccharides and proteins based packaging film with added nanoparticles: A review

Innovations and research on packaging materials are in a fast-growing stage to make them suitable for advanced packaging innovations and sustainability efforts. Biological macromolecules like algal polysaccharides, chitosan, gelatin and others like starch are explored for developing eco-friendly packaging alternatives. Compared to conventional synthetic polymers they have performance limitations that are tried to be overcome with added fillers. The unique properties of fillers in the nano range are explored for this. They can improve the overall property of polymer matrixes by improving barrier properties to oxygen and water vapour, increasing stability and mechanical strength. Exploring the possibilities of new nanoparticle-polymer combinations can bring novel properties in the packaging industry that can be used in smart and intelligent packaging areas. Thus studies on nanocomposite films from polysaccharides, protein compounds and nanoparticles can help to overcome the limitations of bio-polymers for novel packaging applications. This review covers the effect of nanoparticles on the optical, morphological, barrier, thermal and mechanical properties of polysaccharides and proteins based packaging film, along with the types of nanoparticles used in the composite films.

Metallic Nanoparticles in the Food Sector: A Mini-Review

Nanomaterials, and in particular metallic nanoparticles (MNPs), have significantly contributed to the production of healthier, safer, and higher-quality foods and food packaging with special properties, such as greater mechanical strength, improved gas barrier capacity, increased water repellency and ability to inhibit microbial contamination, ensuring higher quality and longer product shelf life. MNPs can also be incorporated into chemical and biological sensors, enabling the design of fast and sensitive monitoring devices to assess food quality, from freshness to detection of allergens, food-borne pathogens or toxins. This review summarizes recent developments in the use of MNPs in the field of food science and technology. Additionally, a brief overview of MNP synthesis and characterization techniques is provided, as well as of the toxicity, biosafety and regulatory issues of MNPs in the agricultural, feed and food sectors.

Migration of Various Nanoparticles into Food Samples: A Review

Nanotechnology has provided new opportunities for the food industry with its applications in food packaging. The addition of nanoparticles, such as clay, silver and copper, can improve the mechanical and antimicrobial properties of food packaging. However, nanoparticles may have an adverse impact on human health. This has led to legislative and regulatory concerns. The inhibitory effects of nano packaging on different microorganisms, such as Salmonella, E. coli, and molds, have been studied. Nanoparticles, like other materials, may have a diverse set of properties that need to be determined. In this review, different features of silver, clay and copper nanoparticles, such as their anti-microbial, cell toxicity, genetic toxicity, mechanical properties, and migration, are critically evaluated in the case of food packaging. Specifically, the viewpoints of WHO, FDA, and ESFA, concerning the nano-silver application in food packaging, are discussed as well.

Metal-based nanoparticles, sensors, and their multifaceted application in food packaging

Due to the global rise of the human population, one of the top-most challenges for poor and developing nations is to use the food produces safely and sustainably. In this regard, the storage of surplus food (and derived products) without loss of freshness, nutrient stability, shelf life, and their parallel efficient utilization will surely boost the food production sector. One of the best technologies that have emerged within the last twenty years with applications in the packaging of food and industrial materials is the use of green mode-based synthesized nanoparticles (NPs). These NPs are stable, advantageous as well as eco-friendly. Over the several years, numerous publications have confirmed that these NPs exert antibacterial, antioxidant, and antifungal activity against a plethora of pathogens. The storage in metal-based NPs (M-NPs) does not hamper the food properties and packaging efficiency. Additionally, these M-NPs help in the improvement of properties including freshness indicators, mechanical properties, antibacterial and water vapor permeability during food packaging. As a result, the nano-technological application facilitates a simple, alternate, interactive as well as reliable technology. It even provides positive feedback to food industries and packaging markets. Taken together, the current review paper is an attempt to highlight the M-NPs for prominent applications of antimicrobial properties, nanosensors, and food packaging of food items. Additionally, some comparative reports associated with M-NPs mechanism of action, risks, toxicity, and overall future perspectives have also been made.

Polymer Nanocomposites of Selenium Biofabricated Using Fungi

Nanoparticle-reinforced polymer-based materials effectively combine the functional properties of polymers and unique characteristic features of NPs. Biopolymers have attained great attention, with perspective multifunctional and high-performance nanocomposites exhibiting a low environmental impact with unique properties, being abundantly available, renewable, and eco-friendly. Nanocomposites of biopolymers are termed green biocomposites. Different biocomposites are reported with numerous inorganic nanofillers, which include selenium. Selenium is a micronutrient that can potentially be used in the prevention and treatment of diseases and has been extensively studied for its biological activity. SeNPs have attracted increasing attention due to their high bioavailability, low toxicity, and novel therapeutic properties. One of the best routes to take advantage of SeNPs' properties is by mixing these NPs with polymers to obtain nanocomposites with functionalities associated with the NPs together with the main characteristics of the polymer matrix. These nanocomposite materials have markedly improved properties achieved at low SeNP concentrations. Composites based on polysaccharides, including fungal beta-glucans, are bioactive, biocompatible, biodegradable, and have exhibited an innovative potential. Mushrooms meet certain obvious requirements for the green entity applied to the SeNP manufacturing. Fungal-matrixed selenium nanoparticles are a new promising biocomposite material. This review aims to give a summary of what is known by now about the mycosynthesized selenium polymeric nanocomposites with the impact on fungal-assisted manufactured ones, the mechanisms of the involved processes at the chemical reaction level, and problems and challenges posed in this area.

Bio-Based Sensors for Smart Food Packaging-Current Applications and Future Trends

Intelligent food packaging is emerging as a novel technology, capable of monitoring the quality and safety of food during its shelf-life time. This technology makes use of indicators and sensors that are applied in the packaging and that detect changes in physiological variations of the foodstuffs (due to microbial and chemical degradation). These indicators usually provide information, e.g., on the degree of freshness of the product packed, through a color change, which is easily identified, either by the food distributor and the consumer. However, most of the indicators that are currently used are non-renewable and non-biodegradable synthetic materials. Because there is an imperative need to improve food packaging sustainability, choice of sensors should also reflect this requirement. Therefore, this work aims to revise the latest information on bio-based sensors, based on compounds obtained from natural extracts, that can, in association with biopolymers, act as intelligent or smart food packaging. Its application into several perishable foods is summarized. It is clear that bioactive extracts, e.g., anthocyanins, obtained from a variety of sources, including by-products of the food industry, present a substantial potential to act as bio-sensors. Yet, there are still some limitations that need to be surpassed before this technology reaches a mature commercial stage.