A review of multilayer and composite films and coatings for active biodegradable packaging

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.

Chitosan nanocoatings N-acylated with decanoic anhydride: Hydrophobic, hygroscopic and structural properties

Thin (ca. 340 nm) chitosan coatings were deposited onto glass substrates via dip-coating, then modified with the methanol solution of decanoic anhydride (0.17-56 mM). NMR, FTIR and XPS measurements confirmed that the acylation degree increased from 18 % to 45 %, and at the highest degree, the whole layer was acylated homogeneously by the reagent molecules. The coating thickness increased (up to 60 %), and the refractive index decreased (from 1.541 to 1.532) due to the acylation, that was determined by UV-visible spectroscopy. The AFM did not reveal morphological changes, but wetting tests showed that the acylation rendered the coating hydrophobic (water contact angle increased from ca. 75° to 100°). The contact angle, however, decreased to 85° due to the development of a second molecular layer of the decanoic acid by-product at the highest (over 25 mM) reagent concentrations. XRD studies showed a self-assembling structuring of the alkyl-chains in the bulk phase, which occurred in the case of the highest degree of acylation. This also manifested itself in a significant decrease of the layer hygroscopicity: the swelling degree decreased from 40 % to 8 % in a saturated water atmosphere monitored by spectroscopic ellipsometry.

Combating micro/nano plastic pollution with bioplastic: Sustainable food packaging, challenges, and future perspectives

The widespread use of plastic in food packaging provides significant challenges due to its non-biodegradability and the risk of hazardous chemicals seeping into food and the environment. This highlights the pressing need to come up with alternatives to traditional plastic that prioritize environmental sustainability, food quality, and safety. The current study presents an up-to-date examination of micro/nano plastic (MP/NP) consumption and their associated toxicity to human health, while also considering bioplastic as safer and eco-friendly alternative materials for packaging. The study contributes to a deeper comprehension of the primary materials utilized for bioplastic manufacturing and their potential for large-scale use. The key findings underscore the distinctive features of bioplastics, such as starch, polyhydroxyalkanoates, polylactic acid, and polybutylene succinate, as well as their blends with active agents, rendering them suitable for innovative food packaging applications. Moreover, the study includes a discussion of insights from various scientific literature, agency reports (governmental and non-governmental), and industry trends in bioplastic production and their potential to combat MP/NP pollution. In essence, the review highlights future research directions for the safe integration of bioplastics in food packaging, addresses outstanding questions, and proposes potential solutions to challenges linked with plastic usage.

Correlations between adhesion and molecular interactions at buried interfaces of model polymer systems and in commercial multilayer barrier films

Sum frequency generation vibrational spectroscopy (SFG) was applied to characterize the interfacial adhesion chemistry at several buried polymer interfaces in both model systems and blown multilayer films. Anhydride/acid modified polyolefins are used as tie layers to bond dissimilar polymers in multilayer barrier structures. In these films, the interfacial reactions between the barrier polymers, such as ethylene vinyl alcohol (EVOH) or nylon, and the grafted anhydrides/acids provide covalent linkages that enhance adhesion. However, the bonding strengths vary for different polymer-tie layer combinations. Here, using SFG, we aim to provide a systematic study on four common polymer-tie interfaces, including EVOH/polypropylene-tie, EVOH/polyethylene-tie, nylon/polypropylene-tie, and nylon/polyethylene-tie, to understand how the adhesion chemistry varies and its impact on the measured adhesion. Our SFG studies suggest that adhesion enhancement is driven by a combination of reaction kinetics and the interfacial enrichment of the anhydride/acid, resulting in stronger adhesion in the case of nylon. This observation matches well with the higher adhesion observed in the nylon/tie systems in both lap shear and peel test measurements. In addition, in the polypropylene-tie systems, grafted oligomers due to chain scission may migrate to the interface, affecting the adhesion. These by-products can react or interfere with the barrier-tie chemistry, resulting in reduced adhesion strength in the polypropylene-tie system.

Advances in Biodegradable Food Packaging Using Wheat-Based Materials: Fabrications and Innovations, Applications, Potentials, and Challenges

This article explores the advancements in biodegradable food packaging materials derived from wheat. Wheat, a predominant global cereal crop, offers a sustainable alternative to conventional single-use plastics through its starch, gluten, and fiber components. This study highlights the fabrication processes of wheat-based materials, including solvent casting and extrusion, and their applications in enhancing the shelf life and quality of packaged foods. Recent innovations demonstrate effectiveness in maintaining food quality, controlling moisture content, and providing microbiological protection. Despite the promising potential, challenges such as moisture content and interfacial adhesion in composites remain. This review concludes with an emphasis on the environmental benefits and future trends in wheat-based packaging materials.

Progress in food packaging applications of biopolymer-nanometal composites - A comprehensive review

Eco-friendly nanotechnology-enabled biopolymers are one of the novel concepts of packaging materials to substitute traditional synthetic polymers and their composites. This article succinctly reviews the recent developments of introducing additional functionalities to biopolymers using metal and metal oxide nanoparticles. The functionality of metal nanoparticles such as silver, zinc oxide, titanium dioxide, copper oxide, gold, and magnesium oxide, as food packaging materials were discussed. The addition of nanoparticles in biopolymers improves mechanical properties, gas barrier properties, durability, temperature stability, moisture stability, antimicrobial activity, antioxidant property, and UV absorbance and can prevent the presence of ethylene and oxygen, hence extending the shelf life of foodstuffs. Other than this, the functional activity of these biopolymer composite films helps them to act like smart or intelligent packaging. The selection of metal nanoparticles, particle migration, toxicological effect, and potential future scope in the food packaging industry are also reviewed.

Bioresorbable Polyester Coatings with Antifouling and Antimicrobial Properties for Prevention of Biofilm Formation in Early Stage Infections on Ti6Al4V Hard-Tissue Implants

Implants made from titanium are used as prostheses because of their biocompatibility and their mechanical properties close to those of human bone. However, the risk of bacterial infection is always a major concern during surgery, and the development of biofilm can make these infections difficult to treat. A promising strategy to mitigate against bacterial infections is the use of antifouling and antimicrobial coatings, where bioresorbable polymers can play an important role due to their controlled degradability and sustained drug release, as well as excellent biocompatibility. In the present study, poly(d,l-lactide) (PDLLA) and poly[d,l-lactide-co-methyl ether poly(ethylene glycol)] (PDLLA-PEG) were studied, varying the PEG content (20-40% w/w) to analyze the effectiveness of PEG as an antifouling molecule. In addition, silver sulfadiazine (AgSD) was used as an additional antimicrobial agent with a concentration ≤5% w/w and incorporated into the PEGylated polymers to create a polymer with both antifouling and antimicrobial properties. Polymers synthesized were applied using spin coating to obtain homogeneous coatings to protect samples made from titanium/aluminum/vanadium (Ti6Al4V). The polymer coatings had a smoothing effect in comparison to that of the uncoated material, decreasing the contact area available for bacterial colonization. It was also noted that PEG addition into the polymeric chain developed amphiphilic materials with a decrease in contact angle from the most hydrophobic (Ti6Al4V) to the most hydrophilic PDLLA-PEG (60/40), highlighting the increase in water uptake contributing to the hydration layer formation, which confers the antifouling effect on the coating. This study demonstrated that the addition of PEG above 20% w/w and AgSD above 1% w/v into the formulation was able to decrease bacterial adherence against clinically relevant biofilm former strains Staphylococcus aureus and Pseudomonas aeruginosa.

Acidochromic Free-Standing Multilayered Chitosan-Pyranoflavylium/Alginate Membranes toward Food Smart Packaging Applications

Food smart packaging has emerged as a promising technology to address consumer concerns regarding food conservation and food safety. In this context, we report the rational design of azide-containing pyranoflavylium-based pH-sensitive dye for subsequent click chemistry conjugation toward a chitosan-modified alkyne. The chitosan-pyranoflavylium conjugate was characterized by infrared (ATR-FTIR), ultraviolet-visible (UV-vis), nuclear magnetic resonance (NMR) spectroscopies, and dynamic light scattering (DLS), as well as its thermodynamic parameters related to their pH-dependent chromatic features. The fabrication of thin-films through electrostatic-driven layer-by-layer (LbL) assembly technology was first screened by quartz crystal microbalance with dissipation monitoring (QCM-D) onto gold substrates, and then free-standing (FS) multilayered membranes from polypropylene substrate were obtained using a homemade automatic dipping robot. The membranes' characterization included morphology analysis and thickness evaluation, assessed by scanning electron microscopy (SEM), pH-responsive color change performance tests using buffer solutions at different pH levels, and biogenic amines-enriched model solutions, demonstrating the feasibility and effectiveness of the chitosan-pyranoflavylium/alginate biomembranes for food spoilage monitoring. This work provides insights toward the development of innovative pH-responsive smart biomaterials for advanced and sustainable technological packaging solutions, which could significantly contribute to ensuring food safety and quality, while reducing food waste.

Exploring chitosan-plant extract bilayer coatings: Advancements in active food packaging via polypropylene modification

UV-ozone activated polypropylene (PP) food films were subjected to a novel bilayer coating process involving primary or quaternary chitosan (CH/QCH) as the first layer and natural extracts from juniper needles (Juniperus oxycedrus; JUN) or blackberry leaves (Rubus fruticosus; BBL) as the second layer. This innovative approach aims to redefine active packaging (AP) development. Through a detailed analysis by surface characterization and bioactivity assessments (i.e., antioxidant and antimicrobial functionalities), we evaluated different coating combinations. Furthermore, we investigated the stability and barrier characteristics inherent in these coatings. The confirmed deposition, coupled with a comprehensive characterization of their composition and morphology, underscored the efficacy of the coatings. Our investigation included wettability assessment via contact angle (CA) measurements, X-ray photoelectron spectroscopy (XPS), and attenuated total reflectance Fourier-transform infrared spectroscopy (ATR-FTIR), which revealed substantial enhancements in surface concentrations of elements and functional groups of CH, QCH, JUN, and BBL. Scanning electron microscopy (SEM) unveiled the coatings' heterogeneity, while time-of-flight secondary ion mass spectrometry (ToF-SIMS) and CA profiling showed moderately compact bilayers on PP, providing active species on the hydrophilic surface, respectively. The coatings significantly reduced the oxygen permeability. Additionally, single-layer depositions of CH and QCH remained below the overall migration limit (OML). Remarkably, the coatings exhibited robust antioxidative properties due to plant extracts and exceptional antimicrobial activity against S. aureus, attributed to QCH. These findings underscore the pivotal role of film surface properties in governing bioactive characteristics and offer a promising pathway for enhancing food packaging functionality.

Stability and Composting Behaviour of PLA-Starch Laminates Containing Active Extracts and Cellulose Fibres from Rice Straw

The stability and composting behaviour of monolayers and laminates of poly (lactic acid) (PLA) and starch with and without active extracts and cellulose fibres from rice straw (RS) were evaluated. The retrogradation of the starch throughout storage (1, 5, and 10 weeks) gave rise to stiffer and less extensible monolayers with lower water vapour barrier capacity. In contrast, the PLA monolayers, with or without extract, did not show marked changes with storage. However, these changes were more attenuated in the bilayers that gained water vapour and oxygen barrier capacity during storage, maintaining the values of the different properties close to the initial range. The bioactivity of the active films exhibited a slight decrease during storage, so the antioxidant capacity is better preserved in the bilayers. All monolayer and bilayer films were fully composted within 90 days but with different behaviour. The bilayer assembly enhanced the biodegradation of PLA, whose monolayer exhibited a lag period of about 35 days. The active extract reduced the biodegradation rate of both mono- and bilayers but did not limit the material biodegradation within the time established in the Standard. Therefore, PLA-starch laminates, with or without the valorised fractions from RS, can be considered as biodegradable and stable materials for food packaging applications.

Influence of Curcuma Longa extract in citral addition on functional properties of thin films with triple-layer structure based on furcellaran and gelatin

In this study, we obtained triple-layer films based on furcellaran and gelatin, in which the middle layer was enriched with extract of Curcuma longa in citral. This newly developed material underwent a comprehensive characterisation process to identify significant improvements in its functional properties. Both SEM, XRD and FTIR analyzes indicated the formation of interactions not only between the components but also between the film layers. Notably, the incorporation of the natural extract led to a significant reduction in solubility, decreasing it from 74.79 % to 57.25 %, while enhancing thermal stability expressed as a melting point elevating it from 147.10 °C in the control film to 158.80 °C in the film with the highest concentration of the active ingredient. Simultaneously, the addition of this active ingredient resulted in decreased water contact angle (WCA) values, rendering the film more hydrophilic. The produced films exhibit great promise as packaging materials, particularly within the food industry, and the conducted research is marked by its forward-looking and developmental approach.

Innovative Biobased and Sustainable Polymer Packaging Solutions for Extending Bread Shelf Life: A Review

Sustainable packaging has been steadily gaining prominence within the food industry, with biobased materials emerging as a promising substitute for conventional petroleum-derived plastics. This review is dedicated to the examination of innovative biobased materials in the context of bread packaging. It aims to furnish a comprehensive survey of recent discoveries, fundamental properties, and potential applications. Commencing with an examination of the challenges posed by various bread types and the imperative of extending shelf life, the review underscores the beneficial role of biopolymers as internal coatings or external layers in preserving product freshness while upholding structural integrity. Furthermore, the introduction of biocomposites, resulting from the amalgamation of biopolymers with active biomolecules, fortifies barrier properties, thus shielding bread from moisture, oxygen, and external influences. The review also addresses the associated challenges and opportunities in utilizing biobased materials for bread packaging, accentuating the ongoing requirement for research and innovation to create advanced materials that ensure product integrity while diminishing the environmental footprint.

Packaging films based on biopolymers from seafood processing wastes: Preparation, properties, and their applications for shelf-life extension of seafoods-A comprehensive review

Biopolymers derived from seafood processing byproducts are used to prepare active and biodegradable films as the packaging of food products. These films possess bioactivities to enhance the shelf life of packed foods by proactively releasing antimicrobial/antioxidative agents into the foods and providing sufficient barrier properties. Seafood processing byproducts are an eminent source of valuable compounds, including biopolymers and bioactive compounds. These biopolymers, including collagen, gelatin, chitosan, and muscle proteins, could be used to prepare robust and sustainable food packaging with some antimicrobial agents or antioxidants, for example, plant extracts rich in polyphenols or essential oils. These active packaging are not only biodegradable but also prevent the deterioration of packed foods caused by spoilage microorganisms as well as chemical deterioration. Seafood discards have a promising benefit for the development of environmentally friendly food packaging systems via the appropriate preparation methods or techniques. Therefore, the green packaging from seafood leftover can be better exploited and replace the synthetic counterpart.

Chitosan Polysaccharides from a Polarizable Multiscale Approach

We report simulations of chitosan polysaccharides in the aqueous phase, at infinite dilute conditions and zero ionic strength. Those simulations are performed by means of a polarizable multiscale modeling scheme that relies on a polarizable all atom force field to model solutes and on a polarizable solvent coarse grained approach. Force field parameters are assigned only from quantum chemistry ab initio data. We simulate chitosan monomer units, dimers and 50-long chains. Regarding the 50-long chains we simulate three sets of ten randomly built chain replica at three different pH conditions (corresponding to different chain protonation states, the chain degree of deacetylation is 85%). Our simulations show the persistence length of 50-long chitosan chains at strong acidic conditions (pH <5) to be 24 ± 2 nm (at weak/negligible ionic strength conditions), and to be 1 order of magnitude shorter at usual pH conditions. Our simulation data support the most recent simulation and experimental studies devoted to chitosan polysaccharides in the aqueous phase.

Control of release in active packaging/coating for food products; approaches, mechanisms, profiles, and modeling

Antimicrobial or antioxidant active packaging (AP) is an emerging technology in which a bioactive antimicrobial or antioxidant agent is incorporated into the packaging material to protect the contained product during its shelf life from deterioration. The important issue in AP is making a balance between the deterioration rate of the food product and the controlled release of the bioactive agent. So, the AP fabrication should be designed in such a way that fulfills this goal. Modeling the controlled release is an effective way to avoid trial and error and time-consuming experimental runs and predict the release behavior of bioactive agents in different polymeric matrices and food/food simulants. To review the release of bioactive compounds from AP, in the first part of this review we present an introductory explanation regarding the release controlling approaches in AP. Then the release mechanisms are explained which are very important in defining the appropriate modeling approach and also the interpretation of the modeling results. Different release profiles that might be observed in different packaging systems are also introduced. Finally, different modeling approaches including empirical and mechanistic techniques are covered and the recent literature regarding the utilization of such approaches to help design new AP is thoroughly studied.

Nanoemulsion-Based Multilayer Films for Ground Beef Preservation: Antimicrobial Activity and Physicochemical Properties

This study aimed to improve the physical, mechanical, and biological properties of a monolayer pectin (P) film containing nanoemulsified trans-Cinnamaldehyde (TC) by incorporating it between inner and outer layers of ethylcellulose (EC). The nanoemulsion had an average size of 103.93 nm and a zeta potential of -46 mV. The addition of the nanoemulsion increased the opacity of the film, reduced its moisture absorption capacity, and improved its antimicrobial activity. However, the tensile strength and elongation at break of the pectin films decreased after the incorporation of nanoemulsions. Multilayer films (EC/P/EC) showed a higher resistance to breaking and better extensibility compared to monolayer films. The antimicrobial activity of both mono and multilayer films was effective in inhibiting the growth of foodborne bacteria during storage of ground beef patties at 8 °C for 10 days. This study suggests that biodegradable antimicrobial multilayer packaging films can be effectively designed and applied in the food packaging industry.

Design of Biodegradable, Climate-Specific Packaging Materials That Sense Food Spoilage and Extend Shelf Life

The AgriFood systems in tropical climates are under strain due to a rapid increase in human population and extreme environmental conditions that limit the efficacy of packaging technologies to extend food shelf life and guarantee food safety. To address these challenges, we rationally designed biodegradable packaging materials that sense spoilage and prevent molding. We nanofabricated the interface of 2D covalent organic frameworks (COFs) to reinforce silk fibroin (SF) and obtain biodegradable membranes with augmented mechanical properties and that displayed an immediate colorimetric response (within 1 s) to food spoilage, using packaged poultry as an example. Loading COF with antimicrobial hexanal also mitigated biotic spoilage in high-temperature and -humidity conditions, resulting in a four-order of magnitude decrease in the total amount of mold growth in soybeans packaged in silk-COF, when compared to cling film (i.e., polyethylene). Together, the integration of sensing, structural reinforcement, and antimicrobial agent delivery within a biodegradable nanocomposite framework defines climate-specific packaging materials that can decrease food waste and enhance food safety.

Improvement of Natural Polymeric Films Properties by Blend Formulation for Sustainable Active Food Packaging

Active packaging manufactured with biopolymers extracted from agri-food waste is one of the most innovative and eco-sustainable strategies for maintaining food quality. However, biopolymers often present poor performances, which hinders their competitiveness compared with plastics. This work focused on developing and optimizing a natural polymeric blend produced by solvent casting based on zein and chitosan to improve the pure biopolymers' properties. The best results were obtained by blending zein and chitosan in a 1:2 weight ratio. The films were characterized in terms of morphology, mechanical and oxygen barrier properties, thermal stability, transparency and wettability. The blend production allowed us to obtain lower brittleness and lower stiffness materials compared with pure polymer films, with oxygen permeability values two orders of magnitude lower than pure zein, better optical properties with respect to pure chitosan and good thermal stability. The wettability properties of the blend did not result in being altered with respect to the single polymer, which was found to have hydrophilic behavior, highlighting the strong influence of glycerol used as a plasticizer. The results suggested that the polymer blending strategy is a viable and cost-effective method for producing packaging materials as alternatives to plastics.

Trends in Bioactive Multilayer Films: Perspectives in the Use of Polysaccharides, Proteins, and Carbohydrates with Natural Additives for Application in Food Packaging

The harmful effects on the environment caused by the indiscriminate use of synthetic plastics and the inadequate management of post-consumer waste have given rise to efforts to redirect this consumption to bio-based economic models. In this sense, using biopolymers to produce materials is a reality for food packaging companies searching for technologies that allow these materials to compete with those from synthetic sources. This review paper focused on the recent trends in multilayer films with the perspective of using biopolymers and natural additives for application in food packaging. Firstly, the recent developments in the area were presented concisely. Then, the main biopolymers used (gelatin, chitosan, zein, polylactic acid) and main methods for multilayer film preparation were discussed, including the layer-by-layer, casting, compression, extrusion, and electrospinning methods. Furthermore, we highlighted the bioactive compounds and how they are inserted in the multilayer systems to form active biopolymeric food packaging. Furthermore, the advantages and drawbacks of multilayer packaging development are also discussed. Finally, the main trends and challenges in using multilayer systems are presented. Therefore, this review aims to bring updated information in an innovative approach to current research on food packaging materials, focusing on sustainable resources such as biopolymers and natural additives. In addition, it proposes viable production routes for improving the market competitiveness of biopolymer materials against synthetic materials.

Novel Antibacterial Metals as Food Contact Materials: A Review

Food contamination caused by microorganisms is a significant issue in the food field that not only affects the shelf life of food, but also threatens human health, causing huge economic losses. Considering that the materials in direct or indirect contact with food are important carriers and vectors of microorganisms, the development of antibacterial food contact materials is an important coping strategy. However, different antibacterial agents, manufacturing methods, and material characteristics have brought great challenges to the antibacterial effectiveness, durability, and component migration associated with the use security of materials. Therefore, this review focused on the most widely used metal-type food contact materials and comprehensively presents the research progress regarding antibacterial food contact materials, hoping to provide references for exploring novel antibacterial food contact materials.

Novel Colloidal Food Ingredients: Protein Complexes and Conjugates

Food proteins, polysaccharides, and polyphenols are natural ingredients with different functional attributes. For instance, many proteins are good emulsifiers and gelling agents, many polysaccharides are good thickening and stabilizing agents, and many polyphenols are good antioxidants and antimicrobials. These three kinds of ingredients can be combined into protein, polysaccharide, and/or polyphenol conjugates or complexes using covalent or noncovalent interactions to create novel multifunctional colloidal ingredients with new or improved properties. In this review, the formation, functionality, and potential applications of protein conjugates and complexes are discussed. In particular, the utilization of these colloidal ingredients to stabilize emulsions, control lipid digestion, encapsulate bioactive ingredients, modify textures, and form films is highlighted. Finally, future research needs in this area are briefly proposed. The rational design of protein complexes and conjugates may lead to the development of new functional ingredients that can be used to create more nutritious, sustainable, and healthy foods.

Electrospun Multilayered Films Based on Poly(3-hydroxybutyrate-co-3-hydroxyvalerate), Copolyamide 1010/1014, and Electrosprayed Nanostructured Silica

In this research, bio-based electrospun multilayered films for food packaging applications with good barrier properties and close to superhydrophobic behavior were developed. For this purpose, two different biopolymers, a low-melting point and fully bio-based synthetic aliphatic copolyamide 1010/1014 (PA1010/1014) and the microbially synthesized poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) and food-contact-complying organomodified silica (SiO₂) nanostructured microparticles, were processed by electrospinning. The production of the multilayer structure was finally obtained by means of a thermal post-treatment, with the aim to laminate all of the components by virtue of the so-called interfiber coalescence process. The so developed fully electrospun films were characterized according to their morphology, their permeance to water vapor and oxygen, the mechanical properties, and their water contact angle properties. Interestingly, the annealed electrospun copolyamide did not show the expected improved barrier behavior as a monolayer. However, when it was built into a multilayer form, the whole assembly exhibited a good barrier, an improved mechanical performance compared to pure PHBV, an apparent water contact angle of ca. 146°, and a sliding angle of 8°. Consequently, these new biopolymer-based multilayer films could be a bio-based alternative to be potentially considered in more environmentally friendly food packaging strategies.

Sustainable and Bio-Based Food Packaging: A Review on Past and Current Design Innovations

Food loss and waste occur for many reasons, from crop processing to household leftovers. Even though some waste generation is unavoidable, a considerable amount is due to supply chain inefficiencies and damage during transport and handling. Packaging design and materials innovations represent real opportunities to reduce food waste within the supply chain. Besides, changes in people's lifestyles have increased the demand for high-quality, fresh, minimally processed, and ready-to-eat food products with extended shelf-life, that need to meet strict and constantly renewed food safety regulations. In this regard, accurate monitoring of food quality and spoilage is necessary to diminish both health hazards and food waste. Thus, this work provides an overview of the most recent advances in the investigation and development of food packaging materials and design with the aim to improve food chain sustainability. Enhanced barrier and surface properties as well as active materials for food conservation are reviewed. Likewise, the function, importance, current availability, and future trends of intelligent and smart packaging systems are presented, especially considering biobased sensor development by 3D printing technology. In addition, driving factors affecting fully biobased packaging design and materials development and production are discussed, considering byproducts and waste minimization and revalorization, recyclability, biodegradability, and other possible ends-of-life and their impact on product/package system sustainability.

Advances in chitin-based nanoparticle use in biodegradable polymers: A review

Chitin-based nanoparticles are polysaccharide materials that can be produced from a waste stream of the seafood industry: crustacean shells. These nanoparticles have received exponentially growing attention, especially in the field of medicine and agriculture owing to their renewable origin, biodegradability, facile modification, and functionality adjustment. Due to their exceptional mechanical strength and high surface area, chitin-based nanoparticles are ideal candidates for reinforcing biodegradable plastics to ultimately replace traditional plastics. This review discusses the preparation methods for chitin-based nanoparticles and their applications. Special focus is on biodegradable plastics for food packaging making use of the features that can be created by the chitin-based nanoparticles.

Solventless Photopolymerizable Paper Coating Formulation for Packaging Applications

Nowadays, packaging applications require the use of advanced materials as well as production methods that have a low environmental impact. In this study, a solvent-free photopolymerizable paper coating was developed using two acrylic monomers (2-ethylhexyl acrylate and isobornyl methacrylate). A copolymer, with a molar ratio of 2-ethylhexyl acrylate/isobornyl methacrylate of 0.64/0.36, was prepared and used as the main component of the coating formulations (50 and 60 wt%). A mixture of the monomers with the same proportion was used as a reactive solvent, yielding formulations with 100% solids. The coated papers showed an increase in the pick-up values from 6.7 to 32 g/m² depending on the formulation used and the number of coating layers (up to two). The coated papers maintained their mechanical properties and presented improved air barrier properties (Gurley's air resistivity of ≈25 s for the higher pick-up values). All the formulations promoted a significant increase in the paper's water contact angle (all higher than 120 °) and a remarkable decrease in their water absorption (Cobb values decrease from 108 to 11 g/m²). The results confirm the potential of these solventless formulations for fabricating hydrophobic papers with potential application in packaging, following a quick, effective, and more sustainable approach.

Overview of the Cast Polyolefin Film Extrusion Technology for Multi-Layer Packaging Applications

The review article presents the technology of producing polyolefin-based films by extrusion casting. Due to the wide use of this type of film as packaging for food and other goods, obtaining films with favorable properties is still a challenge for many groups of producers in the plastics market. The feedblock process and multimanifold process are the main methods of producing multi-layer film. In the case of food films, appropriate barrier properties are required, as well as durability and puncture resistance also at low temperatures. On the other hand, in order to properly pack and present products, an appropriate degree of transparency must be maintained. Therefore, processing aids such as anti-slip, anti-block and release agents are commonly used. Other popular modifiers, such as waxes, fatty acid amides and mineral fillers-silica, talc or calcium carbonate-and their use in film extrusion are discussed. The article also presents common production problems and their prevention.

Colloidal Solutions as Advanced Coatings for Active Packaging Development: Focus on PLA Systems

Due to rising consumer demand the food packaging industry is turning increasingly to packaging materials that offer active functions. This is achieved by incorporating active compounds into the basic packaging materials. However, it is currently believed that adding active compounds as a coating over the base packaging material is more beneficial than adding them in bulk or in pouches, as this helps to maintain the physicochemical properties of the base material along with higher efficiency at the interface with the food. Colloidal systems have the potential to be used as active coatings, while the application of coatings in the form of colloidal dispersions allows for prolonged and controlled release of the active ingredient and uniform distribution, due to their colloidal/nano size and large surface area ratio. The objective of this review is to analyse some of the different colloidal solutions previously used in the literature as coatings for active food packaging and their advantages. The focus is on natural bio-based substances and packaging materials such as PLA, due to consumer awareness and environmental and regulatory issues. The antiviral concept through the surface is also discussed briefly, as it is an important strategy in the context of the current pandemic crisis and cross-infection prevention.

Promoting adsorption performance and mechanical strength in composite porous gel film

Starch is widely used to prepare biodegradable films due to its superior biocompatibility, low immunogenicity, and renewability. In this work, a novel K⁺/carrageenan porous-starch/casein gel film with high oil absorption was prepared using modified porous starch. Optimal gel stability and uniformity were obtained when adding 10 mg/mL k-carrageenan and 2 mg/mL K⁺ to 2 mg/mL microgels, with significantly reduced crystallinity and elasticity and increased tensile strength. The concentration of k-carrageenan was the main factor affecting gel strength and the hydrophilic and mechanical properties of the film. In addition, the film-forming solution showed excellent fluidity and spreading typical of non-Newtonian fluids. The film also exhibited a highly porous structure, as visualized by SEM and AFM, in line with a cumulative oil absorption rate of 87.5 % within 20 min, which was significantly higher than that obtained with glutinous rice starch. In conclusion, reinforcement of starch-based microgels as described in this study can maximize the film's adsorption performance and mechanical properties, with promising applications in skin care and beauty products.

An Overview on Wood Waste Valorization as Biopolymers and Biocomposites: Definition, Classification, Production, Properties and Applications

Bio-based polymers, obtained from natural biomass, are nowadays considered good candidates for the replacement of traditional fossil-derived plastics. The need for substituting traditional synthetic plastics is mainly driven by many concerns about their detrimental effects on the environment and human health. The most innovative way to produce bioplastics involves the use of raw materials derived from wastes. Raw materials are of vital importance for human and animal health and due to their economic and environmental benefits. Among these, wood waste is gaining popularity as an innovative raw material for biopolymer manufacturing. On the other hand, the use of wastes as a source to produce biopolymers and biocomposites is still under development and the processing methods are currently being studied in order to reach a high reproducibility and thus increase the yield of production. This study therefore aimed to cover the current developments in the classification, manufacturing, performances and fields of application of bio-based polymers, especially focusing on wood waste sources. The work was carried out using both a descriptive and an analytical methodology: first, a description of the state of art as it exists at present was reported, then the available information was analyzed to make a critical evaluation of the results. A second way to employ wood scraps involves their use as bio-reinforcements for composites; therefore, the increase in the mechanical response obtained by the addition of wood waste in different bio-based matrices was explored in this work. Results showed an increase in Young's modulus up to 9 GPa for wood-reinforced PLA and up to 6 GPa for wood-reinforced PHA.

Antimicrobial and Gas Barrier Crustaceans and Fungal Chitin-Based Coatings on Biodegradable Bioplastic Films

Chitin nanofibrils (CN) can be obtained from crustaceans and fungal sources and can be used for preparing coatings for bioplastic films, that are fundamental for developing a safe and sustainable biodegradable food packaging. Coatings with different concentrations of CN from shrimps were applied on different bioplastic substrates, like Poly (butylene succinate-co-adipate)/Poly(3-hydroxybutyrate-co-3-hydroxyvalerate (PBSA/PHBV) blend, Polybutylene succinate (PBS), and Polybutylene adipate terephthalate/Poly(lactic acid) (PBAT/PLA) blend, but the adhesion to the substrates was scarce. On the contrary, the fungal-based CN showed a better adhesion. Additionally, it was found that the use of an additive based on oligomeric lactic acid was useful to prepare a coating with an improved adhesion to bioplastics. The gas barrier properties to oxygen and water vapour of coated and un-coated films were measured, revealing an improvement of these properties thanks to applied coatings, especially towards the oxygen. Antimicrobial properties and biodegradation capacity were also evaluated revealing an antibacterial effect of the coatings that did not significantly interfere with their biodegradability. The results are discussed and interpreted considering the correlation between composition and macromolecular structures with the observed functional properties.

Additive Manufacturing of Drug-Eluting Multilayer Biodegradable Films

Drug-eluting films made of bioresorbable polymers are a widely used tool of modern personalized medicine. However, most currently existing methods of producing coatings do not go beyond the laboratory, as they have low encapsulation efficiency and/or difficulties in scaling up. The PLACE (Printed Layered Adjustable Cargo Encapsulation) technology proposed in this article uses an additive approach for film manufacturing. PLACE technology is accessible, scalable, and reproducible in any laboratory. As a demonstration of the technology capabilities, we fabricated layered drug-eluting polyglycolic acid films containing different concentrations of Cefazolin antibiotic. The influence of the amount of loaded drug component on the film production process and the release kinetics was studied. The specific loading of drugs was significantly increased to 200-400 µg/cm² while maintaining the uniform release of Cefazolin antibiotic in a dosage sufficient for local antimicrobial therapy for 14 days. The fact that the further increase in the drug amount results in the crystallization of a substance, which can lead to specific defects in the cover film formation and accelerated one-week cargo release, was also shown, and options for further technology development were proposed.

Physicochemical, Morphological, and Functional Characterization of Edible Anthocyanin-Enriched Aloevera Coatings on Fresh Figs (Ficus carica L.)

In the present investigation, Aloe vera gel (AVG)-based edible coatings enriched with anthocyanin were prepared. We investigated the effect of different formulations of aloe-vera-based edible coatings, such as neat AVG (T1), AVG with glycerol (T2), Aloe vera with 0.2% anthocyanin + glycerol (T3), and AVG with 0.5% anthocyanin + glycerol (T4), on the postharvest quality of fig (Ficus carica L.) fruits under refrigerated conditions (4 °C) for up to 12 days of storage with 2-day examination intervals. The results of the present study revealed that the T4 treatment was the most effective for reducing the weight loss in fig fruits throughout the storage period (~4%), followed by T3, T2, and T1. The minimum weight loss after 12 days of storage (3.76%) was recorded for the T4 treatment, followed by T3 (4.34%), which was significantly higher than that of uncoated fruit (~11%). The best quality attributes, such as the total soluble solids (TSS), titratable acidity (TA), and pH, were also demonstrated by the T3 and T4 treatments. The T4 coating caused a marginal change of 0.16 in the fruit titratable acidity, compared to the change of 0.33 in the untreated fruit control after 12 days of storage at 4 °C. Similarly, the total soluble solids in the T4-coated fruits increased marginally (0.43 °Brix) compared to the uncoated control fruits (>2 °Brix) after 12 days of storage at 4 °C. The results revealed that the incorporation of anthocyanin content into AVG is a promising technology for the development of active edible coatings to extend the shelf life of fig fruits.

Active Starch-Polyester Bilayer Films with Surface-Incorporated Ferulic Acid

Bilayer films of cassava starch-based (with 10% gellan gum) and polylactic (PLA): Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) polyester blend (with 75% PLA) monolayers were obtained by melt-blending and compression-molding, and the subsequent thermocompressing of both monolayers. Ferulic acid (FA) was incorporated into the polyester sheet by spraying and drying. Films were characterized in terms of their microstructure and functional properties throughout two months of storage at 25 °C and 53% relative humidity. The laminates exhibited improved tensile and barrier properties compared to the respective monolayers, which makes them more adequate for food packaging purposes. Surface incorporation of ferulic acid did not significantly modify the barrier and mechanical properties of the films while providing them with antioxidant and antibacterial capacity when applied in aqueous systems, where a complete release of active compounds occurred. The physical properties of the bilayers and layer thermo-sealing were stable throughout storage. Likewise, the antioxidant and antimicrobial active properties were preserved throughout storage. Therefore, these active bilayers represent a sustainable packaging alternative to non-biodegradable, non-recyclable synthetic laminates for food packaging purposes, which could extend the shelf-life of food due to their antioxidant and antibacterial properties.

Enzymatic synthesis of sodium caseinate-EGCG-carboxymethyl chitosan ternary film: Structure, physical properties, antioxidant and antibacterial properties

Proteins and polysaccharides have been frequently used in recent years to prepare environment-friendly packaging materials. However, films based on proteins or polysaccharides alone often have poor performance as packaging, so they need to be combined to improve properties. In this work, we applied enzyme technology to prepare sodium caseinate (SC)-carboxymethyl chitosan (CMC) films, incorporating epigallocatechin gallate (EGCG) as bridging molecules and antibacterial agents. SC-EGCG-CMC ternary conjugate was firstly synthesized by tyrosinase (Tyr), and the composite films were then prepared with the aid of glycerol. Under tyrosinase catalytic conditions, EGCG could cross-link with SC and CMC covalently. The effects of different concentrations of EGCG and tyrosinase on mechanical properties, water vapor permeability, antibacterial properties and free radical scavenging ability were studied. The crosslinking degree and mechanical properties were improved with the increase of EGCG and tyrosinase content. The film showed good antibacterial activity against Gram-positive bacteria. In addition, the antibacterial activity and free radical scavenging ability increased with the increase of EGCG concentration. This work provides an efficient enzymatic method to prepare films with good strength and antibacterial properties, which can be used to improve the storage quality of foods.

Sensitivity Analysis of a Bench-Scale Pyrolysis Model for Composite Materials: A Case Study of Poly(lactic acid)/Melamine/Ammonium Polyphosphate

On the basis of a well-developed bench-scale pyrolysis model that relates material composition to flammability, this paper applied mathematical simulations to explore the model sensitivity for the prediction of fire behavior of composite materials. A pyrolysis model for poly(lactic acid) blended with melamine and ammonium polyphosphate as the reference material was selected as the case for analysis. The model input parameters for simulations include the heat of reaction, apparent activation energy, and pre-exponential factor of 15 reactions, as well as the thermal conductivity, emissivity coefficient, absorption coefficient, and density of 17 condensed-phase components. Each reaction-related or component-related parameter was adjusted from 80% of the model value to 120% with a 5% or 10% gradient. Finally, 826 simulation cases in total were calculated for analysis. Both the mass loss rate and the heat release rate of each case were calculated to characterize the sensitivity, which showed the same pattern. Finally, seven primary reactions and five key condensed-phase components with high sensitivity were identified. The predicted fire behaviors are highly related to the kinetics of the reactions between virgin components or reactions where virgin components play an important role in, including the pyrolysis of melted poly(lactic acid), the first step in the pyrolysis of melamine, the first step in the pyrolysis of ammonium polyphosphate, the reaction between melted poly(lactic acid) and melamine, the reaction between ammonium polyphosphate and melamine, and further decomposition of the generated new condensed-phase component. Particularly, the activation energy of these reactions is of sensitivity larger than 5% or 15%. The heat of decomposition of pyrolysis of melted poly(lactic acid) also showed a sensitivity of 2%-5%. The pre-exponential factor of all reactions showed a sensitivity of less than 2%, which can be ignored. Inputting the proper density is important for the prediction of fire behavior as the sensitivity is larger than 2%. The sensitivity of the milligram-scale model was also processed and compared. These simulations provided a fundamental understanding of the sensitivity of thermophysical and chemical properties and thus provide advanced insights into fire behavior modeling and new composite material design.