Polylactic acid (PLA) polymers are derived from lactic acid and can be created by various polymerization processes including direct condensation, azeotropic polycondensation, and lactide-based polymerization (Rajendran et al., 2024; Wongphan et al., 2024). The lactic acid precursor can be chemically generated or biologically produced as a common organic acid from a wide range of fermentations including food products, silage, gastrointestinal tracts of animals, and as a product of numerous probiotics and starter cultures (Caplice and Fitzgerald, 1999; Ricke et al., 2013; Dittoe et al., 2018; Muck et al., 2018; Rajendran et al., 2024). Given the diverse array of lactic acid producing organisms and renewable substrates for fermentation, there is no shortage of potential sources for lactic acid to generate the corresponding PLA polymer. However, large-scale commercial production can be handicapped by the generation of racemic mixtures of DL-lactate and obtaining pure L-lactate is preferred for PLA generation (Rajendran et al., 2024).

Polylactic polymers have been used as packaging materials for a wide range of both liquid and solid foods including meat products (McMillin, 2017; Panseri et al., 2018; Wongphan et al., 2024; Moldovan et al., 2025). They are considered optimal package film candidates for their high tensile strength and durability, along with transparency, clarity, and insolubility with air, ethanol, methanol, and aliphatic carbon (Halloran et al., 2002; Nasution et al., 2023). In addition, PLA as a biopolymer possesses environmental attributes such as biocompatibility and biodegradability and is compostable (Asadi and Mozafari, 2025; Rajendran et al., 2024). Films made with PLA are classified as GRAS (Generally Recognized as Safe) by the US Food and Drug Administration and offer the potential for compliance with food safety regulations (Panseri et al., 2018; Asadi and Mozafari, 2025). However, PLA as a flexible packaging material can suffer from brittleness at room temperature, poor thermal stability, and low water vapor barrier properties depending on the application (Nasution et al., 2023; Wongphan et al., 2024).

Mechanical improvements can be achieved by incorporating chemical plasticizers, but these leach out and lead to environmental problems (Halloran et al., 2022). Biobased plasticizers such as glycerol have been used as substitutes and have been demonstrated to create PLA blends, exhibiting improved flexibility, minimal leaching, and no toxicity based on in vitro mammalian cell toxicity assays (Halloran et al., 2022). Functional improvements have been explored combining PLA with various additives such as plant-based extracts, antimicrobial compounds, and lignocellulose waste among others for food and meat products (Muñoz-Pabon et al., 2023; Asadi and Mozafari, 2025). Using an agar diffusion antimicrobial assay, Muñoz-Pabon et al. (2023) demonstrated that PLA composites containing nisin, oregano, cassava bran, and coffee husks inhibited Listeria monocytogenes. When they used the corresponding composites that gave the greatest antimicrobial activity to package pork meat, the pH, texture, moisture, and pH qualities were similar to those displayed by pork products held in commercial polystyrene packaging. Further research is continuing to expand the functionality of PLA natural extract composite blends to provide antioxidant properties as well as screening antimicrobial activities against not only other bacteria but fungi as well (Nasution et al., 2023; Asadi and Mozafari, 2025).

Plant-based cellulose. Cellulose polymers consist of β 1–4 linked glucose monomers that, along with hydrogen linkages, possess a crystalline structure that serves as a highly structured matrix (Limayen and Ricke, 2012; Motaung, 2021). Cellulose, as a significant component of plant-cell walls, is one of the most abundant biopolymers present in nature and can be obtained from a variety of sources including wood, cotton, and food waste as well as agricultural and agronomic wastes (Erginkaya et al., 2014; Asgher et al., 2020; Mohamed et al., 2020; Gil and Rudy, 2023; Yang et al., 2024). Not surprisingly, the availability of cellulose, as well as being biodegradable, inexpensive, and edible, has made it attractive as a packaging material for food products (Gil and Rudy, 2023). In addition to cellulose polymers being biodegradable, tasteless, and odorless, they possess a high thermal tolerance and can serve as a barrier to ultraviolet rays, as well as being capable of carrying antioxidant and antimicrobial agents (Erginkaya et al., 2014; Asgher et al., 2020; Mohamed et al., 2020; Romão et al., 2022; Nath et al., 2024). Depending on the preparation procedure, cellulose microfibrils can take on many forms, including microcrystalline, nanocrystalline, and nanofibrillated versions of the polymer microstructures (Romão et al., 2022). Chemically altered versions of cellulose can be generated, involving a range of esters and ethers to create cellulose derivatives with methylcellulose (MC), carboxymethyl cellulose (CMC), and hydroxypropyl methylcellulose (HPMC) being the most commonly used for edible films (von Schantz et al., 2014; Jiang and Ngai, 2022; Romão et al., 2022). The resulting modified cellulose films can provide strength and transparency (Agustin et al., 2014; Guzman-Puyol et al., 2019). While CMC films have been shown to restrict meat protein and lipid oxidation, antioxidant properties can be generated by introducing pomegranate seed extract to MC, CMC, and HPMC films, but such additions may limit the oxygen capability of these films (Nemazifard et al., 2017; Khezrian and Shahbazi, 2018). Immobilizing bioactive agents onto cellulose polymers has also exhibited antimicrobial properties (Irimia et al., 2024).

Bacterial-based cellulose. Despite the attractiveness of cellulose from plant sources, there are limitations due to the complexities associated with extraction and purification needed to retrieve a high-quality polymer that incur technical and economic scale-up hurdles for commercial applications (Nath et al., 2024). Cellulose polymers produced by several aerobic bacteria have received interest as a possible alternative for the food industry (Cazón and Vázque, 2021). Produced by cellulose synthase complexes, extracellular bacterial cellulose is an exopolysaccharide that, unlike plant cellulose, does not contain contaminants such as lignin, pectin, or hemicellulose (Cazón and Vázquez, 2021; Li et al., 2022). The resulting purity generates a product that does not require extraction or chemical purification, possesses a high degree of polymerization, and exhibits crystallinity among other properties (Cazón and Vázquez, 2021; Li et al., 2022). More optimization of bacterial cellulose production remains, including developing low-cost growth media, further identification of candidate bacterial strains, and other approaches to enhance yields and/or create new properties (dos Santos et al., 2024). Given the advancements made in molecular biology, genetically altered bacterial strains could produce a wide range of modified cellulose polymers with potentially more properties for multifunctional packaging materials beyond the chemical approaches currently used for modifying plant-based cellulose polymers.

Another plant-derived carbohydrate polymer that is also biodegradable, as well as economical and renewable for utilization in edible films, is starch (Mose and Maranga, 2011; Pająk et al., 2017; Song et al., 2021; Gil and Rudy, 2023). Starch sources have typically included agronomic products such as corn, potatoes, rice, and wheat, but interest has grown toward deriving starches from more nonconventional sources such as certain beans and vegetable materials (García-Guzmán et al., 2022; Putri et al., 2023). While starch-based films have been extensively used in food and meat packaging due to their desirable gas barrier and organoleptic properties, they suffer from being brittle and hydrophilic and possess overall poor mechanical properties (Onyeaka et al., 2022; Gil and Rudy, 2023; Putri et al., 2023). Consequently, modifications of starch have been explored, employing either chemical or physical treatments (García-Guzmán et al., 2022). Physical treatments to starch polymers have involved administration of high hydrostatic pressure, ozonation, and ultrasound (García-Guzmán et al., 2022; Koshenaj and Ferrari, 2024). Chemical modifications to introduce functional groups into starch polymers have included reduction, substitution, or cross-linking (García-Guzmán et al., 2022). Likewise, combinations with other materials have been introduced to improve these negative characteristics (Gil and Rudy, 2023). For example, the incorporation of plant extracts and essential oils has been shown to improve oxygen barrier characteristics, enhance antioxidation qualities that can lead to improved shelf life, and provide antimicrobials to improve food safety (Radha Krishnan et al., 2015; Yıldırım-Yalçın et al. 2021; Song et al., 2021; Erna et al., 2022; García-Guzmán et al., 2022). In addition, merging biodegradable plastics with starch have been offered to reduce the cost of biodegradable polymers (Song et al., 2021). It is anticipated that newer technologies such as 3-dimensional (3D) printing, electrospinning, force spinning, and others will be further developed, and the opportunities to expand the functionality of starch-based edible films and packaging will become feasible (García-Guzmán et al., 2022).

Chitosan is a natural high-molecular weight cationic polysaccharide comprised of (1,4)-2-amino-2-deoxy-glucose that is produced by the deacetylation of chitin a polymer that occurs primarily in shrimp, crabs, and insects as well as marine diatoms and some fungi (Raafat and Sahl, 2009; Liu et al., 2022). Chitosan and poly(ɛ-lysine) are natural polymers that have natural antimicrobial characteristics (Raafat and Sahl, 2009; Sayed and Jardine, 2015; Sivakanthan, et al., 2020; Chen et al., 2023). These polymers act on bacteria’s negatively charged cell membranes, causing intracellular leakage (Santos et al., 2016; Sofı et al., 2018). These bioactive polymers can be used in composites or coatings (Perinelli et al., 2018; Wang et al., 2018; Vasile and Baican, 2021).

Chitosan films are generally made by casting, which involves dissolving and incorporating a plasticizer and an active compound and nanofiller of choice (Jiang et al., 2023). Chitosans are an attractive alternative packaging material due to their biodegradability, nontoxicity, and renewability (Jiang et al., 2023). Even when combined with metal oxides to form chitosan-metal oxide films, complete degradation in soil still occurs after several weeks (Wrońska et al., 2023). In addition to film and coating applications, chitosans have historically received interest in various uses, from vaccine, peptide, and gene delivery systems and pharmaceuticals for tissue engineering (Raafat and Sahl. 2009). Chitosan has been used in food applications for enzyme stabilization, dye binding, emulsification, antioxidant, and gelling agents (Agulló et al., 2003). Chitosan-based films possess the advantages of flexibility and strength and are resistant to fats, oil, and oxygen (Nayik et al., 2015; Mohamed et al., 2020; Song et al., 2021). In addition to its film-forming utility, chitosan possesses a wide range of antimicrobial activities against both Gram-negative and Gram-positive bacteria, yeast, and filamentous fungi and has been demonstrated to extend shelf life in ready-to-cook meat products (Ferreira et al., 2009; Campos et al., 2011; Alemán et al., 2016; Mohamed et al., 2020; Jiang et al., 2023; Aresta et al., 2024). Chitosan composited with essential oils or phenolic compounds have enhanced antimicrobial and antifungal activities (Jiang et al., 2023). Phenolics included as a composite with certain phenolic compounds have been employed to improve mechanical strength (Jiang et al., 2023).

Fat was used as an edible food coating in 16th-century England (Labuza and Contreras-Medellin, 1981). Waxes (e.g., carnauba wax, beeswax, paraffin wax) and oils (mineral oil, vegetable oil) have been commercially used as protective coatings for fresh fruits and vegetables since the beginning of the 1930s (Baldwin, 1994). Other lipid materials employed include lacs, fatty acids and alcohols, and acetylated glycerides (Ghosh et al., 2021). Compared to protein and carbohydrate-based films and coatings that are hydrophilic, lipid-based materials provide a hydrophobic barrier that decreases penetration of water vapor (Milani and Nemati, 2022). Milani and Nemati (2022) describe several lipid compounds and their sources. They range from natural oils and fats to natural resins and essential oils and can originate from either animal or plant sources.

Waxes are nonpolar lipids possessing long aliphatic chains that can be derived from bees and plant sources (Milani and Nemati, 2022). Over the years, certain waxes have been used to encase fruits and vegetables, allowing for extended shelf life and limiting degradation over time (Milani and Nemati, 2022). Likewise, since the 1950s, several meat processors in the United States have applied strippable coatings of petroleum-derived microcrystalline wax on frozen meats, such as beef, veal, lamb, hamburger patties, and luncheon meats (McGrath, 1955). Although wax coatings are substantially more resistant to moisture transport than most other lipid or nonlipid edible coatings (Schultz et al., 1949; Landmann et al., 1960), wax-, fat-, and oil-based coatings have application problems (i.e., thickness and homogeneity control, greasy surface, cracking) and organoleptic problems (i.e., waxy taste, rancidity)(Bolívar-Monsalve et al., 2019). Thus, pure lipids are combined with hydrocolloids such as protein, starch, cellulose, and their derivatives, providing a multicomponent system that can be applied as meat coatings (Cutter, 2006).

Additional beneficial functions beyond being edible may be possible with certain sources of lipid-based coatings. For example, one agronomic source of wax used for coatings is extracted from rice bran oil, either in a hard or soft form (Milani and Nemati, 2022). Rice bran results from milling, representing 5% to 6% of the rice kernel and comprising anywhere from 15% to 22% lipids (Luh, 1991; Henderson et al., 2012; Bodie et al., 2019). In addition, rice bran is known to exhibit prebiotic activities, and rice bran oil has been associated with health benefits such as tumor reduction (Ryan, 2011; Henderson et al., 2012; Bodie et al., 2019). Rice bran oil has received interest in several food applications due to its high nutritional quality, antioxidant activity, stabilization properties for storage, and different food colorant options based on the different pigmented rice varieties (Das et al., 2025). Some of these characteristics associated with rice bran oil waxes would potentially qualify them as more attractive alternative wax lipid-based edible coatings for multiple food products, including meats. However, this will likely depend on whether they can be retained during extraction. Further compositional research on these waxes from other sources may reveal additional beneficial characteristics that make them more biologically active beyond just serving as edible coatings.

Protein films are attractive because of the potential unique combinations of a wide range of amino acids that can result in various polymer structural forms and intramolecular interactions (Hadidi et al., 2022; Khin et al., 2024). Protein films easily lend themselves to chemical and physical manipulation and form networks for elasticity (Hadidi et al., 2022). Sources for edible protein films can be generally categorized as originating from either plant or animal products (Khin et al., 2024). Collagen, keratin, milk, egg, and whey have served as animal sources, while proteins from corn, wheat, and soy have been used to generate protein-based films (Cazón et al., 2017; Mihalca et al., 2021). Plant edible protein candidates can be derived from many plant sources, including cereals, legumes, oil seeds, green leaves, and nuts (Hadidi et al., 2022). While soy proteins were used for edible protein films early on, agricultural byproduct sources such as wheat gluten, rice bran, and corn zein have received attention as potentially sustainable edible films (Purewal et al., 2024). In addition to the initial protein source, the types of proteins derived from these plant sources are generally categorized as either albumins, globulins, glutelins, or prolamins, which vary in their solubility (Hadidi et al., 2022). Consequently, these differences are reflected in how these protein sources are used in packaging.

For animal products, milk proteins have been a source of films for several decades and consist primarily of casein and a lesser amount of whey (Shendurse et al., 2018). Casein from milk was one of the early sources of edible protein films, particularly for packaging dairy products, and has the advantage of remaining stable over a wide range of temperatures, pH measurements, and salt conditions (Shendurse et al., 2018; Purewal et al., 2024). Whey proteins are generated as a waste byproduct after casein extraction for cheese processing. They are becoming more attractive as a protein film source because of their functional utility as a biodegradable barrier polymer and their ready availability as a surplus waste (Kandasamy et al., 2021). Whey protein contains several fractions, but levels depend on cheese type, manufacturing process, and animal milk source, among other factors (Kandasamy et al., 2021). Gelatins derived from the high-temperature partial acid or alkali hydrolysis of fibrous hydrophobic collagen proteins occurring in animal tissues also emerged as an attractive source for packaging due to their effectiveness as a barrier and biodegradability (Šuput et al., 2015; Loo and Sarbon, 2020; Maciel et al., 2020; Purewal et al., 2024). Collagens occur in various organs and tissues such as cartilage, skin, lungs, tendons, and basement tissues and can compositionally vary, being homogenous in one tissue and heterogenous in another (Bornstein and Sage, 1980). Interest has grown in the utilization of collagen due to its availability in several animal processing operations, for example, chicken skin (Loo and Sarbon, 2020; Ricke et al., 2025a). By repurposing these animal waste byproducts into useful applications such as protein films, there is an opportunity to decrease the environmental footprint of processing waste such as animal hide components that end up in landfills (Matinong et al., 2022; Suurs et al., 2023). However, retrieving products such as collagen from such sources will require developing large-scale economic processing methods.

Proteins have been investigated and used as sources of edible meat film for several years (Chen et al., 2019). Protein films generally have a sound gas barrier, mechanical properties, and poor water vapor permeability (Bourtoom, 2008; Bourtoom, 2009; Otoni et al., 2016). Protein-based edible films have been investigated for salami (Moreira et al., 2011), chicken breast (Fernández-Pan et al., 2014; Di Giorgio et al., 2019), beef (Emiroğlu et al., 2010; Cardoso et al., 2016), and pork (Kaewprachu et al., 2015). However, protein-based films have a low resistance to mechanical stress and water diffusion and may become fragile under dried conditions (Bolívar-Monsalve et al., 2019). Other drawbacks to protein-based films are their susceptibility to native enzymes present in meat. They may be susceptible to native enzymes and may cause adverse reactions in consumers allergic to certain protein fractions (Sánchez-Ortega et al., 2014; Galus and Kadzińska, 2015). In addition, protein films can suffer from low mechanical strength water barrier issues, and interactions among the protein chains may result in rigid structures and brittleness (Calva-Estrada et al., 2019; Tkaczewska, 2020; Purewal et al., 2024). However, these issues can be improved with various chemical and enzymatic modifications or by combining them with other polymers, such as plant protein blends or lipids that provide complementary characteristics to the film composite (Calva-Estrada et al., 2019; Purewal et al., 2024). More specifically, adding a low molecular mass, nonvolatile compound such as sugar, alcohol, as well as gelatin hydrolysates as plasticizers can improve the mechanical properties of protein films while decreasing hardness and stiffness (Calva-Estrada et al., 2019; Kandasamy et al., 2021; Hadidi et al., 2022). As more of the chemistry of polymer blends becomes understood, it is anticipated that more diverse functionality can be added to these types of protein-based films and coatings.

One version of this type of packaging is to soak pads or fill a sachet with the respective antimicrobial to be placed inside the package (Otoni, et al., 2016). These sachets or pads may generate and release or carry and release antimicrobial ingredients of essential oils, allyl isothiocyanate, chlorine dioxide, or ethanol (Otoni et al., 2016). The pads may be absorbent to remove liquids or gases and may be impregnated with silver, copper, or copper oxide nanoparticles (Otoni, et al., 2016). Carbon dioxide emitters may also be placed in the packages. Carbon dioxide can act directly as an antimicrobial (Fang et al., 2017). These sachets and pads have a few drawbacks. They may decrease productivity due to the hand placement of the sachet or pad into the package (Contreras et al., 2018; Pereira de Abreu et al., 2012). There is also a concern that sachets may pose a risk to consumers via disintegration, contamination, or unintentional consumption (Contreras et al., 2018).

Antimicrobials can be incorporated into the packaging film by a method such as coextrusion of packaging films with the antimicrobials (Table 1). Soysal et al. (2015) investigated the effect of nisin, chitosan, potassium sorbate, or silver-substituted zeolite incorporated into low-density polyethylene (LDPE) on the physicochemical and microbiological quality of chicken drumsticks. The active packaging resulted in a lower level of total aerobic mesophilic bacteria, total coliform, mold, and yeast count on the product, with the chitosan-containing film being most successful in extending the shelf life and improving quality (Soysal et al., 2015). Other methods of including antimicrobials in packaging films without affecting bioactivity are solvent compounding, electrospinning, and casting (Sung et al., 2013). Plant extracts (e.g., rosemary extract), peptides, and nisin have been used as antimicrobial agents in active packaging systems (Arvanitoyannis and Stratakos, 2012). Ferrocinoa et al. (2016) used nisin in antimicrobial packaging to retard the growth of total viable bacteria and lactic acid bacteria in refrigerated beef burgers, thus increasing the shelf life of the meat. Nanoscale silver has also been applied to fresh pork loin, inhibiting total bacterial growth (Kuulialaa et al., 2015). Several manufacturers offer commercially available antimicrobial active packaging (Fang et al., 2017).

Packaging can also be coated with a carrier of antimicrobial agents so that the agents can be released onto the surface of food through evaporation into the headspace (volatile substances) or migration into food (nonvolatile substances) through diffusion (Coma, 2008). The cast film method is often used with antimicrobials that cannot tolerate polymer processing temperatures or heat-sensitive antimicrobials, such as volatile chemicals (Appendini and Hotchkiss, 2002; Emamifar, 2011; Sung et al., 2013; Sofı et al., 2018). Conventional coatings, including polyvinylidene chloride, polyvinyl alcohol (PVOH), and ethylene vinyl alcohol, are the most used in antimicrobial food-packaging films (Khaneghah et al., 2018).

High oxygen levels in meat packaging can accelerate microbial growth, lipid oxidation, changes in color and odor, and contribute to nutritional loss (Gómez-Estaca et al., 2014). Antioxidant active packaging can control the level of oxygen the product is exposed to, thus improving shelf life. Antioxidants scavenge oxygen, oxidative radical compounds, or metal ions from the food or the package headspace (McMillin, 2017). Antioxidant active packaging systems can be classified into 2 groups: 1) independent antioxidant devices and 2) antioxidant packaging materials (Gómez-Estaca et al., 2014).

Independent devices can be sachets, pads, or labels added to conventional packaging. These devices contain oxygen scavengers, separated from meat. The most common oxygen scavengers are fine powders of iron and ferrous oxide, although ascorbic acid, sulfites, catechols, ligands, and enzymes such as glucose oxidase have also been used (Brody et al., 2008). There are extensive reviews on the uses and applications of oxygen-scavenging packaging (Brody et al., 2001; Brody et al., 2008; Rooney, 2005; Suppakul et al., 2003). Synthetic antioxidants such as butylated hydroxyanisole are successfully used in antioxidant packaging. However, consumers’ rejection of these synthetic compounds has resulted in a growing trend to use natural antioxidants (Barbosa-Pereira et al., 2014; Sanches-Silva et al., 2014; Fang et al., 2017).

Alternative or “clean-label” additives have received considerable attention for maintaining shelf life in natural and organic ready-to-eat meats and controlling specific foodborne pathogens such as L. monocytogenes (Bodie et al., 2023; Bodie et al., 2024). Given their potential as food additives, it is not surprising that these alternative compounds would be attractive as packaging materials. Numerous combinations of natural antioxidants and films have been investigated. Chitosan and gelatin films with green tea extract, mango, and acerola pulps in starch films; marigold extract and barley husks in LDPE; pimento and oregano essential oils in milk protein films; palm fruit and cocoa/coffee in cassava starch films; and mustard meal in xanthan gum films have all demonstrated antioxidant capabilities (de Souza et al., 2013). Green tea extract, oolong tea extract, and black tea extract incorporated into protein films all decreased lipid oxidation of pork wrapped in the films, with green tea extract films having the highest antioxidant activity (Yang et al., 2016). These plant extracts and essential oils have become emphasized as an alternative to food packaging (Granato et al., 2017; Lorenzo et al., 2017; Poojary et al., 2017; Vinceković et al., 2017). Essential oils often have a strong odor, so it is necessary to determine the least amount that can be used to achieve the desired effect without changing the organoleptic characteristics of the meat (Viuda-Martos et al., 2008; Shen and Kamdem, 2015).

Active packaging films and coatings offer numerous benefits in support of human health and food quality. As discussed in the previous sections, opportunities to include antimicrobial compounds that restrict the proliferation of pathogenic organisms provide a public health safety attribute to package meat products. Similar approaches can also limit the growth of spoilage organisms and, in turn, the onset of spoilage and, ultimately, food waste. Incorporating active packaging is both an economic benefit to large-scale production by the food processor and extends shelf life for the retailer and the nutritive profile for consumers (Umaraw et al., 2020; Petkoska et al., 2021). Natural ingredients incorporated into packaging, such as herbs and spices, provide antimicrobial and/or antioxidant properties and serve as flavorings to add to sensory appeal and extend shelf life (Umaraw et al., 2020). As more active packaging components are developed, many will likely exhibit multifunctional properties.

It is also possible more novel functions can be introduced through active packaging. Peptides and protein hydrolysates have been proposed as potential components of edible biodegradable active packaging that could extend shelf life and possess health benefits when consumed (Tkaczewska, 2020). Khin et al. (2024) have suggested that bioactive compounds such as probiotics, prebiotics, and phenolic compounds could be incorporated into protein-based films and offer the means to maintain gastrointestinal health, decrease inflammation, and improve immune response. Phenolic compounds include phenolic acids, tannins, and lignans, as well as others that have been used in coating and films to improve oxidative stability and color but may also impart several health benefits such as being anticancer, anti-inflammatory, and antiallergic (Khin et al., 2022). Prebiotics are nondigestible compounds that benefit the host by selecting beneficial gastrointestinal microorganisms such as Lactobacillus and Bifidobacterium (Gibson and Roberfroid, 1995). Initially this included only a few β-linked oligosaccharide polymers, such as fructooligosaccharides. Still, as a better understanding of the gastrointestinal tract microbiota through employment of molecular tools such as microbiome 16S ribosomal RNA gene sequencing is being explored, it is now becoming clear that there is greater range of prebiotic candidates including noncarbohydrate compounds (Gibson et al., 2017; Swanson et al., 2025). Certain prebiotic polymers can be incorporated into different films. Khin et al. (2022) have proposed that including such bioactive compounds, if part of an edible film or coating, would help retain the viability of probiotic cultures in a particular food product. It is also possible that the presence of the prebiotic, these compounds could provide more direct benefits to the human gastrointestinal tract when the meat product is consumed.

Probiotics have been defined as viable organisms that, when consumed in sufficient quantities, provide health benefits to the host (Hill et al., 2014). Probiotics have a long history in human health and are additives for animals to modulate immune function and serve as competitive exclusion cultures against foodborne pathogen colonization (Swanson et al., 2025). Probiotics have been incorporated into certain films and coatings (Khin et al., 2022). Better stability can be achieved by including a prebiotic that serves as a substrate for the probiotic as part of the coating, resulting in what is defined as a synbiotic (Swanson et al., 2020; Khin et al., 2022). More recently, postbiotics have emerged as biological additives that consist of inanimate cells and/or their components that provide a health advantage to the host (Salminen et al., 2021). Whether such compounds could also be incorporated into packaging films and coatings remains to be determined. In general, further development of methods to retain the functionality of any of these biological agents will be needed to enhance their active components.

Nanosensors monitor the external and internal conditions of fresh and processed food products (Caon et al., 2017). Zhai et al. (2019) developed colorimetric hydrogen sulfide sensors made up of gellan gum-capped silver nanoparticles to indicate spoilage in chicken breast and silver carp. The sensor changes color from yellow to colorless when exposed to hydrogen sulfide. A starch-polyvinyl alcohol-based film containing zinc oxide nanoparticles is sensitive to pH and could be part of intelligent food packaging (Jayakumar et al., 2019). A soluble soybean polysaccharide film with curcumin and silicon dioxide displayed good antibacterial activity and distinctive color changes due to changes in pH during shrimp spoilage (Salarbashi et al., 2021).

Unfortunately, some studies have indicated that nanoparticles may have toxicological effects on biological systems (Dimitrijevic et al., 2015). The toxicity of nanoparticles depends on their type, concentration, duration of exposure, and sensitivity of the individual (Dimitrijevic et al., 2015). Organic nanoparticles may increase bioavailability, which could lead to toxicity. Consequently, both in vivo and in vitro studies must be performed to ensure food safety (Ashfaq et al., 2022). Numerous studies have been conducted on silver nanoparticles, which can cause neurotoxicity and genotoxicity and can deposit in the liver, kidney, testicles, and brain; however, the migration of silver nanoparticles up to this level in food is very low (Ahmad et al., 2021). Some nanoclay has been shown to cause cytotoxicity on long-term exposure (Bandyopadhyay and Ray, 2019). More studies must be done on migration, toxicity, and permissible limit of nanoparticles in food packaging that come in direct contact with food. Nevertheless, nanotechnology appears to be the front runner in novel food-packaging research.

A barcode is an optical machine-readable symbol relating to the object to which it is attached. They are cheap, easy to use, and widely used (Manthou and Vlachopoulou, 2001). The universal product code barcode consists of a pattern of bars and spaces, representing 12 digits of data that contain limited information such as manufacturer identification number and item number (Yam et al., 2005). Barcodes can be classified as 1-dimensional (1D) or 2-dimensional (2D). The 1D barcode is the familiar pattern of spaces and bars (Müller and Schmid, 2019). 2D bar codes contain more information including food packing date, batch/lot number, package weight, nutritional information, cooking instructions, and the website address of the food manufacturer and are readable by smartphones. These are the familiar quick response (i.e., QR) codes (Fang et al., 2017).

An RFID tag has a significantly larger data storage capacity, is noncontact, can gather real-time data out of the line of sight, and the data can penetrate nonmetallic materials (Mennecke and Townsend, 2005). However, RFID tags are costly compared to barcodes and require a more powerful electronic information network. Depending on the situation, RFID and barcode data carriers will likely continue to be used in the meat industry alone or in combination (Yam et al., 2005).

An RFID tag contains a tiny transponder and antenna with a unique number. The reader emits radio waves to capture data from the RFID tag, which are then passed to a computer for analysis and decision-making (Want, 2004). Low-frequency tags are cheaper, use less power, and are better able to penetrate nonmetallic objects, making these the best for use with meat products, primarily if the meat itself might hide the tags. They are also ideal for close-range scanning of objects with high water content (Kerry et al., 2006). The benefits of using RFID tags in the meat industry include traceability, inventory management, labor-saving costs, security, and promotion of quality and safety (Mousavi, et al. 2002).

A TTI is defined as “a simple, inexpensive device attached to shipping containers or individual consumer packages that can show measurable, time-temperature dependent changes that reflect the full or partial temperature history of a food product” (Taoukis and Labuza, 1989). The basic operation principles of TTI are to alert processors and consumers when temperature conditions reduce quality or may result in food safety concerns (Smolander et al., 2004; Kerry et al., 2006; Taoukis and Labuza, 2003). Commercially available TTI include critical temperature indicators (show exposure above [or below] a reference temperature), partial history indicators (indicate that a product has been exposed to a temperature sufficient to cause a change in product quality or safety), and full history indicators (a continuous temperature-dependent response throughout a product’s history) (Biji et al, 2015).

After the meat is packaged, the gas composition within the package changes due to the activity of the food, the package nature, gas generation by spoilage microorganisms, or gas transmission through the packaging material or leaks (Yam et al., 2005). Gas indicators are small devices that can be part of the package label or printed on the packaging film. Usually the gas indicator changes color to reflect the gas composition changes (Fang et al., 2017). The most common gas indicators detect oxygen, since oxygen is the most deleterious to safety and quality because it induces oxidative rancidity, color change, and microbial spoilage. For instance, the Ageless Eye^® oxygen indicator produced by Mitsubishi Gas Chemical Company can be inserted inside the container. When the oxygen content exceeds 0.5%, the indicator changes color from pink to blue (Fang et al., 2017). Oxygen indicators have also been used to detect improper sealing and quality deterioration of modified atmospheric packaging in fresh beef (Ahvenainen et al., 1997; Smiddy et al., 2002). Carbon dioxide, water vapor, ethanol, hydrogen sulfide, and other gas indicators have also been reported (Fang et al., 2017).

Freshness indicators show the actual spoilage of products (Pereira de Abreu et al., 2012). These indicators are based on the knowledge of metabolites, specifically associated with spoilage bacteria, packaging type, and storage conditions of the meat product (Fang et al., 2017). The major quality-indicating metabolites produced by these bacteria include glucose, organic acids (e.g., lactic acid), ethanol, volatile nitrogen compounds, biogenic amines (e.g., tyramine, cadaverine, putrescine, histamine), carbon dioxide, adenosine triphosphate degradation products, and sulfuric compounds. The presence of these compounds in the package result in a color change in the indicator (Smolander, 2003).

Various freshness indicators have been developed (Han et al., 2005; Kerry et al., 2006; Smolander, 2003). One of the most common freshness indicators in meat packaging is bromothymol blue pH dye, which monitors the carbon dioxide produced by microbial growth (Smolander et al, 1997). Other pH dyes that serve the same purpose are xylenol blue, bromocresol purple, bromocresol green, cresol red, phenol red, methyl red, and alizarin (Horan, 2000). Other metabolites, including sulfur dioxide, ammonium, volatile amines, and organic acids, have been used as target monitoring molecules using pH-sensitive indicators (Smolander, 2003). Many spoilage bacteria produce hydrogen sulfide, which is known to bind to myoglobin to produce a green pigment (sulfomyoglobin). An indicator for this has been developed that explicitly detects hydrogen sulfide even in the presence of nitrogen and carbon dioxide (Smolander et al., 2002).

Indicators to detect pathogens directly have also been developed. These devices are biosensors that can detect, record, and transmit information on biochemical reactions specific to the pathogens (Yam et al., 2005). These devices have a bioreceptor, an organic or biological material such as an enzyme, antigen, microorganism, hormone, or nucleic acid, that recognizes a target analyte coupled with an electrochemical, optical, or calorimetric transducer (Yam et al., 2005). These pathogen indicators change color in the food package to warn consumers/retailers that the food must not be consumed (Yam et al., 2005).

Foodborne pathogen detection has been a targeted area for research and commercial development. SIRA Technologies (California, USA) has a commercially available pathogen indicator called Food Sentinel System^™ (SIRA Technologies, 2019). Antibodies specific to the target pathogen (e.g., Salmonella spp., E. coli O157:H7, or L. monocytogenes) are attached to a membrane that is part of the barcode. If the pathogen is present a localized dark bar forms over the barcode, making it impossible to scan the barcode. Another pathogen indicator is Toxin Guard^™ developed by Toxin Alert (Ontario, Canada), which has biochemical sensors incorporating antibodies in a polyethylene-based plastic packaging. The system can detect Salmonella spp., Campylobacter spp., E. coli, and Listeria spp. (Bodenhamer, 2000). Yousefı et al. (2018) developed a transparent sensing surface that generated a fluorescent signal when encountering a specific bacterium of interest, allowing real-time monitoring without disturbing the packaged project. They accomplished this by attaching an E. coli-specific RNA-cleaving fluorogenic DNA-enzyme probe microarrays to a transparent cyclo-olefin polymer film. While initially specific to E. coli, this technology could certainly be adapted to other foodborne pathogens and eventually to indicator organisms for the onset of spoilage.

Intelligent packaging is expensive and will only be used if the technology increases sales or reduces waste (Heising et al., 2014; Vanderroost, et al., 2014). Although customers say they want better quality and more product information, most will not pay more for them (Müller and Schmid, 2019). Promoting intelligent packaging to consumers to increase confidence in the safety of the systems and spelling out the benefits of intelligent packaging could increase their willingness to pay more for this packaging (Sohail et al., 2018). However, further advances in polymer extrusion technologies are needed to accommodate introduction of these types of packaging materials (Altıparmak et al., 2022; Prabha et al., 2021; Zhou et al., 2021). In addition, further technological developments with nanotechnology, 3D printing, and more advanced polymer composites may help decrease cost, but consumer acceptance may still be challenging.