Introduction

Nowadays, the food packaging sector is encountering a number of challenges to improve the shelf life of perishable and semiperishable food products such as fruits, vegetables, meat and meat products, bakery, and other products in order to maintain their consumer acceptability at minimum health risk [1,2,3]. The leading role of the food packaging sector is to provide protection to the food from physical, mechanical, chemical, and biological effects by creating barrier properties against water transpiration and gas exchange, retaining higher quality attributes, and reducing the microbiological load and solid waste that could affect the shelf life extension of food products [4, 5]. The lack of packaging technologies can affect the environment surrounding by generating a food waste. As per the World Bank report, the total solid waste was accounted as 1.3 billion tons in 2012 and expected to increase up to 2.2 billion tons annually by 2025. The use of non-biodegradable and non-renewable packaging sources can have serious environmental drawbacks [6, 7]. Additionally, the demand for healthy and safe foods with minimum use of chemical-, synthetic-, or plastic-based inputs has rapidly increased in the last few decades due to increasing consumer awareness about environmental and health concerns [8]. The edible packaging in the form of coatings and films can be the best alternative solution for the reduction of non-renewable and non-biodegradable packaging options of food products [9,10,11]. The development of edible coating and films for the shelf life extension of food products has seen remarkable growth in recent years [12]. In the year 2020, the global market of edible coating and films was valued at USD 2.06 billion and projected to grow at a CAGR of 7.64% during 2021–2027. The increase in market share is due to the greater use of edible films and coatings as alternatives to traditional plastic-based food packaging materials. This growth is driven by stringent food packaging laws aimed at ensuring food safety and addressing sustainability concerns. Recently, with the advancement in sustainable packaging, countries are moving ahead from the linear economy to the circular economy [13]. The European Union (EU) in 2020 adopted the Circular Economy Action Plan that aims at reducing the traditional packaging waste and promotes the use biodegradable polymers for safeguarding the environment. Moreover, in the recent years (2000–2021), a large number of research articles in aspects of edible coatings and films for food products have been published in different databases such as Elsevier, Taylor & Francis, Wiley, Springer Nature, Emerald Insight, and Inderscience. Figure 1 schematic indicates the interest of researchers and scientific community in the arena of edible packaging for food products. The number of publications on edible packaging for different types of food products has found approximately 9-fold increase during the period of 2000–2021.

Fig. 1
figure 1

Schematic representation of publications on edible packaging from 2000 to 2021

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Food packaging plays a crucial role in protecting the food products during the supply chain and the storage period that may help in the reduction of food waste and loss. The innovation in packaging technology such as edible packaging and nano-based packaging provides new opportunities to improve the efficiency of packaging materials as well as quality of food products by protection from the deterioration agents [2, 14]. From the past times, the petroleum-derived polymers have been used for packaging purposes which are not beneficial due to the environmental and safety concerns [15]. To overcome this problem, edible packaging helps in reducing the use of synthetic/plastic polymers in food packaging industry.

According to the framework regulations EC 1935/2004, the food packaging and other contact packaging materials must be used as per the Food Safety Act, 1991. This act states that the packaging materials should not release any toxic constituents into the food products at a level that could be harmful to human health. Numerous types of natural biopolymers such as polysaccharide, proteins, and lipids derived from plant and animal sources are available for developing a variety of edible packaging for different food categories; these biopolymers have good film/coating forming ability with biodegradable and non-toxic nature [16, 17]. Therefore, the main aim of this study was to succinctly review the literature the relevant to the different types of edible packaging (coatings and films), edible components, and different types of additives (active agents, nanomaterials, plasticizers), including high-pressure homogenization technologies used for developing nanopackaging to improve their stability. In addition, different types of film formation and deposition methods of edible packaging on food products are also reviewed. In addition, this review also describes the effects of different types of composite edible packaging, including binary and ternary packaging on the quality attributes on different types of food products. Conclusively, this study provides innovative, scientific, and collective information about the concept, mechanism, and application of different types of edible packaging for food products, which could be beneficial for the scholars, researchers, and the scientists’ community to explore the applications of edible packaging in food processing sector.

Edible Packaging

In recent years, at global level, the use of plastic and synthetic packaging materials exceeds a million tons annually [18]. As per reports of research and markets (2020–2025), the annual consumption of plastic-based materials has increased approximately 230 million tons till date. Moreover, the plastic- and synthetic-based materials are non-biodegradable and cause a lot of problems to the environment as well as to human health. The environmental pollutions affect human cardiovascular and respiratory systems and can cause several types of disease risks such as asthma, lung cancer, cardiovascular disease, chronic obstructive pulmonary disease, bronchiolitis, dysfunctions of central nervous system, and cutaneous diseases due to release of harmful gases and polycyclic aromatic hydrocarbons [19]. To minimize these environmental problems and address health and safety issues, edible packaging offers a suitable and renewable solution, in addition to its biodegradable, non-toxic, and biocompatible nature. These packaging can also serve as a carrier of active ingredients, such as different additives, colorants, flavors, antioxidant/antimicrobial agents, plant active agents, nutraceuticals, probiotics, and prebiotics, thereby providing food safety and quality [20, 21]. Edible packaging, i.e., edible coatings and films, are excellent eco-friendly options to extend the shelf life of food products for a longer period of time by retarding the oxidation, moisture transfer, enzymatic metabolic activity, and microbial spoilage [22,23,24]. Historically, the wax-based edible packaging (coating) was firstly used to extend the shelf life of citrus fruits; it was initially used in the twelfth century in China [17]. Technically, the edible coatings and edible films are different terms. For example, edible coating is a liquid form of material that can be applied to the surface of food products using dipping, spraying, panning, and fluidized bed deposition methods. It can also act as a barrier to prevent oxidation and moisture loss in food products. On the other hand, an edible film is a thin layer or solid sheet that can be applied as a wrapping, covering, packaging, or a separation layer for food products to prevent external, environmental, and other physiological damage [23, 25]. The edible coatings and films can be directly applied to the surface of the food products.

The edible packaging (active) is regulated by European Union, regulation No. 1935/2004 and its amended regulation No. 2023/2006 [26]. Several types of biopolymers such as polysaccharides, proteins, lipids, and their composites can be used to develop edible coatings and films for extending shelf life of fruits, vegetables, meat, meat products, and other items [2, 27]. These biopolymers can be derived from renewable and edible sources, i.e., plants, animals, bacteria, fungi, and algae. The main representatives of biopolymers include polysaccharides (cellulose, starch, pectin, hemicellulose, gums, agar, alginates, chitosan, pullulan, and others), proteins (gluten, soy protein, zein, casein, collagen, whey protein, and fish protein), and lipids (bee wax, shellac wax, carnauba wax, free fatty acids, and oils). In general, they are used as thickening agents, gallants, emulsifiers, stabilizers, foaming agents, and protector coating in the food and pharmaceutical sectors [2, 28]. Moreover, biopolymers are non-toxic, eco-friendly, biodegradable, and biocompatible in nature and also act as a carrier of active agents such as organic acids [29], plant extracts [30,31,32], antimicrobial compounds [33], essential oils [34], probiotics, and prebiotics [21, 35]. Additionally, the plasticizers (glycerol, propylene glycol, and polyethylene glycol), as low molecular weight and non-volatile compounds, are used to improve the viscosity, resistance, flexibility, solubility, barrier, thermal, and mechanical properties of the edible films and coatings by reducing the tension of hardness, deformation, density, viscosity, and electrostatic charge of polymers. At the same time, plasticizers change the three-dimensional molecular structure of biopolymers, reducing the required energy for molecular motion and formation of hydrogen bonding between the polymer chains [2, 36]. The poor water vapor barrier property of the polysaccharide-based edible packaging is the only disadvantage due to the presence of polar groups that results in the hydrophilicity of the biopolymers [13]. The hydrophilic nature of the polysaccharide-based biopolymers also results in the cracking and flaking of the edible packaging [37]. On the other hand, the main drawback of the protein-based edible coating and films is poor gas barrier property due to hydrophilic nature like polysaccharide. Therefore, several researchers have worked on the development of polysaccharide and protein-based edible packaging with good water and gas barrier properties using of cross-linking agents as additives [38].

The biopolymer-based edible packaging is a promising technology for preserving food and food products. It helps prolong their shelf life and functionality by retaining higher quality attributes, preserving the freshness of food products, and maintaining their color, vitamins, minerals, and other nutritional and sensory characteristics. Additionally, it minimizes issues such as lipid oxidation, weight loss, and microbial contaminations [39,40,41]. The application and mechanism of edible coating on different types of food products are shown in Fig. 2. The recent investigation has evidentially proved that the application of edible coating could be a potential way to extend the shelf life of fruits and vegetables such as mango [42, 43]; banana [44]; grapes [45]; pomegranate [46]; blueberry, plum, and nectarin [47, 48]; strawberry [49, 50]; cucumber [51]; carrot [52]; tomato [53]; and others fresh cuts [54,55,56], including meat and meat products such as trout fillets [57]; chicken breast fillets [58]; pork chops [59]; chicken and meat ball [60]; meat, beef, and pork patties [16]; beef products [61]; ham and bologna [62]; bacon [63]; and biscuits [64] by retarding the moisture loss, minimizing the lipid oxidation, discoloration, reducing shrinkage, minimizing tyrosine value, and lowering off flavor and microbial load. Moreover, the polysaccharide-based edible packaging has good gas barrier properties with excellent mechanical and thermal properties. On the contrary, the lipid-based edible packaging lacks gas barrier properties; however, it is beneficial in the context of water transpiration barrier properties [65, 66]. According to Yousefi et al. [67], the application of edible-coating material prepared using sodium alginate, pectin, chitosan, gelatin, collagen, soy protein, whey protein, sodium caseinate, acetylated monoglyceride, diglyceride, and acetylated monoglyceride has potential in meat and meat products to maintain their quality attributes and shelf life for a longer period during storage. On the other hand, Rux et al. [68] extended the shelf life of cucumbers using commercially available lipid-based edible coating (LiquidSeal). Their study reported that the application of the coating drastically retarded the water loss and respiration rate. Additionally, a majority of the consumers endorsed the coating as an alternative of plastic-based packaging.

Fig. 2
figure 2

Application, mechanism, and functions of edible coating on food product

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The different types of polysaccharide, protein, and lipid-based biopolymers such as chitosan, cassava starch, pullulan, gelatin [30, 31, 69], starch [70, 71], aloe vera [72], alginate [73], carboxy-methyl-cellulose, hydroxyl-propylmethylcellulose [74], pectin [75], xanthangum, gum arabic [76], guar gum [77], whey protein [78], shellac wax [79], carnauba wax [80], and bee wax [81] were used to extend the shelf life of fruits and vegetables and other food products like guavas, black mulberries, mango, green bell pepper, blue berries, tomatoes, black berries, chili, pineapples, shrimps, cheese, sea bass, and strawberries.

The natural biopolymer components are widely used to develop eco-friendly and biodegradable packaging for different types of food products. Several types of edible packaging such as smart/intelligent and active packaging, composite edible packaging, nanopackaging, and nanoformulations are used to extend the shelf life and quality attributes of the food products. The biopolymer edible packaging acts as a barrier against moisture, oxygen, aroma, oil barrier, and mass transfer and also acts as a carrier of active ingredients such as antioxidants, antimicrobials, colorants, and flavoring agents [82].

General Characteristics of Edible Coatings and Films

In order to acquire the ideal properties of edible packaging, coatings, and films, physical, chemical, mechanical, thermal, barrier, and biological characteristics are very important. These properties usually include the moisture/gas barrier properties, rheological, adhesive properties, transparency, opacity, moisture absorption, solubility, swelling capacity, thermal properties (glass transition), mechanical (tensile strength, young module, elongation at break), color, contact angle, hydrophilic-hydrophobic interaction, particle size, microstructure, functional, antimicrobial, antifungal, antioxidant, organoleptic, and others [83]. They are affected by several factors such as types and properties of polymer matrix, its crystallinity, film-forming conditions, type of solvent used, pH of formulation, casting and drying temperatures, and concentrations of additives, i.e., plasticizer, antimicrobial agents, antioxidants, emulsifiers, and cross-linking agents [24, 84]. Also, the nature of the food item and its surface characteristics are important for application of edible coatings and films as well as the used deposition method. Therefore, the quality of the packed system is determined by the characteristics of the food item, packaging material, and the applied deposition method.

Composite Edible Packaging

In recent years, researchers have focused on developing composite edible coatings and films to improve the shelf life of food products; it is also termed as multicomponent system [85]. Therefore, to develop the composite edible packaging for food products, the biopolymer combinations such as carbohydrates-carbohydrates, protein–carbohydrates, lipid-based binary, and ternary biopolymer combinations are used in general [86]. The composite or blended biopolymer-based edible packaging is more effective to improve the quality attributes of food products [87]. The properties of the composite edible coatings and films are dependent on the compatibility and molecular interactions between the materials and additives within the composition [88, 89]. Sometimes the composite edible packaging achieves synergistic effects of the used polymers. The combination of biopolymers allows enhancing the thermal, mechanical, barrier, and other physico-chemical properties of edible coatings and films, thereby extending their applications in food packaging sector due to intermolecular interaction and microphase separation processes between the blended biopolymers [90, 91]. Cortés-Rodríguez et al. [92] improved the physicochemical and mechanical properties of composite edible packaging developed using chitosan, whey protein, and cassava starch for application on fruits. Previously, there are studies that present composite edible coatings and films for the extension of the shelf life of fruits and vegetables [93] and bakery products, i.e., bread, buns, biscuits, etc. [94,95,96]. The composite edible coatings and films can be classified as binary and ternary materials; the binary edible film contains a combination of two hydrocolloids while ternary including a combination of three hydrocolloids [82, 85]. The composition of binary edible coatings and films can be formulated using a combination of carbohydrate–carbohydrate, carbohydrate–protein, and protein–protein [97, 98]. Many researchers have developed binary and ternary edible coatings/films using different types of biopolymers. The inclusion of carbohydrates with protein-based formulation to developing edible films has shown enormous applications in food packaging sector due to their polymer properties, i.e., water and gas transpiration properties [85]. Several methods like classical, thermo-mechanical, and enzymatic methods can be used to develop binary and ternary complexes. Classical method is the standard protocol used in the preparation of binary complex; in this method, the complexes are boiled in water bath, then cooled overnight, and lastly centrifuged to collect supernatant [99]. Thermo-mechanical and enzymatic methods are used to develop ternary complexes for food packaging. In thermo-mechanical process, rapid visco analyzer is used to produce ternary complex. To obtain the starch–lipid–protein-based ternary complex, the mixture is lyophilized and then ground. In enzymatic method, the ternary composite coatings and films can be produced by polymerization of primers to branched polymers and their enzymatic hydrolysis into smaller parts for interaction between polymers [100]. Previous researchers, Maizura et al. [101] developed a composite edible packaging using hydrolyzed sago starch/alginate and reported that the inclusion of two matrixes improved the mechanical, barrier, and antimicrobial activities with excellent adhesive properties. The binary edible film based on chitosan and pullulan was also prepared by Kumar et al. [90]; their application on different fruits and vegetables was performed on mango [93], bell pepper [30], tomato [31], and litchi [102]; they were investigated and extended their shelf life by 6, 3, 6, and 3 days, respectively, at ambient temperature. In addition to these studies, all the fruits and vegetables were found acceptable at the end of storage time (18 days) at cold storage conditions. The binary and ternary complexes based on gellan gum, 2 hydroxyethyl cellulose, and lignin were prepared for food packaging application by Rukmanikrishnan et al. [103]. The prepared composites were potential to UV protection with improving thermal stability [104]. The higher antioxidant activity of binary and ternary composites was recorded with incorporation of 1%, 5%, and 10% (weight per volume) of lignin. The composite packaging (coating/films) of gelatin–pectin enriched with garlic essential oil [105], sodium alginate–sodium isoascorbate [106], chitosan–montmorillonite nanocomposite [107], corn starch with cellulose nanofiber, emulsifier and basil essential oils [108], konjac glucomannan–curdlan [109], yam starch with aetoxylon bouya essential oils (EOs) and calcium propionate [110], potato starch–sodium abenzoate [111], and hydroxypropyl methylcellulose with cyclodextrin and cellulose nanocrystals [112] were developed to improving the postharvest shelf life of red chilli, freshcut pineapple, Williams pear, mandarin, cherry tomatoes, and strawberry fruits throughout the storage period by minimizing the weight loss, lipid oxidation, maintained higher consumer acceptability, and color attributes.

Based on the previous studies, it can be concluded that the addition of various types of natural ingredients such as plant extracts, essential oils, plasticizers, cross-linking agents, and nanomaterials are used to developed active packaging; most of these ingredients act as an antimicrobial agent and help in minimizing lipid oxidation or improving the functional, mechanical, and barrier properties of the edible coatings/films and at the same time help in the protection food from external environment. The addition of natural ingredient helps in the elimination of unwanted components such as moisture content, harmful gases, and odors. The choice of packaging material and additives depends on the types of commodities and their respiratory and transpiratory actions. Hamed et al. [84] reported that the addition of natural agents, plasticizers, and nanomaterial in the coating formulations improved the mechanical properties and also act as ethylene scavengers, CO2 emitters, O2 scavengers, and antimicrobial/antioxidant effects on the produces, which resulted in prolonged shelf life. The water and oxygen barriers as well as antimicrobial properties of starch [113]- and chitosan [114]-based films were improved with the addition of cinnamon essential oils and luteolin nanoemulsion. On the other hand, Kumar et al. [90] proved that the addition of pomegranate peel extract and glycerol helps in the improving mechanical, physical, barrier, and thermal properties of chitosan: pullulan composite edible packaging for food applications due to intermolecular interaction between the matrixes. The addition of plasticizers may help in binding the materials with together, resulting in a smaller particle size of matrix and improved flexibility, workability, and distensibility of the packaging [36]. However, the encapsulation of nanomaterials and active agents such as plant extract and essential oils may possess antimicrobial properties and also help their controlled and sustainable release due to their chemical natures, relative to the amounts of interaction of their constituents [115]. The antimicrobial effects mainly attributed to the diffusion of active agents to nanoparticle via film and surface of microorganism, damaged their cell wall, and deactivated the microorganism through critical biochemical pathway [116]. Numerous researches have been reported that the synergistic interactions between the major and minor bioactive may result antimicrobial mechanism of essential oils in edible packaging [117]. In addition, the encapsulation of active agents may improve the dispersibility, compatibility between the matrixes, and stability of antimicrobial/antimicrobial activity. Several researchers have previously encapsulated active agents such as essential oils, plant extract, and nanomaterials (nanoemulsion) to improve the antimicrobial mechanism of packaging materials for food applications [118]. For example, Kong et al. [119] and Chen et al. [120] improved the antifungal and antibacterial activity against Escherichia coli, Staphylococcus aureus, and Bacillus cereus in starch–PVA and gelatine nanofiber-based biodegradable packaging with the addition of carvacrol nanoemulsion and eugenol EOs, respectively. On the other hand, the oregano EO nanoemulsion was incorporated in HPMC coating formulations and improved their antimicrobial activity against S. aureus, Listeria monocytogenes, E. coli, Salmonella typhimurium, Pseudomonas aeruginosa, Vibrio parahaemolyticus, etc. [121].

Cross-linking Agents

The cross-linkers agents are important agents to improve the mechanical, structural, thermal, and other properties of edible packaging [122]. Several types of cross-linking agents such as tannic acid [123]; genipin [124]; transglutaminase [125, 126]; galla chinensis extract [127]; clay [128]; glutaraldehyde, sodium trimetaphosphate, and citric acid [129, 130]; sodium chloride [131]; calcium chloride [132,133,134]; carboxymethyl cellulose/hydroxypropyl methylcellulose [135]; and calcium lactate, formaldehyde, carbodimide, hexamethylene, 1,6-diaminocarboxysulfonate, glutaraldehyde, keratin, metal ions, natural extracts zink chloride, heparin, wax, tannic acid, and lactic acid [132, 136, 137] are used to improve the properties of polymers. Based on the recommendation by the competent authority, as well as considering their nature and toxicity/non-toxicity, these cross-linkers can be used to develop edible packaging for food products [138]. The incorporation of cross-linkers with polymer constructs a cross-linked fluid system; they also help to significantly improve the rheological characteristics of the materials by increasing molecular weight of polymers and intermolecular interactions [139]. Furthermore, they help improve the molecular structure of the polymer matrix, develop a porous structure, enhance mechanical strength, and improve functional properties, such as hydration, cohesion, water resistance, and gas barrier properties of edible packaging [140,141,142]. Therefore, the selection and choice of the cross-linking agents depend on the chemical structure, molecular weight, functional groups of the polymers, and their compatibility and molecular interaction with cross-linking agents, suggesting that cross-linking agents must be cost-effective, recognized as safe for consumption, and recommended to be used in food processing sector [28, 123, 143]. Several researchers investigated the effects of cross-linking agents on the properties of different types of edible packaging (films and coatings) — they reported that the addition of cross-linking agents has the potential to improve the functionality of the edible packaging by creating van der Waals forces and hydrophobic and hydrogen bonds and by ion-cross-linking and electrolytic interactions; also, they help to extend the shelf life of food products throughout the storage condition [144, 145].

Zhang et al. [146] reviewed and reported that the cross-linking agents such as citric acid help in the improving physical, mechanical, and antimicrobial properties of packaging films and can be used in preserving the shelf life and organoleptic properties of fresh foods. Duong et al. [147] used calcium chloride and hexyl acetate as cross-linking agents to improve the functional properties, such as barrier and mechanical properties, of alginate-based packaging. This led to prolonged shelf life of fresh-cut rose apple by up to 10 days at 4 °C, achieved through delayed browning, reduced respiration rate, and microbial load.

Active Edible Packaging

Nowadays, the development of edible packaging (coating/film) with natural antimicrobial and antioxidant agents has great potential due to food safety and extending shelf life of food products by minimizing oxidation with the retention of higher quality attributes of the food products, i.e., fruits, vegetables, fresh cuts, meat, and dairy products [120, 148, 149]. The incorporation of additives such as plasticizer, emulsifier, nanoparticles, and natural active agents (essential oils, plant extracts, etc.) significantly improves the properties of edible packaging [150], which helps to maintain the shelf life and quality attributes of the package food products, i.e., fruits, vegetables, and others [24, 151]. As per EU Commission regulation (No. 450/2009), the incorporation of active agents deliberately in food packaging or the surrounding environment of food products would enable the absorption or release of substances in various food packaging forms [152]. Some of the commercially available active packagings such as Active-Film™, PEAKfresh, BIOPAC, ATCO, SANDRY, FreshPax, Celox™, ZERO2, Biomaster, Food-touch, ATOX, Pure Temp, and Green box are available in the market for food packaging purposes [153]. These active packaging methods help in the food protection by controlling moisture loss, reducing water vapor transmission rates, inhibiting ethylene synthesis, and improving antimicrobial and antioxidant activities. The naturally derived active agents such as essential oils and plant extracts can be incorporated in edible coatings and films to enhance their functional properties. They act as antioxidant and/or antimicrobial agents, helping to reduce the oxidative stress and microbial contamination. The incorporation of active ingredients is responsible for the destruction of both outer and inner membranes of microbial cells, leading to their death [154, 155]. The multifunctional intelligent and pH-senstitve active packaging was developed by Kong et al. [156] using cross-linked zein. The prepared packaging was found effective to monitoring the freshness of the pork at 4 °C up to 9 days of storage. The mesoporous silica nanoparticles were used with tea tree essential oils and blueberry extract, serving as antimicrobial and antioxidant agents, respectively, while also functioning as a colorimetric pH indicator. The packaging can be easily monitoring the freshness of meat by cell phone.

Essential Oils

Nowadays, the consumer awareness and demand of the natural antimicrobial and preservative free food packaging have been increasing due to food safety and health concern [157]. Essential oils (EOs) are one of the most important naturally derived products with natural antimicrobial, antioxidant, and antifungal properties due to the presence of phenolic and bioactive compounds [158]. They are generally recognized as safe for human consumption, and they have been approved by United States Food and Drug Administration (US FDA) to use as additives and flavor agents in food or food products. Usually, EOs are used in food packaging industry to develop antimicrobial packaging against several types of foodborne pathogens [159, 160]. Recently, many researchers considerably investigated the effects of EOs such as tea tree [161]; oregano, rosemary, and garlic [162]; thyme, lemon grass, and sage [163]; Origanum vulgare L. [164, 165]; lime [157]; Zataria multiflora [166]; citral [167]; clove [168]; sunflower [34]; curcuma oil [169]; basil oil [170]; and ornage peel [171] to improve the physical, mechanical, barrier, and biological properties of PLA, quince seed mucilage, alginate and pectin sodium alginate, hydroxypropyl methylcellulose, chitosan, chitosan/zein, pectic and basil seed gum–based edible, and composite films by minimizing mentioned flaws [172, 173]. Therefore, the incorporation of EOs into edible packaging provides a sustained release of bioactive ingredients which helps to minimize oxidation and mask the undesirable aroma [174, 175]. Additionally, the EOs are used to develop antifungal coating, especially for fruits and vegetables, to retard the green and blue molds in highly perishable and perishable horticulture commodities. Furthermore, the addition of EOs as potential natural antimicrobial additive is concerned with improving the properties of edible films/coatings as well as food products, such as beverages, fruits and vegetables, milk, and dairy-based products [158, 176].

Plant Extracts

Plant-derived natural polyphenols are attractive components to fabricate and improve the functionality of the food packaging. Plant parts such as leaves, flower, seed, root, and peel waste have potential to extract antimicrobial and antioxidant polyphenols and bioactive compounds and incorporate them into edible coating and films. This offers an alternative to traditional packaging methods and helps to overcome postharvest losses by extending shelf life [148, 177]. These plant extracts can act as antibrowning agents, nutrients, colorants, and antimicrobial agents in edible packagings [178]. In addition, plant-derived natural extracts are recommended for incorporating in the food and are generally recognized as safe for the consumption. The incorporation of plant-derived extracts in polymer matrix provides mechanical, thermal, biological, and other physicochemical properties of the packaging materials. These properties of edible films and coatings depend on the interaction between the matrix and plant extract, their molecular interaction, and the crystallinity of the polymers [90]. The previous scientific evidences have proved that the incorporation of plant extracts such as pomegranate peel extract [24, 90], raspberry extract [179]; green tea extract [180]; blueberry extract [181]; bilberry extract [182]; parsley, grape, and blueberry pomace extracts [183]; green tea extract [161]; tea extract [184]; cinnamon, clove, and star anise extracts [185]; and grape fruit seed extract, improves the thermal, mechanical, biological, and other properties of edible packaging and food products [178].

Nanomaterials

Nanotechnology is an emerging technology used in the food packaging sector for developing the nanopackaging with an excellent barrier, mechanical, thermal, antioxidant, and antimicrobial properties. It is expected that the manufacturing of the nanopackaging will cover 25% of the total food packaging in near future. The nanotechnology intervention in the food packaging sector helps to extend the shelf life of the food products by ensuring the food safety, reduced food losses and shortage, and repairing the tears in packaging for improving the consumer health. Several types of nanomaterials including nanoparticles, polymer nanocomposite, nanoemuslions, nanoformulations, and nanofillers, such as nanostarch, nanocellulose, nanochitosan, nanoproteins, and nanolipids, have been used to develop active packaging by extending the major properties of the packaging systems such as containment, convenience, protection, preservation, marketing, and eco-friendliness [186,187,188]. Nanoparticles, such as silver, gold, titanium dioxide, zinc, and nanoclay, have been used to improve the properties of food packaging [189, 190]. The nanomaterials and other forms of nanotechnology processes generally improve the packaging system by developing active, smart, and intelligent packaging systems by protection of food from mechanical, physical, microbial, and UV damages [191]. Additionally, they could control the release of preservatives and other active agents to extend the shelf life of food products.

Regulatory Aspect of Nanomaterials

Nanomaterials (NMs) have demonstrated their potential in improving the functional properties of the packaging materials, but NMs due to their relatively small size, migration from the packaging material into food, and high power of penetration in human cells could be a real threat to public health [192, 193]. The various regulatory organizations around the globe have laid down various laws and safety guidelines for the use of NMs for the food and the packaging applications [194]. These regulatory laws and guidelines differ from country to country and include the explicit or implicit mention of NMs in the regulatory documents [195]. The EU (European) Commission in 2011 through its recommendation 2011/696/EU has explicitly talked about the definition of nanomaterials. They defined NMs as “a natural, incidental or manufactured material containing particle, in a unbound state or as an aggregate or as an agglomerate and where, for 50% or more of the particles in the number size distribution, one or more external dimensions is in the size range of 1 nm–100 nm” [196]. NMs used for the packaging applications fall under the regulations of plastic food contact materials [197], and risk associated with NMs will be performed case-by-case basis. The FDA regulatory body of the USA has published the guidelines for the use of nanomaterials in food packaging applications and stressed the importance of evaluating the safety of NM on a case-by-case basis. The FDA has approved titanium dioxide and silicon dioxide NMs for use as food contact materials [198, 199], and zinc oxide NM has been granted generally recognized as safe (GRAS) status [200].

Techniques for Development of Nanoformulations

In food packaging sector, several types of techniques such as high-energy and low-energy techniques were used for the development of nanoformulations and nanoemulsions. High-energy techniques like high-pressure homogenizer, ultrasonication, and microfluidizer are used for the formation of nanomaterials; on the other hand, the low-energy techniques include phase inversion temperature and composition and spontaneous emulsification methods [201]. For the development of minimum particle size formulations, the high-energy emulsification techniques preferred to develop packaging for food purposes [202]. The high-energy techniques promote the high mechanical force application to develop nanoformulations by reducing larger droplets into smaller sizes. They help to increase the surface area of the matrix by reducing their particle size which improves mechanical, physical, thermal, barrier, and other functional properties of the edible coatings and films [203]. These techniques reduce the particle size of the matrix through cavitation mechanism by supplying an adequate amount of energy. High-pressure homogenization process is divided into two parts, i.e., hot high-pressure homogenizer (HHPH) and cold high-pressure homogenizer (CHPH) techniques. In HHPH, mixtures are dispersed in warm surfactants above melting point and stirred at high-speed rotation, while in CHPH, the mixture is dispersed in cold surfactants [202]. The high-pressure homogenization techniques provide more uniformity and dispersion of the materials [204], which results in increasing the surface area of the material by reducing the particle size and promoting microphase separation between two materials and additives [205].

Film Formation and Deposition Methods of Edible Packaging on Food Products

The applicability of the edible coatings on food products like meat and meat products, fruits and vegetables, and others is an important part to prolong the shelf life of these products. This is achieved by retarding moisture loss, reducing microbial count, preventing color degradation, minimizing oxidation, and minimizing loss of sensory characteristics. The edible packaging can be applied on the different types of food products according to the product types, their characteristics, and physical properties such as viscosity, density, and surface tension of the matrix. The wet process mechanism is based on the dispersion of the polymers. Several types of deposition techniques are known like dipping, brushing, spraying, fluidized bed coating, electrospraying, panning, electrostatic deposition, and vacuum impregnation [12, 206, 207]. Figure 3 represents the coating application methods on food products. However, dipping and spraying techniques are generally used to apply edible coatings on fruits, vegetables, and fresh-cut produce due to their cost-effectiveness and better efficiency [2, 23, 207,208,209]. Besides, very few studies have been available on the comparative analysis on coating application techniques. Several researchers have applied different techniques to extend the shelf life of food products (Table 1). On the other hand, the edible films are generally used for wrapping and packaging of food products; these films can be produced by wet (casting) and dry (extrusion) methods for food application [23]. The wet (casting) method is the most popular method on laboratory scale; on the other hand, the dry method (extrusion) is used to develop edible films at commercial scale. The properties of edible films depend on the density, rheological characteristic, surface tension, and food immersion speed of coating solution [12, 13]. In the casting method, the coating solution is spread on a Teflon glass plate and dried using methods such as vacuum, air oven, tray dryer, and microwave, until the solvent has evaporated. The films are then subjected to further drying. Generally, the casting methods include 3 different steps including (i) solubilization of matrix with suitable solvent, (ii) casting, and (iii) drying [23]. The developed edible films using casting method should be free from imperfections, consistent, and without air bubbles. The wet (casting) method is a low-cost method, easy to manufacture edible films, and leads to improve molecular interaction between the matrix-matrix and matrix additives [210]. Furthermore, the extrusion (dry) method of film formation is a more efficient technology which takes a shorter time for film formation, is solvent-free, consumes less energy, and is easier to control mechanically when handling highly viscous matrixes as compared to the casting method [211]. Mostly, the application of edible packaging as wrapping has been used for the meat and meat-based products; therefore, the dipping method is mostly preferred for the application on fruits and vegetables to extend their shelf life for a longer period throughout the storage periods.

Fig. 3
figure 3

Application methods of edible coating on different food products

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Table 1 Application and deposition methods of edible packaging on different food products
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Effects of Edible Packaging (Coating/Film) on Food Products

Meat and Meat Products

Nowadays, the demand of meat and meat-based products are increasing day by day due to the increased consumption around the world except Europe. The meat consumption has been remarked 346.16 million tons in 2018, worldwide, and it is expected that it will increase by 44% (453 MT) by the year of 2030 [246]. Meat is considered as an important source for the nutritional components such as protein, minerals, amino acids, fatty acids (oleic acid, linoleic and linolenic acid), vitamins (B1, B2, B3, and other B complex), and micronutrients [16, 248]. The degradation of quality attributes of meat and meat products is influenced by the chemical, physical, and biological factors such as light, pH, air temperature, and microbial attack [249]. Several mechanisms such as lipid oxidation, rancidity, microbial spoilage, and enzymatic autolysis are the major factor for meat spoilage [250]. The higher level of oxygen level caused lipid oxidation, increased decay rate, and reduced the shelf life of meat and meat products [251]. Generally, the microbial population such as Salmonella typhimurium, S. aureus, E. coli, and Clostridium perfringens is responsible for the reducing quality attributes and reducing shelf life of meat and meat products [246]. The oxidation and enzymatic autolysis factors degrade the quality and organoleptic attributes of the meat and meat products by degradation of water holding capacity, textural properties, color, odor, degradation of lipids, proteins, pigments, carbohydrates, vitamins, and production of biogenic amines [252]. Therefore, due to highly perishable nature and wastage of the meat and meat products during processing, transporting, and exporting, there is a need of a proper packaging to overcome these problems. Generally, most of the non-biodegradable packaging produced from non-renewable source such as plastic, polyester, and nylon has been used to protect the meat and meat products [253]. Furthermore, due to increasing consumer demand for eco-friendly packaging to improve food safety and quality, edible packaging represents a potential approach for preserving meat and meat products for a longer time during storage [250, 254]. Edible packaging based on renewable plant and animal-derived materials has the potential to protect the quality attributes and preserve the shelf life of meat and meat products by retarding water loss, gas transmission, and enzymatic autolysis, as well as inhibiting discoloration and microbial growth [250]. Many researchers have presented extension of the shelf life of meat and meat-based products using different edible packaging, i.e., films and coatings, during the storage period. Table 2 summarizes the effects of different types of edible packaging on the shelf life and quality attributes of the meat ad meat products. On the other hand, the rising demand and production of the meat and meat products are linked with the environmental degradation and health complications [255]. Therefore, the plant-based meat derived from pulses, grains, oils, and other plants can directly replace meat and meat products due to their ability to mimic taste and texture [256]. The production of plant-based meat helps in the environmental protection by reducing the emission of greenhouse gases and mitigating climate change [257].

Table 2 Effect of different edible/active packaging on meat and meat products
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Fruits and Vegetables

The fruits and vegetables play an important role in the human diet due to the presence of nutrient and phytochemical such as vitamins, proteins, minerals, fiber, carbohydrates, amino acids, phenolic compounds, flavonoids, and anthocyanin compounds [277]. The consumption of fruits and vegetables helps in the reducing the risk of disease such as cardiovascular, diabetes, stroke and others [278]. According to the World Health Organization (WHO), 400 g of different fruits and vegetables should be consumed in a day for a better health [279]. However, postharvest management of fruits and vegetables during the supply chain and storage presents the biggest challenges for the food processing industry due to the perishable nature of most fruits and vegetables. Several types of factors such as physical, mechanical, chemical, and biological are responsible for the postharvest losses in fruits and vegetables; which lead to landfill and environmental pollution [280]. Therefore, the edible packaging is a sustainable ecofriendly approach to reduce the postharvest losses in fruits and vegetables by maintaining their shelf life, controlling gas exchange, and retarding moisture, respiration rate, ethylene biosynthesis, enzymatic browning, firmness, decay, aroma, and color loss due to semipermeable nature of the edible coating, which acts as a barrier against water vapor and gas transpiration [93, 281]. Several researchers have confirmed that the application of edible packaging developed from polysaccharides, proteins, and lipids provides protection against mechanical, physical, chemical, and biological damages in fruits and vegetables during the supply chain and storage period [30, 282]. Table 3 depicts the postharvest management of fruits and vegetables to extend their shelf life using different types of edible/active packaging around the world.

Table 3 Effect of different edible/active packaging on fruits and vegetables
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Dairy, Bakery, and Other Food Products

Dairy products, such as cheese, milk, and yoghurt, are considered as staple foods; they contain an excellent number of nutritional components such as carbohydrates, proteins, fibers, lipids, minerals, and vitamins [310]. Maintaining the shelf life of dairy-based products is a major challenge for the food industries and manufactures due to highly perishable nature. Apart from the physical factors, the mold spoilage is the major cause of the contamination in dairy products [311]. Edible packaging is the best way to allow maintenance of the quality attribute and shelf life for a longer time of dairy-based food products by reducing microbial load and minimizing oxidation [2]. Several researchers reported that the application of different biopolymer-based edible packaging with and without active agents has the potential to improve the shelf life of dairy-based food products by controlling the growth of harmful microorganism sand minimizing the rate of oxidation. For example, Desrizal et al. [312] extended the shelf life of brown seaweed dodol using chitosan and carrageenan-based edible coating by retarding the growth of mold count; the chitosan-based coating was found most effective as compared to carrageenan-based edible coating. On the other hand, various researchers have investigated the effects of edible coatings formulated using agar [313], whey protein with antimicrobial agents [314], chitosan [315], galactomannan [149], and sweet whey–based edible coatings [316] on different types of cheeses. They reported that the application of different types of edible coatings significantly improved the shelf life and sensory attributes of the cheese by maintaining the acidity, pH, taste, color, and firmness, reducing the growth of food-borne pathogens (Listeria monocytogenes) yeast and molds, minimizing the gas exchange, and reducing the weight loss.

On the other hand, flavor and firmness are the major factors, which indicate the acceptability of the bakery and bakery food products. The major problems of the shelf life reduction of bakery and other types of products are higher moisture content and water activity which attract mold and yeast growths during the storage period [311, 317]. Edible packaging has the potential for improving the shelf life of the bakery and other types of food products by maintaining their firmness and organoleptic properties. Many researchers have applied different types of edible packaging to improve the shelf life of bakery food products. Table 4 summarizes the effects of edible packaging on the shelf life and quality or sensory attributes of the bakery products.

Table 4 Effect of different edible/active packaging on bakery products
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Challenges and Limitations for Edible Coating and Films

Edible coatings represent a highly promising avenue in the realm of sustainable and ecologically friendly food packaging solutions. Their potential lies in mitigating the environmental impact of traditional packaging materials, aligning with the global call for more sustainable practices. However, to fully harness the benefits of edible coatings, it is essential to acknowledge and effectively address the inherent limitations they present. By engaging in a comprehensive exploration of these constraints and offering inventive remedies, both researchers and the wider industry can collaboratively lay the groundwork for the widespread acceptance and integration of edible coatings into mainstream packaging practices. As the world increasingly prioritizes environmentally responsible approaches, surmounting these challenges takes on a pivotal role in facilitating a seamless and successful transition toward a future where sustainable packaging solutions are the norm rather than the exception. Despite, the advantage of edible packaging, there are some challenges associated with the production, storage, and use of edible packaging at commercial scale with maintained the consumer acceptability and food safety in terms of nutrition aspects and shelf life extension [325]. The major challenges of the biopolymers such as polysaccharide and protein-based edible films and coatings are poor in water and gas barrier properties. Therefore, the composite packaging with the addition of plasticizes, emulsifiers, and other components is one of the best solutions to improve the mechanical, barrier, and thermal resistance of biopolymer-based packaging [326]. On the other hand, the higher concentrations of biopolymers and active agents such as essential oils and plant extract also may have some negative impacts on the flavor of the produce, which directly affected the consumer acceptability. This is also related to the toxicity of the material. Moreover, the safety and regulations related to the use of active agent’s concentrations in edible coatings are very limited. Therefore, consumer awareness and regulations related to edible packaging and its benefits to the environment and consumers should be promoted by regulating agencies to overcome the consumer acceptance challenges at a commercial scale [280, 327]. Several challenges are discussed below, along with possible solutions.

Regulatory Requirements

The development and implementation of safety standards, laws, and policies for the use of edible coating and nanomaterials in food packaging films require additional information from regulatory authorities like the Food and Drug Administration (FDA) and the European Union (EU) [118]. Before being employed for commercial reasons, edible coating materials must have safety certification since they come into close touch with food. The American FDA government agency must therefore deem the edible material to be generally recognized as safe (GRAS) before it may be used. Additionally, depending on the dosage, the usage of legal natural plant extracts and essential oils might cause certain allergic responses [3, 328]. Therefore, appropriate measures must be put in place to regularly verify the toxicity and allergenicity of extracts and essential oils used in the manufacturing of edible coatings. So, the ingredients used to create edible coatings must be of food-grade quality, non-toxic, and processed with suitable sanitation. Therefore, the US Environmental Protection Agency financed research to produce pectin-based edible coatings that might improve the shelf life and quality of packaged foods [13, 328]. According to the US FDA rules from 2006 and a European Directive from 1998, edible coatings are often classified as food additives, food coating ingredients, and food packaging materials. Fresh fruits and vegetables can be coated with edible coatings that are GRAS or authorized as food additives by the FDA. For example, the use of synthetic resins and modified resins for the edible coating of fruits and vegetables is regulated in accordance with US FDA and European legislative requirements. Food coating ingredients (FCI) are substances that are added to coating formulations as nanoparticles, antibacterial, antibrowning, antioxidant, and antifungal agents. Food contact articles (FCA) are coatings or films that are used for packaging, whereas food contact substances (FCS) are the materials used to make them [84, 118]. The use of nanomaterials in food packaging films has generated a lot of attention. It promises the creation of food packaging with improved properties that assist in extending the shelf life of food goods. However, there is a pressing need for an established international body to supervise and control the use of nanomaterials in the food industry. According to plastic food contact materials, such as Regulation (EU) 10/2011, only nanoparticles or nanomaterials have been approved and specifically listed in the specification of Annex I of the rules that may be employed behind a functional barrier. Contrarily, Regulation 450/2009/EC integrated the general requirement for the safe use of active and intelligent packaging, which stated that active substances should either be directly incorporated into the packaging material [118].

Mechanical Strength

Edible coatings hold promise in extending the shelf life of food products; they sometimes exhibit variability in their mechanical strength and durability. This can raise concerns, particularly when juxtaposed against the robustness of conventional petroleum-based plastics. In order to overcome the current constraint, scientists and researchers are profoundly involved in the comprehensive exploration of methodologies aimed at fortifying the mechanical attributes of edible coatings. These efforts encompass the deliberate integration of various strategies, prominently including the amalgamation of diverse biopolymers as well as the incorporation of strengthening elements like nanomaterials. Through these innovative approaches, the overarching objective is to significantly amplify the overall structural robustness and lasting resilience of these coatings, ultimately paving the way for their more effective utilization and broader application in various industries.

Gas and Water Vapor Barrier Constraints

Edible coatings, although displaying commendable performance in certain aspects of maintaining food quality over time, can exhibit limitations in terms of their ability to effectively restrict the passage of gases and water vapor when contrasted with the capabilities of synthetic plastics. While these coatings derived from natural sources or edible materials offer advantages such as reduced environmental impact and potential health benefits, their inherent structure and composition might result in compromised gas and water vapor barrier properties, allowing for relatively higher permeability rates. In contrast, synthetic plastics, while less sustainable and often associated with environmental concerns, can outperform edible coatings in creating robust barriers against the ingress and egress of gases like oxygen and water vapor. This makes them more effective in prolonging the shelf life and preserving the quality of packaged foods. Consequently, the choice between these two preservation strategies involves a trade-off between environmental considerations, health aspects, and the imperative to maintain optimal food protection, prompting ongoing research to enhance the gas and water vapor barrier properties of edible coatings while retaining their overall advantages in sustainable food packaging. In the cutting-edge field of food technology, researchers are venturing deep into the realm of nanocomposites, a class of materials that combine nanoscale components to create innovative structures with remarkable properties. Their focus lies specifically in advancing the capabilities of edible coatings, which are applied to food surfaces to extend shelf life, preserve freshness, and enhance overall quality. This leap forward involves the strategic incorporation of nanomaterials possessing exceptional barrier properties into these coatings. By ingeniously integrating these nanomaterials, such as nanoparticles or nanofibers, into the edible coating’s composition, a transformational enhancement in their ability to thwart the infiltration of gases and impede the transmission of water vapor is achieved. This pioneering approach holds immense promise, potentially revolutionizing food preservation by creating a shield at the nanoscale level that effectively safeguards against external factors that degrade food quality, thus offering a substantial stride forward in food safety, sustainability, and reducing food waste.

Compatibility Challenges with Diverse Foods

Edible coatings, while promising, may encounter challenges in their universal applicability across a wide range of food products, primarily stemming from inherent disparities in texture, moisture content, and acidity among these products. The successful implementation of edible coatings to enhance preservation, appearance, and overall quality could potentially be hindered by the intricate interplay between the coating material and the diverse surfaces and compositions of different foods. Varied textures, ranging from crisp fruits to delicate baked goods, coupled with fluctuating moisture levels and varying levels of acidity in foods, present complexities that demand tailored coating solutions for optimal results. Achieving a seamless adaptation of edible coatings to this diverse array of food products necessitates a comprehensive understanding of the specific requirements and characteristics of each food item, which could lead to the development of customized coating formulations capable of effectively addressing the challenges posed by texture variations, moisture differentials, and acidity disparities. In order to overcome this challenge, researchers are actively investing their endeavors into the individualized modification of edible coating compositions, taking into account the distinct attributes exhibited by various types of food. This method of customization guarantees the optimal utilization of the advantages offered by these coatings, effectively spanning a diverse range of food items and their specific requirements.

Sensory Attributes

Edible coatings play a multifaceted role in the realm of food products, occasionally bringing about sensory modifications that intricately influence the taste, texture, and visual presentation of these consumables. These coatings, often composed of natural materials like proteins, lipids, carbohydrates, and other food-grade compounds, serve purposes beyond mere protection, extending to moisture retention, preservation, and even enhanced shelf life. However, their application can occasionally introduce perceptible alterations in the sensory experience of the food item. These changes might manifest as shifts in flavor perception, adjustments in the mouth feel or tactile sensation upon consumption, and even visible variations in the food’s overall appearance. While the primary intention is to improve the food’s quality, safety, and marketability, the potential for sensory transformations underscores the importance of meticulous formulation and application of edible coatings to strike a harmonious balance between functional benefits and the intrinsic sensory attributes of the final product. Innovators in the field of food technology are diligently focused on the enhancement of formulation parameters and the development of advanced application techniques, all aimed at achieving a significant reduction in the extent to which sensory attributes are altered during food processing. A strategic approach to preserving the intrinsic qualities of various food products involves the adoption of nearly transparent coatings that possess minimal flavor profiles. This deliberate choice of coatings, while maintaining a visually unobtrusive presence, contributes to the preservation of the innate characteristics and sensory experiences that consumers associate with these foods. By seamlessly integrating these innovations, the industry is poised to offer food items that not only boast extended shelf lives and improved processing efficiency, but also resonate with the authentic sensory appeal that consumers seek in their culinary experiences.

Ensuring Coating Shelf Life

Edible coatings, while offering various benefits such as extending the shelf life of perishable products and enhancing their visual appeal, can themselves face a potential limitation in the form of a limited shelf life. This inherent constraint in certain edible coatings could give rise to a notable concern, as their effectiveness in preserving the quality and freshness of the coated products might diminish as they age. The very attribute that makes these coatings advantageous could paradoxically become a drawback, impacting their ability to fulfil their intended purpose over an extended period. This underscores the need for careful consideration of the formulation and composition of edible coatings, taking into account not only their immediate benefits but also their long-term stability and viability. As researchers and manufacturers continue to innovate in the realm of edible coatings, addressing the challenge of maintaining their efficacy over time will be a crucial aspect of ensuring the consistent delivery of quality and freshness in coated products. To tackle this issue, experts are actively working on implementing cutting-edge preservation methods and refining packaging approaches to effectively counteract the potential infiltration of moisture and oxygen. By doing so, they aim to significantly prolong the lifespan of these coatings. These efforts involve the integration of innovative technologies and meticulous packaging designs that serve as barriers against the entry of moisture and oxygen, both of which are major contributors to the deterioration of coatings over time. This comprehensive approach not only ensures the integrity of the coatings during storage and transportation but also enhances their overall quality and durability. Through these advancements in preservation and packaging, experts are paving the way for coatings to maintain their efficacy and appeal for extended periods, ultimately benefiting industries reliant on these products.

Future Perspectives

Edible packaging coatings and films are effective strategies to maintain the quality and sensory attributes of different types of food products by reducing the weight loss, barrier against gas transmission, and water transpiration. The composite packaging is most desirable to maintain the quality attributes of food products as compared to edible coating prepared from single polymer due to excellent barrier properties against gas and water transpiration. Several types of methods have been used to develop composite packaging for food products, and each method has its own limitations. Therefore, the high-pressure homogenization technologies, such as microfluidization and ultrasonication, should be used to develop biopolymer-based edible packaging nanoformulations to improve their stability on the surface of food products for a longer period of time. There is a need for further research to identify the compatible biopolymers, their interactions with other ingredients such as plasticizers and emulsifiers, and to investigate their efficacy in improving the quality and sensory attributes of food products along with shelf life extension. The selection of coating method for the application on the variety of food products is also important for ensuring the applicability of materials on the surface of food products and their effects on food quality. Furthermore, most research and novel technologies require reducing the hygroscopic nature of plant-based biopolymers such as gums. In addition, the most suitable composition with other biopolymers and additives like active ingredients should be further explored in more details. Additionally, the application methods for edible coating on food products should also be explored further for their applicability, stability, and the cost of the coating formulations. Besides, the effects of high-pressure homogenization technologies on the properties of coating materials and applicability on the surface of food products require more detailed studies as well. The main focus of researchers should be on the recovery of biopolymers, such as cellulose, pectin, starch, proteins, hemicellulose, lignin, collagens, gelatin, chitin, agar, alginates, whey, and casein, from the different types of food waste and by-products obtained from different parts of fruits, vegetables, animals, and dairy-based products, and subsequently valorize them to develop biodegradable and safe coating for food products. Therefore, most of the by-products and biowastes (peels, seed, pomace, pulp, bagasse, skin, stones, husk, bran, corn cobs, fins, scales, muscles, viscera, shells, and other biomasses) can serve as valuable renewable sources for components of edible packaging. Specifically, food, agro-, and industrial substances based on polysaccharide, protein, or lipid, due to their high bioavailability, biodegradability, and/or nutritional value, can be effectively used for this purpose while also contributing to the reduction of waste disposal areas. In this context, plant-based substances like fruit and vegetable by-products and waste (peels, seeds, shells, etc.) could possess a high-commercial value and could be considered suitable candidates for this purpose. Their combination or composite edible packaging is something that overcomes traditional barrier or mechanical issues for this type of packaging compared to single-used biopolymers. This is also in line with most of the Sustainable Development Goals because the utilization of biowaste and by-products is a sustainable trend that has social, economic, and environmental impacts on the planet, meaning less pollution for air, soil, and water resources, which is good for planetary health; additionally, it offers health benefits for humans due to the potential functional and nutritive values of bioactives extracted from biowaste when combined with food.

Moreover, there are a limited number of studies available investigating the effectiveness of edible coatings in combination with other non-thermal preservation techniques like pulsed light, ultraviolet electromagnetic radiation like ultraviolet (UV-C), gamma irradiation on the quality attributes, and shelf life of food products. Therefore, further research is needed on the use of non-thermal preservation techniques coupled with edible coatings based on hurdle concepts to maintain the quality attributes of food products. From an engineering perspective, there is also a further need to develop the low-cost spraying machine at the lab scale for coating application on food products, especially for fruits, vegetable, and fresh cuts.

Conclusion

Edible packaging is an integral part of the sustainable packaging system. It aids to reduce the reliance on non-renewable resources. The efficacy and functional attributes of edible packaging materials are greatly reliant on the inherent properties of the film-forming materials. Biopolymers such as polysaccharides, lipids, and proteins derived from natural sources are used to develop edible coatings and films. Edible packaging (films and coatings) is substantial in extending the shelf life of food products. Therefore, composite materials such as binary and ternary edible packaging have even greater potential in maintaining the freshness, color, vitamins, minerals, firmness, and other nutritional and sensory attributes of food products. This might be possible due to barrier properties of the edible packaging against water transpiration and gas transmission. Furthermore, the incorporation of active agents such as essential oils and plant extracts can act as natural antimicrobial agents which inhibit the growth of harmful microorganism in food products. This study also concludes that the application of high-pressure homogenization techniques such as ultrasonication and microfluidization is effective in reducing the particle size of materials at the nanoscale, thereby improving the stability of packaging materials for a longer time period. Therefore, the replacement of traditional synthetic polymer-based coatings with biodegradable films should be emphasized as an extremely desired approach.