Sustainability in Bio-Based Edible Films, Coatings, and Packaging for Small Fruits

Abstract

Sustainability in bio-based edible films, coatings, and packaging integrates environmental, economic, and social sustainability using renewable resources. These materials offer an eco-friendly alternative to traditional petroleum-based plastics and can extend the shelf life of fruits. The wine industry’s by-products, rich in bioactive compounds, can create bio-based films and coatings. However, some challenges and limitations may occur. Producing bio-based films and coatings on a commercial scale can be challenging, requiring significant investment in research and development. While bio-based materials offer many benefits, they may not always match synthetic plastics’ mechanical strength and barrier properties. However, ongoing research is actively working to improve the functionality and durability of these materials, offering hope for the future. Bio-based materials can be more expensive to produce than conventional plastics, which may limit their widespread adoption without economic incentives or subsidies. Therefore, this review, which aims to provide a literature review about the benefits, challenges, and prospects of the sustainability offered using bio-based edible films, coatings, and packaging, particularly in small fruits and grapevine by-products, is important in the field.

1. Introduction

The need for humans to preserve food has been crucial throughout history and remains relevant today. Food naturally decomposes due to bacteria, yeast, and mold growth, which can cause spoilage and foodborne illnesses [1]. Preservation techniques help inhibit or slow down this process while diminishing oxygen exposure, which is particularly important in fat-rich products, which can go rancid [2].

Food preservation allows us to keep perishable items for extended periods, reducing waste and ensuring a consistent food supply, especially in times of scarcity or when fresh produce is unavailable due to seasonal availability. So, preserving allows people to enjoy fruits, vegetables, and other items year-round, even when they are out of season. Specific preservation methods can help retain the nutritional value of food for extended periods, providing essential vitamins and minerals during off-seasons. And, of course, reducing food waste through preservation can help save money, both at the individual and community levels. It allows people to buy in bulk, take advantage of discounts, and store surplus food for future use.

The need to preserve food arises from the desire to ensure a consistent food supply, minimize waste, maintain health, and support economic stability. This initiative aligns with the Sustainable Development Goals (SDGs), also known as the Global Goals, which are a set of objectives within a universal agreement aimed at ending poverty, protecting the environment, and ensuring that all people enjoy peace and prosperity [3]. Although there are specific targets and indicators for the 17 goals, it is essential to recognize that they are closely interconnected.

Bio-based edible films are thin materials made from natural, biodegradable ingredients such as polysaccharides, proteins, and lipids. These films can function as food coatings or packaging that can be consumed along with the food, thereby reducing waste and offering an eco-friendly alternative to traditional plastic packaging. Their properties align with several Sustainable Development Goals (SDGs), particularly those focused on human well-being, such as No Poverty (Goal 1), Zero Hunger (Goal 2), and Good Health and Well-being (Goal 3), as well as environmental sustainability, specifically Life on Land (Goal 15) [3]. In this manuscript, “coatings” and “food packaging” refer to substances/products in direct contact with food.

Bio-based edible films are typically made from polysaccharides such as starch, microbial cellulose, chitosan, or alginate. These materials originate from animal, fungal, or plant sources and are utilized in various applications, particularly within the food industry (

Table 1. Examples of bio-based edible film material, their provenance, application, and properties.

Material	Provenience	Applications	Properties	Ref.
Starch	Starch-rich crops (Vegetal origin)	Food and beverage, cosmetics, pharmaceuticals, and consumer goods	Enhanced shelf life and improved food safety; good printability and sealability, allowing for branding and labeling customization while ensuring product integrity and safety;	[3]
Cellulose	Microbial cellulose is obtained by cultivating Acetobacter aceti in fruit waste media (orange, kiwi, and guava fruit peel, blended in 200 mL distilled water). (Microbial origin)	Food, biomedical, biosensing, and environmental applications.	Biodegradability, biocompatibility, high crystallinity, non-toxicity, hydrophilicity, elevated tensile strength, extensive polymerization, in-situ moldability, and porosity; Extending the nutritional value and shelf life	[4]
Chitosan	A polysaccharide of N-acetyl D-glucosamine and D-glucosamine units, obtained by the partial deacetylation of chitin exoskeletons of insects, cephalopods, and crustaceans. (Animal origin)	Food, biomedical, biosensing, and environmental applications.	Antimicrobial activity, biocompatibility, biodegradability, and non-toxic profile	[5]
Alginate	Alginate, a polysaccharide derived from brown macroalgae (Seaweed origin)	Packaging and storing perishable food items	Extend the freshness and shelf-life of perishable food items; Inhibits lipid oxidation in meat and animal-based products; Allows respiration of fruit and vegetables; Antimicrobial properties.	[6]

). Polysaccharides form the base structure for many edible films. They offer good gas barrier properties but may lack water resistance. Proteins can also be used. Protein sources like casein, whey, soy, and gelatin provide films with robust mechanical properties. Protein-based films often offer suitable oxygen barriers. Lipids like waxes and oils are also an alternative. They are added to enhance water resistance but can affect the film’s transparency and flexibility [2].

The first edible coating, wax, was developed in 1992 and used on fruit surfaces [7]. An edible film or coating less than 0.3 mm thick uses biopolymers dispersed in water. Some authors use “edible film” and “coating” interchangeably, while others differentiate based on the food product’s incorporation method. An edible film is previously made and then adhered to the food product [1], while the coating is formed directly on the food [2]. For other authors, the term “edible coating” is used when it has a thickness below 0.025 mm, whereas it is considered an “edible film” when the thickness is above 0.050 mm [7].

These films and coatings can slow spoilage by controlling moisture exchange and acting as barriers to gases like oxygen, which can lead to oxidation [8]. They can also be infused with flavors, nutrients, or active ingredients (such as antimicrobial agents), enhancing the taste or shelf life of the food [9]; since these films are biodegradable and made from renewable resources, they help reduce plastic waste and are within a circular economy view [10]. Sustainable packaging is essential to tackle traditional materials’ environmental, social, and economic challenges [11]. Conventional packaging made from petroleum-based plastics poses serious environmental risks, including resource depletion, greenhouse gas emissions, pollution, and plastic waste accumulation in landfills and oceans [12]. These environmental impacts threaten ecological integrity and human health while worsening issues of injustice and inequity [13].

Sustainable packaging is a proactive approach aimed at reducing the negative impacts of packaging on the environment and society while fulfilling its essential functions like containment and protection. It considers the entire lifecycle of packaging materials, from sourcing to disposal. Key principles include using renewable resources, reducing material consumption, optimizing design, and promoting recyclability and biodegradability. Transitioning to sustainable packaging offers benefits such as environmental stewardship, resource efficiency, enhanced brand reputation, and consumer satisfaction. Additionally, it fosters innovation and value creation in the industry, making it a strategic and ethical responsibility to protect the planet for future generations [14,15].

Due to their characteristics, they can be employed in coating fruits and vegetables, meat, and fish products to extend shelf life by preventing moisture loss, respiration, and oxidation. Nowadays, they present a myriad of uses, are part of the movement towards sustainable packaging, and offer a functional alternative in industries like food processing and packaging [2], Figure 1.

The ripening and aging process of small fruits after harvest can be delayed using various preservation methods. These methods help maintain the taste and quality of the fruits, allowing them to be available for sale and consumption out of season. Preservation also contributes to a wider variety of products in the market and helps stabilize food prices by balancing supply and demand. In simple terms, preserving small fruits involves handling and treating them to prevent or slow down decay and spoilage, such as contamination by microorganisms, loss of nutritional value, loss of flavor, changes in texture, and microbial and enzymatic decomposition. This ensures a longer shelf life for the food [16].

Fruits are vulnerable to different post-harvest diseases caused by bacteria and fungi, which can result in visible decay and a decline in quality. Additionally, various physiological changes during ripening and post-harvest can affect fruit quality, including maturity, respiration, ethylene production, and enzymatic reactions [17]. After harvesting, fruits lose water through their skin, leading to shriveling and weight loss, impacting the fruit’s appearance and texture [18]. Additionally, damage caused by handling can cause bruising and create openings for disease organisms, further accelerating deterioration and quality loss. For example, the effects of using medicinal and aromatic plant extracts (Satureja montana L. and Thymus vulgaris L.) as edible coatings for sweet cherry postharvest storage were studied by Afonso et al. [19]. Results showed that aqueous extracts could represent an innovative and natural approach to preserving sweet cherry physical and chemical quality in postharvest storage.

Grapevine by-products are produced during the winemaking process, and this waste is harmful to the environment [20]. Grapes and grape by-products, known as grape pomace, are rich in bioactive compounds such as lipids, dietary fibers, and polyphenols, making them valuable. Developing new food products, like infusions, could help minimize waste and harness the benefits offered by grape by-products. Indeed, Vilela et al. [21] found that different organic matrices (encapsulating agents such as alginate and chitosan, among others) could protect the dehydrated and crushed grapes in the form of small spherical balls (0.8–1.0 cm diameter, Figure 2) covered with the organic matrix, preventing their degradation over time. Moreover, with chitosan, the infusions did not show significant color changes when compared with the control infusion, with deficient amounts of sugars found and pH levels in the acidic range, and all the matrices maintained their integrity after two months of encapsulation and none of the matrices showed negative characteristics in the infusions.

This review aims to overview the benefits, challenges, and prospects of using bio-based edible films, coatings, and packaging for small fruits, focusing on sustainability.

2. Edible Films and Coatings: Definitions and Regulations

Edible films are thin layers of edible material formed into a film that can be placed on or between food products. They act as a barrier to moisture, gases, and solutes, helping to preserve freshness and quality. These films are made from natural polymers like proteins, polysaccharides (e.g., starch or cellulose derivatives), and lipids. Edible coatings, unlike films, are applied directly to the surface of food products. They are thin layers made from substances similar to those used for films. They aim to create a protective barrier that improves shelf life, reduces moisture loss, or enhances appearance (e.g., glossy coatings for fruits or candies) [4].

The food industry has grown interest in edible films and coatings. When using PubMed to search for and place the keywords “edible coatings and film in food,” we found 1591 publications (Figure 3) from 1972 to 2025.

The regulation of edible films and coatings varies by region but generally focuses on the safety of ingredients, manufacturing processes, and the intended use of food. The U.S. Food and Drug Administration (FDA) regulates edible films and coatings under the Food Additives Amendment of 1958. Ingredients used in these films or coatings must either be Generally Recognized As Safe (GRAS) [22], meaning they are widely recognized by qualified experts based on scientific evidence, or be approved as food additives, meaning they have undergone safety evaluations and received FDA approval. When used appropriately, everyday materials like starch, pectin, and chitosan often fall under the GRAS category [16]. The European Food Safety Authority (EFSA) regulates food-contact materials, including edible coatings. Regulations fall under Regulation (EC) No 1935/2004 [23], which outlines general safety requirements for materials that come into contact with food. Specific approval may be needed for novel or non-traditional materials, mainly when they include functional additives such as antimicrobials or preservatives. The Codex Alimentarius Codex [24], developed by the Food and Agriculture Organization (FAO) and the World Health Organization (WHO), provides international guidelines and standards for food safety, including edible coatings and films. While Codex standards are voluntary, they serve as a reference for national food safety regulations. In summary, edible films and coatings are carefully regulated to ensure their safety for consumption, and compliance with regulatory standards is required for their use in food products.

3. Biological Sources of the Compounds Used in Films, Coatings, and Packaging

3.1. Marine Processing By-Products

Marine processing by-products like seafood are increasingly used to create biodegradable and active packaging materials. These materials offer a sustainable alternative to traditional plastic packaging and have added benefits for food preservation. Marine biopolymers include proteins and polysaccharides derived from seafood processing by-products. Typical examples are collagen, gelatin, chitosan, and muscle proteins, which create robust and sustainable food packaging materials [25,26]. These biopolymers are valued for their biocompatibility, biodegradability, and non-toxicity [26].

Preparing films and coatings from marine biopolymers involves incorporating bioactive compounds such as plant extracts, essential oils, and phenolic compounds. These additives enhance the antimicrobial and antioxidative properties of the packaging, thereby extending the shelf life of food products [25,27,28]. Techniques such as nanostructuring (e.g., nanofibers, nanoparticles, and nanoemulsions) are employed to improve the moisture barrier properties and delay oxidation and microbial spoilage [28]. Marine biopolymer-based films and coatings are particularly effective in preserving aquatic food products, which are prone to microbiological spoilage, chemical oxidation, and physical deterioration. Integrating natural antioxidants, phenolic compounds, probiotics, and bacteriocins into these films has shown the potential to prolong the shelf life of these products [28]. Additionally, these materials can be combined with nonthermal methods like ozonation, high hydrostatic pressure, and irradiation to enhance their preservation capabilities [28]. Using marine biopolymers in food packaging significantly reduces the reliance on plastic packaging, offering considerable environmental benefits. These biodegradable materials help minimize plastic waste and its associated ecological impact [26]. Moreover, using seafood processing by-products adds economic value to what would otherwise be waste, promoting a more sustainable and circular economy [26,27]. Despite the promising benefits, producing and applying marine biopolymer-based packaging presents challenges. Production flaws, better isolation methods, and safety concerns must be addressed [26,28]. Future research is directed toward improving the extraction and preparation techniques, enhancing the functional properties of the films, and ensuring their safety for food-contact applications. Using marine-processed by-products for packaging small fruits is an emerging area of interest in sustainable food packaging. This approach leverages the natural properties of marine by-products to create biodegradable and edible packaging solutions that can enhance the shelf life and quality of small fruits. Marine-processed by-products like fish scales, shells, and seaweed are rich in bioactive compounds like chitosan, collagen, and alginate. These compounds’ unique properties make them suitable for developing biodegradable packaging materials. They can help in reducing lipid oxidation, minimizing weight loss, and retarding respiration and enzymatic browning of small fruits, thereby extending their shelf life [29].

These compounds can significantly enhance packaging systems’ physical, mechanical, antioxidant, and antimicrobial properties. For instance, chitosan derived from shrimp shells has been shown to provide excellent barrier properties against oxygen and moisture, which are crucial for maintaining the freshness of small fruits. Additionally, incorporating marine by-products into packaging can improve their tensile strength and flexibility, making them more durable and practical [29].

Materials from Fish and Shellfish

Biopolymers derived from fish and shellfish offer an eco-friendly alternative to synthetic plastics, addressing environmental concerns and enhancing food preservation.

There are different types of biopolymers from fish and shellfish. Fish gelatin is a prominent biopolymer used for developing biodegradable films. It is valued for its film-forming capacity and ability to protect food against drying, light, and oxygen. Fish gelatin films can be enhanced with other biopolymers like soy protein isolate, oils, fatty acids, and polysaccharides to improve their physical properties and add functional attributes such as antimicrobial and antioxidant activities [30,31,32].

Chitosan, derived from crustacean shells, is known for its antimicrobial properties and film-forming ability. Chitosan-based films can be blended with nanomaterials to enhance their mechanical properties and extend food products’ shelf life [28].

Collagen and muscle proteins, extracted from seafood processing byproducts, are used to create robust and sustainable food packaging. They can be combined with antimicrobial agents or antioxidants to prevent food spoilage and chemical deterioration [25]. Biodegradable films from fish and shellfish can be incorporated with bioactive compounds such as essential oils, plant extracts, and vitamins to create active packaging. These films release antimicrobial and antioxidative agents, extending the shelf life of perishable foods like fish and meat by inhibiting microbial growth and delaying oxidation [30,33,34,35].

Edible films and coatings made from fish gelatin and other marine biopolymers are used to preserve fresh fish and meat products. These films prevent moisture loss, microbial spoilage, and nutrient degradation, extending the shelf life and maintaining the packaged products’ sensory quality [26,33,35]. Combining different biopolymers, such as gelatin and myofibrillar proteins, can improve the mechanical and barrier properties of the films. These blends result in intense, flexible films with low water vapor permeability, making them suitable for food packaging [36]. Moreover, eco-friendly crosslinking agents like alginate dialdehyde can enhance fish gelatin films’ stability and mechanical strength. This process also improves the films’ resistance to moisture and increases their antioxidative capacity [31]. Some authors, such as [36], also mention the possible utilization of nanocomposites. Incorporating nanomaterials into chitosan-based films can significantly enhance their antimicrobial properties and mechanical strength, making them practical for extending the shelf life of various food products. Consumer awareness of the benefits and safety of biodegradable packaging materials should also be increased. Ensuring these materials meet safety standards is crucial for their acceptance [33]. Regarding cost and scalability, developing cost-effective methods for large-scale production of biopolymer-based films is a significant challenge. Innovations in extraction and processing techniques are needed to make these materials commercially viable [26,33]. Moreover, while biopolymer-based films are biodegradable, their environmental impact during production and disposal must be thoroughly assessed to ensure they are a sustainable alternative to synthetic plastics [25,32].

3.2. Agricultural Processing Byproducts

Agricultural processing by-products are secondary materials generated during crop cultivation and processing, as well as from livestock and dairy farming [34,37,38]. Often viewed as waste, these by-products include crop residues, fruit and vegetable peels, husks, and food processing waste [38,39,40]. Despite being considered non-primary goods, these materials hold significant potential for recycling and repurposing, offering valuable resources that can be transformed into industrial raw materials or value-added products [41].

3.2.1. Materials from Vegetables and Fruits

Edible films and coatings derived from plant-based materials have emerged as promising alternatives to conventional packaging, offering sustainable and environmentally friendly solutions for the food industry [42,43,44]. These bio-based materials utilize various components, including polysaccharides, proteins, and lipids, each contributing unique properties to the final product. Polysaccharide-based films are particularly relevant in this context, as they can be derived from fruit and vegetable by-products. Polysaccharides like cellulose, pectin, starch, and alginate have attracted significant interest because of their plentiful availability, cost-effectiveness, biodegradability, and excellent film-forming properties [44]. Extracted from plant cell walls, cellulose can create strong, transparent films with exceptional mechanical properties [45,46]. These films exhibit superior mechanical properties and exceptionally high tensile strength compared to many synthetic plastics [47,48]. This enhanced strength allows for thinner packaging materials while maintaining structural integrity [49]. The optical clarity of cellulose films is another key benefit, making them ideal for food packaging where product visibility is desired [47,48]. Consumers can quickly inspect the contents without compromising the protective barrier [48]. Perhaps most importantly, unlike conventional plastics, cellulose films are bio-degradable [47,48,49]. This property allows them to decompose naturally after disposal, significantly reducing environmental impact and addressing growing concerns about plastic pollution plastics [44,47]. As cellulose-based films can be derived from abundant plant sources and agricultural by-products, they contribute to resource sustainability plastics [44,48].

Recent research has focused on improving the functionality of cellulose films by incorporating antimicrobial agents to extend the shelf life of packaged foods plastics [48]. Additionally, cellulose can be combined with other biopolymers or nano-particles to enhance properties such as water resistance and barrier performance plastics [47,48]. Pectin, commonly found in fruit peels and pomace, forms flexible films with good barrier properties, making it suitable for coating small fruits [42]. Although not derived from grapes or small fruits, alginate, a seaweed-derived polysaccharide, is frequently used in fruit coatings due to its film-forming abilities and compatibility with food products [49]. Protein-based films and coatings have emerged as a promising sustainable alternative to conventional petroleum-based packaging materials. Protein-based films and coatings can be derived from various sources, including animal proteins like casein, gelatin, and whey and plant proteins such as soy, corn zein, and wheat gluten [50]. These materials have shown great potential in extending the shelf life of various food products, including fruits, vegetables, dairy products, and meat [51]. These films offer beneficial properties for food packaging applications, such as excellent gas barrier properties, effectively protecting against oxygen and carbon dioxide [50,52]. Additionally, they are biodegradable and, in many cases, edible, allowing them to be consumed along with the food product [53]. Another advantage is their ability to incorporate active compounds, such as antimicrobials and antioxidants, to enhance food preservation [50,54]. Additionally, grape seed proteins extracted from winery by-products show potential for use in film production, although further research is needed to optimize their application [51]. These proteins have demonstrated antioxidant and antimicrobial properties when incorporated into films [55,56]. In addition, grape seed protein films have shown promising mechanical strength and water vapor barrier properties, making them suitable for food packaging applications [51,57]. Recent studies have focused on improving the functionality of grape seed protein films through various methods: (i) blending with other biopolymers like chitosan or cellulose to enhance mechanical and barrier properties [51]; (ii) incorporating active compounds such as essential oils or nanoparticles to impart additional functionality like antimicrobial activity [57]; (iii) optimizing extraction and film-forming conditions to maximize protein yield and film performance [51]. Lipid-based coatings are crucial in improving the water vapor resistance of edible films. Grape seed oil, a by-product of wine production, could be incorporated into coating formulations to enhance moisture barrier properties [49]. Natural waxes such as beeswax or carnauba wax are often blended with other biopolymers to improve film properties, particularly hydrophobicity [42]. The combination of these various components allows for the creation of tailored edible films and coatings to address the specific preservation needs of small fruits and grapevine by-products. By utilizing these sustainable materials, the food industry can work towards reducing environmental impact while maintaining product quality and extending shelf life.

3.2.2. Materials from Cereals

Cereals have emerged as a significant source of materials for developing sustainable bio-based edible films, coatings, and packaging [49,58]. These materials offer numerous advantages, including biodegradability, renewability, and abundance [59]. The most commonly used cereal-derived compounds for these applications are starches and proteins [60]. Starch, a polysaccharide in high concentrations in cereals such as corn, wheat, and rice, has gained considerable attention in edible packaging. Its film-forming properties, low cost, and wide availability make it an attractive option for sustainable packaging solutions [43]. Starch-based films and coatings have demonstrated excellent oxygen barrier properties and moderate moisture resistance, making them suitable for various food packaging applications [42]. Figueroa López et al. [58] indicate that starch-based films, particularly those with a high amylose content, hold substantial promise as eco-friendly packaging solutions for preserving food products. While starch offers promising characteristics for edible packaging, another agricultural by-product, zein, presents complementary properties that expand the potential applications of bio-based packaging materials. Indeed, zein, a corn protein, can be used at higher concentrations in film formulations, providing unique properties to the coating [42,61]. This prolamine protein extracted from corn has excellent film-forming abilities and creates transparent, glossy, and hydrophobic films with good barrier properties against oxygen and moisture [2,50]. Zein films are particularly effective for coating nuts, candies, and pharmaceutical tablets due to their resistance to microbial attack [62]. Wheat gluten, another cereal protein, has been extensively studied for its film-forming abilities. Gluten-based films possess good mechanical strength and barrier properties against gases and aromas [54]. However, their hydrophilic nature often necessitates incorporating plasticizers or other additives to improve moisture resistance. Rice bran protein, a by-product of rice milling, has also been explored for its potential in edible packaging. Films made from rice bran protein have good mechanical properties and moderate water vapor permeability [63]. Additionally, these films can be enhanced with various bioactive compounds to impart antimicrobial or antioxidant properties. Recent innovations in cereal-based materials for edible packaging include the development of composite films that combine different cereal components. Composite films are two types of biomolecules, like hydrocolloids and lipids, combined to prepare films [63].

For instance, starch-protein blends have been created to leverage the strengths of both materials, resulting in films with improved mechanical and barrier properties [43,54]. Incorporating nanoparticles, such as cellulose nanocrystals or nanoclays, into cereal-based films has also been investigated. Compared to their non-reinforced counterparts, these nanocomposites often exhibit enhanced mechanical strength, barrier properties, and thermal stability [2,42]. Furthermore, researchers have explored the potential of cereal by-products, such as bran and husks, in developing sustainable packaging materials. These efforts reduce waste and add value to agricultural residues [63]. In conclusion, cereal-derived materials offer many possibilities for developing sustainable bio-based edible films, coatings, and packaging. Their abundance, biodegradability, and versatile properties make them promising candidates for replacing conventional plastic packaging in various food applications. Ongoing research continues to focus on improving the performance of these materials and expanding their potential uses in the food packaging industry.

3.3. Animal Processing Byproducts

The search for more sustainable and “green” solutions in food preservation has led to the increasing use of biological compounds of animal origin in films, coatings, and packaging [64]. Using natural materials responds to increased consumer demand for more sustainable products free of synthetic substances, that is, healthy food options free of chemicals. The meat industry produces many by-products, such as skins, collagen, gelatin, fats, and proteins, which can be used to make films and coatings for food preservation. In addition to being abundant and low-cost, these by-products have functional properties that make them suitable for use in packaging [65]. Using renewable resources and promoting environmental sustainability, aligning with the principles of the circular economy, are the main objectives of current research [1].

3.3.1. Materials from the Meat Industry

Films based on natural components (such as gelatin) are innovative solutions due to their abundance, excellent film-forming properties, low cost, biodegradability, and compostability [66]. Gelatin’s use has become famous due to its application in the most varied fields of industry [67]. Gelatin is a natural biopolymer derived from the partial hydrolysis of collagen [68], mainly from untanned skin and animal bones (cattle and pigs, for example), chicken feet [69], and fish by-products [32,70]. Gelatin consists of a set of protein segments carrying different molecular weights (100 to 300 kDa), together with high molecular weight aggregates and peptide fractions (<100 kDa). The origin and the extraction process influence the average molecular weight of gelatin, hence its ability to form films [71]. According to Al-Kahtani et al. [72], a Bloom value in the range of 125–250 g is most commonly used in gelatins used in foods. Applying gelatin as an edible coating usually involves dipping the fruit in a gelatin solution and then drying it, forming a thin, colorless, flexible layer. This gelatin-based edible film is safe, cheap, biodegradable, and can absorb ultraviolet light due to the aromatic amino acids present in its structure [73]. Moreover, it has been proven to have antimicrobial and antioxidant properties, extending packaged products’ shelf-life [74]. Therefore, gelatin is considered a natural and sustainable alternative, widely used to replace synthetic coatings, especially in products that require good visual presentation and preservation for more extended periods. Amani and his collaborators [74] report that a significant advantage of this product is when combined with other biopolymers as it increases the thermal stability and mechanical and barrier properties of the coating. The non-toxicity of gelatin and chitosan is an essential attribute that expands their possibilities for use in food products. Furthermore, these substances have antimicrobial and antifungal properties, which give them great potential in applications related to food preservation, particularly with their coating. The films obtained by mixing gelatin and chitosan present antioxidant characteristics and exhibit a high suppression of the growth of Staphylococcus aureus and Escherichia coli [75,76]. These multifunctional characteristics make gelatin associated with chitosan versatile and promising options for advancing innovative technologies, especially in areas where sustainability and functional efficiency are essential. Several studies have been carried out to prove this potential. Some examples are the studies by Fatima et al. [77], in which fresh grapes were preserved in packaging made of gelatin extracted from chicken feet mixed with zinc oxide and chitosan nanoparticles. This edible coating revealed a decrease in microbial growth and a reduction in browning, remaining attractive after 14 days. Greater firmness, less weight loss, and a total bacterial count were also observed in studies by Chen et al. [78] when they tested a gelatin-based coating with chitosan, nisin, and cornstarch on cherry tomatoes. On the other hand, Ahmed et al. [79] observed good antioxidant capacity and better stability at higher temperatures using gelatin films with bergamot and lemongrass essential oils as active packaging materials. In recent years, innovative packaging composed of these two components has become a creative solution to improve food conservation [80]. Indeed, among the mechanisms most used in these innovative packaging are active eliminators, which include specific technologies for removing oxygen, moisture, and ethylene [81]. Oxygen scavengers, for example, help prevent food oxidation, slowing down processes that lead to fat rancidity and the growth of aerobic micro-organisms. Moisture eliminators are essential to avoid mold formation and degradation of water-sensitive foods, while ethylene eliminators effectively preserve fruits and vegetables, delaying ripening and degradation [82]. By promoting active control of the packaging’s internal environment, these technologies not only extend the shelf life of products but also preserve their sensory and nutritional quality. Thus, innovative packaging with active ingredients has become indispensable in the food supply chain to reduce waste and meet growing demands for safer and more sustainable products.

3.3.2. Materials from the Dairy Industry

Many researchers are concerned with the biotechnological valorization of whey to produce value-added products. The leading group of dairy proteins found in cow’s and goat’s milk is casein, which is about 75–78% [83]; the remaining percentage includes whey proteins, among other components. Casein has four main subunits in its constitution: αs1-casein (38%), αs2-casein (10%), β-casein (36%), and k-casein (13%) that influence the degree of availability for the formation of films given its flexible structure. The polar and hydrophobic domains they present provide this high degree of flexibility. In addition to this property, other properties, such as high thermal stability and biodegradability, can also be recognized [78]. Edible casein coatings for fruits have high nutritional value and prevent excellent gas permeability barrier [84]. According to Shendurse et al. [85], milk protein can be used to obtain several films. The interaction between the proteins will always determine the structure of the films formed. Mixing casein with other substances can produce great edible films and coatings [86]. Examples are the films obtained from casein and natamycin that control microbial activity and fungal growth [87], and the mixture of casein with beeswax obtained from emulsions to reduce white blush and increase resistance to water vapor [88]. Extended studies by Chevalier and his collaborators [89], using a mixture of casein with different natural film waxes (bees-wax, candelilla, and carnauba wax) where potassium sorbate was integrated, showed bacteriostatic properties, controlling the growth of E. coli up to 20 days of storage at 15 °C. Brzoska et al. [90] concluded that caseinate films where sorbitol was added were less flexible than those with glycerol in their composition. The addition of plant extracts to casein-based films has also been studied. Therefore, supplementing the films with essential oils such as linseed oil [91], rosemary [92], cinnamon [93], and canola [94] demonstrated better moisture resistance, sound water barrier, and better strength and flexibility. Other additives incorporated into casein films or whey proteins have also been studied to improve their attributes, namely inorganic substances such as TiO₂ nanoparticles or ZnO [88], which stood out for presenting high antimicrobial activity. Halloysite, aluminum and magnesium silicate [95], sodium sulfite, sodium dodecyl sulfate, and urea [96], antimicrobial agents and preservatives such as E1105 (chicken egg lysozyme), viable strains of lactic acid bacteria and probiotic strains of various Lactobacillus spp. and Bifidobacterium spp. [97] can be added to those films. Whey proteins can be obtained using the main by-products of the dairy industry, such as cheese whey. They are globular proteins and form new polymeric structures through cross-linking, making them an excellent raw material for film production [98]. According to Nunes et al. [99], whey proteins, protein hydrolysates, and bioactive peptides, polymers of animal origin, are known to have natural antimicrobial properties. Although its mechanism of action is not yet fully understood, it is inevitable that factors such as temperature, pH, and fat influence its microbial activity. When whey protein nanofibrils were incorporated into edible films, inhibitory action was observed against bacteria such as Listeria monocytogenes, Staphylococcus aureus, Escherichia coli, and Salmonella Enteritidis [100].

Because they have bioactive peptides with antimicrobial activity and beneficial effects on consumers’ health, whey proteins are a promising raw material for manufacturing coatings and films. In addition to their nutritional value [101], they help mitigate environmental impacts, contributing to sustainable industrialization [102].

3.4. Microorganisms-Based Materials

Packaging small fruits using materials derived from microorganisms is an emerging field aimed at enhancing fresh produce’s shelf life and safety. This approach leverages bio-based materials’ biodegradable and antimicrobial properties to reduce microbial contamination and improve the overall quality of the packaged fruits.

Studies on microbial contamination and packaging materials have shown that cardboard packaging can significantly reduce microbial contamination compared to plastic. Cardboard’s ability to entrap microbial cells results in lower contamination levels of fruits like peaches, leading to better microbiological quality and extended shelf life [102] and MAP (Modified Atmosphere Packaging), especially with low oxygen levels, has been effective in reducing microbial growth in fresh-cut fruits such as persimmons and cactus pears. Combined with antimicrobial coatings, this method can significantly inhibit the growth of harmful bacteria like E. coli, Salmonella, and Listeria [103,104].

Biopolymers derived from biomass, microbes, and bio-derived monomers create biodegradable films. While these films are environmentally friendly, they often require additives to improve their mechanical and barrier properties [105]. Incorporating antimicrobial agents such as cinnamaldehyde into polylactic acid (PLA) films has been shown to enhance the antibacterial activity and barrier properties of the packaging. These films can effectively inhibit the growth of E. coli and Listeria, providing a sustained release of the antimicrobial agent over time [106].

Pectin-based edible coatings, combined with MAP, have successfully maintained fresh-cut fruits’ sensory and microbiological quality. These coatings can reduce enzymatic browning and microbial growth, extending the shelf life of products like persimmons [104]. One of the main challenges with bio-based films is their inferior mechanical and barrier properties compared to conventional plastic films. Research is ongoing to improve these properties by incorporating various additives and nanomaterials [105]. While there have been successful laboratory-scale implementations of these innovative packaging materials, scaling up for commercial use remains a challenge. Cost, consumer acceptance, and regulatory approvals must be addressed [107].

4. The Incorporation of Nanomaterials in Bio-Based Films and Sustainability

As discussed in various paragraphs of point 3 of this article, using nanomaterials in food packaging provides several advantages, including enhanced barrier properties, increased mechanical strength, and antimicrobial activity. However, there are significant safety concerns, particularly regarding the potential migration of nanomaterials from the packaging into the food, which could pose health risks to consumers. This migration can lead to human exposure to nanomaterials, raising possible health risks [108,109,110]. The extent of migration and its safety implications are still under debate, necessitating further research and regulatory oversight [109].

The presumed toxicity of nanomaterials, especially in acidic conditions, is a significant concern. There is a lack of comprehensive data from clinical trials and risk assessments, which limits the understanding of the potential health impacts of these materials [109,111]. However, nanomaterials’ unique properties, such as their small size and large surface area, may pose potential risks, including toxicity and health complications [112,113,114]. The potential toxicity of nanomaterials in food is a significant concern, with studies indicating risks such as oxidative stress, genotoxicity, and carcinogenicity [112,113]. These risks arise because nanoparticles can easily cross human anatomical barriers through various respiratory, dermal, and gastrointestinal pathways [114].

The rapid development of nanotechnology in food packaging has outpaced the establishment of specific regulations. There is an urgent need for binding legislation to manage the risks associated with nanomaterials in food packaging and ensure consumer safety [110,115]. Nevertheless, the regulation of nanomaterials in food applications varies globally, with some regions having more comprehensive frameworks than others. In the European Union, the European Food Safety Authority (EFSA) plays a crucial role in assessing the safety of nanomaterials used in food contact materials. EFSA has established guidelines requiring specific nanoparticle assessments, focusing on solubility, dissolution rate, and potential consumer exposure [116,117]. These guidelines aim to minimize exposure to nanomaterials to prevent health risks [117]. In contrast, some countries, such as India, lack strict regulations for nanofood products, highlighting the need for more robust regulatory measures to manage the potential risks associated with nanomaterials in food [114]. The EU and Switzerland are noted for incorporating nano-specific provisions into their legislation, whereas other regions rely on general guidance for industry [118].

While nanomaterials in food packaging offer significant advantages, such as improved preservation and antimicrobial properties, safety concerns related to their migration and potential toxicity remain unresolved. More detailed risk assessments and the development of specific regulations are needed to ensure the safe use of nanomaterials in food packaging.

5. Edible Film and Coating Functionalities Important for the Small Fruit Industry

Eating fresh fruit and vegetables is one of the recommendations for a healthy lifestyle. However, they are only available seasonally in some parts of the world. An equally important issue is post-harvest durability. This applies especially to small berries with high water content. The shelf life of such unprocessed fruits is a maximum of several days. They belong to the group of non-climacteric fruits, which means they do not ripen after being picked. Thus, they must be harvested when fully ripe, making them even more susceptible to rapid spoilage. High water and straightforward sugar content in ripe berries are the main factors contributing to their susceptibility to the development of microorganisms. Generally, fruit losses are estimated at 25–50% of total production. Berries are susceptible to mechanical damage, water loss, and contamination during harvesting, packaging, and storage. Hence, the shelf life of fresh berries such as raspberries, blackberries, boysenberries, and loganberries, even if stored at a temperature around 0 °C and relative humidity around 90%, is usually between 2 and 5 days [108]. Strawberries are suitable for fresh consumption for 5–7 days [109]. Sweet cherries (2–3 weeks) and grapes (up to 24 weeks) are slightly more durable [110].

In the old days, fresh fruit was consumed only immediately after harvest, often still in the field. With the development of transport and distribution of fruit over long distances, the time from harvest to consumption has been significantly extended. This places significant demands on harvesting, handling, storage, and transport techniques. If appropriate protection systems are not provided, delicate berries spoil, losing their attractive appearance, taste, and nutritional value, and, what is more, they become contaminated with bacteria and molds, which poses a real threat to consumers’ health [111].

Edible coatings, i.e., those suitable for consumption, are made from food-grade biopolymers derived from plants, animals, or marine organisms, as well as food processing by-products. These packaging materials can also be used as carriers for various active ingredients that can extend shelf life, improve the nutritional value and organoleptic properties, and even enhance the health-promoting potential of the final product. The efficiency of using edible coatings to extend the shelf life of fresh berries depends on the properties of the polymer itself, which is the basis for producing the film, but also on functional additives such as plasticizers or various biologically active substances [119]. The plasticizer is a necessary additive ensuring the integrity of the coating without pores and cracks. Some of the most commonly used plasticizers are sorbitol, glycerol, or polyethylene glycol. Surfactants such as Tween 20, Tween 80, or oleic acid can improve the wettability and homogeneity of coatings [120].

There are many challenges and expectations regarding post-harvest edible coatings for low-durability fruits. First, these coatings should not contain toxic, allergenic, or indigestible ingredients, ensuring consumer safety. It is also vital to protect these soft and delicate fruits from damage during transport; therefore, these coatings must adhere well and evenly to the surface and be structurally stable. The appropriately selected composition aims to ensure the semi-permeability of the coating to gases and water vapor. None of the coating components should adversely affect the product’s nutritional, organoleptic, and aesthetic properties. Biochemical and microbiological stability, i.e., protection against contamination and spoilage, is one of the most critical challenges in the functionality of edible coatings [16]. Additionally, edible films and coatings can be carriers of desired flavor additives, fragrances, colorants, nutrients, or vitamins. Incorporating compounds with antioxidant and antimicrobial properties can also increase the storage stability of the raw material [120].

5.1. Bioactivity of the Edible Films and Coatings

Bioactive compounds incorporated into edible coatings used to protect small fruits can include diverse compounds (Table 2), such as colorants, flavors, nutrients, and compounds with antimicrobial or antioxidant properties [119].

Researchers are increasingly interested in using natural sources of antioxidants and antimicrobials, such as natural extracts [121]. This is due to consumer expectations, their health concerns about using synthetic antioxidants or antibiotics, and the broadly understood concern for the natural environment [122,123,124,125]. An additional challenge for innovation in edible coatings may be the introduction of natural substances with targeted health-promoting effects, e.g., antihypertensive, anti-inflammatory, or anticancer.

Table 2. The antioxidative and antimicrobial activities of edible coatings/films used in perishable fruits.

Fruit	Coating/Film Compounds	Activity	Reference
Blackberries	chitosan, lactic acid starch-nystose	anti-mold	[126,127]
Blueberry	chitosan and alginate-bases with inulin, oligofructose, and apple or orange fibers	antioxidative anti-fungal	[128]
	chitosan and quinoa proteins with thymol oil	antimicrobial	[129]
	chitosan enriched with blueberry leaf extract	antimicrobial	[130]
Blue honeysuckle	chitosan and Aloe vera gel	antioxidative	[131]
Highbush blueberry	starch and gelatin bases with cinnamon oil	antioxidative	[132]
Grapes	Aloe vera gel	antioxidative	[133]
	Brazilian pine seeds starch, citric pectin, and feijoa fruit extracts	antimicrobial	[134]
Raspberries	zein, Argentinian propolis extracts	antimicrobial	[135]
Strawberries	chia seed mucilage and bacterial cellulose nano-fiber	antioxidative	[136]
	gum Arabic and bergamot pomace extract and oil	antioxidative	[137]
	xanthan gum and sodium nitroprusside	antioxidative	[138]
	chitosan and peony extracts	antimicrobial	[139]
	chitosan	antioxidative	[128]
	chitosan and leaf and olive pomace extracts	antifungal	[140]
	gum Arabic carrageenan and xanthan with lemongrass essential oil	anti-yeast and anti-mold	[141]
	chitosan with gelatin, starch, and sorbitol with or without monoterpenes (geraniol and thymol)	antioxidative	[142]
Perishable fruits	chitosan derivatives conjugated with gallic acid	antioxidative and antimicrobial	[143]

Table 2. The antioxidative and antimicrobial activities of edible coatings/films used in perishable fruits.

Fruit	Coating/Film Compounds	Activity	Reference
Blackberries	chitosan, lactic acid starch-nystose	anti-mold	[126,127]
Blueberry	chitosan and alginate-bases with inulin, oligofructose, and apple or orange fibers	antioxidative anti-fungal	[128]
	chitosan and quinoa proteins with thymol oil	antimicrobial	[129]
	chitosan enriched with blueberry leaf extract	antimicrobial	[130]
Blue honeysuckle	chitosan and Aloe vera gel	antioxidative	[131]
Highbush blueberry	starch and gelatin bases with cinnamon oil	antioxidative	[132]
Grapes	Aloe vera gel	antioxidative	[133]
	Brazilian pine seeds starch, citric pectin, and feijoa fruit extracts	antimicrobial	[134]
Raspberries	zein, Argentinian propolis extracts	antimicrobial	[135]
Strawberries	chia seed mucilage and bacterial cellulose nano-fiber	antioxidative	[136]
	gum Arabic and bergamot pomace extract and oil	antioxidative	[137]
	xanthan gum and sodium nitroprusside	antioxidative	[138]
	chitosan and peony extracts	antimicrobial	[139]
	chitosan	antioxidative	[128]
	chitosan and leaf and olive pomace extracts	antifungal	[140]
	gum Arabic carrageenan and xanthan with lemongrass essential oil	anti-yeast and anti-mold	[141]
	chitosan with gelatin, starch, and sorbitol with or without monoterpenes (geraniol and thymol)	antioxidative	[142]
Perishable fruits	chitosan derivatives conjugated with gallic acid	antioxidative and antimicrobial	[143]

5.1.1. Antimicrobial Properties

The quantity and quality of microorganisms present in fruits after harvesting depends on the pH of the environment, water activity, and the availability of nutrients [111,144,145,146]. Most small fruits, including berries, require storage at a reduced temperature. Hence, populations of bacteria from the genera Enterobacteriaceae (especially Erwinia herbicola and Rahnella aquatilis) and Pseudomonadaceae (especially P. fluorescens) and some species of lactic acid bacteria (especially Leuconostoc mesenteriodes) may occur on the surface [147]. At the same time, the presence of various species of yeast from the genera Torulaspora, Pichia, Trichosporon, Cryptococcus, Rhodotorula, and Candida is often observed, as their development is favored by the low pH of the fruit [148].

These pathogens on the fruit surface may lead to foodborne diseases. Several mechanisms are distinguished among the methods of preventing the development of pathogenic microorganisms (Figure 4) [148]. An alternative may be edible coatings, which, in addition to barrier properties, limit evaporation and water absorption or reduce ethylene production. These can significantly slow down fruit spoilage. They may additionally have properties that restrict the development of pathogenic microflora or contain additional substances with documented antimicrobial properties [149].

Polysaccharides, proteins, and lipid compounds can create edible coatings. Antimicrobial agents can be incorporated into the packaging material, coated on the surface of the packaging film, or added to the package in a sachet [150] (Figure 5).

Some of the polymers used to produce edible coatings have antimicrobial properties themselves. Such effects have been confirmed, among others, for polysaccharide films based on chitosan. Chitosan is obtained by the deacetylation of chitin, which improves its solubility in the starting material and facilitates the preparation of a film-forming solution. Additionally, its unique properties deserve special attention, i.e., confirmed safety of use, non-toxicity, biodegradability, biocompatibility, and potential applications in post-harvest preservation. Numerous studies of chitosan itself and films made from it confirm antimicrobial activity against many bacteria and mildew. Among the proposed mechanisms of this activity are the binding of positively charged chitosan glucosamine subunits to the negatively charged cell wall of the pathogen, which causes changes in the permeability of the cell membrane and the binding of chitosan to DNA, which results in the inhibition of cell division and, consequently, death [151,152]. Similarly, the development of pathogenic microflora was inhibited by edible coatings made from other polysaccharides, such as guar gum [153] or gum Arabic [154], pectin [155], fucoidan [156], or even [157]. Antimicrobial activity was also confirmed for films made from some proteins, such as casein or hydrolysates of milk proteins [158], and lipids, e.g., candelilla wax [159]. Very often, edible coatings are a composition of two or more polymers mixed in various proportions. Such a solution not only modifies the physicochemical properties of the obtained coatings but, at the same time, can enhance biological properties, including antimicrobial ones [160]. Kritchenkov et al. [161] demonstrated that blends of triazole betaine chitosan (TBC) with succinyl chitosan sodium salt (SC-Na) significantly increased antibacterial properties compared to SC-Na alone. A better effect for E.coli (Gram-) than S. aureus (Gram+) was observed. Gram-positive bacteria are more susceptible to antibacterial compounds than Gram-negative, which have a less permeable, lipid-based outer membrane [162].

Biologically active compounds are added to the film-forming solutions to enhance the antimicrobial properties of edible films and coatings. These can be typical preservatives, such as potassium sorbate or benzoic acid. They can be bacteriocins but are often very effective; they are essential oils with well-documented antimicrobial activity. Natural and safe antimicrobial agents from the crucial oil group include thymol, carvacrol, eugenol, cinnamaldehyde, rosemary, and citral. Strong antimicrobial properties were demonstrated by the essential oil of carvacrol and cinnamic aldehyde added to the edible film. Similarly, adding lemon and bergamot essential oil as an antimicrobial agent to the coating based on whey protein isolate with glycerol as a plasticizer effectively combats Escherichia coli and Staphylococcus aureus [162]. A film-forming mixture of chitosan and quinoa proteins enriched with thymol oil used as a coating on blueberries showed strong antimicrobial properties against Salmonella Typhimurium, Staphylococcus aureus, and Listeria innocua [129]. The level of antimicrobial activity was increased by adding essential oils from lemongrass, mint [163], or Chinese orange [164] to the films. Antifungal activity was effectively increased by incorporating edible coatings based on pectin with lemon oil [158] or whey protein-based film with cinnamon essential oil addition [141]. Coatings based on gum Arabic, carrageenan, and xanthan with lemongrass essential oil significantly reduced yeast and mold count compared to uncoated strawberries during storage [165]. Coatings containing Argentine propolis extract applied to raspberry fruits showed strong antifungal properties [135]. More and more often, metabolites of lactic acid bacteria are used as antimicrobial agents added to film-forming solutions. They are natural probiotics and antagonists of pathogenic microflora. These metabolites include, among others, bacteriocins or bacteriocin-like inhibitory substances, i.e., proteins or peptides with documented antibacterial properties, such as nisin, pediocin, lacticin, and enterocin. They can also be antifungal compounds, e.g., propionate, phenyl acetate, or cyclic dipeptides. Similarly, organic acids (benzoic, sorbic), some fatty acids, hydrogen peroxide, or diacetyl, formed in lactic fermentation, can effectively inhibit the development of harmful microorganisms [125]. A promising addition to edible coatings used to protect berries against microorganisms are various plant extracts containing biologically active compounds with a diverse chemical structure. Yang et al. [130] showed that blueberry leaf extract (BLE) showed a significant effectivity against E. coli and S. aureus with an inhibition zone >7.5 mm. Blueberries coated with chitosan enriched with 8–12% BLE lower the decay rate of fruit during extended storage compared to uncoated control [130]. The results of the antimicrobial assays indicate that the peony extracts in chitosan were able to counteract effectively the growth of the fungus Candida valida and Pichia kluyveri isolated from deteriorated strawberries, which prolongs the shelf life of strawberries to about 16 days [139]. Extracts obtained from food industry waste products are worthy of attention. Grapefruit seed extract incorporated into carnauba wax coating caused total growth inhibition of M. fruticola and R. stolonifera [166]. Chitosan coatings enriched with leaf and olive pomace extracts showed antifungal activity against P. expansum and R. stolonifer applied to strawberries [140]. Coating blackberries with chitosan at 17.5 mg/mL dissolved with lactic acid (LA-17.5) effectively reduced soft mold caused by M. racemosus during the postharvest period [126]. Films based on Brazilian pine seeds starch, citric pectin, and feijoa fruit extracts applied on grapes demonstrated the effectiveness for food conservation. The release of bioactive compounds indicates that the films are a rich source of compounds with potent antimicrobial activity against Escherichia coli, Salmonella, and Shigella [134]. The number of mesophilic and psychrotrophic bacteria and the number of yeasts and molds in blackberry fruits coated with edible starch-nystose during 20 days of cold storage resulted in recommended microbial counts of less than 10⁶ CFU/g of fruit. They were statistically lower than that determined for uncoated fruits [126]. Among the bactericidal ingredients incorporated into edible films and coatings are also ingredients of animal origin, including enzymes, e.g., lysozyme isolated from hen egg or lactoferrin or lactoperoxidase from milk. Lysozyme causes hydrolysis of peptidoglycan, a component of gram-positive bacteria’s cell wall. A particular advantage of antibacterial-enriched edible films is that they eliminate food-borne pathogens or food-spoilage microorganisms on food surfaces by diffusing the antibacterial agent into the food product, but do not result in the overall increase of the additive in the food.

5.1.2. Antioxidant Properties

The ability of edible films/coatings to maintain and enhance the antioxidant activity (Figure 6) of fruits is closely tied to their role in modifying physiological processes such as limiting respiration, reducing ethylene production, and delaying ripening.

In many studies devoted to determining the antioxidant properties of edible films, the ability to scavenge DPPH (2,2-Diphenyl-1-picrylhydrazyl) and/or ABTS (2,2′-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid)) radicals and the iron-reducing antioxidant capacity (FRAP) are most often used. The most effective method of extending the shelf life of small fruits is to use a polymer matrix with the addition of antioxidant compounds.

Nia et al. [133] investigated the effects of pre-harvest foliar applications of chitosan (2.0% and 3.0%) and post-harvest coatings of Aloe vera gel (25% and 33%) on the antioxidant activity of table grapes during storage. The results showed that the foliar application of 3.0% chitosan with a 33% Aloe vera gel coating extends the storage life of fruit up to 15 days by significantly maintaining antiradical activity against DPPH.

Mousavi et al. [136] investigated the effect of chia seed mucilage (CSM)—bacterial cellulose nano-fiber (CNF) edible coating on bioactive compounds and antioxidant enzyme activity of strawberries. The antioxidant activity of uncoated and coated samples, assessed by the DPPH method, decreased during storage. The use of CSM-CNF edible coatings preserved the antioxidant activity of strawberries, and this effect was more evident in the CSM-coated sample containing 0.8% cellulose nano-fiber.

The study by Alvarez et al. [128] aimed to compare the effects of different types of coatings—chitosan-based (CH) and alginate-based (AL) enriched with inulin, oligofructose, and apple or orange fibers—on the quality and shelf life of blueberries. The study also evaluated the antioxidant activity of blueberry samples using the DPPH scavenging assay, focusing on the effects of chitosan-based (CH) and alginate-based (AL) coatings. The results showed that CH-based coatings were more effective in consistently enhancing antioxidant activity throughout storage when enriched with fibers than AL-base coatings. The antioxidant effect of active films based on blends of gelatin and/or chitosan containing different bioactive agents (hop extract, hop α-acids, or hop β-acids) using DPPH and FRAP assays was investigated by Xu et al. [167]. The films containing β-acids showed the highest antioxidant potential, followed by those containing α-acids, films containing hop extract, and finally, the control films.

According to the findings of Qiao et al. [131], coating blue honeysuckle (Lonicera caerulea L.) with 1% chitosan (CH) and 30% Aloe vera gel solution significantly increased their antioxidant capacity, as assessed by DPPH, ABTS, and FRAP assays. The authors observed that coating with CH, Aloe vera, and CH + Aloe vera significantly enhanced the fruit’s antioxidant capacity. This improvement contributed to an overall enhancement of the fruit’s quality during storage.

In another study, the DMPD (N,N-dimethyl-1,4-phenylenediamine) radical scavenging method was applied to evaluate the antioxidant potentials of the extracts of strawberries chitosan coated with incorporated with gelatin, starch, and sorbitol with or without monoterpenes (geraniol and thymol) formulation (T1–T7) [142]. Among the coatings, the one that incorporated 0.02% thymol (T4 and T5) was the most effective in terms of antioxidant activity. Lee et al. [143] explored the potential of chitosan (CS) derivatives conjugated with gallic acid (GA) as edible coatings for perishable fruit shelf life. The resulting CS-GA conjugate films exhibited excellent antioxidant properties ((DPPH method) compared to CS films. In recent years, numerous researchers have explored specific food by-products and residues with potential applications as components in biodegradable and edible films for preserving fruits and vegetables [168]. Adding a natural antioxidant extract from bergamot pomace (Citrus bergamia Risso) and bergamot essential oil in the coating obtained by De Bruno et al. [137] contributed to achieving an antioxidant activity preserving strawberries’ quality. Using the ABTS assay, the measured antioxidant capacity was higher than the DPPH assay. During fruit storage, the total antioxidant activity generally increased, with the most notable rises observed in samples containing 100 ppm BHT, both 1% and 5% bergamot pomace extract. In Bodana et al. [169] research, pomegranate peel extract of varying concentrations was incorporated into jackfruit seed starch-based edible films and coatings to evaluate their antioxidant activity. Moreover, the effect of the optimized edible coatings was investigated on the postharvest shelf life of white grapes. The results showed a significant increase in the prepared edible films’ antioxidant activity (DPPH assay) but decreased water vapor permeability.

Studying the antioxidant properties of edible coating and films is still a largely understudied field, and adding different compounds to these films (Figure 7) can significantly improve those properties.

5.1.3. Anti-Enzymatic Capacity

One of the leading causes of loss of fruit quality during storage is oxidative stress in plant cells. Many biotic and abiotic factors contribute to the excessive increase of reactive oxygen species (ROS) and, thus, to the disturbance of the oxidation-reduction balance of cells. ROS causes oxidative damage to cell components and alters the permeability and integrity of cell membranes [170]. As a result, this leads to a reduction of enzymatic and no enzymatic antioxidant activity and, consequently, to a deterioration in the quality of the fruit. The first line of defense in plant cells against oxidative stress involves antioxidant enzymes such as superoxide dismutase (SOD), catalase (CAT), peroxidase (POD), glutathione peroxidase (GPX), or ascorbate peroxidase (APX). These enzymes help maintain reactive oxygen species at safe levels, essential for protecting cells from damage. Keeping ROS at an optimal level can significantly improve the storability of fruits, delaying spoilage and extending freshness. On the other hand, other essential enzymes produced by plants in response to insects and pathogens include phenylalanine ammonia-lyase (PAL), peroxidases (POD), and polyphenol oxidase (PPO) [171]. Moreover, the PPO is an enzyme associated with browning and quality degradation in stored fruits. Therefore, it is desirable to inhibit its action.

Many scientific studies have shown that edible films/coatings are an alternative method of extending the life of fruit after harvest. The films/coatings constitute a barrier to water loss and volatile aromas, exhibit antioxidant activity, and prevent browning and gas exchange, reducing the rate of oxidative reaction during storage. Edible films and coatings can be carriers of active substances such as antioxidants, antibacterial compounds, and enzyme inhibitors. Due to the nutrients, vitamins, or minerals in their structure may also have health-promoting functions [16,48,109].

Petriccione et al. [172] investigated the effect of 1% and 2% chitosan coatings on the enzyme activity of three selected strawberry varieties stored in cold conditions. Chitosan-coated fruit showed significantly lower lipoxygenase (LOX) activity than control fruit in all the analyzed cultivars. Although catalase (CAT) and ascorbate peroxidase (APX) activities in chitosan-coated strawberry fruits also decreased during cold storage, this decrease was smaller than in fruits without chitosan coating. Moreover, chitosan coating significantly delayed PPO and guaiacol peroxidase (GPOD) activity. The use of edible films/coatings incorporating bioactive components has emerged as an effective method for prolonging the shelf life of perishable fruits by modulating enzymatic activity. These coatings can either inhibit enzymes responsible for spoilage or promote the activity of antioxidant enzymes that protect the product from degradation.

The investigation obtained by Mousavi et al. [136] showed that bacterial cellulose coatings (CNF) infused with chia seed mucilage (CSM), a by-product of chia processing, demonstrated inhibitory effects on both PPO and POD activities, reducing browning and spoilage rates. The activity of PAL was also significantly reduced by using coatings, especially the one containing bacterial cellulose. Whereas the activity of SOD in the control and CSM- coated strawberries was considerably higher than in the other samples [136]. The study by Badawy et al. [141] focused on developing biodegradable coatings based on a combination of natural polymers like chitosan, gelatin, starch, and sorbitol, with and without the addition of monoterpenes (geraniol and thymol). These coatings also aimed to enhance the shelf life and quality of strawberries. The activity of followed enzymes, guaiacol peroxidase (GPX), polyphenol oxidase (PPO), and catalase (CAT), were investigated in the experimental fruits, and they were compared with that of controls. The authors observed inhibited the increase in GPOD and PPO activities; and retarded the reduction in CAT activity. Nia et al. [133] also observed that the PPO activity of postharvest coatings of 33% Aloe vera gel-treated grapes was reduced.

Piechowiak et al. [132] studied the impact of incorporating cinnamon oil into starch-based and gelatin-based edible coatings on the level of ROS and the activity of blueberries. Fruit coated with cinnamon oil was characterized by a lower ability to produce ROS and a lower activity of antioxidant enzymes (SOD and CAT). In the case of fruit packed in coatings, the APX, GPX, and PPO activities were significantly lower than that of the control fruit. However, PAL activity, both in the control and test samples, decreased as the storage period extended. Edible coating/films can also inhibit the activity of enzymes such as cellulase, pectin lyase, and polygalacturonase, which break down the polysaccharides in fruit cell walls, thereby preventing their spoilage [173].

All of the coatings proposed by Badawy et al. [142] inhibited cell wall degrading enzymes: polygalacturonase (PGase) and pectin-lyase (PLase). Among the seven tested coatings, 1% chitosan, 1% starch, 0.5% sorbitol, 0.05% tween, and 0.02% thymol were the best. Gautam et al. [138] investigated the impact of a coating made from xanthan gum (XG) combined with sodium nitroprusside (SNP) on the antioxidant defense mechanisms of strawberries during storage. Their findings demonstrated that strawberries treated with XG 0.50% + SNP coating exhibited significantly increased selected antioxidant enzyme activities (CAT, POD, and PAL). Moreover, this coating effectively inhibited polyphenol oxidase (PPO) activity.

5.1.4. Anti-Cracking

Edible films and coatings offer several essential functionalities for the small fruits industry, particularly their bioactivity [84,174]. Another crucial aspect is their ability to prevent cracking, a significant concern for many small fruit varieties. Indeed, small fruits, such as cherries, grapes, and berries, are highly susceptible to cracking, which can significantly reduce their market value and shelf life [175]. Cracking occurs when the fruit rapidly uptakes water due to rainfall or high humidity, causing the fruit skin to split [175]. Edible films and coatings can mitigate this issue through various mechanisms: (i) moisture barrier, which creates a semi-permeable barrier on the fruit surface, regulating moisture transfer between the fruit and its environment [176]. This barrier helps prevent excessive water uptake during periods of high humidity or rainfall, reducing the internal pressure that leads to cracking. Polysaccharide-based coatings, such as those made from alginate or pectin, have shown particular promise in this regard due to their ability to form cohesive films [42]; (ii) structural reinforcement, as some edible coatings can enhance the mechanical strength of the fruit skin. For instance, protein-based coatings derived from whey or soy proteins can form a flexible yet strong layer that reinforces the fruit’s natural protective barrier [43]. This added strength helps the fruit withstand the internal pressure caused by water uptake, thus reducing the likelihood of cracking; (iii) elasticity enhancement, as specific coating formulations can improve the elasticity of the fruit skin, allowing it to expand without breaking when the fruit absorbs water. Lipid-based coatings, often used in combination with hydrocolloids, can contribute to this effect by providing flexibility to the coating layer [176]; (iv) controlled ripening, by modifying the internal atmosphere of the fruit, edible coatings can slow down the ripening process. This is particularly beneficial for cracking prevention, as overripe fruits are more susceptible to splitting. Coatings that create a modified atmosphere with reduced oxygen permeability can delay ripening and maintain fruit firmness [2]; (v) integration of active compounds, as edible coatings, can be enriched with various bioactive compounds contributing to cracking prevention. For example, incorporating calcium salts into the coating formulation can enhance the structural integrity of the fruit cell walls, making them more resistant to cracking [177,178]. Similarly, adding antioxidants can help maintain the elasticity of the fruit skin by preventing oxidative damage [42,179]. Research has demonstrated the effectiveness of anti-cracking edible coatings on various small fruits. For instance, a study on sweet cherries showed that a chitosan-based coating significantly reduced cracking incidence compared to uncoated fruits [47]. Similarly, alginate coatings have been found to reduce water uptake and cracking in grapes while also maintaining their overall quality during storage [180,181]. In conclusion, the anti-cracking functionality of edible films and coatings represents a valuable tool for the small fruits industry. By providing a protective barrier, enhancing structural integrity, and allowing for the incorporation of beneficial compounds, these coatings can significantly reduce fruit losses due to cracking. Indeed, cracking can occur due to physiological, genetic, or environmental factors. The combination of those factors makes fruit cracking challenging to study, even in controlled conditions, and the basic mechanisms involved remain unclear [174]. As research in this field advances, we can expect even more effective and tailored solutions for specific fruit varieties and environmental conditions, further improving the quality and marketability of small fruits.

5.2. Encapsulation Techniques and Mechanisms of Shelf-Life Extension Through Encapsulation Techniques

From a conventional point of view, edible film formation requires adding bioactive ingredient(s) to the film-forming solution, followed by the film’s casting [182]. An alternative approach is encapsulating the active component before mixing it with the film-forming materials [183]. Encapsulation can be defined as keeping compounds of interest within a carrier/matrix to improve the delivery of these active substances into food products while aiming to improve their properties or enhance stability to external factors [184,185]. The used carriers can comprise several substances, including carbohydrates, proteins, lipids, and other organic and inorganic materials [186]. Nonetheless, they must conform to some criteria to be suitable for encapsulation systems, some of those regarding structure (composition and phase state), functionality (solubility, viscosity, particle size, morphology of surface, total charge of particles), organoleptic characteristics (color, flavor, and aroma) physicochemical parameters (resistance to changes in pH, temperature, humidity, oxidizing agents and radiation), physiological behavior (release mechanism, conformational changes in gastrointestinal tract, release rate, and toxicity), economic feasibility (financial availability of materials and technologies), and finally cultural, religious, and food restrictions [187,188]. Carriers can be classified according to their morphological structure, phase state, or material nature [189].

The techniques used to achieve encapsulation can also be classified into different categories according to their carrier material, delivery systems, or state of the core material [189,190]. A standard classification includes three main classes: physical-mechanical, physical-chemical, and chemical methods [191]. All of them present several advantages and limitations. Even so, encapsulation is viewed by the food industry as a beneficial technology that provides numerous benefits, such as easy handling and protection of active compounds, controlled release, control of sensory properties, and specific marketing effects. In the food industry, encapsulation can be used aiming at multiple effects, from improvement of the core material characteristics, focused on its release conditions or rate [192] or protection of the core material from environmental factors, that will ultimately improve the shelf life the encapsulated material [193]. Encapsulation can be used to make edible films or coatings that can be applied to fruits and vegetables, aiming to extend their shelf-life [194]. To be used in encapsulation materials for the food industry, ingredients have to be “generally recognized as safe” (GRAS) [195].

Several approaches to the encapsulation exist, including electrospinning, electrospraying, spray drying, microfluidics, extrusion, 3D printing, coacervation, lyophilization, incorporation into nanotubes, porous micro/nanospheres, nanocomposites, isoelectric precipitation, antisolvent coprecipitation, and ionic gelation, depending the physical state of core (solid, liquid or gas), summarized in

Table 3. Technical principles and characteristics of solid/liquid/gas-state core encapsulation systems. Adapted from Xu et al. [201].

Encapsulation System	Principle	Features
Spray–Drying Technology	Emulsion dried into granules using atomization in the hot air stream	Advantages: short drying process, good solubility, low cost and process operation, proper transportation and storage. Disadvantages: uneven particle dimension, partial rupture of core material.
Spray–Cooling–Drying	Material combined with emulsifier and wall material. Creation of microcapsules by freezing at a temperature of −20 °C and then placing freeze-dried	Advantages: minimal core damage. Disadvantages: it requires crushing and sieving and has high equipment requirements.
Fluidized Bed	Hot air-flow of fluidized bed is used to wrap core material with wall material solution	Advantage: uniform and moderate wall thickness. Disadvantages: the surface is easy to damage and has a low yield.
Oil-Phase Separating Method	The core material is added to a shell polymer and solvent solution, mixed and dispersed into a suspension, then added to a nonsolvent liquid and precipitation solvent, encapsulating the core material into microcapsules.	Advantages: simple equipment needs and a varied range of shell materials. Disadvantages: potential environmental pollution from solvents.
Extrusion	The core and wall material emulsion is extruded through pore membranes at low temperatures. Wall material in direct contact with a dehydrating agent forms microcapsules due to dehydration.	Advantages: improved closure of the capsule. Disadvantages: low surface oil content.
Interfacial Polymerization	Two monomers of different solubility are uniformly added to the continuous phase of wall material and the dispersed phase of core material. Polycondensation occurs at the phase interface, resulting in the formation of microcapsules.	Advantages: good densification and faster reaction rates. Disadvantage: retention of the monomers in microcapsules.
Air Suspension	An aqueous solution containing wall material is sprayed on the surface of the suspended core material. Solvent vaporization is performed using low hot air.	Advantages: a range of wall materials and uniform wall thickness of the capsule. Disadvantages: control factors and limitations regarding core material.
Electrostatic Spinning	Charged polymer solution flow deformed in an electrostatic field, followed by solvent evaporation or melt–cooling.	Advantages: easy to operate, no organic solvents, low cost, high efficiency. Disadvantages: difficulty in obtaining nanofiber filaments or separate staple fibers.
Phases Emulsion Method	Core material is combined with an emulsifier and mixed with wall material to form an emulsion. Microcapsules are obtained by curing after removing the solvent from the suspension emulsion.	Advantages: simple, high stability. Disadvantages: residual toxic organic solvents.
Tiny Hole-Coagulation Method	Microcapsules are formed by placing a mixture of core and wall materials into a tiny hole-coagulation device, followed by calcium chloride or aldehydes, for a cross-linking reaction.	Advantages: simple operation and absence of the use of organic solvents. Disadvantages: larger particle size and low encapsulation rate.
Liposome Encapsulation Technology	The wall material consists of spherical or approximately spherical vesicles with an biofilm structure composed of phospholipid bilayers or thin layers.	Advantages: reduced degradation in extreme environments. Disadvantages: difficult elimination of organic solvents, challenging storage conditions.
Emulsion Encapsulation	In oil–an oil-water system, emulsion is formed, creating colloidal particles to be encapsulated.	Advantages: simple process, improved digestibility, antibacterial and antioxidant activity. Disadvantages: low stability and demulsification in extreme environments.
Complex Coacervation	After dilution, pH value, or temperature adjustment, the reaction between the wall materials is condensed and precipitated.	Advantages: minor preparation process, high efficiency. Disadvantages: difficult control of reaction conditions and high production costs.
Nanoencapsulation Technology	Bioactive substances are encapsulated through nanocomposite, nanoemulsification, and nanoconstruction.	Advantages: stability, improved in vivo absorption, effective core quality improvement, safety, and functionality. Disadvantages: obliges high precision.
Supercritical Impinging Stream Technology	The solute is dissolved in supercritical fluid to saturate and then introduced into the low-pressure chamber, causing it to precipitate in tiny particles.	The advantages are the low-temperature process, minimal residual solvent in particles, recycling of solvent and antisolvent, and uniform particle size. The disadvantages are the nozzle anti-blocking, sealing simplification, and equipment investment.

. Spray drying is one of the most used and old techniques due to its flexibility, continuous operation, and economical value [196,197,198]. Other methods are extrusion methods, where droplets of an aqueous solution of polymer and the desired compound to be encapsulated are dropped into a gelling bath [199]. Another common technique is emulsions, which can be used in two main combinations, water/oil emulsions or oil/water emulsions, that can be further dried to produce a powder. Fluid bed coating can also be applied, where core particles are suspended in airflow and sprayed with an atomized coating material that might be an aqueous solution of cellulose or starch derivatives, proteins, and gums [200]. Spray-chilling or spray-cooling are two technologies that allow the production of lipid-coated substances, with the main difference between them being the melting point of lipids, that, in case of chilling, it is in the range of 34–42 °C and cooling temperature is higher [186]. Vacuum and freeze-drying are very similar drying processes, but freeze-drying depends on a high energy input and long processing time [200].

Encapsulation systems, combined with edible coatings or films, extend the shelf-life of fruits by offering protection from environmental factors and shielding sensitive compounds from heat, oxygen, light, and moisture, which are common causes of degradation in food products. They can also act as a barrier to microbial contamination, extending the shelf life of perishable goods like fruits and vegetables by reducing spoilage rates. Furthermore, encapsulating bioactive compounds allows for the gradual release of those bioactive compounds, which helps maintain the quality and safety of food over time. Encapsulated antimicrobials and antioxidants can be released in response to specific conditions, such as temperature or moisture, reducing microbial growth and delaying spoilage. The release of such compounds can occur in several manners, including diffusion, dissolution, erosion, swelling, osmosis, degradation, and fragmentation [202,203,204,205]. Diffusion from an encapsulation system depends on the solubility and its permeability, and the release rate can be affected by the bioactive compound characteristics (molecular weight, polarity, and vapor pressure) but also on the encapsulation system itself (polarity, physical state, interactions, and rheology). Dissolution can occur in two different ways, one being the encapsulation–dissolution-controlled system, in which bioactive compounds are encapsulated in dissolving materials and dissolution rates are controlled by the solubility of the bioactive compounds and the physicochemical proprieties of the carrier, and the other, the matrix–dissolution-controlled system, in which the bioactive compounds are distributed homogeneously in the particle, influencing the dissolution rate. Another release mechanism is erosion, in which the chemical degradation of the particle-matrix occurs in a specific environmental condition, causing the release of the bioactive compound. Swelling and osmosis release act similarly, where the release of the bioactives occurs by the swelling of the capsule due to solvent absorption or osmotic pressure. Finally, degradation occurs by disrupting the encapsulation systems by microorganisms, and fragmentation occurs when the systems suffer rupture due to environmental factors, such as pressure, pH, or enzymatic.

5.3. Pitfalls of the Bioactives Present in Edible Films and Coatings

Even though edible coatings and films present enormous advantages, there are still some limitations or disadvantages. Indeed, the interaction of encapsulated compounds with the capsule or the food that they are “protecting” must be carefully characterized to limit alteration caused by the mode of action of bioactive compounds [2] or to reduce changes in color or sensory characteristics of coated products [206]. The effect on sensory characteristics has to be carefully monitored. Indeed, different studies show that edible coating can positively or negatively affect the sensory traits of coated products. Storage conditions (like temperature or humidity) that allow the expected activity of edible films and their encapsulated material must be detailed [207]. As referred to before, the encapsulated bioactive compounds must be GRAS to avoid cytotoxic effects, toxicological reasons, or allergenicity, and, in addition, nanoparticles, due to their small size, can enter human tissues and damage them. Hence, the size and quantity of nanoparticles are key when added to edible packaging [125]. The use of antimicrobial coatings must also address the issue of microbial resistance, aiming at the use of compounds or extracts that do not cause such a phenomenon. In contrast, the release speed of encapsulated compounds must be correlated with the growth rate of microorganisms. Otherwise, and if the release rate of an antimicrobial agent is faster than the growth of the organisms, the bioactive agent will be depleted before the storage period. The packaging system will lose its activity, resulting in the development of microorganisms, and, on the other hand, when the release rate is too slow, the organisms may grow before the antimicrobial agent is released. Edible films and coatings are biodegradable and environmentally friendly packaging, and the bioactive compounds to be added to those coatings must follow the same rationale. Using the more economical and green methodologies, possible extraction procedures will focus on two major concerns: the costs of extracting some bioactive and using toxic solvents. Finally, regulations exist for edible coatings, their ingredients and additives, dosages, and concentrations.

5.4. Health Effects and Biodegradability of the Films

So far, there are few studies on the effect of edible coatings on human health. Generally, substances that should be edible and safe are used to coat fruits. Among the film-forming materials themselves, chitosan deserves attention. Ajayi et al. [208] analyzed the effect of chitosan and edible coatings made from it on inhibiting inflammation, which is one of the factors in the development of metabolic syndrome in the body [208]. Fucoidan has numerous health-promoting properties: antioxidant and antimicrobial, antiviral, anti-inflammatory, antithrombotic, and even immunomodulatory and anticancer properties [209]. Compounds introduced into film-forming solutions and then applied to the surface of fruit as a coating exhibit several health-promoting properties. Phenolic compounds possess documented antioxidant, anti-inflammatory, and anti-cancer effects. Their biological activity, however, depends on their bioavailability and bioabsorption, as well as on the interactions that may occur between them and the matrix from which the edible coating is created [210]. Anti-inflammatory and anti-cancer properties are also attributed to terpenoids, which include many components of essential oils. These compounds are often chosen as active ingredients incorporated into edible coatings. In addition to terpenes, oils also contain phenols (such as carvacrol, thymol, and eugenol), alcohols (such as linalool), and aldehydes (such as cinnamaldehyde) that possess antitumor properties. Studies on cell lines have confirmed the anticancer activity of many of the abovementioned compounds [211]. Probiotics are becoming more and more common among coating additives. Edible polymer matrices used in the food packaging industry can serve as carriers for bacteria and yeasts with documented probiotic properties. They can be incorporated into biopolymer matrices to develop active food packaging materials to control pathogenic microorganisms. However, to confer health benefits from probiotics, it is crucial to maintain their viability at an appropriate level (recommended daily dosage of ~10⁹ viable cells). Different technological strategies have been investigated to protect probiotics, the most important being the inclusion of probiotics into edible films and coatings or their microencapsulation into polymeric matrices. This improves food stability and safety and, most importantly, favors consumers’ health [212]. The survival of probiotic microorganisms can be enhanced by adding prebiotics to the film-forming solution, e.g., inulin, polydextrose, wheat dextrin, and glucose-oligosaccharides [213].

Usually, the bioactive components of coatings can be released into food. Still, in the case of probiotics, this is not even necessary because they are consumed together with the coating [214]. Research into the health-promoting properties of edible films and coatings and the fruits to which they are applied is an open path for developing intelligent edible packaging. In recent years, growing awareness and concern for the natural environment have intensified research on edible coatings. One undoubted advantage of producing edible coatings is their potential biodegradability. They should, therefore, be a good alternative to the synthetic packaging still commonly used. Biopolymers, whether polysaccharides, proteins, lipids, or their mixtures, have already been studied relatively well. However, to obtain a durable coating that will stay on the surface of a product, e.g., a small fruit, it is necessary to add a plasticizer. While most biopolymers are highly hydrophilic and easily degradable, adding a plasticizer can affect the film disintegration [215]. The European standard EN13432 applies to testing the biodegradability of packaging materials. Most biodegradability tests are performed in soil [216]. The biodegradability of edible films and coatings varies depending on the polymer used. Starch films decompose in simulated composting conditions at the fastest rate of about ten days [217], while Thakwani et al. [218] report that this time is 5–7 weeks at 25–30 degrees. In turn, gelatin-based protein films can decompose after about 12 days in soil [219]. Soil microorganisms can additionally accelerate the degradation of coatings. This is confirmed by experiments conducted on chitin, gelatin, and cellulose films [220]. For pullulan, levan, and chitosan, degradation can take about a week [221], while for cellulose and guar gum about a month [222]. Generally, lipid-based films, being more hydrophobic, are less biodegradable. This is confirmed by the research of Chettri et al. [223]. Undoubtedly, more research and standardization of the methods used are needed to verify the biodegradability of edible films and coatings.

5.5. Innovations in the Edible Film, Coating and Packaging Industry

Due to innovation in this field, edible films and coating have gained new functionalities, like pathogen inhibition or food preservation characteristics, allowing the food industry to provide fresher, pleasanter, healthier, and high-quality products to consumers [2]. Nanotechnology can help improve the aspects of materials [43] and reduce the problems of degradation, low solubility or bioavailability, and undesirable taste of specific compounds. Indeed, nanostructuring of plant-based materials, a process involving incorporating nanoparticles or nanoscale structures into plant-based materials to improve mechanical, barrier, and antimicrobial properties, can be a significantly important line of research [224]. Another application of nanotechnology is the creation of nanocomposite edible films, where nanofillers, such as nanoparticles or nanoclays, are incorporated to modify mechanical strength, gas permeability, or functional characteristics [225].

Nanoencapsulation can still be further developed to enhance compounds’ stability, release, and delivery and to better link bioactive compounds with shell materials used in encapsulation. Indeed, research continues to evaluate different biopolymers to encapsulate ingredients, including polysaccharides, fats waxes, or proteins [226]. A novel development uses aerogels, a light, and highly porous material with a large surface area, mechanical rigidity, and low thermal conductivity, made of polysaccharides [227]. The importance of these aerogels arises from the fact that they can be easily incorporated with other components and are biodegradable, biocompatible, and edible. Another exciting research field is the 3D printing of plant-based edible films. It allows a customized design with exact control over the deposition of materials, enabling the creation of complex geometries and shapes [228]. However, it still presents several challenges, namely adjusting rheological properties and ensuring food safety and functionality, which are key to enhancing this technique.

6. Final Remarks

Several resources are available to improve the sustainability of the food chain by reusing the so-called “by-products” and reducing losses in post-harvest periods. Marine processing by-products offer a valuable resource for developing biodegradable and active packaging materials while helping to reduce plastic waste. Their biodegradability, film-forming properties, and ability to incorporate bioactive compounds make them suitable for extending the shelf life of perishable foods. Using microorganisms-based materials for packaging small fruits offers a promising solution to enhance food safety and sustainability. These innovative packaging methods can significantly impact the fresh produce industry by reducing microbial contamination and extending shelf life. However, further research and development are needed to overcome the challenges associated with their mechanical properties and commercial scalability.

Agricultural processing by-products, including crop, fruit, vegetable residues, and livestock waste, can be converted into bio-based films and coatings for food packaging, replacing conventional plastics. Materials like cellulose, pectin, and starch, derived from plant sources, are promising due to their biodegradability, film-forming properties, and cost-effectiveness. Protein-based films from animal and plant proteins, including casein, gelatin, and zein, also show potential, offering gas barriers and antimicrobial properties. Cereal by-products, such as starch and wheat gluten, are commonly used for edible packaging due to their excellent barrier properties and biodegradability. Innovations like composite films and nanoparticle incorporation enhance these materials’ strength and functionality. However, integrating nanotechnology into the food industry presents both opportunities and challenges. While nanomaterials can improve food quality and safety, their potential health risks necessitate stringent regulatory frameworks and thorough risk assessments. The EU has led the establishment of specific regulations for nanomaterials, but there is a global need for harmonized guidelines to ensure consumer safety and environmental protection. Further research is essential to fully understand the implications of nanomaterials in food applications and develop sustainable and safe nanotechnology practices.

Nevertheless, these bio-based alternatives help reduce environmental impact and contribute to waste reduction and resource sustainability in the food industry. Even though there is an increased focus on these alternatives, continuous research is needed further to optimize the characteristics and properties of the edible coating, aiming for a more sustainable food chain.