Bionanocomposite Coating Film Technologies for Disease Management in Fruits and Vegetables

Abstract

Fruit and vegetable production is often impacted by microbial pathogens that compromise the quality of produce and lead to significant economic losses at the postharvest stages. Due to their efficacy, agrochemicals are widely applied in disease management; nevertheless, this practice has led to the appearance of microbial strains resistant to these types of agrochemicals. Additionally, there is growing concern among consumers about the presence of these chemical residues in fruits and the negative impacts they cause on multiple ecosystems. In response, there is a growing need for safe, effective, green, and sustainable disease control technologies. Bionanocomposites, with their unique ability to combine nanomaterials and biopolymers that have attractive properties, represents a promising alternative for postharvest disease control. These technologies allow for the development of functional coatings and films with antimicrobial, antioxidant, and barrier properties, which are critical for extending shelf life and preserving fruit quality. Recent advances have demonstrated that integrating nanoparticles, such as ZnO, TiO₂, Ag, and chitosan-based nanosystems, into biopolymeric matrices, like alginate, pectin, starch, or cellulose, can enhance mechanical strength, regulate gas exchange, and control the release of active agents. This review presents systematized information that is focused on the creation of coatings and films based on bionanocomposites for the management of disease in fruits and vegetables. It also discusses the use of diverse biopolymers and nanomaterials and their impact on the quality and shelf life of fruits and vegetables.

1. Introduction

Nowadays, society demands fresh, nutritious, and safe fruits and vegetables that preserve their quality characteristics. This expectation has posed a significant challenge for producers and the food industry in meeting consumer demands. Consequently, it has prompted the food industry and researchers worldwide to explore suitable technologies to extend the postharvest shelf life of fruits and vegetables and reduce food losses [1,2,3]. The most significant postharvest losses occur in fruits, with annual estimates of these losses reaching as high as 45% [4]. The primary cause of postharvest losses is pathogen infection, particularly when fruits are in the ripening stage [5,6]. In addition to economic losses, the increased production of mycotoxins from fungus poses a potential risk to human health [7,8].

From this perspective, nanotechnology has emerged as a highly promising alternative, driven by the pressing demand for sustainable and eco-friendly strategies to mitigate the postharvest losses caused by a wide range of pathogens [3,9]. Among the various nanomaterials investigated, particular attention has been directed toward the design of hybrid systems composed of two distinct chemical components, a nanomaterial and a biopolymer, which are collectively referred to as a bionanocomposite [10]. These materials not only exhibit enhanced antimicrobial properties but also offer significant potential for the development of functional coating films [11]. Such films can be effectively applied in postharvest management through diverse incorporation techniques in fresh fruits and vegetables.

In this context, the development of bionanocomposite coatings and films represents a sustainable and highly promising strategy to reduce postharvest losses caused by pathogen infections [3,11]. Compared with other postharvest treatments, bionanocomposite coatings have demonstrated high efficiency and offer several advantages, including biodegradable compounds, versatility in application methods, cost effectiveness, and broad applicability across various fruit and vegetable types. The incorporation of bionanocomposites with different chemical properties can alter the mechanical, functional, nutritional, and organoleptic characteristics of edible coatings [12,13,14]. Moreover, they have proven to be a viable alternative for reducing losses and extending the shelf life of postharvest fruits and vegetables [15,16,17]. Due to their barrier properties, these coatings can regulate gas exchange and prevent microbial deterioration by forming functionalized layers capable of reducing the metabolic and oxidative reactions associated with the senescence of fresh produce [18,19].

Bionanocomposite coatings and films are of interest because they consist of a thin layer of material that can be consumed and applied directly to the fruit surface, providing a barrier against oxygen, moisture, bacteria, fungus and harmful environmental effects. It is important to emphasize that ongoing research is essential to understand the interactions between the biopolymer and the nanomaterial in the bionanocomposite and to optimize their synergistic effects, particularly their antimicrobial properties. Therefore, conducting in vitro studies is indispensable as a preliminary stage prior to testing bionanocomposite coatings and films on fruits and vegetables. Consequently, the creation of bionanocomposites presents a promising approach for preserving the quality and safety of postharvest fruits and vegetables. In this context, the objective of this review is to present systematized information focused on the development of bionanocomposite coating films for the management of diseases in fruits and vegetables. It also aims to discuss the use of various biopolymers and nanomaterials in in vitro assays and their direct application to fruits and vegetables. Additionally, our study aims to examine how bionanocomposites can enhance the quality and shelf life of fruits and vegetables.

2. Postharvest Diseases in Fruits and Vegetables

Fruits and vegetables are essential components of human nutrition; unfortunately, they are susceptible to postharvest loss during handling, storage, and transport [20]. According to Chaboud et al. [21], “postharvest losses” are defined as the losses that occur during the harvesting of food crops until the product reaches the final consumer. These losses can occur at various stages of the value chain, including handling during harvest, storage, packaging, processing, distribution, transport, and marketing. Specifically, postharvest losses refer to all food products that have undergone a change in availability, safety, or quality, making them unfit for human consumption [22]. On the other hand, “waste” refers to healthy and edible products that are not consumed but rather discarded and are generally associated with consumer or retailer behavior [23]. Losses due to postharvest disease are influenced by diverse factors, such as temperature, pre- and postharvest atmospheric composition, mishandling, relative humidity, the pathogenicity and virulence of the causal agent of the disease, cultivar susceptibility, handling and postharvest disease control techniques, physiologic parameters and, especially, fruit ripening [24,25]. These losses have economic and social impacts, particularly affecting food and nutrition security, supply chain disruptions, environmental impact, income and livelihoods, and overall social well-being [25].

• Impact of fruit ripening on postharvest control

Fruit ripening is a key factor in the development of postharvest diseases; therefore, understanding the physiological and biochemical changes that occur during ripening is essential, as these changes alter the composition and nutritional quality of the fruit during the postharvest stage [26]. In most fruits, the most visible and significant change during ripening is the change in color, which is caused by chlorophyll degradation, chloroplast development, and the accumulation of pigments such as carotenoids [27,28]. During this color change, there is a progressive degradation of the components of the fruit’s cell wall, including the presence of hemicellulose, cellulose microfibrils, and pectin, leading to fruit softening. However, some modifications to the cell wall are species specific [29,30]. In addition, as the fruit ripens, its nutritional content is also modified, as certain organic acids and starches are gradually metabolized and hydrolyzed into soluble sugars that accumulate in the cytoplasm of the fruit pulp, resulting in a sweeter aroma [26]. Although ripening is an essential attribute that makes fruit edible, more palatable, and attractive for consumption, overripening can increase susceptibility to pathogen attacks. Fleshy fruits can be classified as follows: (i) climacteric fruits (banana, pear, apple, peach, mango, tomato, and kiwi), which show a rise in respiration rate and a sudden increase in ethylene production at the onset of ripening, and (ii) non climacteric fruits (grape, melon, cherry, orange, and strawberry), which do not exhibit either of the two characteristics of climacteric fruits, maintaining a basal level of respiration and ethylene production [28,30]. Both climacteric and non-climacteric fruits rely mainly on abscisic acid (ABA) and ethylene. At the beginning of ripening, there is an accumulation of ABA, which subsequently precedes and therefore modulates ethylene production in climacteric fruits and triggers ripening in non-climacteric fruits [28,30,31]. Overall, these changes in the fruit during ripening result in a softer texture, making it more susceptible to infection by pathogens, especially fungi, and thus more prone to rapid spoilage and higher incidence of disease [6].

b.

The process of postharvest pathogen infection

The major postharvest losses in fruits and vegetables are caused by fungi from the phylum Ascomycota, including genera such as Alternaria alternata [32,33], Botrytis cinerea [34], Colletotrichum gloeosporioides [35], Colletotrichum acutatum [36], Dothiorella [37], Fusarium proliferatum [38], Lasiodiplodia theobromae [39], and Phomopsis spp. [40]; from phylum Oomycota, including Phytophthora parasitica [41] and Pythium aphanidermatum [42]; and the phylum Zygomycota, including Rhizopus stolonifer [43] and Mucor circinelloides [44]. In the phylum Basidiomycota, Sclerotinia sclerotium [45], Sclerotium rolfsii [46] and Rhizoctonia solani [41] are particularly significant for certain vegetables, such as carrot, tomatoes and potatoes [46]. Postharvest diseases caused by bacteria are primarily attributed to Bacillus cereus [47], Erwinia [48], Pseudomonas aeruginosa [49], Salmonella typhimurium [50], Escherichia coli [51], and Xanthomonas vesicatoria [52]. In

Table 1. Postharvest diseases and pathogens of fruits and vegetables.

Host	Disease	Pathogens	References
Oranges	Green mold, blue mold, sour rot	Penicillium digitatum, Penicillium italicum, Geotrichum citri aurantii.	[53,54,55,56]
Papaya	Soft rot, anthracnose	Rhizopus oryzae, Mucor irregularis, Gilbertella persicaria, Colletotrichum plurivorum, Colletotrichum brevisporum, Colletotrichum truncatum, Colletotrichum fructicola.	[57,58]
Grapes	Anthracnose, gray mold	Colletotrichum gloeosporioides, Botrytis cinerea.	[59,60,61]
Pome fruit	Blue mold, bull’s eye rot, bitter rot	Penicillium expansum, Neofabraea spp, Colletotrichum spp.	[62,63]
Mango	Anthracnose, stem-end rot	Colletotrichum gloeosporioides, Colletotrichum asianum, Colletotrichum fructicola, Colletotrichum siamense, Dothiorella spp.	[35,37,64]
Loquat	Anthracnose	Colletotrichum acutatum	[36]
Peach	Brown rot	Monilinia fructicola	[65]
Plum	Brown rot	Monilinia fructicola	[65]
Apples	Blue mold, anthracnose	Penicillium expansum, Botrytis cinerea, Penicillium expansum.	[62,66]
Kiwi	Soft rot	Phomopsis spp., Botryosphaeria dothidea	[40]
Cherry	Brown rot	Monilinia fructicola	[65]
Banana	Anthracnose	Colletotrichum musae	[67]
Apricot	Brown rot	Monilinia fructicola	[65]
Mume fruit	Brown rot	Monilinia fructicola	[65]
Litchi	Soft rot	Alternaria alternata	[68]
Blueberry	Gray mold	Botrytis cinerea	[34]
Tomatoes	Anthracnose, soft rot	Alternaria alternata	[32,33]

, the most common postharvest diseases and pathogens of fruits and vegetables are shown.

Postharvest fruit diseases are caused by a wide variety of pathogens, principally fungi, such as those shown in Table 1. The causal agents of disease can infect the fruit at various developmental stages, from preharvest to postharvest, and throughout the supply chain (including classification, packaging, storage, transport, distribution, and retail) [69]. It is important to highlight that many of these fungi can only penetrate and establish themselves after physical damage or through wounds present on the surface or caused by birds, insects, handling and transportation, weather conditions or equipment. Even microscopic wounds can be sufficient for the disease to develop [8,24,70]. The infection and disease development depend on the fungus. For example, anthracnose disease is caused by Colletotrichum spp., gray mold in strawberries by Botrytis cinerea, transit rot by Rhizopus stolonifer, and green and blue mold by Penicillium spp. The presence of fungi in fruits and vegetables is particularly concerning because diseases caused by filamentous fungi such as Aspergillus spp., Penicillium citrinum, Aspergillus flavus, Alternaria alternata, Aspergillus niger, and Penicillium expansum pose health risks to humans and animals due to the production of mycotoxins such as citrinin, aflatoxin B1, alternariol, ochratoxin A, and patulin. These mycotoxins can cause cancer, allergies, and organ toxicity [5,7,8,71,72]. Postharvest diseases in fruits and vegetables are primarily caused by fungi and bacteria; however, some root crops, such as potatoes, are particularly vulnerable to infection by Fusarium spp., especially during storage [73,74]. On the other hand, certain fungi, such as Botrytis cinerea and Penicillium expansum, infect fruit through wounds [5]. However, others, like Neofabraea spp. and Colletotrichum spp., can infect latently (quiescently) during long term storage [63,75]. The main mechanism of fruit infection involves damage caused by insect vectors, improper handling, and physical or mechanical injury. Additionally, microcracks in a fruit’s cuticular membrane play an important role as entry points for pathogenic fungi [5,76].

The fungal infection process typically occurs in four stages, schematically represented in Figure 1. (i) Adhesion of spores or conidia to the fruit cuticle via hydrophobic interactions [77], (ii) stabilization of the fungus through the production of infection structures, (iii) invasion of fruit tissues mainly through wounds, natural openings such as stomata and the pedicel fruit interface, or by directly penetrating the cuticle using an appressorium or penetration peg formed by the germ tube [78], and (iv) colonization and spread, influenced by environmental factors favorable for fungal germination, for example, pH, temperature, humidity, phytohormones, nutrient availability, and surface topography [79].

It is important to mention that this infection process occurs in fruits as well as vegetables. During this infection process, fruits possess antifungal defense systems such as phytohormone synthesis, oxidative burst (characterized by the release of harmful substances like superoxide radicals, hydrogen peroxide, hydrolytic enzymes, and flavonoids), activation of defense-related enzymes, and overexpression of pathogen related proteins [5]. However, some of these defense responses are insufficient to serve as effective antifungal mechanisms. Once the fungus becomes intimately established within the fruit, it releases proteins that promote necrosis [5]. Methods for managing postharvest diseases in fruits and vegetables focus on preventing infection, eliminating latent infections, and halting the spread of pathogens [63,80]. Chemical treatments are generally the most used method due to their ability to precisely target pathogens. They are characterized by low cost, ease of application, and effectiveness as both curative and preventive approaches [70,81]. However, growing concerns over pathogen resistance and the adverse effects on human health and the environment highlight the urgent need to develop safer, more effective, and environmentally friendly alternatives [82,83]. Therefore, fungal infections in fruits remain a pressing issue, encouraging the development of new, sustainable postharvest control strategies with reduced impact on human health. In recent years, research has focused on the development of coatings using bionanocomposites with antimicrobial activity.

3. Bionanocomposites

Nanotechnology in the field of postharvest technology has increased significantly over the past decade, primarily due to the urgent need for green and sustainable alternatives to address various challenges associated with the management of diseases in fruits and vegetables. In this context, bionanocomposites have been developed. According to Ruiz-Hitzky et al. [10], bionanocomposites are a family of hybrid or biohybrid materials composed of at least two chemical entities, where one is a nanomaterial and the other a biopolymer, which interact at the nanoscale. Within bionanocomposites, various interactions contribute to their enhanced functionality. These include Van der Waals forces, electrostatic attractions, hydrogen bonding, intermolecular bonding, chemical bonding, mechanical interlocking, as well as processes such as adsorption, surface tension, diffusion, and surface wettability [2].

The most used biopolymers in the fabrication of bionanocomposites are cellulose, chitosan, starch, pectin, alginate, and gelatin. Figure 2 illustrates the biopolymeric unit structures of each of these biopolymers. The primary advantages of these biopolymers include their biodegradability, non-toxicity, biocompatibility, low cost, cost effectiveness, and eco-friendly nature [11]. On the other hand, it is possible to use a variety of nanomaterials to create bionanocomposites, such as TiO₂, ZnO, -NPs Clays, SiO₂, Ag-NPs, Cu-NPs, Au-NPs, F₃O₄, essential oils in nanoemulsion, organic compounds (cinnamaldehyde, chlorogenic acid), nanofibers, inorganic salts (potassium sorbate) and carbonaceous nanostructures, that present antimicrobial activity. The technological relevance of bionanocomposites lies in their ability to integrate nanomaterials into the agricultural sector through multiple application pathways, such as nanofertilizers, water retention agents, seed coatings to enhance germination, crop protection, disease detection, and biosensors [3]. One of the most promising technologies with broad applications in disease management in fruits and vegetables is the use of bionanocomposite coating films [11].

The core objective of the development of bionanocomposite coating films is to overcome the disadvantages of conventional plastics used for the same purpose in fruits and vegetables. Therefore, it is essential that the bionanocomposite should have improved properties such as the following:

(i) Mechanical: bionanocomposite coating films should guarantee the least damage to breakage during the processing, handling and storage of fruits and vegetables. It is common that the incorporation of a nanomaterial to a biopolymeric matrix results in higher tensile strength, Young’s modulus and elongation at break [84,85,86,87].

(ii) Water barrier: During transport and storage, fruits and vegetables can lose or gain moisture, and this has a direct impact on the proliferation of microorganisms, texture, nutrient content and flavor [2,88]. This translates into a reduction of the shelf life of the fruit and vegetables. It is therefore necessary that bionanocomposite coating films can prevent both scenarios with respect to moisture. Generally, the water barrier properties of a bionanocomposite are evaluated by water vapor permeability, with this property usually being influenced by the porosity, crystallinity, relative humidity and hydrophobicity/hydrophilicity of the composites [88,89].

(iii) Gas barrier: Gas diffusion is of vital importance in the storage of fruits and vegetables due to its intimate relationship with their respiration and ripening [90]. Gas permeability is especially associated with oxygen (O₂) consumption, and also, in some cases, the release of carbon dioxide (CO₂) and ethylene (C₂H₄). What is sought in bionanocomposite coating films is (i) a reduction in oxygen consumption to slow down the respiration rate; (ii) control of the accumulation of CO₂, which in excess can cause damage; and (iii) a limiting of the effect of the ethylene generated during ripening. This property is generally related to polarity, functional groups present in the structure, degree of cross-linking, tortuosity and application methodologies on the fruit and vegetable [2,9].

(iv) Thermal: According to the literature, biopolymers have lower thermal decomposition temperatures compared with synthetic polymers; therefore, the creation of a bionanocomposite represents an attractive alternative to improve its thermal stability. The main parameters sought are the maximum decomposition temperature, glass transition temperature, crystallization temperature and thermal deformation temperature [91]. These characteristic parameters of the bionanocomposite are obtained from techniques such as thermogravimetric analysis, differential scanning calorimetry and thermo-mechanical analysis [91,92,93]. It is important to establish that, in order to achieve greater thermal stability, some type of interaction between the biopolymer and the nanomaterial is required.

(v) Optical: The transparency of bionanocomposite coating film is an important parameter in fruit and vegetable applications. It has a direct impact on the appearance and visual perception of the food. In addition, during the whole life cycle of fruits and vegetables they are exposed to natural or artificial light [94], which can cause nutrient degradation and sensory alterations of the food [95]. In addition, ultraviolet radiation damages foods by provoking photo-oxidation reactions [96]. Therefore, the development of UV-blocking bionanocomposite coating films has aroused interest in recent research. For the calculation of transparency and opacity it is recommended to consult the literature [97,98].

(vi) Antimicrobial: This is the most important property related to the postharvest application of bionanocomposite coating films. This property is primordial and of major relevance, as it is necessary for the inhibition of the growth of pathogens in the fruits and vegetables to which it is applied. This property is where the antibacterial or antifungal activity of the nanomaterial stands out, with such activity related to electrostatic interactions, receptor–ligand and hydrophobic interactions and Van der Waals forces. It also involves the rupture of cell membranes, alterations in membrane permeability, leakage of cellular components, generation of reactive oxygen species (ROS), oxidation of cellular components, DNA damage and, finally, cell death [99,100].

(vii) Cytotoxicity: The use of nanomaterials in food and agriculture presents notable challenges for risk assessment and management [101]. A major concern is the potential harm to human health resulting from direct ingestion, as the toxicological characteristics of nanomaterials depend on factors such as particle size, chemical composition, shape, crystalline structure, solubility, and hydrophobicity [102,103]. Therefore, addressing this emerging field requires comprehensive cytotoxicity evaluations. These studies are essential to ensure the safe application of nanomaterials in postharvest control, particularly in the development and use of bionanocomposites. For example, Qiu et al. [104] evaluated the cytotoxicity of CMCS@COF-AgNP film-forming solution (10 μL) using human gastric mucosal epithelial cells (GES-1). The results show that the bionanocomposite exhibited a GES-1 cell survival rate of 98%. Even when the maximum amount of COF-AgNP in the bionanocomposite (5% w_COF-AgNPs/w_CMCS) was used, a survival rate of 89% was achieved. These findings confirm the low cytotoxicity of the films developed in this study. On the other hand, Mousavi et al. [105] developed a bionanocomposite based on ZnO–halloysite nanotubes (3–5% w_ZnO-Hal/w_total)-LRE (5–10% w_LRE /w_total) and assessed its cytotoxicity using NIH-3T3 fibroblast cells. Their results indicate that all bionanocomposite films synthesized in this work exhibited cell viability above 80%, demonstrating their low cytotoxicity. Moreover, a 10% loading of licorice root extract (LRE) in the bionanocomposite further increased cell viability, reaching a value of 100%. This was attributed to the flavonoids present in LRE, which enhance the survival rate of fibroblast cells. Similarly, other cytotoxicity tests of various bionanocomposite films for postharvest control have also been reported [106,107]. It is also crucial that these concerns are addressed in alignment with the guidelines and regulations established by leading food safety authorities.

• Coatings and edible films

An edible film is defined as a thin layer that can be used as a cover or separation layer. The characteristics that an edible coating must have depend directly on the specific requirements of the product to be coated, including the degradation modes to which it is most susceptible [108]. However, the main characteristics of an edible coating for fruit or vegetables are (i) moderately low permeability to carbon dioxide and oxygen; (ii) low water vapor permeability; (iii) sensory inertness or compatibility; (iv) safety, without containing any allergic or toxic substances; and (v) compatibility with other active substances [109]. In particular, the successful application of edible coatings to preserve the quality of fruits and vegetables largely depends on their ability to maintain a low internal O₂ level to delay ripening; however, it should not be too low, as this can cause anaerobic respiration and degrade quality. It also depends on the coating’s ability to act as a barrier against water vapor while being thin enough to remain pleasant for the consumer [110]. Bionanocomposite edible coatings are generally made principally of polysaccharides and biopolymers; however, the main ingredients are biopolymers, such as cellulose, chitosan, starch, gums, pectin, alginate, gelatin, and solvents (mainly water), along with smaller proportions of additional ingredients to improve functionality, such as emulsifiers, plasticizers, cross-linkers, additives and nanomaterials with antimicrobial activity [111,112]. From Figure 3, a scheme displaying the typical route of creation of a bionanocomposite coating film, it is important to highlight that the main structural compound of a bionanocomposite is the biopolymer, because it acts as the global matrix of the coating or film and provides stability and good applicability.

Polysaccharide-based coatings are effective barriers to the transfer of gases such as O₂ and CO₂; however, these materials are generally very hydrophilic, resulting in a poor water vapor barrier [114]. Chitosan has been widely studied as a bionanocomposite matrix maker due to its polycationic characteristics, which are believed to enhance the effects of other antimicrobial active substances [115]. On other hand, protein-based coatings and films include biopolymers derived from both animal and plant sources. Animal-derived proteins include whey protein, casein, egg white protein, keratin and gelatin, while plant-derived proteins include soybean protein, and gluten [116]. Compared with other materials used for coating preparation, proteins are characterized by their electrostatic charges, conformational denaturation, and amphiphilic nature. Additionally, protein structures can be modified by irradiation, thermal denaturation, mechanical treatments, pressure, alkaline or acid treatments, the addition of salts, cross-linkers, and hydrolysis or enzymatic treatments to achieve the desired coating properties. Protein possesses excellent barrier properties against carbon dioxide, oxygen and lipids; however, their hydrophilic nature makes them sensitive to water and provides a limited water vapor barrier [117]. On the other hand, lipid-based coatings and films serve as excellent barriers to water loss due to their hydrophobic properties. They are also used to reduce respiration, prolong shelf life, and improve the gloss of fruit and vegetable products [118]. The most used lipid materials include waxes (carnauba, candelilla and beeswax), fatty acids, alcohols, acetylated glycerides, and cocoa-based compounds [119]. Lipid coatings have some disadvantages, as it is difficult to apply a well-defined and continuous coating, and the resulting films are usually stiff and brittle [120].

b.

In vitro effectiveness

The application of bionanocomposite coatings and films represents a novel alternative for protecting, extending the shelf life, and preserving the postharvest quality of fruits and vegetables [121,122]. However, bionanocomposites face limitations, such as insufficient information on additive or nanoparticle migration, life cycle, and chemical resistance. Therefore, conducting in vitro studies is crucial for their application in food packaging [2,123]. In most cases of bionanocomposites, the biopolymer helps to enhance the effect of the active component, thereby enhancing their overall efficacy. Consequently, the potential of these biopolymers, when combined with nanomaterials, to inhibit the growth of various pathogens has been extensively investigated. The first step in evaluating the antimicrobial activity of a bionanocomposite is its application in an in vitro test. For example, Kang et al. [124] developed a bionanocomposite with carboxymethylcellulose incorporated with decorated MOF (Ag@ZIF-67). The first in vitro tests consisted of mixing an amount of the nanomaterial in a solution of bacteria, subsequently spread on the surface of solid medium, and cultured at 37 °C for 24 h. The results of the antibacterial activity showed a significant effect of incorporating Ag-NPs into the MOF for the Escherichia coli, Staphylococcus aureus, Penicillium expansum and Botrytis cinerea microorganisms. Using SEM, it was demonstrated that the cell surfaces of Escherichia coli and Staphylococcus aureus were severely collapsed, distorted, and wrinkled. In addition, the cytoplasm flowed out of the cell and the phenomenon of adhesion appeared. Similarly, this phenomenon was found in the mycelium of B. cinerea and P. expansum, where Ag@ZIF-67 treatment led to the shrinkage and distortion of hyphae, accompanied by distinct craters on the cell walls. This antimicrobial activity of the nanomaterials, in conjunction with the biopolymer, demonstrated a direct relationship when applied directly to peach, providing an efficient protective coating. Likewise, other MOFs have been applied in in vitro tests, for example, Men et al. [51] developed a bionanocomposite with lipoic acid/Cu-MOF in alginate, the results of antibacterial and antifungal activity in vitro showed an inhibition of more than 90% for Staphylococcus aureus, Escherichia coli and Botrytis cinerea. The main mechanism of growth inhibition is the controlled release of lipoic acid and the direct contact of Cu-MOF with the cell membrane.

On other hand, Chávez-Magdaleno et al. [125] synthesized a bionanocomposite of chitosan containing Schinus molle EO and was evaluated for its efficacy against the in vitro growth of Colletotrichum gloeosporioides. This work shows that this combination inhibits 68.7% of mycelial growth and 96.7% of spore germination compared with the control. Additionally, damage at the spore level of Colletotrichum gloeosporioides was observed, attributed to the loss of cellular membrane properties. Another quantifiable result highlighting the advantages of using chitosan in bionanocomposites synthesis was reported by Saharan et al. [126], for whom the application of Cu-chitosan inhibited the in vitro mycelial growth of Alternaria solani and Fusarium oxysporum by 70.5% and 73.5%, respectively, both of which are recurrent pathogens in tomato fruits. Additionally, spore germination of these fungi was inhibited by 61.5% and 83%, respectively. These results were compared with the inhibition percentages achieved when applying Cu and chitosan separately, which were significantly lower. This demonstrates once again the synergistic effect achieved by employing a bionanocomposite as a fungal control agent. In this case the ability of Cu as a producer of hydroxyl radicals means it is highly reactive to the pathogen and that there is damage caused by the chitosan to the fungus cellular membrane by its electrostatic interaction. Ali et al. [127] have demonstrated that hydrolyzed styrene maleic anhydride nano chitosan exhibits superior in vitro results when compared with hydrolyzed styrene maleic anhydride chitosan against Fusarium oxysporum, Alternaria alternata, Aspergillus niger and Cladosporium herbarum, with inhibition zones of 48.1 mm, 43.6 mm, 40.2 mm and 44.4 mm, respectively. Another quantifiable result highlighting the advantages of using chitosan in bionanocomposites synthesis is reported by [32,48,127,128].

On the other hand, cellulose acetate was studied using Ag-NPs, organo-clay and thymol as active substances against Aspergillus niger and Aspergillus flavus mycelial growth. These bionanocomposites showed a moderate reduction in fungal growth, with a growth of 19 mm on the plate compared with the control [129]. The ability of the silver nanoparticles compound to interact with DNA and proteins may cause rupture of the fungal cell membrane, which could be the possible action mechanism against fungal pathogens. In addition, thymol oil can alter the fatty acid composition of the cell wall, leading to fungal cell lysis. These findings highlight the additive effect of using bionanocomposites rather than employing active substances and metals individually. In addition, metal materials (Cu, Zn, CuO and ZnO) combined with chitosan were tested to inhibit Aspergillus flavus, Rhizoctonia solani, and Alternaria alternata [130]. The growth inhibition percentage was higher when applying the Zn/chitosan bionanocomposite, with values exceeding 85%, and the inhibition of Aspergillus flavus was exceptionally high, reaching 93%. These positive results suggest that the combination of these bionanocomposites is effective due to the positive charges they carry, enhancing their antifungal effect. In the field of bionanocomposites research, in vitro evaluation is one of the most important steps within the physical, chemical and biological evidence that must be conducted to ensure the effectiveness and efficiency of new alternative control agents as substitutes for synthetic agrochemicals. Moreover, in vitro testing is typically considered a preliminary stage prior to the subsequent evaluation of bionanocomposite coating on fruits. As previously mentioned, edible films and coatings offer the practical advantage of incorporating active ingredients into the polysaccharide or biopolymer matrix. The incorporation of these compounds can enhance their physicochemical properties and antimicrobial characteristics, thereby improving postharvest shelf life, the nutritional and sensory quality of fruits and vegetables. For this reason, edible coatings are considered a valuable tool for preserving the quality of postharvest food products [108,111,119,131,132,133].

c.

Application on fruits and vegetables (in vivo studies)

In recent years, environmentally friendly bionanocomposites have been developed for various applications, such as medicine, food packaging, and disease management in fruits and vegetables. Importantly, the composition of bionanocomposites is carefully tailored to meet the specific requirements of the intended applications [134,135]. In this regard, in fruit and vegetable disease management, coatings and films using bionanocomposites with superior properties, such as improved water barrier, mechanical and thermal stability, gas barrier, antibacterial activity, and other functional attributes that contribute to effective postharvest disease control are sought to be employed [2,14,136]. One of the most widely explored properties in the field of postharvest control is the antimicrobial activity of nanomaterials, which is often lacking in some biopolymers. Therefore, the combination of these materials may result in a compound capable of suppressing diseases and improving fruit quality [12,13,14,123,133].

The functional properties of coatings and films are achieved when application techniques are used correctly [137]. The techniques used for the application of bionanocomposite coating are as follows: (i) Dipping (Figure 4a): This widely used technique consists in immersing fruits or vegetables in a bath containing the coating solution for 30 s–5 min, the excess of coating solution is drained and then dried, which ensures application on all surfaces, even rough surfaces [33,49,119]. In addition, it is important to consider that the thickness of the coating on the fruit and vegetables depends on the viscosity, concentration, density and draining time of the coating solution [138]. (ii) Spraying (Figure 4b): In this method, droplets of the coating solution are deposited on the surface of the product using an atomizer bottle or spray nozzle [139,140]. (iii) Brushing (Figure 4c): This technique involves the application of coatings using a brush or brushing equipment [141,142]. It is important to consider a good contact between the film-forming solution (FFS) and the food, as visible cracks and pores are often created. For example, Chettri et al. [142] coated sapota fruits using soybean starch extracted through three different application techniques: dipping, spraying, and brushing. The results indicate that the dipping method was the most effective in preserving the physicochemical and sensory qualities of the fruit, significantly extending its shelf life, particularly under refrigerated storage conditions. Similarly, Wang et al. [143] evaluated the preservation of mangoes using four coating methods: dipping, brushing, spraying, and electrostatic spraying applying a sodium alginate/TiO₂ bionanocomposite. Their results demonstrate that the most notable differences among the application methods were related to the quality of the coating and the overall efficiency of the process. Electrostatic spraying produced a thinner, more uniform film, ensured complete fruit coverage, reduced drying time, and lowered film-forming solution (FFS) consumption compared with the other methods. In contrast, while the dipping method also produced a high-quality coating, the resulting film was thicker and required a longer drying time. Brushing and conventional spraying methods exhibited the highest incidence of defects, such as cracks and uneven distribution, which facilitated microbial growth and accelerated fruit deterioration [143]. These findings highlight the variability in effectiveness among application techniques. Therefore, the selection of coating methods for bionanocomposite films should consider not only performance but also infrastructure availability and operational feasibility. Overall, dipping remains the most commonly used and operationally accessible method, delivering consistent protective results. However, when appropriate infrastructure is available, the implementation of more advanced techniques, such as vacuum impregnation [144] and electrostatic spraying [145], should be considered for improved coating performance.

In the case of the formation of bionanocomposite films, there are mainly two methodologies: (i) A wet process, solvent casting (Figure 5b): In this method, the biopolymer is dissolved in a solvent (water or ethanol) to form a film-forming solution (FFS) where all the components are mixed with the help of low-speed stirrings, ultrasonication or temperature, before casting the FFS into molds or Teflon-coated plates considering the thickness required. Subsequent drying of the casted FFS is usually carried out at ambient air condition or at low temperature (<60 °C) in an oven, before finally removing the film and storing at a suitable relative humidity and temperature [146,147]. It is important to emphasize that the FFS and the final film must be free of air bubbles, so as not to affect its structural integrity. (ii) A dry process, extrusion (Figure 5a): In this methodology, the bionanocomposite must be converted into pellets or powder. First the bionanocomposite must be fed into the feed hopper, then the rotating screw compresses the bionanocomposite to produce a homogeneous solid material unit. During the extrusion, the FFS heating and passing through the nozzle allows one to obtain an extruded film, or it might be obtained as a blown film in a circular nozzle [148,149]. It is important to mention that the high temperatures used in the extruder can cause important changes in the bionanocomposite, so the temperature must be selected with this effect in mind.

Applying bionanocomposites in the postharvest preservation of fruits and vegetables is a promising strategy with great potential, because bionanocomposites are characterized by a synergistic effect between the biopolymer and the nanomaterial, which leads to improved composite properties such as antimicrobial activity. Among the various biopolymers, chitosan stands out as one of the most effective due to its antimicrobial activity [19]. Chitosan is a biopolymer derived from the deacetylation of chitin, which is obtained from the shells of crustaceans. This biopolymer is classified as Generally Recognized as Safe (GRAS) due to its biodegradability and non-toxic nature. Numerous studies have demonstrated the practical application of chitosan in the postharvest treatment of fruits and vegetables [17,150]. Its primary mechanisms of action include forming an edible coating, exhibiting antifungal activity, and inducing defense responses [151]. As an edible coating, chitosan helps regulate respiration and ethylene production in treated products, reducing metabolic activity and extending shelf life. Chitosan has been used as a matrix to incorporate various compounds, including antifungal agents, to further enhance its ability to preserve the quality parameters of fruits and vegetables. For example, Khamis and Hashim [152] have evaluated the incorporation of clay nanoparticles into a chitosan matrix, reporting the formation of a reinforced material with improved mechanical and barrier properties. Structural and morphological analyses of the bionanocomposite demonstrated efficient interaction and dispersion between these materials, which was attributed to electrostatic interactions between the amino groups (NH₂) of chitosan and the negatively charged sites of the clay. Once characterized, the bionanocomposite was applied to oranges to assess its effectiveness in controlling the fungal pathogen Penicillium digitatum. The results showed complete inhibition of fungal growth after seven days of storage at room temperature. These authors suggest that this bionanocomposite is a cost effective and efficient approach for the extension of such an application to other fruits and for controlling additional pathogens.

On the other hand, nanomaterials, such as titanium dioxide (TiO₂), zinc oxide (ZnO), copper (Cu), and silver (Ag), have also been used at controlled concentrations for food preservation due to their reported antifungal potential [153,154]. In strawberries, Cu/ZnO nanoparticles combined with chitosan reduce the incidence of Botrytis cinerea, decreasing fungal infection by 28% after three weeks of storage when compared with control fruits. These authors confirmed that the bionanocomposite coatings enhanced the antifungal effect. Similarly, in mangoes, a chitosan/TiO₂ bionanocomposite reduced the percentage of infected fruits by 15% when compared with untreated mangoes [128]. The antifungal effect of TiO₂ was attributed to its ability to generate reactive oxygen species (ROS), such as hydroxyl radicals, which are highly reactive and cause irreversible damage to fungal structures upon contact [154]. Bionanocomposites can also be composed of more than two materials. For the preservation and control of Botrytis cinerea in grapefruits, a film made of silica, chitosan, and copper nanoparticles was used. The treatment controlled pathogen development for over two months, whereas untreated fruits showed 50% infection [155]. Moreover, in a recent study, cherry tomatoes (Solanum lycopersicum) treated with chitosan containing titanium dioxide (TiO₂) exhibited lower ethylene production rates, maintaining acceptable firmness and extending shelf life without altering the natural ripening processes [154]. Likewise, chitosan bionanocomposites with TiO₂ applied to Mango fruits (Mangifera indica L.) reduced ethylene production, improved firmness preservation, and decreased the enzymatic activity of polyphenol oxidase and peroxidase. Additionally, these coatings increased the phenolic compounds and flavonoid content in the pulp when compared with control fruits [128]. On the other hand, De-Menezes et al. [156] have demonstrated that the film they developed using chitosan and TiO₂ reduced weight loss, delayed the ripening process, and maintained the quality of papaya under both light and dark conditions. This effect was attributed to the presence of TiO₂, which acts as a UV light absorber, reducing skin damage and stabilizing parameters such as firmness, color, pH, and vitamin C content. This demonstrates that the use of semiconductors in bionanocomposites also provides photoactive protection, which can extend the shelf life of the fruit under real postharvest conditions [13,96,156].

Similar to chitosan-based coatings, starch-based coatings have also been applied in postharvest control and packaging applications [157]. Starch is a polysaccharide with excellent film-forming ability, high availability, and lower cost than other biopolymers [158]. Many fruits and vegetables contain high concentrations of starch, making them valuable sources of this polysaccharide [159,160]. However, starch has a high solubility in water and is not an efficient barrier to water vapor when used as an edible coating [158]. For this reason, there have been ongoing attempts to reinforce it with other biopolymers and nanomaterials in order to improve its mechanical strength and barrier properties. In peaches, a bionanocomposite coating composed of rice starch, chitosan, and Ag/ZnO nanoparticles improved the visual appearance of the fruits, leading to extended storage life when compared with untreated peaches [161]. On the other hand, Li et al. [162] found that the application of a corn starch film reinforced with curcumin-loaded nanocomplexes significantly reduced weight loss and maintained higher firmness in blueberries. In addition, high levels of anthocyanins, phenolic compounds, ascorbic acid, and glutathione were preserved, indicating better retention of nutritional quality. Finally, the film demonstrated the ability to mitigate oxidative stress during storage, thereby delaying fruit senescence.

Alginate is a food additive classified as a GRAS compound commonly used as an edible coating. This polysaccharide occurs naturally as a structural component of the cell walls of marine algae [163]. It has been applied to different fruits and vegetables as an alternative to reducing the damage caused by ripening and microbial attacks. The gelling capacity of this biopolymer allows the encapsulation of additives such as vegetable extracts, essential oils (EOs), and nanomaterials, enhancing its antifungal effect. Emamifar et al. [164] have reported the incorporation of zinc nanoparticles into a sodium alginate matrix to develop an antimicrobial film. This bionanocomposite extended its shelf life and demonstrated its antimicrobial efficacy when applied to strawberries. Moreover, Saputri et al. [165] have reported that the addition of nanosilica (SiO₂) fillers to films made from semi-refined kappa carrageenan (derived from red seaweed) significantly enhances the mechanical and thermal properties of the biopolymer matrix. Additionally, zinc oxide (ZnO) nanoparticles provide UV protection, improve water barrier properties, and enhance a film’s mechanical and antimicrobial performance. Similarly, Ni et al. [166] have developed a bionanocomposite with antibacterial activity by creating a negatively charged graphitic carbon nitride (gC₃N₄)/chitosan film. This composite demonstrated antimicrobial activity, UV sensitivity, biocompatibility, and non-toxicity, along with improved mechanical, thermal and hydrophobic properties when compared with pure chitosan films while maintaining a low production cost.

Protein-based coatings are also widely used in food preservation. Gelatin, a biopolymer with gel forming potential, lacks sufficient barrier and mechanical properties to function effectively as a standalone food coating. However, these properties of gelatin, along with its antifungal potential, can be enhanced by incorporating additional materials into a biopolymer. Mehmood et al. [167] have demonstrated this effect by applying a bionanocomposite coating containing gelatin and magnetic iron oxide to grapefruits. This bionanocomposite effectively extended the fruit’s shelf life and controlled microbial growth. Bionanocomposites composed of soy protein, cinnamaldehyde, and zinc oxide reduced the changes in firmness and quality parameters such as soluble solids content, acidity, and peel browning in banana fruits (Musaceae L.) during storage. Furthermore, treated fruits maintained their weight, extending their shelf life when compared with untreated samples [168].

Lipid-based coatings have also been employed to prolong the postharvest quality of harvested products. Due to their low polarity, lipid compounds reduce moisture migration but often result in coatings with a thick and brittle texture. Their barrier properties are usually enhanced by combining lipids with polysaccharides, while antimicrobial compounds can be incorporated to inhibit microbial development [132]. One of the most widely used lipid coatings is carnauba wax, derived from Brazilian palm Copernica cerifera leaves. This wax functions as an edible coating, reducing weight loss in fruit while enhancing its visual appeal. Motamedi et al. [169] have reported that orange fruits coated with carnauba wax and clay bionanocomposites remained free of pathogen infections. In contrast, uncoated control fruits developed angular spots, which, according to the literature, may be attributed to the presence of the Phaeoisariopsis spp. Finally,

Table 2. Application of bionanocomposite coating films in vitro and in vivo in fruits and vegetables.

Nanomaterial	Biopolymer	Complementary Materials	Pathogen	Fruit	References
Cellulose nanofibrils (3–5%)	Chitosan	Acetic acid	-	Strawberries	[170]
Cellulose nanofibrils (0.1–0.3%)	Alginate	Glycerol	-	Blueberries	[163]
Nanocrystalline cellulose (0.05 g)	Sugar palm starch	Glycerol, sorbitol, cinnamon EO (0.8–2%), tween-80	Escherichia coli, Bacillus subtilis, Staphylococcus aureus	-	[171]
Cellulose nanofiber (2–10%)	Wheat starch/chitosan	Glycerol	Escherichia coli, Bacillus subtilis	-	[172]
Cellulose nanofiber (0.1–0.3%)	Gelatin	-	-	Cherry tomato	[141]
ZnO-NPs (0.25–1.25%)	Yam starch	Sodium tripolyphosphate, sorbitol, microcrystalline cellulose, eugenol	Escherichia coli, Staphylococcus aureus	-	[87]
ZnO/Halloysite (3–5%)	Sodium alginate	Xanthan gum, CaCl2, licorice root extract	Escherichia coli, Staphylococcus aureus	-	[105]
ZnO-NPs (50 mg/mL)	Hydroxypropyl starch	PVA, palmitic acid, glycerol	Escherichia coli, Staphylococcus aureus, Fusarium oxysporum, Aspergillus niger, Penicillium expansum, Aspergillus flavus	-	[173]
ZnO-NPs (1–5%)	Alginate	Aloe vera gel, glycerol	Escherichia coli, Syncephalastrum racemosum, Staphylococcus aureus	Tomatoes	[174]
ZnO nanorods (1%)	Cassava starch	Plasticizers, glycerol, sorbitol, citric acid, sodium hypophosphite, PVA, rosemary extract	Escherichia coli	-	[175]
ZnO-NPs (1–3%)	PLA	Cinnamaldehyde	-	Apple	[176]
ZnO-NPs (2 mg/mL)	Soybean protein isolate	Cinnamaldehyde, glycerol, tween-80	-	Bananas	[168]
Nano ZnO (0.25–1.25 g/L)	Alginate	Glycerol	-	Strawberries	[164]
ZnO-NPs (10 ppm), Ag-NPs (10 ppm)	Chitosan/rice starch	-	Escherichia coli, Staphylococcus aureus	Peach	[161]
Ag-NPs/COFs (1–5%)	Carboxymethyl chitosan	Glycerol	Escherichia coli, Staphylococcus aureus, Bacillus cereus, Cronobacter sakazakii, Listeria monocytogenes, Salmonella	Citrus	[104]
Ag-NPs (3–5%)	Cellulose acetate/gelatin	Triethyl citrate, organo-clay, thymol	Escherichia coli, Salmonella, Pseudomonas, Aspergillus niger, Aspergillus flavus, Staphylococcus aureus	-	[129]
Ag-NPs (0.03 mg/L)	Gum guar	Carboxymethyl cellulose	-	Kinnow	[177]
AgNO3 (40 μL, 1M)	Rice starch	PVA	Salmonella typhimurium, Staphylococcus aureus	-	[88]
Ag-NPs (0.5%), TiO2-NPs (0.5–1%)	PLA	-	Escherichia coli, Listeria monocytogenes	-	[86]
TiO2 (0.01%)	Chitosan/alginate	Cinnamon EO, acetic acid, glycerol	-	Mango	[143]
Nano-TiO2 (0.02%)	Chitosan	PVA, tween-80, trans-cinnamaldehyde, acetic acid	Escherichia coli, Staphylococcus aureus	Mushrooms	[178]
Nano TiO2 (0.01–0.03 g)	Chitosan	Glycerin, acetic acid	-	Mango	[128]
TiO2 (1–5%)	Sago starch	Glycerol, sorbitol, cinnamon EO	Escherichia coli, Salmonella typhimurium, Staphylococcus aureus	-	[179]
TiO2 (1–2%)	Chitosan	Acetic acid, glycerol	-	Papaya	[156]
Nano clay (1%)	Chitosan	Acetic acid	Penicillium digitatum	Oranges	[152]
Nano clay (5%)	Whey protein	Calcium caseinate, potassium sorbate, glycerol	-	Strawberries	[180]
Nano clay (4.8%)	Corn starch	Glycerol, carvacrol, thymol	Botrytis cinerea	Strawberries	[181]
Nano clay (0.01 g)	Corn starch/Chitosan	Glycerol, sorbitol, potassium sorbate	Rhodococcus opacus, Aspergillus niger	-	[182]
Nano clay (0.5–1%)	Carnauba Wax/ beeswax	Oleic acid, ammonia	-	Oranges	[169]
MgO-NPs (3–10%)	Chitosan	Acetic acid, sodium tripolyphosphate, Piper betle leaf extract	Escherichia coli, Staphylococcus aureus	Chili peppers	[183]
Nano SiOx (0.1–0.4 g/g)	Soy protein	Glycerol	-	Apples	[184]
Graphene oxide (0.03–0.1%)	Corn starch/Chitosan	Carboxymethyl cellulose, citric acid, urea	Escherichia coli, Staphylococcus aureus	Tomatoes	[185]
Cu-MOF (0.1–0.9 g)	Sodium alginate	α-Lipoic acid, glycerol	Botrytis cinerea, Escherichia coli, Staphylococcus aureus	Peaches, grapes, blueberries	[51]
Substituted imidazolate MOF (5–20 mg)	Corn starch	PVA, glycerol	Escherichia coli, Staphylococcus aureus	-	[186]
Lemongrass EO (5–10%)	Cassava starch	Glycerol, tween-80, cocoa butter, brewery spent grain	Escherichia coli, Staphylococcus aureus	-	[187]
Nanoemulsion (lemongrass EO) (0.1–1%)	Alginate	Tween-80	Escherichia coli	Fuji apples	[188]
Schinus molle EO (100 μL)	Chitosan	Acetic acid	Colletotrichum gloeosporioides	-	[125]
Chlorogenic acid (0.5–3%)	Corn starch/sweet whey	Glycerol	Escherichia coli	Banana	[189]
Benzalkonium chloride (2.5 mL)	Corn starch	Glycerol, sorbitol, rice husk fiber	Escherichia coli, Staphylococcus aureus, Bacillus subtilis, Klebsiella pneumoniae.	Strawberries	[190]
Tannic acid (1–8%)	Corn starch	Fe3+	Escherichia coli, Staphylococcus aureus	-	[191]
Curcumin-loaded nanocomplexes (2–11%)	Corn starch	Perilla seed protein isolate, glycerol	-	Blueberries	[162]

EO: Essential oil, PLA: Polylactic acid, PVA: Polyvinyl alcohol, NPs: Nanoparticles.

shows bionanocomposites that have been evaluated in in vitro and in vivo tests against various pathogens, as well as in fruits and vegetables.

4. Future Perspectives

The development and application of bionanocomposite coating films in disease management in fruit and vegetables represents a novel technology with a promising future. Numerous studies have explored the use of biopolymers, such as chitosan, alginate, starch and cellulose, that, in combination with nanomaterials, enhance their thermal, mechanical, gas barrier, water barrier, optical, and antimicrobial properties. Although the synergistic effect of bionanocomposites has been demonstrated, it is still essential to optimize the integration of nanomaterials in biopolymers.

In addition, there is still a need to establish the mechanisms by which bionanocomposites can delay ripening, suppress or inhibit microbial growth and modify the physiology of fruits and vegetables, as well as to address the gap between laboratory and pilot or industrial scale tests. In this sense, the incorporation of economic feasibility or techno-economic analysis of the new bionanocomposites reported is a relevant proposal in the area of coatings and films on fruits and vegetables.

Bionanocomposites represent a promising alternative for controlling diseases in fruits and vegetables. However, it is essential to consider food regulatory aspects, as some coatings and films are intended for fresh produce that is in turn intended for direct consumption. In particular, the toxicity and safety of using nanomaterials must be addressed, as their toxicological characteristics often depend on factors such as size, surface charge, solubility, morphology, and potential toxic mechanisms. Additionally, possible short-, medium-, and long-term health risks must be considered. These concerns should be addressed in alignment with major food regulatory bodies such as the Food and Drug Administration (FDA), the Food and Agriculture Organization of the United Nations (FAO), the World Health Organization (WHO), the European Food Safety Authority (EFSA), and the Organisation for Economic Co-operation and Development (OECD). Nevertheless, it is important to note that many countries lack specific regulations regarding the use of nanomaterials in food, indicating that significant progress remains to be achieved in this area.

In addition, the impact of these bionanocomposites on the taste, texture and aroma of fruits and vegetables can be integrated into further studies. In addition, biodegradability, life cycle analysis, carbon footprint and waste management can be addressed in the development of bionanocomposites and enhance the development of the material, which can also improve its differentiation and advantages over synthetic polymers.

5. Conclusions

Substantial losses in fruit production are now being recorded worldwide. Although agrochemicals remain highly effective for disease control, their extensive use has raised serious environmental and public health concerns. In addition, increasing consumer demand for chemical-free fruit underscores the urgent need for safer, environmentally friendly and effective postharvest disease management strategies. Bionanocomposites represent a promising alternative, as they allow the incorporation of nanomaterials that enhance efficacy against a broad spectrum of plant pathogens. However, it is essential to ensure that such treatments do not compromise fruit quality, which is a critical factor for consumer acceptance. Further research is needed to better understand how bionanocomposite coatings interact with and may alter the nutritional composition of treated fruits. In addition, large-scale application studies should be conducted to assess their feasibility, cost-effectiveness, and long-term impact on postharvest shelf life.