Polymeric Biocoatings for Postharvest Fruit Preservation: Advances, Challenges, and Future Perspectives

Abstract

The growing demand for fresh fruit, coupled with high postharvest losses, highlights the need for sustainable and effective preservation technologies. In this context, polymeric biocoatings are emerging as a promising alternative to conventional synthetic packaging, thanks to their biodegradability, film-forming capacity, and potential to incorporate bioactive compounds. This review article summarizes recent advances in the development of coatings based on polysaccharides, proteins, and nanomaterials, analyzing their physicochemical, functional, and sensory properties, and the main conventional and emerging application methods used in fresh fruit. It also highlights the role of phenolic compounds and essential oils as antioxidant and antimicrobial agents, along with the valorization of agro-industrial by-products under circular economy schemes. Finally, it discusses the challenges associated with standardization, industrial scaling, and consumer acceptance, proposing future perspectives aimed at designing multifunctional systems that extend the shelf life and improve the quality of fresh products, in line with environmental sustainability objectives. Unlike recent reviews, this work unifies structure–function relationships with quantitative comparisons of coating performance across fruits. It further contributes a critical evaluation of emerging application technologies and their technological and regulatory readiness, offering a distinctly more integrated perspective.

1. Introduction

Global fruit production is increasing due to rising demand driven by improved living standards, favorable public policies, and growing global awareness about the benefits of fruit consumption. According to the Food and Agriculture Organization [1] and official data [2], global fruit production reached approximately 908 million tons in 2023, representing a nearly 68% increase compared to 2000. These figures are derived from consolidated historical records and reflect a sustained upward trend driven by rising global demand and the agricultural expansion of tropical and subtropical regions. However, post-harvest losses remain a major challenge, with an estimated 40% to 50% of fruit lost due to inadequate harvesting and storage and adverse environmental conditions [3]. In this context, postharvest losses are reduced to the quantity and quality of the fruit, mainly due to metabolic processes such as respiration and transpiration, as well as physical damage and unwanted chemical reactions [4].

These processes release CO₂ and ethylene, which accelerate ripening and, consequently, deterioration [5]. In addition, their high water content (70–90%) increases their susceptibility to microbial growth, mechanical damage, and moisture loss. These effects are exacerbated by poor handling, lack of pre-cooling, and inadequate storage temperature control [6,7]. Therefore, reducing postharvest losses becomes an urgent concern that requires attention. The approach of preserving fruit by slowing down internal metabolism and limiting the penetration of external agents through the use of packaging demonstrates a practical approach [8,9].

There are different types of materials used for fruit packaging, which are classified as biodegradable and non-biodegradable. Currently, it is common to use non-biodegradable packaging made from plastics and chemical compounds [10]. In this regard, non-biodegradable packaging has a significant environmental impact, affecting both terrestrial and marine ecosystems [11]. On the other hand, biodegradable packaging materials offer advantages over synthetic plastics, such as biodegradability, compostability, and the use of renewable resources [12]. Therefore, biodegradable packaging, especially edible coatings for fruit preservation, is considered a sustainable green approach that is receiving a lot of attention [6].

Biocoating is a preservation technique that involves applying a polymer layer to the surface of fruit and other foods. Its purpose is to inhibit microbial activity, reduce oxidation, and protect against external contaminants [13]. Biopolymers are often chosen because they are biodegradable. In this regard, biocoating technology for fruit packaging allows the use of biopolymers derived from polysaccharides, proteins, lipids, and their derivatives, originating from plant and animal sources [14]. Some natural polymer components used for biocoating technology include alginate, carrageenan, chitosan, collagen, pectin, cellulose, starches, lignin, and waxes, among others [15].

However, the efficiency of edible coatings depends on the type of biopolymers in their composition and the interaction these compounds may have with packaged foods [16]. It should be noted that one of the important characteristics of packaging biocoatings is their ability to serve as carriers of active substances such as antimicrobial compounds, which can extend the post-harvest shelf life of fresh produce. In this regard, essential oils are one of the most widely used active compounds in packaging films for fruit preservation [16]. However, compared to synthetic plastic-based biocoatings and films, polysaccharide-based biocoatings and films have certain limitations, including high hydrophilicity and poor mechanical properties [17].

To overcome these challenges, extensive efforts have been undertaken to enhance the physical performance of polysaccharide-based biocoatings and films through various strategies, including polysaccharide modification, the use of layer-by-layer (LBL) assembly, and the incorporation of reinforcing fillers [18,19,20]. In addition to strengthening mechanical properties and reducing hydrophilicity, the use of polysaccharides to produce active and intelligent packaging has become a prominent area of research. One approach involves adding bioactive compounds, such as phenolic compounds or extracts rich in polyphenols, to formulate multifunctional films and coatings [21], producing active and/or smart packaging. Phenolic compounds are widely distributed in various plant sources, such as fruits, vegetables, cereal grains, and legumes, and exhibit considerable functional and structural diversity [22]. Given their unique functional groups, phenolic compounds can be incorporated into polysaccharide films and coatings to improve their functional and mechanical properties [23]. Furthermore, the incorporation of phenolic compounds into polysaccharide-based coatings and films has been shown to enhance their antimicrobial activities, as these compounds exhibit a pronounced capacity to inhibit microbial growth and delay fruit spoilage.

This article aims to summarize recent advances in the development and application of polymeric biocoatings for the postharvest preservation of fruits, with particular emphasis on the main types of polymers employed, the incorporation of bioactive compounds, and the existing challenges associated with their implementation. In addition, prospects are discussed with the aim of contributing to the design of sustainable and effective solutions capable of reducing postharvest losses and improving the quality of fresh produce.

Although the number of review studies dedicated to edible coatings has increased between 2024 and 2025, several aspects remain insufficiently explored in the current literature. Analyses directly addressing the structure-function relationship of polysaccharides in postharvest applications are still scarce, as are quantitative comparisons assessing how different formulations influence the physiological responses of specific fruits such as citrus, berries, and tropical species. Similarly, the discussion of emerging application technologies, such as nanoemulsions, layer-by-layer assembly, and electrospinning, remains limited, particularly about their technological maturity and associated regulatory constraints.

References related to non-fruit food matrices, such as meat or indicator-based systems, are cited exclusively for contextual or methodological comparison and are not discussed as direct applications. All analyses and conclusions in this review are strictly framed within the context of postharvest fruit preservation.

Therefore, this review seeks to bridge these knowledge gaps through a functional and comparative approach supported by quantitative data, with the aim of elucidating their implications for industrial scalability and practical implementation.

2. Search Methodology

This review was prepared using a structured approach to searching, selecting, and analyzing the literature to summarize recent advances in polymeric biocoatings applied to the postharvest preservation of fruit. To compile the information, the main international scientific databases Scopus, ScienceDirect, SpringerLink, MDPI, and Web of Science were consulted, covering the period from January 2015 to August 2025. Combinations of keywords in English and Spanish were used, such as “edible coating”, “biobased film”, “biopolymer”, “postharvest preservation”, “fruits”, “active packaging”, “antimicrobial film”, “essential oils”, and “phenolic compounds”. The inclusion criteria considered original articles, reviews, and experimental studies published in peer-reviewed scientific journals in English that address the development, characterization, or application of biocoatings and biodegradable films on fresh or minimally processed fruits. Works without full access, patents, technical reports, brief communications, and studies focused on non-fruit products or non-food coatings were excluded. From the initial total of approximately 250 articles identified, 132 works that met the criteria of relevance, timeliness, and methodological rigor were selected. In addition to the inclusion and exclusion criteria described above, the selected studies were prioritized based on their scientific relevance, experimental robustness, and direct contribution to advances in polymeric biocoatings for postharvest fruit preservation. Studies were chosen that evaluated physicochemical, antimicrobial, and barrier properties; reported practical performance in fruits during postharvest; or introduced emerging technologies with potential for industrial scalability. This approach ensured a representative, current, and high-impact synthesis of the most relevant scientific evidence in the field. The articles were thematically classified into five categories: polymeric fundamentals and materials; physical-mechanical and barrier properties; application methods; incorporation of bioactive compounds; and prospects and challenges. This methodological strategy allowed for the critical integration of the most recent scientific evidence, the identification of innovation trends, and the consolidation of an updated vision on the use of sustainable biocoatings for postharvest fruit preservation.

The analysis of the selected studies (2015–2025) revealed three predominant trends in recent literature. First, there is a growing interest in polysaccharide-based matrices such as alginate, pectin, CMC, and chitosan, owing to their film-forming ability, biocompatibility, and broad availability [7,24]. Second, recent studies prioritize the incorporation of phenolic extracts and essential oils, often formulated through nanoemulsions or encapsulation, to enhance antimicrobial and antioxidant performance [17,25]. Third, there is notable progress in the use of emerging technologies such as nanocellulose, layer-by-layer systems, and electrohydrodynamic techniques, all aimed at optimizing mechanical and barrier properties [18,26]. These trends reflect the current scientific priority of developing biodegradable, efficient, and scalable alternatives to synthetic postharvest treatments.

3. Properties of Biocoatings

3.1. Materials Key in Biocoatings

Current trends are moving towards obtaining food with as little chemical residue as possible and without the use of aggressive technologies, thus promoting more sustainable practices. In this context, consumer preferences regarding methods and technologies to extend shelf life and ensure food safety reflect a marked inclination towards the use of natural alternatives [27,28]. In line with these principles, which aim to market minimally processed, natural fruits with low environmental impact, edible coatings and films stand out as a sustainable and viable alternative [29,30,31].

In the context of postharvest preservation, edible coatings and edible films are polymeric systems derived primarily from polysaccharides and proteins; however, they differ in their mode of formation and application. In this review, the term polymeric biocoatings is used specifically to refer to polymer-based coatings applied directly onto the surface of fresh fruits, whereas films denote pre-formed sheets intended for packaging purposes. Coatings are applied in liquid form, typically by dipping or spraying, and form an in situ film following solvent evaporation [32,33]. In contrast, films are produced beforehand through drying, melting, or casting prior to being placed on the food product. This operational definition enables a precise interpretation of the properties and performance of both systems within the postharvest context. The materials used in the formulation of biocoatings can be classified into three main groups: (i) polysaccharides such as alginate, pectin, carboxymethyl cellulose, and chitosan which are widely applied due to their ability to form cohesive matrices with controlled gas permeability [7,24]; (ii) plant or animal derived proteins, which provide mechanical strength, thermal stability, and favorable film forming properties [34]; and (iii) lipids, which contribute hydrophobicity and reduce water vapor permeability when incorporated as waxes, triglycerides, or lipid emulsions [35]. This classification organizes the functional properties of each category and facilitates comparisons among formulations based on different biopolymers.

In addition, biocoatings can be enriched with essential nutrients, vitamins, or bioactive compounds that contribute to the nutritional value of fresh fruits [36]. These nutrients can come from natural sources or be incorporated in encapsulated form, which facilitates controlled release and greater stability. Likewise, the addition of essential oils or plant extracts helps inhibit the growth of microorganisms responsible for fruit spoilage [37,38]. Finally, the ability of biocoatings to adapt their composition and functionality opens up new possibilities for developing innovative packaging solutions that address the dual objectives of food preservation and quality improvement [7]. Figure 1 summarizes the main advantages offered by biocoatings, considering their functional and nutritional benefits and their contribution to sustainability.

3.2. Physico-Mechanical and Barrier Properties

Some studies show that coatings based on starch–chitosan blends simultaneously improve mechanical strength and reduce solubility, resulting in more stable performance under high-humidity conditions [39]. In lipid-based formulations, the incorporation of waxes such as candelilla, carnauba, or beeswax significantly reduces water vapor permeability in protein and polysaccharide-based systems, thereby enhancing moisture retention in fruits during storage [40,41]. Likewise, nanoemulsions applied in CMC- or plant gum–based coatings have been shown to improve stability and reduce mass loss, while also facilitating the incorporation of bioactive compounds [42,43]. Finally, nanocellulose-based coatings exhibit high mechanical strength and an ability to retain antioxidant compounds in sensitive fruits, although their cost and scalability still pose limitations [26,44].

3.2.1. Mechanical Properties

Various physical evaluations have been used to characterize the mechanical and barrier properties of edible coatings and films. These include tensile tests, which provide key mechanical parameters such as modulus of elasticity, tensile strength, and elongation at break [32]. For example, one study reported that adding epoxidized castor oil to soy protein-based films improved mechanical properties, increasing elongation at break by approximately 23% [45]. Similarly, lipids can enhance the mechanical strength and barrier properties of films, but their concentration and chemical nature strongly influence overall film performance, highlighting the need for precise and controlled proportioning [46].

3.2.2. Water Vapor Permeability

The quality of packaged foods is closely linked to the ability of films to regulate mass transfer between the product and its environment [47]. In this regard, barrier properties are crucial for service life, as they determine water vapor permeability, gas migration, and the transfer of volatile compounds [48,49]. For this reason, films with low water vapor permeability help maintain texture, prevent moisture loss, avoid shrinkage, and minimize unwanted chemical reactions, thereby preserving the freshness of foods, including fruits [48]. However, the low mechanical strength and limited vapor barrier properties of natural polymers restrict their use in packaging for fruit and other foods [50]. To counteract these limitations, they are combined with other biopolymers or hydrophobic compounds, such as waxes or oils, which are incorporated [41]. Consequently, studies show that adding waxes, such as candelilla, beeswax, and carnauba wax, to films and coatings based on sodium caseinate, starch-gluten, and chitosan significantly improves moisture barrier properties [40].

3.2.3. Solubility

Water solubility is a fundamental property of biocoatings, as it determines their ability to interact with the humid environment and, therefore, influences the release of active compounds, structural integrity, and film durability [48]. In general terms, high solubility facilitates the rapid release of antimicrobial agents, although it can compromise barrier stability, while low solubility prolongs the coating’s resistance to environmental moisture [51]. Various studies have shown that the composition of the polymeric material, as well as the proportion of plasticizer and the incorporation of lipids, are determining factors in this property [52]. For example, films made from breadfruit starch reduced their solubility from 36 to 8% by increasing the starch concentration, resulting in a more efficient barrier against water [48]. Similarly, the combination of starch with chitosan improves mechanical strength and modulated solubility, promoting coating stability in high humidity conditions [39].

3.2.4. Viscosity

The viscosity of the film-forming solution is another critical parameter, as it determines the ease of application, the uniformity of the deposited layer, and the final thickness of the coating [53]. Insufficient viscosity may lead to the formation of uneven or excessively thin films, while too high a viscosity can make application difficult and cause defects such as drips or localized accumulations [54]. This property is influenced by factors such as polymer concentration, the type of biopolymer used, processing temperature, and the addition of bioactive compounds [39]. Recent research shows that 1% chitosan solutions have viscosities close to 86 mPa·s, which allows for greater retention of material on the fruit surface and better coverage [33]. Likewise, the rheological behavior of these dispersions, typically pseudoplastic, facilitates their application through immersion and spraying, provided that the viscosity is appropriately adjusted to the selected method [53].

3.2.5. Adhesion and Coverage

The adhesion and coverage of biocoatings are crucial to ensuring their effectiveness, as a poorly adhered film can create micro-spaces that promote moisture loss or the entry of pathogens [35]. The performance of chitosan films developed with different molecular weights applied to fruits such as bananas, apples, and strawberries has recently been studied (Table 1). The results showed that formulations with an intermediate range achieved more uniform and stable adhesion to the surface, which favored better coverage and contributed to reducing weight loss during storage [55].

3.3. Functional Properties

3.3.1. Antimicrobial Activity

The antimicrobial properties of polymeric biocoatings are associated with their function as a physical barrier, as well as the incorporation of active agents that enhance postharvest preservation. These coatings can incorporate antimicrobial compounds that act through controlled release mechanisms, immobilization within the matrix, or interactions with absorption systems during storage [49,56]. In this context, certain biopolymers exhibit inherent antimicrobial activity, such as the oligopeptide chains of gelatin or the positively charged amino groups of chitosan, which interact with negatively charged bacterial membranes [34]. Likewise, the incorporation of essential oils can enhance this effect, achieving activity levels comparable to those of commercial antimicrobials [57,58]. These interactions also depend on the type of polymer and its compatibility with the coated food products, factors that ultimately determine the antimicrobial effectiveness and functional properties of the film [59,60]. Overall, these characteristics help delay microbiological spoilage and extend the postharvest shelf life of various fruits.

3.3.2. Antifungal Activity

Antifungal coatings have established themselves as a sustainable alternative for reducing postharvest losses caused by pathogens such as Botrytis cinerea and Penicillium. Perilla frutescens has been shown to significantly inhibit the growth of Botrytis cinerea in strawberries, reducing weight loss and visual deterioration during cold storage, which demonstrates the positive synergy between biopolymers and natural compounds [61]. Similar antifungal activity against Botrytis cinerea has been reported in tomatoes, confirming the relevance of hybrid materials in the formulation of active coatings with greater stability and functionality [62]. On the other hand, recent research highlights that chitosan itself has intrinsic antifungal activity, attributed to the presence of positively charged amino groups that interact with the cell membrane of fungi, altering its permeability and causing cell death, making it a versatile matrix for the incorporation of bioactive compounds without compromising its biocompatibility [63]. Taken together, these findings demonstrate that antifungal biocoatings not only act as physical barriers but also offer bioactive protection capable of partially replacing synthetic fungicides [64]. However, limitations persist in relation to the standardization of evaluation methodologies and validation under real post-harvest conditions, which raises the need for research aimed at industrial scalability and technology transfer.

3.3.3. Emulsifying Properties

In biocoatings that incorporate essential oils or lipophilic compounds, emulsification properties play a decisive role, as they determine the stability of the dispersion, the homogeneous distribution of the active ingredients, and, therefore, their antimicrobial and antioxidant efficacy [65]. The formation of stable emulsions, measured by parameters such as the emulsifying activity index (EAI) and stability index (ESI), allows lipophilic compounds to remain dispersed during the preparation and application of the coating, preventing phase separation [66]. Recent technologies, such as nanoemulsions, have been shown to improve stability, reduce droplet size, and increase the bioavailability of essential oils, resulting in coatings with an increased ability to inhibit microbial growth and delay the deterioration of fresh fruits [67]. Likewise, Pickering emulsions stabilized with nanocellulose are emerging as a sustainable alternative, as they do not require synthetic surfactants and provide excellent physical-chemical stability [68].

3.3.4. Sensory and Optical Properties

The optical characteristics of edible films, including color, opacity, and light transmission, influence consumer acceptance [69]. These characteristics, along with others related to the packaging, are determined by the type and nature of the additives incorporated [70]. Among these properties, color plays a fundamental role in influencing the visual appearance of food and, therefore, consumer choice [71]. Various studies have shown that the addition of tea extract can significantly alter the color of packaging material due to the presence of polyphenols that provide natural pigments such as chlorophyll, carotenoids, and yellow-green hues [72]. Likewise, transparency and the packaging’s ability to transmit light are determining factors, especially when films are applied directly to food [73]. These properties not only affect consumer preference but also play key roles in protecting against light, particularly ultraviolet radiation, reducing lipid oxidation, product discoloration, and loss of nutritional compounds [74,75]. Since ultraviolet radiation can induce oxidative processes in food, it is essential to use packaging films with a high capacity to block UV rays to prevent discoloration and preserve nutrients against photooxidation [76,77]. The optical properties of biodegradable films intended for food use are particularly relevant due to their visual impact, with a degree of crystallinity in the range of 42% to 56% being recommended to achieve an adequate appearance [78].

Table 1. Properties of films and coatings applied to fruit.

Properties	Raw Material/System	Typical Range and Units	Measurement Method and Conditions	Main Results	Application	References
Mechanical properties	Soy protein + epoxidized castor oil Starch + chitosan	TS: 5–25 MPa, EB: 10–40%	ASTM D882-16; 25 °C; 50% RH; crosshead speed 10 mm/min	↑ elongation at break (23%) ↑ mechanical strength and cohesion	Fresh fruits, tomatoes, apples	[39,45,79]
Water vapor permeability	Sodium caseinate + beeswax Starch + gluten + carnauba wax	0.5–4.0 × 10−9 g·m/(m2·s·Pa)	ASTM E96/E96M-16; 25 °C; 75% RH	↓ permeability, improved moisture retention. Greater stability against moisture	Grapes, strawberries, mango, papaya	[40,41,80]
Antimicrobial	Chitosan + olive oil Gelatin	Inhibition zones: 8–20 mm; Log-reduction: 1–4 log CFU	Disk diffusion; plate count method; 25 °C	Antimicrobial activity like gentamicin. Intrinsic antibacterial activity	Strawberries, blueberries, among various fruits	[34,57]
Antifungal	Chitosan + oregano essential oil	Mycelial inhibition: 60–100%	PDA culture, storage at 4–20 °C; relative humidity 80–90%	Inhibits Botrytis cinerea	Grapes, blueberries	[81,82]
Optical	Tea extract (polyphenols) Natural antioxidants	Light transmission (600 nm): 20–60%; ΔE color: 3–10	UV–Vis spectrophotometry; CIEXYZ colorimetry	Green-yellow pigmentation, UV protection. UV blocking, ↓ oxidation	Direct coating, blueberries, cherries	[72,76]
Antioxidants	Chitosan + rosemary extract	DPPH inhibition: 40–80%; ORAC: 500–1200 µmol TE/g	DPPH, ABTS, ORAC assays; 25 °C	↓ lipid oxidation, ↑ phenolic stability	Avocado	[83,84,85]
Solubility	Breadfruit starch Starch + chitosan	8–36% (w/w)	25 °C; 24 h hydration; gravimetric analysis	↓ solubility (36% to 8%) Better stability in moisture	Papaya, strawberries, grapes	[39,48,86]
Viscosity	1% chitosan solutions	60–120 mPa·s	Brookfield viscometer; spindle 2; 25 °C	86 mPa·s; better coverage	Tomatoes, pears	[33]
Emulsification	Pickering with nanocellulose. Nanoemulsions with essential oils	Droplet size: 50–300 nm; EAI: 20–50 m2/g	Dynamic light scattering (DLS); turbidimetry	Excellent stability without surfactants. ↓ droplet size, ↑ bioavailability	Mangoes, kiwis, strawberries	[67,68]
Adhesion/coverage	Chitosan + glycerol	Adhesion rating: high (qualitative); thickness 20–60 μm	Visual analysis; cross-section SEM	Uniform coverage and high adhesion to skin	Apples, peaches	[87]
Enzymatic activity	Alginate + green tea extract	PPO/LOX inhibition: 20–60%	PPO/LOX assays; 4–10 °C	Inhibits polyphenol oxidase, ↓ browning	Avocados, pears, strawberries	[88,89]
Biodegradability	Starch films + PLA	Complete degradation: <90 days	Composting test (ISO 14855-1:2012)	Compostable in <90 days	Coating and packaging	[90,91]

Abbreviations: ASTM = American Society for Testing and Materials; ↑ = increase; ↓ = decrease; TS = tensile strength; EB = elongation at break; RH = relative humidity; CFU = colony-forming units; ΔE = total color difference; PDA = potato dextrose agar; UV = ultraviolet; DPPH = 2,2-Diphenyl-1-picrylhydrazyl; ORAC = oxygen radical absorbance capacity; ABTS = 2,2′-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid); EAI = emulsifying activity index; SEM = scanning electron microscopy; PPO = polyphenol oxidase; LOX = lipoxygenase; TE = Trolox equivalents; ISO = International Organization for Standardization.

Table 1. Properties of films and coatings applied to fruit.

Properties	Raw Material/System	Typical Range and Units	Measurement Method and Conditions	Main Results	Application	References
Mechanical properties	Soy protein + epoxidized castor oil Starch + chitosan	TS: 5–25 MPa, EB: 10–40%	ASTM D882-16; 25 °C; 50% RH; crosshead speed 10 mm/min	↑ elongation at break (23%) ↑ mechanical strength and cohesion	Fresh fruits, tomatoes, apples	[39,45,79]
Water vapor permeability	Sodium caseinate + beeswax Starch + gluten + carnauba wax	0.5–4.0 × 10−9 g·m/(m2·s·Pa)	ASTM E96/E96M-16; 25 °C; 75% RH	↓ permeability, improved moisture retention. Greater stability against moisture	Grapes, strawberries, mango, papaya	[40,41,80]
Antimicrobial	Chitosan + olive oil Gelatin	Inhibition zones: 8–20 mm; Log-reduction: 1–4 log CFU	Disk diffusion; plate count method; 25 °C	Antimicrobial activity like gentamicin. Intrinsic antibacterial activity	Strawberries, blueberries, among various fruits	[34,57]
Antifungal	Chitosan + oregano essential oil	Mycelial inhibition: 60–100%	PDA culture, storage at 4–20 °C; relative humidity 80–90%	Inhibits Botrytis cinerea	Grapes, blueberries	[81,82]
Optical	Tea extract (polyphenols) Natural antioxidants	Light transmission (600 nm): 20–60%; ΔE color: 3–10	UV–Vis spectrophotometry; CIEXYZ colorimetry	Green-yellow pigmentation, UV protection. UV blocking, ↓ oxidation	Direct coating, blueberries, cherries	[72,76]
Antioxidants	Chitosan + rosemary extract	DPPH inhibition: 40–80%; ORAC: 500–1200 µmol TE/g	DPPH, ABTS, ORAC assays; 25 °C	↓ lipid oxidation, ↑ phenolic stability	Avocado	[83,84,85]
Solubility	Breadfruit starch Starch + chitosan	8–36% (w/w)	25 °C; 24 h hydration; gravimetric analysis	↓ solubility (36% to 8%) Better stability in moisture	Papaya, strawberries, grapes	[39,48,86]
Viscosity	1% chitosan solutions	60–120 mPa·s	Brookfield viscometer; spindle 2; 25 °C	86 mPa·s; better coverage	Tomatoes, pears	[33]
Emulsification	Pickering with nanocellulose. Nanoemulsions with essential oils	Droplet size: 50–300 nm; EAI: 20–50 m2/g	Dynamic light scattering (DLS); turbidimetry	Excellent stability without surfactants. ↓ droplet size, ↑ bioavailability	Mangoes, kiwis, strawberries	[67,68]
Adhesion/coverage	Chitosan + glycerol	Adhesion rating: high (qualitative); thickness 20–60 μm	Visual analysis; cross-section SEM	Uniform coverage and high adhesion to skin	Apples, peaches	[87]
Enzymatic activity	Alginate + green tea extract	PPO/LOX inhibition: 20–60%	PPO/LOX assays; 4–10 °C	Inhibits polyphenol oxidase, ↓ browning	Avocados, pears, strawberries	[88,89]
Biodegradability	Starch films + PLA	Complete degradation: <90 days	Composting test (ISO 14855-1:2012)	Compostable in <90 days	Coating and packaging	[90,91]

Abbreviations: ASTM = American Society for Testing and Materials; ↑ = increase; ↓ = decrease; TS = tensile strength; EB = elongation at break; RH = relative humidity; CFU = colony-forming units; ΔE = total color difference; PDA = potato dextrose agar; UV = ultraviolet; DPPH = 2,2-Diphenyl-1-picrylhydrazyl; ORAC = oxygen radical absorbance capacity; ABTS = 2,2′-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid); EAI = emulsifying activity index; SEM = scanning electron microscopy; PPO = polyphenol oxidase; LOX = lipoxygenase; TE = Trolox equivalents; ISO = International Organization for Standardization.

4. Natural Polymers Used in Biocoatings

Biocoatings for post-harvest preservation use various families of natural polymers (mainly polysaccharides and proteins) valued for their biodegradability, food safety, and functional properties. The main types used, their characteristics, and most notable applications are presented in

Table 2. Natural polymers used in biocoatings for fruit.

Polymers	Origin/Nature	Key Properties	Applications	Key Limitations	References
Chitosan	Derived from chitin (crustaceans)	Antimicrobial, film-forming, biodegradable	Fresh-cut apple, reduced fungal growth	High cost; variable quality depending on deacetylation degree; limited solubility at neutral pH.	[92,93]
Starch	Tubers and grains	Film-forming, economical, requires plasticizers	Coated mangoes, reduced weight loss	High hydrophilicity; poor mechanical strength; sensitivity to humidity.	[94]
Pectin	Citrus and apple waste	Gas barrier, flexible in blends	Strawberries with cinnamon essential oil, improved color	High water sensitivity; requires blending for mechanical stability.	[95,96]
Hydroxypropyl methylcellulose	Derived from cellulose	Transparent, adhesive, hydrophobic	Mandarins, reduced transpiration	Relatively high cost; limited antimicrobial activity	[97]
Carboxymethyl cellulose	Derived from cellulose	Hydrophilic, emulsifier	Fruits (fresh pistachios) coated with nanoemulsions	High moisture sensitivity; potential stickiness on the fruit surface	[43]
Alginate	Brown algae	Gelation with Ca2+, O2 barrier	Mangoes (Kent), reduced browning	Requires calcium crosslinking; brittle films if not plasticized	[98]
Carrageenan (kappa)	Red algae	Forms gel, reduces respiration	Bananas, maintain firmness	Sensitivity to ionic strength; poor water resistance	[99]
Pullulan	Microbial polysaccharide	High transparency, O2 barrier	Blueberries, reduced dehydration	High production cost; sensitivity to humidity	[100]
Gellan gum	Bacterial polysaccharide	Stability, gelling agent	Mandarin, reduces P. digitatum	Brittle without plasticizers; limited availability in some regions	[101]
Xanthan gum	Microbial fermentation	High viscosity, stabilizer	Strawberries and grapes, mixed with starch	High viscosity may hinder uniform coating; often requires blending	[102]
Gelatin	Animal protein	Flexible, transparent	Coated strawberries, color retention	Sensory concerns (odor/taste); sensitive to high temperatures	[103,104]
Zein	Corn protein	Hydrophobic, grease barrier	Granny Smith apple, inhibits Listeria sp.	High cost; brittle structure without plasticizers	[105,106]
Whey proteins	Dairy by-product	O2 barrier, flexible	Golden Delicious apple, reduced browning	Allergenicity issues; sensitive to humidity	[107]
Nanocellulose	Derived from plant fibers	High mechanical strength	Strawberries, biodegradable packaging and maintain anthocyanins	High production cost; aggregation tendency; scalability challenges	[26,44]
Gum arabic	Acacia exudate	Emulsifier, water-soluble	Raspberries, grapes, and strawberries, mixed with essential oils	High solubility causes weak moisture barrier; cost variability	[42]

below.

In the development of biocoatings for post-harvest fruit preservation, polysaccharides, proteins, and nanomaterials are the most commonly used materials due to their biodegradability, film-forming capacity, and compatibility with the food industry [24]. Among them, chitosan exhibits strong antimicrobial activity thanks to its positively charged amino groups, which are capable of altering microbial membranes, reducing the incidence of fungi in apples and strawberries treated with chitosan enriched with essential oils; this combination prolonged firmness and delayed browning in fresh-cut fruit [107], confirming its potential as a natural alternative to synthetic fungicides. Similarly, starch is used as a polymer matrix due to its abundance and low cost, although its marked hydrophilicity limits its direct applications; for this reason, it is formulated together with plasticizers or secondary polymers [108]. For example, cassava starch combined with glycerol was shown to improve the flexibility and gas barrier capacity of coatings applied to mangoes, resulting in a 20% reduction in weight loss compared to the control [109]. Likewise, pectin, a polysaccharide derived from agro-industrial waste, has been used on strawberries in combination with cinnamon essential oil and modified atmosphere packaging, resulting in lower loss of titratable acidity and better color retention during prolonged storage [96].

On the other hand, cellulose derivatives, such as HPMC and CMC, have gained importance in citrus fruits due to their ability to form thin, transparent films with high adhesion. In mandarins, the application of HPMC to hydrophobic surfaces reduced transpiration and slowed down pulp softening, demonstrating its potential as a coating for active compounds [97]. Similarly, alginate, extracted from brown algae, has been extensively studied as a carrier of anti-browning agents; in mangoes, coatings with alginate incorporating ascorbic acid were able to delay enzymatic browning and preserve higher vitamin C content, improving the appearance and firmness of the fruit [98].

Carrageenan, especially in its kappa form, is used in bananas and has been shown to reduce respiration rates and browning, extending shelf life in tropical conditions. In treated fruits, firmness was significantly better preserved compared to uncoated controls, validating the effectiveness of this sulfated polysaccharide in international transport and marketing systems [96]. Similarly, gums such as pullulan, xanthan, and gellan allow the incorporation of antimicrobial compounds; in mandarins coated with gellan gum and oregano essential oil, the incidence of Penicillium digitatum was significantly reduced and commercial appearance was maintained for more than three weeks of storage [102] while a pullulan-based film reduces weight loss and maintains firmness, polyphenol, anthocyanin, and antioxidant capacity of blueberry preservation [100] these results indicated that biodegradable film is a potential material for fruit coating.

In terms of proteins, zein, derived from corn, has been applied to various foods in combination with nisin, successfully inhibiting the growth of Listeria monocytogenes and maintaining the crunchy texture of foods for longer [106]. For their part, whey proteins stand out for their ability to form coatings with good oxygen barrier properties; in Golden Delicious apples, this type of coating significantly reduces enzymatic browning and preserves phenolic content, highlighting its potential in fruits that are highly susceptible to browning [104]. Finally, nanocellulose is emerging as a polymer with exceptional mechanical and barrier properties. When applied to strawberries as part of a system combined with antioxidant compounds, it improved anthocyanin retention and delayed the loss of firmness, confirming that cellulose nanostructures can enhance the stability and effectiveness of biocoatings [44].

In comparative terms, chitosan, especially in combination with essential oils, stands out for its high antifungal activity. For example, it inhibits up to 100% of the growth of Neofusicoccum parvum in post-harvest avocados without compromising the visual or enzymatic quality of the fruit, although its high cost and seasonal availability may limit its widespread application [110]. On the other hand, starch, which is abundant and inexpensive, suffers from high hydrophilicity, which reduces its effectiveness as a barrier; however, the incorporation of plasticizers such as glycerol or cross-linking agents significantly improves the water resistance and thermal stability of the films, as shown by recent studies on modified starches [111]. Meanwhile, emerging nanopolymers such as nanocellulose offer exceptional mechanical and barrier properties, although their production cost and scalability remain critical challenges for industrial application [112].

Thus, the selection of the polymer depends not only on its availability and cost, but also on the desired functional properties and the type of fruit to be coated. In this context, it is pertinent to review the main methods of applying biocoatings, since the technique used directly influences the efficacy and stability of these systems.

5. Methods of Applying Biocoatings to Fruit

Application procedures are critical to performance, as they determine essential factors such as uniform distribution, layer thickness, ability to adhere to the fruit, and activation of their functions. Therefore, selecting the appropriate technique is strategic in the design and scaling process of these bioactive systems [113].

5.1. Conventional Methods

Among conventional techniques, immersion is the most widely used due to its simplicity and low cost; however, it can produce films or coatings with excess moisture or uneven thickness, depending on factors such as solution viscosity, immersion time, and the withdrawal speed of the fruit [114]. Alternatively, spraying allows for thinner and more uniform coatings, especially with high-pressure atomizers; it is an ideal option for industrial operations, although it requires greater investment in equipment and process control [115]. In laboratory settings, brushing or manual application are useful for exploratory testing, although they have limited scalability and lower uniformity [7].

5.2. Emerging Methods

In addition to traditional methods, emerging techniques have emerged that stand out for their precision and efficiency in application. Electrospinning is emerging as an alternative capable of generating ultra-thin nanofibrillar layers with a high surface-to-volume ratio, which improves coverage, enhances functionality, and facilitates the controlled release of active compounds; however, its adoption on an industrial scale remains limited by costs and specialized equipment [116]. Similarly, fluidized-bed coating has gained interest for obtaining homogeneous coatings on small particles or fruits, such as seeds or blueberries, although its implementation in fresh fruit is still under development [117]. Recent studies indicate that process performance can be optimized using three spray modes (top, bottom, or rotary), depending on the available industrial design [118]. Finally, innovative approaches such as nanoemulsification and panning, still in the experimental phase for fresh fruit, aim to apply ultrathin layers of bioactive compounds with better release control, opening up opportunities for precision coatings [119].

The selection of the method must be aligned with the characteristics of the fruit (size, morphology, surface sensitivity), the rheological properties of the formulation, and the functional objective of the coating (barrier, antimicrobial, controlled release), balancing coverage efficiency, homogeneity, and scalability (Figure 2 and

Table 3. Technological approaches for biocoating applications on fruits.

Method	Main Advantages	Main Limitations	Application on Fruit	References
Dip coating	Economical; requires simple equipment	Variable thickness; excess moisture	Apples, mangoes, strawberries, citrus fruits	[120]
Spraying	Thin, uniform coatings; adaptable to industrial scale	Greater investment in atomization equipment	Grapes, blueberries, tomatoes, peaches	[121]
Brushing/manual	Simple; useful in preliminary laboratory testing	Not very homogeneous; not scalable	Papayas, pears, bananas (exploratory trials)	[121]
Electro-spinning	Ultra-thin nanofibers; controlled release of bioactive compounds	Expensive; requires specialized equipment	Apples, strawberries, grapes (coatings with antioxidants)	[122]
Electro-spraying	Uniform layers with droplet size control	Experimental; limited to laboratory use	Blueberries, cherry tomatoes, strawberries	[123]
Fluidized bed	Uniform coverage of small particles	Initial development for fresh fruit; technical complexity	Blueberries, cherries, coated seeds	[24,124]
Nanoemulsification/Atomization	Ultra-thin layers improve controlled release of bioactive compounds	Experimental status; high technical level	Guava	[125]

).

5.3. Selection Criteria by Fruit Type and TRLs

The selection of an appropriate application method depends on fruit morphology, firmness, surface hydrophobicity, and susceptibility to mechanical damage. Fruits with smooth and firm peels, such as apples, pears, and citrus fruits, generally allow for homogeneous coverage through immersion or spraying due to their low surface porosity [120,121]. In contrast, small or waxy fruits such as grapes, blueberries, guava and cherry tomatoes require techniques that provide finer droplet control, such as atomization or nanoemulsion-based systems, to ensure proper wetting and minimize surface defects [67,68,125]. Highly fragile fruits, including strawberries and raspberries, benefit from low-impact application strategies that mitigate mechanical stress and excessive moisture deposition [121].

From a technological maturity perspective, each application method exhibits a specific Technology Readiness Level (TRL). Traditional immersion and spraying methods currently show the highest TRL, as they are well established in commercial packing operations and postharvest industrial settings [120,121]. Emerging technologies such as electrospinning and electrospraying remain at laboratory TRL due to equipment complexity, low throughput, and the need for controlled conditions to generate ultrathin nanostructured layers [122,123]. Meanwhile, nanoemulsion-based spraying is currently positioned at a pilot TRL, as it demonstrates improved stability, reduced droplet size, and enhanced antimicrobial activity; however, optimization is required to ensure scalability and process robustness under industrial environments [67,125].

In addition to fruit morphology and process requirements, regulatory acceptance and compliance play a key role in determining both the technological readiness level (TRL) and the real industrial feasibility of each application method.

6. Regulatory Section and Industrialization

The regulatory approval of polysaccharide-based edible coatings varies across regions. In the United States, the FDA regulates them through the “Generally Recognized as Safe” (GRAS) system and the Code of Federal Regulations (CFR Title 21), under which alginate, pectin, starch, and certain chitosan derivatives are authorized [126]. In the European Union, Regulation (EC) No. 1333/2008 and Regulation (EC) No. 1935/2004 require comprehensive migration data and toxicological assessments, particularly when formulations contain essential oils or nanostructured systems.

The safety of nanomaterials remains a critical concern. According to the EFSA Scientific Committee (EFSA, 2021), nano-enabled materials intended for food-contact applications require genotoxicity studies, subchronic toxicity assessments, and migration tests under real storage conditions. However, many postharvest studies report only antimicrobial performance or physicochemical properties, leaving important gaps in risk evaluation.

From an industrial perspective, scalability represents an additional limitation. Some polysaccharide-based formulations exhibit high viscosity, require multi-step emulsification, or incorporate unstable bioactive compounds, which complicates their integration into high-throughput packaging lines. Industrial dipping and spraying systems require controlled rheological properties, rapid drying times, and stability during storage, requirements that do not always align with formulations developed at the laboratory scale.

Finally, regulatory harmonization remains limited. In Latin America, many countries follow Codex Alimentarius guidelines, yet national differences persist in the lists of permitted additives. This variability may restrict the export of fruits coated with novel formulations, particularly those containing nanostructured components. Greater alignment among FDA, EFSA, and Codex criteria would significantly facilitate industrial adoption.

Beyond regulatory compliance, these frameworks directly influence formulation design, the selection of application methods, and scalability constraints discussed throughout the manuscript. In particular, regulatory readiness must be considered in parallel with technological maturity (TRL) when evaluating emerging techniques such as nanoemulsification, electrospinning, or layer-by-layer systems for postharvest fruit applications. This integrated perspective ensures that regulatory considerations are aligned with practical implementation and industrial feasibility.

7. Incorporation of Bioactive Compounds

This review prioritizes the analysis of natural bioactive compounds such as phenolic extracts and essential oils due to their safety, regulatory acceptance, and compatibility with the polysaccharide- and protein-based matrices used in edible coatings. These compounds are considered safe for direct application on fruits, providing antimicrobial and antioxidant activities without generating toxic residues. In contrast, inorganic or metallic nanoparticles, although effective in other types of active packaging, present limitations related to their potential migration into food, lower consumer acceptance in fresh products, and regulatory restrictions for direct food-contact applications. For these reasons, this review focuses on natural bioactive compounds that meet the criteria of safety, functionality, and industrial feasibility.

The incorporation of bioactive compounds into biocoatings and biodegradable films based on polysaccharides or proteins is a robust strategy for improving the post-harvest stability of fruits, combining physical barriers with antioxidant and/or antimicrobial functions. In technological terms, these coatings attenuate gas and water vapor exchange, reduce browning, and delay softening, thereby extending shelf life and preserving health-promoting compounds in fruits. At the same time, their edible and plant-based nature aligns them with sustainability objectives [127].

Similarly, polyphenols play a key role due to their ability to neutralize reactive species and modulate browning, but their effectiveness depends on the coating matrix (alginate, chitosan, starch) and the microenvironment (pH, light, temperature). In this regard, biodegradable films and coatings enriched with polyphenols show improvements in barrier and mechanical properties, as well as controlled release that preserves activity during storage [17]. Likewise, formulating coatings with nanoemulsions of essential oils or phenolic extracts increases the stability and bioavailability of the active ingredients, reducing volatility and sensitivity to oxidation [25].

The phenolic compounds mentioned above in relation to biocoatings mainly comprise flavonoids and phenolic acids, whose chemical structures determine their antioxidant and antimicrobial effects. Among the most widely reported flavonoids are quercetin, catechins, and anthocyanins, recognized for their high capacity to neutralize free radicals and delay browning in fruits such as strawberries, apples, and grapes [21,23]. Quercetin and catechins also contribute to strengthening the polymer network when incorporated into chitosan or starch matrices, improving mechanical and barrier properties [16]. For their part, anthocyanins, although more sensitive to pH and light variations, provide an immediate antioxidant effect and give active coatings natural functional colors.

Among phenolic acids, gallic, ferulic, and chlorogenic acids are the most commonly reported in polysaccharide-based films, demonstrating antimicrobial activity and the ability to modulate water vapor and oxygen permeability [128,129]. Similarly, the essential oils most frequently reported, such as thyme, clove, cinnamon, citronella, and citrus, owe their activity to compounds such as thymol, carvacrol, eugenol, cinnamaldehyde, and limonene, respectively. Among these, thymol and carvacrol stand out for their strong antifungal action, while eugenol and cinnamaldehyde combine antioxidant and antimicrobial effects, reducing the deterioration of fresh fruit [25,130]. Citrus oils, on the other hand, have a more moderate effect, but improve the aroma and sensory acceptance of the final product.

Evidence suggests that the synergistic combination of natural polymers with phenolic compounds and essential oils enhances the effectiveness of biocoatings by acting simultaneously as a physical barrier and a controlled release system for bioactive compounds [119,131]. However, it is important to consider that the incorporation of phenolic compounds and essential oils influences the sensory properties of the fruit, especially its flavor and aroma, so their concentration and mode of release must be optimized to maintain consumer acceptance.

From an antimicrobial perspective, the incorporation of polyphenols and essential oils into biocoatings enables the destabilization of microbial membranes, interference with cellular proteins and nucleic acids, and, in the case of terpenoids, the inhibition of biofilm formation. The result is control of pathogens and disruptive microbiota on the surface of the fruit [119]. In recent years, interest in active coatings has grown. Films and coatings incorporating plant extracts and essential oils have been shown to improve texture, color, and antioxidant activity, while reducing the presence of microorganisms. However, these effects are dependent on factors such as the concentration applied, the type of emulsification, and compatibility with the food matrix [130].

In terms of applications in fresh fruit, the use of chitosan enriched with thymol and thyme oil, nanoencapsulated or combined with non-thermal technologies, stands out. It has been shown to reduce fungal deterioration and maintain quality in berries and blueberries. In addition, the synergy with UV-C light or modified atmospheres enhances the effect [131]. More generally, essential oil nanoemulsions used as nanocoatings improve sustained release and antimicrobial and antioxidant activity compared to conventional emulsions and have been specifically proposed for fresh and minimally processed fruits [25].

At the same time, the circular economy opens a supply route for bioactive compounds: peels, seeds, and pulp residues often contain high concentrations of polyphenols with antioxidant and antimicrobial properties. The recovery of these by-products, such as citrus peels, pomegranates, and mangoes, enables the formulation of functional coatings and contributes to reducing agro-industrial waste, provided that green and scalable extraction processes are employed [128]. In this context, natural eutectic solvents (NADES) and other emerging techniques offer high phenol yields with a lower environmental footprint, facilitating their incorporation into edible matrices without compromising safety or functionality [129].

Regarding advanced extraction techniques, microwaves and ultrasound shortened processing times and improved the recovery of phenolic compounds from fruit peels and waste, with reports of richer and more stable extracts for coating applications [132]. In addition, recent reviews on green extraction summarize routes and parameters that preserve bioactivity, which is essential for polyphenols to maintain their function once embedded in the biodegradable films [133].

From a technological analysis, the incorporation of phenolic extracts or nanoemulsions modulates the film microstructure, reinforcing the polymer network and reducing permeability to water vapor and oxygen; however, excessive doses or phase-matrix incompatibility weaken the film or cause opacity [17]. Likewise, the design of delivery systems (nanoemulsions, protein–polyphenol complexes) has been shown to improve the stability and functionality of active ingredients within coatings for fresh products [119].

Finally, biocoatings and biodegradable films added with polyphenols and essential oils provide physical-chemical protection and antioxidant and antimicrobial functions, facilitating the sustainable use of by-products through green extractions. Their industrial implementation requires optimization of formulation, processability, and sensory attributes. Recent literature supports their effectiveness in extending the shelf life of fresh fruits [67,129].

From the authors’ perspective, although significant scientific advances have been made in the formulation and functional evaluation of polymeric biocoatings, their adoption in real-world conditions is still limited due to the variability of natural raw materials, production costs, and the lack of standardized protocols for post-harvest evaluation. Therefore, future research should focus not only on improving physicochemical and antimicrobial performance, but also on ensuring process scalability, regulatory harmonization, and consumer acceptance to facilitate successful industrial implementation.

8. Reinforced Quantitative Examples and Sensory Implications

Recent studies provide quantitative evidence of the improvements achieved when incorporating phenolic compounds and essential oils into polysaccharide- (

Table 4. Representative polysaccharide-based edible coatings applied to major fruit groups and their quantitative effects on postharvest quality.

Fruit Type	Fruit Example	Polysaccharide Matrix	Active Compound(s)/ Additive	Application Method	Quantitative Effects (vs. Control)	Shelf-Life Extension	Reference
Citrus	Mandarin, tangerine	Chitosan; gellan gum	Essential oils (oregano, thyme), phenolic extracts	Dipping/spraying	Weight loss ↓ 15–35%; better firmness; lower rind disorders; improved color retention	7–12 days	[9,20,95,101]
Berries	Strawberry, blueberry	Chitosan; Carboxymethyl cellulose; pullulan	Essential oils; nanoemulsions; ε-polylysine	Dipping/coating	Weight loss ↓ 15–40%; delayed softening; higher anthocyanin retention; lower ΔE	3–6 days	[35,43,44,120,131]
Tropical fruits	Mango, banana, papaya, guava, avocado	Starch; seaweed polysaccharides; chitosan	Plant extracts, essential oils	Dipping	Weight loss ↓ 15–35%; delayed softening; improved color; fewer physiological disorders	5–8 days	[47,48,55,98,99,110]
Pome fruits	Apple, pear	Alginate; chitosan; polysaccharide blends	Essential oils; phenolic compounds	Dipping/spraying	Weight loss ↓ 10–25%; better firmness; reduced browning and scalding	7–14 days	[41,54,67,107,121]

Abbreviations: ↓ = decrease.

) or protein-based matrices. For instance, coatings enriched with thymol, thyme oil, or oregano oil have been shown to reduce fungal incidence in strawberries and blueberries by 50–80%, depending on concentration and storage period [57,130,131]. Similarly, the incorporation of polyphenols such as gallic, ferulic, or chlorogenic acids at levels between 0.5% and 1.0% (w/w) can lead to 10–25% decreases in water vapor permeability and increases of 15–30% in antioxidant activity due to stronger intermolecular interactions with the polymer network [21,23,125]. Furthermore, nanoemulsified essential oils applied at concentrations of 0.1–0.3% (w/w) enhance antimicrobial efficacy and physicochemical stability while reducing volatility and improving controlled release of active compounds [25,67,68].

However, the incorporation of bioactive compounds also entails important sensory considerations. Essential oils with intense volatile profiles, such as clove, cinnamon, thyme, or oregano, may impart noticeable aroma and flavor even at low concentrations [25,130]. In most fruit matrices, concentrations above 0.1–0.2% (w/w) approach the sensory rejection threshold, leading to off-flavors, herbal overtones, or masking of the natural aromatic profile of the fruit [130,131]. Likewise, polyphenol-rich extracts may alter color or introduce astringency if applied at excessive levels [21,23]. Therefore, achieving a balance between antimicrobial performance and sensory acceptance is essential, requiring careful optimization of concentration, encapsulation method, and release kinetics to preserve fruit quality without compromising consumer preference.

9. Future Prospects

The development of polymeric biocoatings for fresh fruit still faces challenges that limit their scalability and industrial adoption. These include the variability in the properties of natural biopolymers, the need to standardize evaluation methodologies under real post-harvest conditions, and the costs associated with emerging technologies such as electrospinning or nanoemulsification. Likewise, strengthening the compatibility between bioactive compounds and polymer matrices is a priority, as inadequate interactions can compromise the functionality and structural stability of the coating.

In the short and medium term, opportunities are emerging in the integration of green extraction technologies (such as natural eutectic solvents, ultrasound, or microwaves) for the sustainable production of phenolic compounds and essential oils from agro-industrial by-products, which is in line with the principles of the circular economy. Similarly, the incorporation of nanomaterials such as nanocellulose, metal nanoparticles, or hybrid biocomposites opens up the possibility of designing smart coatings with the ability to respond to environmental changes (pH, temperature, or presence of pathogens).

In view of the escalation, it will be essential to establish clear regulatory protocols that guarantee food safety and consumer acceptance. At the same time, research must move toward multifunctional systems that, in addition to extending shelf life, provide nutritional benefits, improve sensory appearance, and reduce the environmental footprint throughout the supply chain. Together, these approaches will consolidate biocoatings as a competitive alternative to conventional plastics in the food industry.

Furthermore, based on the authors’ analysis, future progress in this field will require: developing cost-effective and scalable production processes for natural biopolymers; standardizing physicochemical, microbiological, and shelf-life evaluation methods under real storage and distribution conditions; optimizing encapsulation and controlled release systems for bioactive compounds to ensure their stability and functionality; integrating circular economy strategies to obtain functional compounds from agro-industrial waste; and establishing regulatory frameworks that support the use of edible biocoatings while ensuring food safety and transparency for consumers. These aspects will be fundamental to accelerating technology transfer and enhancing the commercial viability of polymeric biocoatings as a sustainable alternative to conventional plastic packaging.

10. Conclusions

Polymeric biocoatings represent a sustainable and effective tool for mitigating post-harvest fruit losses by combining the action of natural polymers with the incorporation of bioactive compounds of plant origin. Recent evidence shows that these technologies help preserve quality parameters such as firmness, color, flavor, and nutritional content, in addition to conferring antimicrobial and antioxidant properties.

Although the results obtained in laboratory conditions are encouraging, large-scale implementation requires overcoming limitations associated with production costs, formulation standardization, consumer acceptance, and regulatory validation. Despite this, advances in nanotechnology, green encapsulation, and agro-industrial waste recovery allow us to project a favorable scenario for its consolidation in the food industry. In conclusion, polymeric biocoatings are not only an innovative strategy for extending the shelf life of fresh fruit, but also promote the transition to healthier, biodegradable packaging systems that are aligned with global sustainability goals.

To complement these conclusions, the key insights and actionable research priorities derived from this review can be summarized as follows:

I.

Polymeric biocoatings show strong potential to extend the shelf life of fresh fruits by integrating natural polymers with antimicrobial, antioxidant, and barrier-active compounds.

II.

The performance of these systems depends heavily on polymer type, formulation strategy, and application method, which determines coating uniformity, controlled release, and overall fruit quality.

III.

Emerging approaches, including nanoemulsions, nanocellulose-based systems, and electrohydrodynamic technologies, offer promising functional advantages but still require optimization for industrial scalability.

IV.

Standardizing postharvest evaluation protocols under realistic storage, distribution, and retail conditions is essential to ensure comparable datasets and accelerate technological adoption.

V.

Developing scalable controlled-release systems (such as nanoemulsions or polymer–phenolic complexes) remains a priority to maintain stability, reduce the required load of active compounds, and preserve sensory quality.

VI.

Advancing the use of circular economy inputs such as phenolics, essential oils, and polysaccharides extracted from agro-industrial by-products through green and low-energy extraction techniques will be critical for reducing formulation costs and strengthening sustainability.