Emerging Trends and Application of Edible Coating as a Sustainable Solution for Postharvest Management in Stone Fruits: A Comprehensive Review

ABSTRACT

Stone fruits, also known as drupes, include apricots, peaches, plums, cherries, and nectarines that have high global demand due to their nutritional benefits and palatable characteristics. Being soft fruits, they are susceptible to various postharvest issues, reducing their shelf life, with postharvest loss reaching 15%–50%. Among various postharvest management techniques, edible coating is emerging as a popular method due to its positive effects on the quality, physiochemical, phytochemical, and organoleptic characteristics of these fruits. By creating a modified atmosphere, edible coatings can effectively reduce weight loss to less than 10%, meeting the international standard for marketing stone fruits. They also help delay firmness loss, as observed in peaches, where coated samples retained a firmness of 5.6 N compared to 1.8 N in control. Furthermore, edible coating can extend shelf life beyond 7 days at ambient temperature and up to 35 days in cold storage, as reported in literature. These coatings create a semipermeable barrier to gaseous exchange and moisture, helping preserve aroma compounds and delay ripening and respiration rates. Thus, this comprehensive review investigates the importance of edible coating in enhancing the quality attributes and the shelf life of stone fruits. This article also evaluates most current research done on edible coating applications in stone fruits and provides details on ideal coating conditions and requirements for these fruits. The study also discusses current developments in the application of bioactive compounds and nanotechnological techniques to enhance the functional properties and performance of edible coatings. Nevertheless, because this technology is still in its infancy, commercial technological adoption necessitates both widespread consumer acceptance and economic viability.

1. Introduction

The population globally is expected to exceed 9 billion by 2050. However, approximately half of the fruits and vegetables produced worldwide go to waste, largely because of the high moisture content that increases the risk of decay (Bancal and Ray 2022; Shankar et al. 2024). This significant loss poses a major challenge to food security and increases environmental issues. These losses hinder the achievement of the UN Sustainable Development Goals (SDGs) by 2030, principally goal two “to eradicate hunger.” Additionally, postharvest loss extends to environmental pollution and economic setbacks, highlighting the need for sustainable solutions.

Large‐scale food production follows the idea of “farm to fork” to retain the shelf life and food quality until it reaches the consumer. Therefore, it is essential to pack the food. Packaging prevents chemical, physical, and biological damage to the food product (Chhikara and Kumar 2022). There has been large‐scale use of synthetic packaging material (with the highest demand for plastics) in the food industry, which has caused adverse effects on the environment. Plastics are linked to fossil fuels, non‐biodegradability, toxicity, and climate changes. In US landfills, about a quarter of waste is plastic that is associated with food and beverages (Jahangiri et al. 2024). The environmental pollution caused by plastics is estimated to be 12,000 mt worldwide by 2050 (Olunusi et al. 2024). The degradation of plastic waste has the potential to reach the marine environment as microplastics, which can be ingested by marine organisms and thus enter the human food chain (Jahangiri et al. 2024). As a result, single‐use plastic bags have been banned by various nations, underscoring the need for a highly efficient and sustainable methodology to improve the shelf life of foods (Olunusi et al. 2024).

Recent research is centered on creating packaging materials that are sustainable, biodegradable, safe, and without compromising the quality. To resolve the issues of non‐biodegradable plastic packaging materials, bio‐based packaging materials have received significant attention (Roy and Rhim 2021). One of the innovative solutions is biopolymer‐based edible packaging. These edible packaging materials are created either in the form of coatings or films and have acquired enormous research interest across the globe (Ayub et al. 2021; Rohasmizah and Azizah 2022). Edible coatings and films (ECFs) are part of green technology. ECFs can be described as thin layers of natural and environmentally friendly biopolymers that are cohesive and cover the surface of food products (Andriani and Handayani 2023; Chhikara and Kumar 2022). The ideal qualities of ECFs are represented in Figure 1.

FIGURE 1.

A schematic representation of ideal qualities of ECFs. Source: Figure has been adapted and redrawn by the authors in Canva from Olunusi et al. (2024) with permission from Elsevier, copyright 2024 (license number: 5927110292322).

Edible packaging is characterized as a “thin layer” of edible polymer applied onto the food surface (Rohasmizah and Azizah 2022). ECFs can be developed from natural polymers, which possess structural integrity and barrier properties. These properties protect food from the outside environment, thereby enhancing its shelf life (Yadav et al. 2022). The terms edible films and edible coatings are usually used interchangeably, but in the case of films, they are prepared by solution casting and put on the surface of food, whereas the coatings are directly applied to food materials. The ideal thickness of the coating is ≤25 mm (Chavan et al. 2023). The polymers used for the development of edible packaging must be naturally available, biodegradable, environment friendly and non‐toxic. Apart from this, they must also provide the structural and functional properties to the packaging (Benbettaïeb et al. 2019; Rohasmizah and Azizah 2022; Yadav et al. 2022).

Basic materials for edible coating can be obtained from diverse resources, for instance, polysaccharides, proteins, and lipids, or a combination of these (Andriani and Handayani 2023). Commonly used polysaccharide‐based polymer matrices include starch (Santhosh et al. 2024), alginate (Metha et al. 2024), pectin (Panahirad, Naghshiband‐Hassani, and Mahna 2020; Rohasmizah and Azizah 2022), cellulose, gums (Salehi 2020; Zhang et al. 2020), and chitosan (CH) (El‐Araby et al. 2024; Martiñon et al. 2014). Zein, whey protein, casein, gluten, soy protein, and gelatin are protein‐based, whereas oil or fatty acids and waxes are lipid‐based. A combination of these can be used to obtain blends or composites by combining hydrocolloids or lipids (Aaqil et al. 2024; Yadav et al. 2022) (Figure 2). Now, coming to the various methods by which a coating can be applied, they include dipping, brushing, panning, or spraying to produce a coating of the desired thickness as shown in Figure 3. Dipping is the most commonly used method for applying edible coatings, in which the food sample is immersed in the viscous coating solution for a specific duration, ensuring an even distribution of the matrix on the food surface (Suhag et al. 2020). Multilayer coating is a kind of dipping process in which the food product is dipped into one coating solution and later dipped in another solution to form a layer‐by‐layer (LBL) coating (Sowmyashree et al. 2021). Spraying is another method in which the coating matrix is sprayed onto the food surface, thus forming a thin film having uniform thickness. One advantage of this method is its ability to reduce drying time, as the sprayed solution evaporates directly from the food surface (Lara, Yakoubi et al. 2020). The spreading or brushing method of application of edible coating involves the use of a sterile brush. It is used to spread the coating formulation of high viscosity uniformly on the surface (Shiekh et al. 2022). The coating materials used for fabrication are intended to be eaten with the product and are thus fabricated from constituents that are Generally Recognized as Safe (GRAS) by the US Food and Drug Administration (USFDA) or other regulatory jurisdictions (Aayush et al. 2022).

FIGURE 2.

Different matrices for edible coating application. Source: This image is drawn by authors using Canva.

FIGURE 3.

Schematic representation of the development of edible coating and various methods its application on stone fruits  (A) Spraying, (B) Electrospraying, (C) Dipping, and (E) Multilayer coating. Source: Figure has been adapted and redrawn by the authors in BioRender from Shiekh et al. (2022), with permission from MDPI, copyright 2021 (open access).

Several studies have highlighted the significance of ECFs on shelf life of fresh produce (Matloob et al. 2023; Zaidi et al. 2023). Despite the growing interest in this area, one broad review on the use of ECFs on stone fruit has been published to date (Riva et al. 2020). The review explored the influence of edible coating on enhancing the postharvest life of stone fruits, also focusing on different coating formulations and their effect on the physiological responses, physicochemical properties, physiological disorders, phytochemical content, and antioxidant attributes of stone fruits. Additionally, a review specifically targeting peaches was published by Aaqil et al. (2024). Given that stone fruits are climacteric and are highly perishable in nature, they are susceptible to moisture loss and result in shriveling. To reduce such losses, stone fruits are subjected to cold storage, which could lead to chilling injury (CI) (Kumar et al. 2017; Valero et al. 2013). As a natural and sustainable alternative to chemical treatments and traditional packaging, edible coating offers a promising approach for natural preservation of stone fruits (Riva et al. 2020). For this study, articles related to edible coating were obtained from PubMed, Web of Science, and Google Scholar, which were also filtered by year. In this short period from 2020 to 2025, significant amount of research has been published, focusing on multivariate approaches and nanotechnological advances in edible coating of stone fruits—aspects not covered in previous reviews. The objective of this review is to offer a comprehensive understanding of how ECFs can increase the shelf life of stone fruits. This study aims to summarize recent trends in coating applications, examine stone fruit physiology, and identify factors influencing its quality. Moreover, this review also explores the desirable characteristics of coating materials in relation to stone fruit quality indicators, as well as the recent developments in the incorporation of bioactive compounds and the integration of nanotechnology into edible coatings for stone fruits.

2. Overview of Stone Fruits

Stone fruits are “deciduous tree species” of the Rosaceae family, subfamily Amygdaloideae or Prunoideae (Milošević and Milošević 2019; Potter 2012; Flore 2018; Zagrai and Zagrai 2023). These soft‐fleshed fruits, also known as “drupes,” feature a seed enclosed in a stone‐like endocarp and are hence called stone fruits (Manganaris et al. 2023; Riva et al. 2020; Siddiq 2015). They consist of (i) a thin (delicate), edible epicarp, or exocarp, without an ovary; (ii) a fleshy and juicy mesocarp; and (iii) lignified endocarp (stone or pit) that typically encloses a single seed and rarely two (Aaqil et al. 2024; Manganaris et al. 2023) as shown in Figure 4.

FIGURE 4.

Longitudinal cross‐section of a ripe peach displaying the skin, flesh, and stone. Source: The figure is created by the authors and edited in Microsoft PowerPoint.

The fruits belong to the genus Prunus, encompassing peaches and nectarines (P. persica), apricots (P. armeniaca), sweet cherries (P. avium), and sour or tart cherries (P. cerasus) as well as Asian/Japanese plums (P. salicina) and European plums (P. domestica). These fruits are cultivated for their edible fleshy mesocarp, whereas almonds (P. dulcis) are cultivated for their edible seeds (Famiani et al. 2020; Potter 2012; Siddiq 2015).

According to the report by the Food and Agriculture Organization (FAO) for the 2023–2024 marketing year, nectarine and peach production in the European Union (EU) is projected to increase by 12% compared to the previous season. This increase in stone fruit production is primarily attributed to Spain, the largest producer in the EU. Additionally, China's production is expected to rise to 17.5 million. Conversely, there is a noted reduction in production trend by the United States (USDA 2023a, 2023b). The global production of cherries increased to 4.8 million. Turkey, China, Chile, and the United States are anticipated to experience a rise in production, whereas the EU is forecasting a decrease in production (USDA 2023a, 2023b). During the 2022/2023 period, China was the largest producer of peaches and nectarines, with a production volume of approximately 17 million metric tons. The EU ranked second, producing about 3.25 million metric tons, followed by Turkey and Iran (Statista 2023).

Due to a surge in demand for health‐promoting foods, the market for stone fruits is expanding. The nutritional composition of fruits varies depending on cultivars and agronomic practices (Meena et al. 2021). Stone fruits are abundant in bioactive compounds, as well as minerals such as calcium, iron, and potassium, along with a variety of vitamins (Meena et al. 2021; Potter 2012; Siddiq 2015). Numerous studies have demonstrated that stone fruits are rich in phenolic compounds and terpenoids (Lara, Bonghi et al. 2020). They are also sources of antioxidants like anthocyanins and carotenoids (Meena et al. 2021). Peaches and nectarines are particularly rich in vitamin C and carotenoids. Peach is an abundant source of potassium, followed by phosphorus, magnesium, calcium, fluoride, manganese, iron, and zinc (Reig et al. 2023). Additionally, the antioxidant activity is higher in yellow‐fleshed peaches than in their light‐fleshed counterpart (Elsadr and Sherif 2015). Apricots are very diverse and rich in phenolic compounds, including catechin, epicatechin, chlorogenic acid, neochlorogenic acid, and others (Gómez‐Martínez et al. 2021; Ruiz et al. 2005). Moreover, almonds serve as a valuable resource of polyphenols and flavonoids (Meena et al. 2021).

The second most common stone fruit after peach is plums (Brar et al. 2020; Meena et al. 2021). European plums can be consumed either fresh or dried, known as prunes, whereas the Japanese plums are usually consumed fresh and canned (Topp et al. 2012). Peaches have a higher carbohydrate content compared to plums. Japanese plums have a low glycemic index and are low in calories, rich in vitamin C, and are also a good source of anthocyanins and phenolic compounds (Lozano et al. 2009; Mitic et al. 2016; Subramanian et al. 2018). Prunes are also rich in potassium, copper, sodium, magnesium, and calcium (Meena et al. 2021). Sweet cherries are more valued by consumers due to their organoleptic properties. Both sweet and sour cherries are rich in vitamins C and E and are found to be a reliable source of polyphenols such as anthocyanins and flavonols as well (Blando and Oomah 2019; Gonçalves et al. 2017; Wills et al. 1983). Peaches and apricots are found to be rich in fiber, providing roughage, aiding in gastric mobility, and preventing constipation (Elsadr and Sherif 2015; Meena et al. 2021). Both the cherries are a moderate source of dietary fiber (Blando and Oomah 2019; McCune et al. 2011). Stone fruits are available commercially in a variety of packaged forms. They undergo processing to produce juice, puree, canned or frozen products, dried fruits, concentrates, jams, and jellies (Siddiq 2015).

3. Postharvest Challenges Associated With Stone Fruits

3.1. Physiological Disorders

Physiological disorders in fruits significantly affect their quality and yield, often arising from non‐pathogenic factors (Zheng et al. 2019). These disorders arise from abiotic changes associated with climatic shifts or management practices (Malik et al. 2021). Specifically, they result from environmental stresses, such as temperature fluctuations, water stress, and relative humidity, as well as exposure to chemicals like herbicides and pesticides. Additionally, nutrient deficiencies, toxicities, and imbalances, along with certain genetic conditions, can also contribute to abnormal growth patterns in fruits (Figure 5). Although physiological disorders resemble diseases in appearance, they differ as they can often be prevented by adjusting environmental conditions (Zheng et al. 2019).

FIGURE 5.

Causes of physiological disorders. Source: The figure has been drawn by the authors based on Zheng et al. (2019).

In temperate regions, stone fruits are well‐known as healthy summer delicacies. However, these fruits have relatively short postharvest lives, and depending on handling practices and temperature, they can quickly transition from ideal ripeness to an overmature stage (Mari et al. 2019). The fruit's maturity at harvest is a critical determinant of its postharvest life. Harvesting fruits at minimal maturity results in lower flavor and higher firmness, leading to reduced consumer acceptance. On the contrary, harvesting fruits at advanced or higher maturity increases susceptibility to decay, thereby reducing shelf life. CI, for instance, is caused by storage temperature variations (Mari et al. 2019).

Temperate fruits undergo these changes during both preharvest and postharvest stages, which may not be readily noticeable during development (Malik et al. 2021). Stone fruits are adversely affected by physiological disorders that diminish their market value and consumer acceptability. Internal breakdown, split and shattered pits, gummosis, fruit discoloration, pit burning in apricots, and gel breakdown, as well as fruit cracking in cherries, are among the commonly observed physiological disorders (Malik et al. 2021). General physiological disorders in stone fruits in Figure 6.

FIGURE 6.

General physiological disorders in stone fruits. Source: The figure is drawn based on the information from Malik et al. (2021).

Higher physiological responses such as increased respiration and ethylene biosynthesis lead to fruit softening, color changes, acidity loss, and increased total soluble solids (TSS) (Riva et al. 2020). However, these changes may improve eating quality, but they reduce the shelf life and, in turn, the economic value (Riva et al. 2020). Other physiological disorders in these fruits include CI, shrivel, and overripeness due to moisture loss or adverse storage conditions. Physical and mechanical damage, along with increased risk of microbial attack, contribute to significant postharvest losses (Riva et al. 2020). Overall postharvest losses in all fruits range from 15% to 50% (Ayub et al. 2021), emphasizing the need to control losses to meet the demands of a growing population.

3.2. Climacteric Behavior

Fleshy fruits can be classified into two groups depending on respiratory patterns: climacteric, which display a characteristic rise in respiration and ethylene production during ripening after harvest, and non‐climacteric, which do not undergo such an increase (Fukano and Tachiki 2021; Paul and Pandey 2014). Stone fruits predominantly exhibit a climacteric ripening pattern, with exceptions such as cherries and certain plum varieties, which display non‐climacteric behavior. As a result, climacteric fruits undergo continued maturation and ripening processes even after harvesting due to ongoing respiration (Riva et al. 2020; Yadav et al. 2022). Respiration includes a sequence of biochemical reactions, including enzymatic and oxidative‐reductive processes, facilitating the breakdown of complex organic matter within cells into simpler substances, releasing CO₂, water, and heat in the presence of O₂ (Yadav et al. 2022). The relationship between respiration and ethylene production significantly impacts fruit shelf life. Conversely, most non‐climacteric fruits achieve full ripeness only when attached to the parent plant. Once detached, they exhibit minimal ethylene production and reduced respiration rates when stored at room temperature (Minas et al. 2015).

Throughout the climacteric phase, a rapid rise in the cellular respiration rate occurs, which is referred to as the climacteric rise (Paul and Pandey 2014). This surge is accompanied by a rapid release of ethylene, leading to the breakdown of cell walls. This breakdown facilitates the movement of moisture from the interior to the surrounding environment, allowing O₂ to enter and accelerate the process of senescence (Yadav et al. 2022). Parameters such as relative humidity, atmospheric air composition, as well as storage temperature influence rate of respiration (Yadav et al. 2022). Generally, climacteric fruits tend to perish more rapidly and severely compared to non‐climacteric fruits (Paul and Pandey 2014).

3.3. Postharvest Decay

Stone fruits are prone to fungal and bacterial decay due to their higher water activity, sugar content, and pH conditions favorable for microbial growth (Ram and Bhardwaj 2006). This susceptibility leads to several types of rot, including blue or green mold rot, soft rot, grey mold rot, and brown rot. The primary causative organisms include Rhizopus stolonifer (soft rot), Monilinia fructicola (brown rot), Botrytis cinerea (grey mold), and Penicillium expansum (blue or green mold) (Aaqil et al. 2024; Manganaris et al. 2022; Mari et al. 2019). Scab (freckles or black spot) is a prominent disorder in nectarines, almonds, peaches, and apricots, and it is rarely observed in cherries and plums. The fungus causing peach scab, “Cladosporium carpophilum,” was first observed in 1877 after analyzing fruit specimens from Australia (Khan et al. 2021).

Bacterial diseases that are of more importance in stone fruits include canker, crown gall, and bacterial spot (Ram and Bhardwaj 2006). Bacterial spot, prevalent in most stone fruit‐growing areas, can cause severe loss by reducing fruit marketability and weakening the plant (Ram and Bhardwaj 2006). The causative organism is Xanthomonas campestris pv. pruni (Khan et al. 2021; Ram and Bhardwaj 2006). Bacterial canker, also known as gummosis, twig blight die‐back, blossom blast, and spur blight, occurs in major fruit‐growing regions worldwide. The pathogen responsible is Pseudomonas syringae pv. syringae (Ram and Bhardwaj 2006). In 1918, plum pox (belonging to genus Potyvirus group responsible for “Sharka” disease) was first detected in Eastern Europe and has subsequently spread worldwide. This causes significant losses in nectarine, plum, apricot, and peaches, as it lowers fruit quantity and quality (Khan et al. 2021).

3.4. Mechanical Damage

Stone fruits are renowned for their tender nature, therefore requiring careful handling to avoid physical and mechanical damage. One of the primary concerns for stone fruit producers on the farm revolves around mitigating mechanical damage that may occur (Ahmadi and Gholami 2023). Improper physical handling throughout the processes of harvesting, grading, packaging, and transportation can lead to structural, tissue, and cellular damage in fruits, resulting from impact, compression, abrasion, puncturing, testing, or a combination thereof. This may increase susceptibility to decay and microbial proliferation. In addition to these concerns, these fruits are susceptible to bruise damage due to the impact force exerted during the aforementioned processes (Li and Thomas 2014). This leads to a reduction in product quality, postharvest losses, and economic losses. Surface and internal breakdown also occur because of mechanical forces. By studying factors such as fruit ripeness, skin thickness, and internal structure, researchers and growers can develop strategies to reduce bruising and improve overall fruit quality. Techniques, such as proper packing, cushioning, and temperature management, can alleviate the effect of improper handling on stone fruits and preserve their quality during storage and transportation (Fadiji et al. 2023).

3.5. Chilling Injury

Stone fruits undergo rapid ripening and decay at room temperature, necessitating the need for cold storage. However, CI shortens their shelf life at lower temperatures (Puig et al. 2015). CI is evident in stone fruits as internal or flesh browning, occurring more rapidly and severely at 2.2°C–7.6°C compared to storage at or below 0°C but above freezing point (Lurie and Crisosto 2005; Subramanian et al. 2018). The CI symptoms mostly become visible during ripening post‐cold storage, potentially going unnoticed until the fruit reaches consumers. Optimal storage temperature ≤0°C, depending on the fruit's soluble solids, maximizes storage life (Lurie and Crisosto 2005) (Figure 7).

FIGURE 7.

Chilling related disorders in (A) peach and (B) plum. Source: Figures are reproduced from Manganaris and Crisosto (2020), with permission from Elsevier, copyright 2024 (license number: 5927120574666).

CI is influenced by genetics and triggered by the exposure to specific temperature (Manganaris and Crisosto 2020). It is demonstrated as dry, mealy, or woolly textures characterized by juice deficiency (mealiness or wooliness), hard‐textured fruit without juice (leatheriness), flesh or pit cavity browning (internal browning), and flesh bleeding or internal reddening (Lurie and Crisosto 2005; Manganaris and Crisosto 2020; Subramanian et al. 2018). Off‐flavors develop well before these symptoms appear (Manganaris and Crisosto 2020). These symptoms can appear within 1‐ or 2‐week during storage at 2°C–5°C, whereas fruits stored at 0°C may last 3 weeks or more without visible damage (Lurie and Crisosto 2005). In advanced stages, CI may lead to cavity formation and flesh tissue separation, particularly in white‐flesh peach cultivars. Harvest maturity significantly influences peach ripening, flavor, and market quality (Lurie and Crisosto 2005).

Peaches and nectarines are highly susceptible to CI. Physiological disorders due to extended cold storage significantly limit peach fruit storage to a few weeks. Flavor loss precedes visual CI symptoms in all susceptible cultivars (Manganaris and Crisosto 2020). Most plum cultivars exhibit CI symptoms, along with red pigment accumulation (bleeding), flesh browning, mealiness, gel breakdown, flavor loss, and flesh translucency after prolonged cold storage followed by room temperature ripening (Minas et al. 2013). Apricots are also prone to disorders such as internal (flesh browning) or gel breakdown (characterized by gelatinous mass, translucent) (Manganaris and Crisosto 2020). Because temperature impacts the postharvest life of various cultivars, maintenance of appropriate temperatures throughout handling is essential to prevent postharvest disorders and minimize economic losses (Manganaris and Crisosto 2020).

4. Edible Coating for Postharvest Management

The use of edible coatings in food preservation traces back to the 12th century, with the earliest recorded instance in China, where waxes were applied to citrus fruits to prevent moisture loss (Baldwin and Hagenmaier 2011; Cagri et al. 2004; Dehghani et al. 2018). In the 15th century, Japan utilized edible films made from soymilk, known as Yuba, for food preservation (Cagri et al. 2004; Dehghani et al. 2018). During 1967, the commercial application of edible films was initially limited to using wax for preserving fruits and vegetables. However, by 1986, the concept gained significant attention (Dehghani et al. 2018). Figure 8 summarizes the history of ECFs.

FIGURE 8.

History of edible coating in fresh produce.

ECFs are extensively utilized to preserve shelf life in the case of numerous food products, such as meat, vegetables, dairy, fish, and fruits (Yadav et al. 2022). These coatings help to reduce oxidation and microbial contamination, along with minimizing respiration rate and ripening (Aaqil et al. 2024; Yadav et al. 2022). Recently, a significant number of studies have focused on edible coating applications to fruits and vegetables (fresh and minimally processed) (Chavan et al. 2023; De Corato 2020; El Khetabi et al. 2022; Filho et al. 2021; González‐López et al. 2023; Kotiyal and Singh 2023; Martins et al. 2024; Panwar et al. 2024; Riva et al. 2020; Salehi 2020; Teixeira et al. 2022; Wibowo et al. 2024). The coating imparts a more durable barrier in contrast to the natural waxy cuticle. The natural waxy material is removed during postharvest handling and washing procedures (Riva et al. 2020). The epicarp or the pericarp of the fruit or vegetable is completely covered by the coating material; it additionally seals the stomata and lenticels, covering the pores and cracks on the fruit surface, thereby acting as a semipermeable barrier (Aaqil et al. 2024; Riva et al. 2020; Yadav et al. 2022). This improvement in shelf life occurs by managing the movement of gases, moisture, and solutes (Owusu‐Akyaw Oduro 2022; Priya et al. 2023). This barrier particularly targets gases like O₂ and CO₂, which, in turn, decrease respiration rates and ultimately slow down ripening by limiting ethylene biosynthesis (Patil et al. 2023). Therefore, the coating retards physiochemical changes, slows down decay, and delays ripening (Aaqil et al. 2024). ECFs must exhibit (a) adhesive nature, (b) structural and microbiological surface stability, (c) semipermeability, and (d) the ability to maintain and enhance aesthetics and sensory attributes (Chavan et al. 2023). This technology is composed of edible constituents with barrier properties, thus creating a hurdle between the product and the environment. Consequently, it improves protection and shelf life without compromising aesthetics (imparts a glossy surface) (Aaqil et al. 2024; Chavan et al. 2023).

ECFs are extensively used across a wide range of foods, with the market valued at USD 2.6 billion in 2021, projected to grow to USD 4.98 billion by 2030, at a compound annual growth rate of 7.50% (Straits Research 2023). This technology stands out as a cost‐effective method to maintain quality and ensure safety (Dehghani et al. 2018). In recent times, numerous industries have emerged to produce edible coatings for commercial purposes. Some notable examples include the vegetable oil‐based protective coating for stone fruit and vegetables available under the trade name PrimaFresh 60 OR. This coating reduces fruit shrinkage due to moisture loss during cold storage and enhances the fruit appearance (PaceInternational 2022). The NatureSeal coating is a vitamin and mineral blend fabricated to protect fresh‐cut fruits from oxidation, retaining color and natural texture for up to 21 days without changing flavor (NatureSeal 2022). Commercially available water‐based coating is from Akorn Natural. Partially wet fruits can be treated with this formulation, applied by dipping or spraying, acting as a substitute for waxes. They may be cleaned up with water and dried quickly through heated or non‐heated tunnels without leaving any sticky residue. Studies reveal that stone fruits coated with Akorn Natural exhibit lower weight loss, reduction in internal breakdown, and maintained higher firmness after 28 days under cold storage compared to untreated fruit (Akorn 2022). Table 1 outlines the commercially available coatings.

TABLE 1.

Coatings commercially available for fruits and vegetables.

Company	Brand	Country	Coating material	Key observations	Fruits/vegetables	References
Akorn technology	Akorn Natural	United States	Vegetable protein to slow down ripening, a natural wax to reduce moisture loss, and vegetable oil to maintain color For some produces, a combination of plant‐derived essential oils to disrupt the propagation of fungi and increase antioxidant activity	–Stone fruits demonstrated lower weight loss –85% reduction in internal breakdown and higher firmness	Apple avocado, mango, pear, citrus, stone fruit, pineapple	Akorn (2022)
Pace International, LLC	PrimaFresh 60 OR	United States	Vegetable oil‐based protective coating	–Effective shrinkage control during cold storage and distribution –Enhances fruit color –It can be mixed with postharvest fungicides	Stone fruit and vegetables	PaceInternational (n.d.)
	Semperfresh		Sucrose ester‐based coating	–Semperfresh inhibits water loss while allowing gas exchange –Reduces weight loss, firmer cherries with less pitting –Cherry stems stay greener longer –Gives sheen to cherries without leaving an oily or greasy film on the fruit	Cherries
	Natural Shine		Carnauba‐based coating	–Extends shelf life –Controls dehydration	Tropical fruits and citrus
	Shield‐Brite		Shellac‐based		Apple
	PrimaFresh 3000		Carnauba	–Carnauba‐based controls dehydration and extended shelf life	Pome fruits
	PrimaFresh 3500		Carnauba	–Carnauba‐based coatings enhance fruit color	Pomegranate
	PrimaFresh pear coat		Carnauba		Pear
	PrimaFresh 45		Carnauba	–Carnauba‐based coatings can be mixed with postharvest fungicides	Stone fruit
	Natural Shine SP		Carnauba		Sweet potatoes
Sufresca	Sufresca	Israel	—	–Requires no specialized equipment and dry fast –Any application line such as waxing or washing works –Slows down maturation, weight loss, and subsequent degradation and decay—even under cold, ambient, and changing conditions	Avocado, tomato, mango, cucumber, citrus, bell pepper, onion, garlic, pomegranate arils	Sufresca (2022)
AgriCoat NatureSeal Ltd	NatureSeal	United Kingdom	Vitamin/mineral‐based blends	–Maintains freshness of fruits after cutting for up to 7 days –Protect cut produce from browning, without altering the natural flavor	Avocado, apple, bananas, root vegetables	NatureSeal (2022)
JBT Fresh Produce Technologies	Sta‐Fresh 740	United States	Xanthan gum‐based coating	–Maintains high shine from packing house to final market destination –Minimizes shrinkage appearance in cold and ambient storage –Easy to apply with good leveling and no smudging on fruit surface	Stone fruit	JBT (2017)

4.1. Key Considerations for Stone Fruits

A key aspect to to consider when developing edible coatings for stone fruits is the selection of polymeric materials, which is driven by three goals: (i) improving shelf life; (ii) achieving sensory neutrality or improving quality; and (iii) sustainability. In this context, the product's appearance, which is a crucial indicative of its freshness and quality, greatly influences the decisions made by consumers when it comes to fresh fruit. Consequently, when creating edible coatings, materials should be carefully chosen based on their impact on the final appearance of the product as well as their functionality and performance (Jurić et al. 2024).

Because stone fruits are climacteric, the coating should have barrier properties against gases and water, thereby efficiently controlling their passage between fruits and surrounding atmosphere. It is this regulating role that slows down physiological ripening, preserves naturally occurring volatile components, and decelerates respiration (Jurić et al. 2024; Olunusi et al. 2024).

An ideal coating solution should form a uniform layer on the fruit's surface. The wettability properties of the food product determine the adherence of coatings on their surface. Wettability (spreading coefficient) is obtained by measuring the contact angle and is a result of interfacial interactions between the cohesive force of the fruit skin or peel and the adhesive force of the liquid coating substance. According to literature, sweet cherry is found to have an average water contact angle of 94.2° (Peschel et al. 2003), and peach 140°–150° (quasi‐superhydrophobic) (Fernández et al. 2011; Lu et al. 2015). Therefore, the coating should also have a similar contact angle to facilitate uniform wetting. Overall, the selected coating should not interfere with the organoleptic properties of the fruits, and it should be transparent and provide antimicrobial and antifungal properties. Therefore, prior to selection, a thorough knowledge of edible film or coating qualities is required.

4.2. Components for Edible Coating

The foremost concern regarding an edible coating is that it must be composed of food‐grade materials, ensuring its suitability for consumption together with the food product (Yaashikaa et al. 2023). The edible polymers suitable for application on stone fruit include polysaccharides (Khan et al. 2023; Li et al. 2019; Sowmyashree et al. 2021; Zhang et al. 2020; Ziaolhagh and Kanani 2021), proteins (Baysal et al. 2010; Mendes‐Oliveira et al. 2022), lipids (Gonçalves et al. 2010; Kim et al. 2013), or a combination thereof, which form a composite edible coating (Abediyan et al. 2018; Navarro‐Tarazaga et al. 2008; Zhang et al. 2018). Table 2 summarizes the details of various coatings applied to stone fruits. The advantages and disadvantages of these components are depicted in Figure 9.

TABLE 2.

Coatings applied on stone fruits for prolonging the shelf life.

Coating matrix	Coating type	Stone fruit variety	Storage conditions	Key findings	References
Gum arabic	Polysaccharide	Peach	4°C ± 0.5°C, 85%–95% RH for 35 days followed by storage at 20°C ± 1°C at 85%–95% RH for 3 days	–The coating at a concentration of 10% was effective in mitigating the issues of CI –Inhibited the enzymatic degradation of phenolic compounds, thus maintaining high levels of TPC and flavonoids –Enhanced antioxidant activity	Gan et al. (2024)
Peach gum	Polysaccharide	Peach	For 25 days at 8°C	–Peach gum treatment partially prevented weight loss and delayed the formation of ethylene and fruit softening	Zhang et al. (2020)
Carnauba wax	Lipid	Plums and nectarines		– Rhizopus stolonifer was completely inhibited (except concentration 1%) –There was no mycelial growth of Monilinia fructicola –On nectarines, a 9% carnauba wax coating displayed 90% inhibition for R. stolonifer and 50% the spores of M. fructicola –The occurrence of diseases in both fruits was dramatically decreased by applying protective layers of 4.5% and 9% carnauba wax	Gonçalves et al. (2010)
Alginate	Polysaccharide	Sweet cherry	2°C, 90% RH for 16 days and the storage at 20°C for 2 days	–Post 16 days of cold storage, the coated fruits (with a greater hue angle) retained their characteristic bright red color, particularly when combined with 3% or 5% alginate –The quality parameters in coated fruits were better compared to control	Díaz‐Mula et al. (2012)
Hydroxypropyl methylcellulose (HPMC)‐beeswax	Composite	Plum	1°C for 22 days and 20°C for 5 days	–Significant reduction of weight loss compared to control –Firmness was higher than the uncoated samples –Coated samples maintained better color –Coating application delayed acidity losses and maintained a higher TA	Gunaydin et al. (2017)
Alginate	Polysaccharide	Plum	2°C, 90% RH for 35 days and then at 20°C, 65% RH for 3 days	–Ethylene production in alginate‐treated plums was reduced, especially in 3% coating, climacteric peak highly inhibited –Coating reduced weight loss, delayed acidity loss, and color changes –Coating delayed the softening process, thus maintaining the firmness	Valero et al. (2013)
Carboxymethylcellulose (CMC) and gum arabica (GA)	Polysaccharide	Nectarine	1°C ±  1°C and 85%–90% RH for 28 days	–1% CMC coating helped retain TPC and total antioxidant activity in contrast to control fruits –The coating of nectarines with 10% GA demonstrated high ascorbic acid levels in comparison to control fruits –Coating fruits with 1% MCC demonstrated the lowest pectin methylesterase (PME) activity –Coating of fruits with 1% CMC and 10% GA exhibited a shelf life of 21 days in comparison with control (14 days)	Jayarajan and Sharma (2020)
Sucrose monoester combined with palmitate and stearate	Composite	Plumcot	—	–Flesh firmness is higher in coated fruits compared to control –Fruits’ shelf life was extended to 9 days	Jung and Choi (2021)
Chitosan	Polysaccharide	Plum	1°C ± 1°C and 90% ± 5% RH for 35 days	–Firmness, TA, and chroma/hue angle higher in coated fruits –Lower TSS in coated fruits –Coating reduced ethylene production and respiration rate	Kumar et al. (2017)
Hydroxypropyl methylcellulose (HPMC)–beeswax (BW)	Composite	Plums	1°C for a month and later 20°C for 1–3 weeks	–BW coatings were efficient in reducing weight loss in contrast to HPMC –Plum softening and bleeding were decreased by coatings; the more successful coatings had lower BW contents –The application of the coating had no effect on flavor
Alginate, gellan gum, chitosan, gum arabic Commercially available: high‐shine (carnauba wax‐based coating) and Sta‐Fresh (xanthan gum‐based coating)	Polysaccharide High‐shine—lipid Sta‐Fresh—polysaccharide	Plums	For 5 weeks at −0.5°C ± 2°C and 90% ± 5% RH (representing the shipping condition) and at 20°C ± 2°C, 75% ± 5% RH for 20 days	–Coated fruits were observed to have reduced weight loss and a reduction in shrivel incidence –Chitosan coating had a higher respiration rate compared to other coatings –During cold storage, alginate, gum arabic, and high‐shine maintained the firmness –At 20°C alginate, chitosan, and gum arabic maintained the firmness of the fruits –Fruits coated with chitosan and alginate maintained their color –Gum arabic coating represented similar property as that of commercial coatings	Fawole et al. (2020)
Gum arabic or almond gum	Polysaccharide	Sweet cherry	2°C, 90%–95% RH for 8 days	–In coated fruits, respiration rate and ethylene production have been substantially decreased –Compared to control coated fruits, it retained its firmness, TA, hue angle, and soluble solids content (SSC)	Mahfoudhi and Hamdi (2015)
Composite coating of rice starch‐ι carrageenan (RS‐ι‐car) combined with sucrose fatty acid esters (FAEs)	Composite	Plum	20°C for 3 weeks	–Coating helped in improving quality attributes –Throughout the storage period, there was no change in the coated fruit's phenolic content, antioxidant capacity, flavonoid content, or DPPH activity –The RS‐ι‐car‐FAEs coating keeps plum fruit's overall quality and extends its shelf life	Thakur et al. (2018)

FIGURE 9.

Advantages and disadvantages of polysaccharide, lipid‐, and protein‐based edible coatings.

4.2.1. Polysaccharide

Polysaccharides are naturally occurring, biodegradable macromolecules composed of monosaccharides linked through glycosidic bonds (Díaz‐Montes 2022). They are widely used in stone fruit coatings due to their abundance, non‐toxicity, allergen‐free nature, biocompatibility, and affordability (Aaqil et al. 2024; Yadav et al. 2022). Polysaccharide materials such as alginate (Abediyan et al. 2018; Díaz‐Mula et al. 2012; Maftoonazad et al. 2008; Valero et al. 2013), cellulose (and its derivatives) (Jayarajan et al. 2020; Maftoonazad et al. 2008; Panahirad, Naghshiband‐Hassani, Bergin et al. 2020), pectin (Panahirad, Naghshiband‐Hassani, and Mahna 2020; Panahirad, Naghshiband‐Hassani, Bergin et al. 2020; Ramirez et al. 2015), CH (Abediyan et al. 2018; Jiao et al. 2019; Zhang et al. 2019; Ziaolhagh and Kanani 2021), and various gums, including peach gum, gum Arabic (GA) xanthan gum, guar gum, and gellan gum (Fawole et al. 2020; Hashemi et al. 2017; Zhang et al. 2020; Ziaolhagh and Kanani 2021), have been extensively reported in the coating of various types of stone fruits. Among these, extensive research has focused on alginate and its derivatives, like sodium alginate (Díaz‐Mula et al. 2012; Li et al. 2019; Maftoonazad et al. 2008; Valero et al. 2013). These materials exhibit exceptional mechanical and gas barrier properties, even though they exhibit weak water barrier properties because of their hydrophilic nature. The hydrophilic nature of polysaccharides enables the formation of strong hydrogen bonds with solvents, leading to a well‐ordered and tightly packed structure that contributes to these desirable characteristics (Aaqil et al. 2024; Riva et al. 2020). In the latest research, Ren et al. (2024) developed a coating film based on CH. The film incorporates temperature‐sensitive liposomes and CH‐stearic acid nanoclusters with trans‐2‐hexanal. The coating was effective in maintaining the freshness and storage life of peach by contributing excellent antibacterial and antioxidant activity. It also demonstrated temperature‐responsive release behavior at 10°C–40°C.

4.2.2. Proteins

Proteins are categorized based on their sources into two types: (i) globular proteins, derived from plant sources, and (ii) fibrous proteins, sourced from animals (Wittaya 2012). Plant proteins include wheat gluten, zein, pea protein, and soy protein, whereas animal proteins encompass whey, casein, collagen, and gelatin (Chiralt et al. 2017; Mihalca et al. 2021). Globular proteins exhibit solubility in water, as well as in aqueous solutions of acids, bases, and salts, whereas fibrous proteins are insoluble in water (Wittaya 2012).

The fundamental structure of proteins consists of amino acids that are linked together through peptide bonds to form amino acid chains (polypeptide chains) (Cannon 1973). During coating formation, these chains interact with each other, enhancing mechanical strength and providing barriers against lipids and gases (Yadav et al. 2022). However, a notable disadvantage is their reported tendency to become brittle, flake, or form cracks due to inadequate water barrier properties. Furthermore, the application of proteins in coatings is limited due to allergic restrictions and religious or ethical beliefs associated with animal proteins (Aaqil et al. 2024; Riva et al. 2020; Yadav et al. 2022).

4.2.3. Lipids

Lipid‐based coatings, owing to their hydrophobic nature, exhibit excellent moisture barrier properties while also limiting mechanical and gas permeability (Debeaufort and Voilley 2009). These coatings typically include fatty acids, waxes, oils, and lipids (Milani and Nemati 2022). Commonly employed lipid‐based materials encompass waxes like beeswax (BW), carnauba wax, and vegetable oils (Abdi et al. 2021; Gonçalves et al. 2010; Kim et al. 2013). They effectively reduce respiration rates, thereby extending shelf life, and contribute to a glossy finish, enhancing aesthetics. Additionally, due to their water barrier properties, they prevent water loss and dehydration (Aaqil et al. 2024). It demonstrates optimal compatibility with other coating agents, enhancing properties such as flexibility, improving cohesion, and enhancing the hydrophobicity of edible films (Milani and Nemati 2022).

4.2.4. Composites

Composite‐based edible coatings mean a combination of proteins, polysaccharide, or lipids to develop edible coatings, encompassing the properties of individual materials, thereby addressing their respective limitations (Riva et al. 2020). This approach typically involves the integration of lipids and hydrocolloids (for instance, proteins or polysaccharides) (Aaqil et al. 2024; Ju et al. 2019). Hydrocolloids offer excellent film‐forming capabilities, mechanical strength, and gas barrier properties but tend to have poor water barrier property. Conversely, lipids are hydrophobic and exhibit outstanding water barrier properties. Therefore, combining these materials results in a coating that encompasses all desired attributes (Ju et al. 2019). There has been enormous research devoted to developing composite coatings for food preservation. Studies have demonstrated that composite coatings enhance the shelf life of stone fruits (Abediyan et al. 2018; Navarro‐Tarazaga et al. 2011, 2008; Zhang et al. 2018).

4.3. Additives and Active Substances in Coating

The functionality of coatings will significantly improve by the integration of additives and active ingredients. Additives encompass a variety of substances such as anti‐browning agents, plasticizers, emulsifiers, and flavor agents. These additives serve to amend the thermal, mechanical, and physical properties of the coatings (Yadav et al. 2022).

Bioactive agents further enhance the antioxidant and antimicrobial capabilities of the coating. Both natural and synthetic bioactive ingredients are utilized, including essential oils (EOs) (Hashemi et al. 2017; Kim et al. 2013), plant extracts (Gull et al. 2021; Li et al. 2019; Sowmyashree et al. 2021), nisin (Mendes‐Oliveira et al. 2022), natamycin (Shao et al. 2025), organic acids, sorbates, and butylated hydroxy anisole (BHA). These agents increase the properties of fruits and vegetables along with improving consumer acceptance.

4.3.1. Plasticizers

Due to the presence of weak intermolecular forces and their highly branched structure, natural polymers are brittle. Plasticizers are those materials added to improve the polymer processability and flexibility. They lower the hardness, viscosity, tension of deformation, and electrostatic charge of polymer, while along with improving the flexibility, dielectric constant, and resistance (Fundo et al. 2015). Stone fruits commonly experience shrinkage and shriveling during postharvest storage (Riva et al. 2020). The flexible nature of a coating allows it to adapt to the changes occurring within the fruit. Plasticizers are vital in enhancing compatibility and functionality of biopolymers within composite coatings (Yadav et al. 2022). Commonly used plasticizers are glycerol, polyethylene glycol, mannitol, xylitol, sucrose, and acetylated monoglyceride (Riva et al. 2020; Saberi et al. 2017; Yadav et al. 2022). These substances, due to their hygroscopic nature, facilitate additional water absorption, thereby reducing intermolecular interactions within the polymer chains and preventing issues such as blisters, flakes, and cracks (Eslami et al. 2023).

Baysal et al. (2010) demonstrated that the addition of glycerin to zein films reduces brittleness. The efficacy of a plasticizer in plasticizing a polymer network depends on its physiochemical properties, including shape, chemical structure, physical state, polarity, chain length, and number of active functional groups. The effects of glycerol and mannitol (plasticizers) on hydroxypropyl methylcellulose (HPMC) and BW in a composite coating were examined by Navarro‐Tarazaga et al. (2008). The authors discovered that the film brittleness increased without change in water vapor permeability (WVP) upon an increasing mannitol content, whereas enhanced film flexibility, durability, and WVP were observed on increasing glycerol content. Glycerol proved more effective in weakening interactions among HPMC polymer chains and enhancing film mechanical properties compared to mannitol. Glycerol's lower molecular weight and hygroscopic nature contribute to its superior plasticizing effects compared to mannitol. The optimum solution for preserving fruit quality was provided by coatings with 20% BW and glycerol, which showed enhanced integrity, plum firmness retention, and decreased bleeding without compromising fruit flavor (Navarro‐Tarazaga et al. 2008). However, the careful consideration of plasticizer concentration is essential, as it can influence intermolecular spacing and, consequently, alter barrier properties (gas and water vapor) (Navarro‐Tarazaga et al. 2008).

4.3.2. Emulsifiers and Surfactants

Stone fruits exhibit considerable diversity in the characteristics of their epicarp surfaces. For instance, the epicarp of peaches is sinuous and hairy, whereas that of cherries and plums is waxy and smooth. As a result, it may be necessary to modify edible coatings’ surface‐active characteristics, such as surface tension and wettability, to suit the specific requirements of different stone fruit applications (Riva et al. 2020).

To enhance the homogeneity and wettability of coatings, specified emulsifiers or surfactants can be utilized (Firdous et al. 2023). Lecithin, tweens, spans, vegetable oils, and fatty acid salts have been employed as surfactants to enhance the adhesion and wettability of the coating (Firdous et al. 2023; Md Nor and Ding 2020). Emulsifiers, including sucrose fatty acid esters, soy lecithin, sodium lauryl sulfate, and polysorbate, play a crucial role in creating polysaccharide–lipid and protein–lipid composite coatings, resulting in homogeneous aqueous solutions. In the ECFs, emulsifiers play a major role in dispersing the hydrophobic lipid materials within the solution; in this manner, it improves emulsion stability and promotes even particle distribution (Md Nor and Ding 2020).

Certain polymers exhibit emulsifying properties, thus preventing the need for the addition of emulsifiers. Gelatin serves as an effective colloid stabilizer and exhibits surface‐active characteristics. Additionally, various polysaccharides, such as GA, methylcellulose, alginate, octenyl succinic anhydride‐modified starch, and water‐soluble soy polysaccharides, are commonly utilized as efficient emulsifiers (Łupina et al. 2019). Mahfoudhi et al. (2014) evaluated that the emulsifying properties of GA and almond gum were. The application of 10% coating of either gum on sweet cherries improved the shelf life and quality, exhibiting a notable reduction in respiration rate and ethylene production, and prevented decay and off‐flavor (Mahfoudhi and Hamdi 2015). Similarly, Gan et al. (2024) found that a 10% GA coating mitigated CI in peaches while maintaining high phytochemical levels.

4.3.3. Bioactive Components

Bioactive compounds are “extra‐nutritional constituents” (Kris‐Etherton et al. 2002; Song and Zhang 2023) that occur in minute quantities in food, extracted from various sources, including plants, marine organisms, microorganisms, or animals (Santos et al. 2019), and they enhance the functional attributes of edible coatings used in food preservation (Benbettaïeb et al. 2019; Silva‐Weiss et al. 2013). Bioactive compounds that find application in stone fruits include plant extracts (Gull et al. 2021; Li et al. 2019; Sowmyashree et al. 2021), bacteriocins such as nisin and natamycin (Mendes‐Oliveira et al. 2022), organic acids such as ascorbic acid and citric acid (Alali et al. 2023; Liu et al. 2014; Yang et al. 2019), and EOs (Hashemi et al. 2017; Kim et al. 2013).

4.3.4. Organic Acids

Organic acids, such as citric acid and ascorbic acid, have found use in stone fruits to enhance quality and storage life. Citric acid is safe as an organic food additive, which not only retards bacterial and fungal growth in fruits and vegetables but also boosts disease resistance in vegetables (Gurtler and Mai 2014). It effectively limits browning and fruit diseases by minimizing postharvest fruit respiration. Additionally, it serves as a useful additive for enhancing acidity and flavor in foods, thereby improving quality and preventing spoilage (Alexandri et al. 2021; Moon et al. 2020).

The research by Yang et al. (2019) analyzed the influence of citric acid on preserving the quality of peach varieties. Citric acid effectively maintained attributes such as firmness, inhibited decay, and sustained titratable acidity levels when fruits were stored at 20°C for 15 days. However, it did not effectively inhibit ethylene production. The findings indicated that a concentration of 10 g/L citric acid could sustain peach quality. Comparable results were observed in research by Alali et al. (2023), where fruits were stored for 40 days at 0°C ± 5°C and RH of 85%–90%. A concentration of 3 mM citric acid proved most efficient in inhibiting disorders and sustaining peach quality.

Ascorbic acid, a well‐known water‐soluble antioxidant, aids in active oxygen detoxification and improves postharvest quality. Several studies investigated the effect of both ascorbic acid and CH on plum postharvest quality. The most effective treatment for extending shelf life and retaining quality upon storing fruits at 5°C ± 1°C and relative humidity of 90% ± 5% for 20 days was reported as 1.0% CH in combination with 40 mM ascorbic acid (Gallie 2013; Liu et al. 2014).

4.3.5. Plant Extracts

Plant extracts have received growing interest as a natural alternative to the use of synthetic chemicals to control postharvest loss of fruits and vegetables (Ncama et al. 2018). The plant extracts are vital sources of bioactive compounds obtained from various plant parts (Abdullahi et al. 2022). These non‐toxic and edible compounds in the coating enhance consumer acceptance (Bajaj et al. 2023). Combining various plant extracts that are rich sources of antioxidants and antimicrobial constituents will enhance the functional properties of edible coatings (Bajaj et al. 2023). Various research studies utilized the potential of natural plant extract in stone fruit, which are summarized in Table 3. ECFs enriched with plant extracts have been widely used in preservation of stone fruits. Rhubarb extract, having antifungal property, has been used along with sodium alginate in the research conducted by Li et al. (2019). The coating containing rhubarb extract was efficient in reducing the growth of P. expansum. The coating improved postharvest quality without affecting the organoleptic properties of the coated peaches. Similarly, in two different studies on incorporation of Anemone vitifolia extract and Ginkgo biloba leaf extracts to sodium alginate for peach coating, the authors observed antifungal activity in the extracts. Among all the coatings, n‐butanol extracts of both the plant materials with sodium alginate preserved the quality of peaches. This research provides a promising sustainable alternative for synthetic preservatives (Mou et al. 2022, 2023).

TABLE 3.

Edible coating incorporated with essential oil or plant extracts for application in stone fruit.

Fruit	Bioactive component	Polymer matrix	Active constituent	Key findings	References
Peach	Tannic acid	Chitosan and beeswax	—	–Higher antibacterial activity than Kanamycin against Escherichia coli and Bacillus subtilis –Coated samples demonstrated lower weight loss than control –An improvement in overall quality attributes was observed	Ali et al. (2024)
Sweet cherry	Polygonatum cyrtonema extract (PCE)	Soyprotein isolate and chitosan	Ferulic acid, quercetin, p‐coumaric acid, rutin	–The incorporation of PCE enhanced the mechanical, thermal, and optical properties of the film along with biodegradability after 7 days –There was an improvement in antioxidant and antibacterial activity against S. aureus and E. coli –Reduced weight loss in coated fruits, improved quality attributes, and storage life	Pan et al. (2025)
Peach	Neem leaf extract	—	Azadirachtin, gedunin, salannin, margolonone, and nimbidin	–The application of the extract suppressed changes in the fruits and maintained the quality –Application of 30% of the extract is a useful method to maintain the quality attributes –Extended the storage life for 9 days	Li et al. (2025)
Peach	Marigold flower extract	—	—	–The extract helped in delaying weight loss and decay and improved the overall quality attributes –The extract at a concentration of 30% is an eco‐friendly approach in peach postharvest treatment	Hanif et al. (2025)
Peach	Rhubarb extract	Sodium alginate	Emodin, aloe‐emodin, and rhein	–Improved overall quality attributes –Extended the shelf life of peaches without causing any negative impact on sensory attributes –Delayed the decay caused by Penicillium expansum	Li et al. (2019)
Peach	Cinnamon leaf essential oil	Pectin	Cinnamaldehyde, eugenol	–The use of the coating treatment improved the antioxidant activity, odor acceptability, and reduced bacterial growth of coated fresh‐cut peaches	Ayala‐Zavala et al. (2013)
Sweet cherry	Ginseng extract (GSE)	Guar gum (GG)	Ginsenosides, alkaloids	–GG‐GSE coatings improved quality attributes of coated fruits –Shelf life extended by 8 days	Dong and Wang (2018)
Plum	Rosehip oil (RO)	Aloe vera (AV) and Aloe arborescens (AA) gel	—	–AA + RO‐based coating improved overall quality attributes of coated plums –Both the coatings showed a twofold increase in plum storability –The best coating was found to be AA + RO for maintaining quality and bioactive composition	Martínez‐Romero et al. (2017)
Nectarine	Plant extracts of moringa, eucalyptus, and marigold (MPE)	Carboxymethylcellulose (CMC) and chitosan (CH) layer‐by‐layer coating	—	–Shelf life extended up to 25 days	Sowmyashree et al. (2021)
Apricots	Oregano essential oil (OEO)	Basil seed gum	Carvacrol	–The most effective treatment in reducing microbial load was BSG + 6% OEO –The phenolic content and antioxidant activity of the coated fruits were improved with the addition of OEO –Coating with OEO improved the overall acceptability, and it maintained the overall quality of fresh‐cut apricots	Hashemi et al. (2017)
Apricots	Basil seed mucilage (BSM)	Aloe vera gel (AVG)	—	–The combined treatment effectively increased the ascorbic acid, antioxidant activity, and TPC in apricots –There was no evidence of adverse effects from AVG and BSM on the flavor or exterior appearance of coated fruits	Nourozi and Sayyari (2020)
Peach	Ginkgo biloba L. Leaf extract	Sodium alginate	Phenylpropanoids	–The sodium alginate coating containing n‐butanol extract rich in phenylpropanoids had the lowest decay index along with the best preservation effect –This study provides a natural, safe, and sustainable alternative to chemical/synthetic preservatives	Mou et al. (2023)

Plant extracts of moringa, eucalyptus, and marigold, in combination with carboxymethyl cellulose (CMC) and CH, were used for improving nectarine quality (Sowmyashree et al. 2021). The study evaluated the performance of all the materials alone and an LBL coating of the fruits. All the coatings were successful in improving the functional quality, reducing weight loss and fruit decay, and improving firmness. In a study on apricots, the authors used basil seed mucilage (BSM) and Aloe vera gel (AVG). The fruits were coated either with AVG or BSM or with their combination. Incorporating BSM into AVG effectively suppresses ethylene production and preserves fruit firmness than their application individually. Combination of 30% AVG and 1% BSM showed a beneficial effect as an edible coating, considering the quality parameters (Nourozi and Sayyari 2020).

Thus, several plant extracts can be incorporated into biopolymer matrices to improve the properties of edible coating, which, in turn, enhances the fruit quality.

4.3.6. Essential Oil

Edible coatings can be used as a potential carrier of active components like EOs (Yousuf et al. 2021). These secondary plant metabolites with diverse properties, including antibacterial, antifungal, antiviral, and antioxidant activities, are acquired from numerous plant parts using distillation techniques (da Silva et al. 2023; Krishnan et al. 2023). This naturally occurring volatile oil is GRAS additive for use in food products (Krishnan et al. 2023; Yousuf et al. 2021). The antibacterial effect of different EOs varies against the type of bacteria; for instance, higher resistance is shown by Gram‐negative bacteria because of the presence of hydrophilic lipopolysaccharide layer in bacteria (Cao et al. 2022). The presence of aldehydes, phenols, and alcohols in EOs renders them with strong antimicrobial activity. Generally, the hydrophobic nature of EOs enhances their interaction with the bacterial cell membrane (increasing membrane permeability), which, in turn, leads to the leakage of ions and collapse of bacterial cells (El Khetabi et al. 2022). The EO concentration used in the coating must be cautiously maintained to ensure its antibacterial effect without compromising the organoleptic properties (Yadav et al. 2022) (Figure 10).

FIGURE 10.

Common action mechanism of essential oil or plant extracts on bacteria. Source: The figure is reproduced from Álvarez‐Martínez et al. (2021) with permission from Elsevier, copyright 2021 (license number: 5927121346273).

In a study by Hashemi et al. (2017), an edible film containing oregano EO (OEO) was applied to fresh‐cut apricots. The film containing 6% EO was found to be the most acceptable. EO successfully improved the functional qualities of the film. The quality of fresh‐cut apricots was maintained by inhibiting bacterial growth and preserving sensory attributes. Likewise, plums were coated with Aloe arborescens gel (AA) and AVG individually or incorporated with rosehip oil (RO). AA + RO coating was most efficient in retaining quality of fruit and bioactive compounds (Martínez‐Romero et al. 2017). In another study, Ayub et al. (2021) employed the use of multivariate techniques and analyzed the effect of various EOs and sodium alginate on peach fruit. EOs of cinnamon, basil, and thyme were used. Coating fruit using thyme and alginate demonstrated maximum shelf life (13 days).

5. Impact of Edible Coating on Quality Attributes and Physiological Responses of Stone Fruits

Numerous studies have aimed at the application of edible coating to stone fruits. It has been successfully proven that these coatings improve physiochemical attributes, quality, and shelf life.

5.1. Moisture Content

The parameters of quality, such as weight loss, firmness, and freshness, are influenced by the moisture content. Stone fruits lose moisture through transpiration, whereby epidermal cells losses their turgor, leading to reduction in fruit volume and shrivel (Fawole et al. 2020). Edible coating aids in maintaining the postharvest life through the formation of a cohesive molecular semipermeable structure that regulates gaseous exchange and moisture loss (Thakur et al. 2018). The coating based on polysaccharide has been reported to have barrier to moisture. In the study by Fawole et al. (2020), among the coatings of plum with CH, alginate, GA, and gellan gum, GA was effective in reducing the moisture loss. Similarly, plums coated with rice starch‐based edible coating containing sucrose fatty acid esters and carrageenan were also effective in reducing the moisture loss (Thakur et al. 2018).

5.2. Weight Loss and Firmness

Weight loss is caused by reduction in moisture content (Riva et al. 2020). The difference in water vapor pressure between fruit and surrounding air results in transpiration leading to weight loss. Loss of saleable weight, shriveling, loss in texture and flavor, wilting, and browning can occur in fruits due to weight loss. This, in turn, leads to acceleration of senescence (Lufu et al. 2020). The water loss rates of peaches and nectarines stored at low temperatures (2°C and 90% RH) are 0.77% and 0.74% d⁻¹ respectively, whereas plums exhibit a lower rate 0.17%–0.31% d⁻¹ at the same storage condition (Lufu et al. 2020). Edible coating reduces moisture loss by transpiration. It covers the epicarp of the fruit, leading to sealing of pores, lenticels, and stomata (Riva et al. 2020). Because of this quality, a variety of coating materials have been tried on stone fruits to reduce weight loss.

Polysaccharides used in edible coatings offers a reduction in WVP. Along with polysaccharide, the addition of glycerol as plasticizer will provide additional benefits in reducing weight loss (Valero et al. 2013). Alginate coating enhanced with oxalic and salicylic acid applied on plums resulted in lower weight loss (Bal 2019; Valero et al. 2013). Coating apricot with alginate, gellan gum, and CH revealed that gellan gum was efficient in reducing weight loss. The combination of rhubarb extract and alginate was more effective in reducing weight loss in peaches (Li et al. 2019). Alginate acts as an efficient barrier in preventing moisture loss, seals wounds, delay dehydration, and protects skin from mechanical injuries. Compared to higher concentrations, the lower concentration of all coating materials was less effective in reducing weight loss as thicker coatings were effective in reducing the loss (Morsy and Rayan 2019). The coating of sweet cherry using GA and almond gum reduced weight loss compared with the control (Mahfoudhi and Hamdi 2015).

Polysaccharide coating in combination with lipids reduces weight loss by increasing hydrophobicity. A study focused on the impact of composite coating material made from β‐d‐glucan stearic acid ester and arabinoxylan along with shellac on moisture loss of peach was determined. As observed in other studies, the loss was greater in control fruits in contrast to the coated fruits for 6 days storage (Ali, Kaur et al. 2021). Addition of BW to the HPMC film matrix improved film moisture barrier without affecting organoleptic properties (Navarro‐Tarazaga et al. 2011).

Flesh firmness is another important quality parameter for stone fruits (Scalisi and O'Connell 2021a). Structural rigidness of cell walls (leading to loss of membrane integrity) and water content of fruits affect the fruit firmness (Bae et al. 2014; Thakur et al. 2018). Enzymes such as β‐galactosidase, 1,4‐β‐d‐glucanase/glucosidase, polygalacturonase, and pectin methyl esterase degrade cell walls. This enzymatic hydrolysis causes a reduction in cell wall strength and a reduction in cell–cell adhesion that ultimately leads to loss of firmness (Fawole et al. 2020). Edible coating of fruits delays the activity of cell wall‐degrading enzymes and fruit respiration. Various research studies have shown that this technology helps maintain firmness in contrast to uncoated counterparts.

Fawole et al. (2020) reported that GA‐coated Japanese plum fruits maintained their firmness throughout the cold storage period for 20 days, but gellan gum coating failed to maintain firmness. Their work also proved that alginate and CH were effective in maintaining fruit firmness compared to the control group. Similarly, starch composite coating had a positive impact in maintaining firmness of plum. The semipermeable nature of coating helped in restricting gaseous exchange, resulting in reduction of the enzymatic activity (Thakur et al. 2018). Moreover, coating treatments using alginate, CH, and gellan gum significantly improved the firmness values of apricots. The coating lowered loss of water vapor, thus preserving the integrity of fruit (Morsy and Rayan 2019). Martínez‐Romero et al. (2017) evaluated influence of RO in AVG‐based coating. The application of this coating had a positive impact on firmness values of peach and nectarine, whereas plums and sweet cherry showed no effects. The addition of the EO improved the firmness values of peaches compared to the application of AVG alone.

5.3. Shriveling

Shrivel is an economically important physiological disorder in stone fruit (Figure 11). Alleviation of this disorder is of immense importance to improve the salability of stone fruits. A principal factor responsible for shriveling is moisture loss along with peel permeability. During moisture loss, the cell loses its turgor, leading to a reduction in fruit volume, and as the cuticle has a lower elasticity and to maintain its surface area, wrinkles appear on the fruit surface. When the fruit loses ≈5%–8% water with respect to the weight at harvest, fruit shriveling is said to occur. In the case of peaches and nectarines, this loss of water is sufficient to cause visual shriveling (Crisosto and Day 2012). Shriveling is also associated with textural losses (Riva et al. 2020). Considering this factor, it is essential to maintain lower temperatures and high relative humidity throughout all postharvest operations, including transportation and distribution (Crisosto and Day 2012).

FIGURE 11.

Shriveled and non‐shriveled plum. Source: The figure is reproduced from Fawole et al. (2020), with permission from MDPI Copyright 2020, open access.

One promising approach that decreases the instances of shrivel development in stone fruits is edible coating. The latest research by Fawole et al. (2020) observed that coating the plum fruits reduced shrivel compared to control. But CH was not effective in controlling the shrivel. The moisture barrier properties of the coatings helped in reduction of shrivel incidence in contrast to the case of CH. The authors also suggest that CH could have modified the biomechanics of cuticle, which, in turn, led to the incidence of shrivel (Fawole et al. 2020). A previous study reporting the effectiveness of edible coating in alleviating shrivel was conducted by Certel et al. (2004). The study showcased that coating cherries with sodium caseinate alone or its combination with stearic–palmitic acid blend or BW, milk protein concentrate alone, or its combination with stearic–palmitic acid blend or BW was effective in delaying and reducing both shriveling and softening of the cherries compared to uncoated counterpart. These are the only studies available regarding the effectiveness of edible coating in shrivel alleviation. But there are multiple studies available on the efficiency of edible coating on other parameters such as moisture loss, textural loss, and peel permeability.

5.4. Respiration Rate

Respiration rate is one of the aspects responsible for postharvest loss in stone fruits. Respiration rate is inversely proportional to the postharvest life of fruits (Kumar et al. 2017). During respiration, O₂ is absorbed (used in metabolic activities), and CO₂ and water are released as by‐products. In these fruits, the rate of respiration increases throughout ripening up to a point that marks the initiation of senescence, referred to as climacteric peak (Riva et al. 2020; Yadav et al. 2022).

ECFs are based on a principle similar to modified atmosphere packaging (Md Nor and Ding 2020). They modify the internal atmosphere of the coated produce by increasing CO₂ and reducing the level of O₂. It also reduces the permeability of CO₂, O₂, and water vapor. This aids in reduction of respiration rate and transpiration, along with suppressing ethylene production (Chavan et al. 2023; Maringgal et al. 2020). The reduction of respiration rate helps in delaying the synthesis and use of metabolites that lower the soluble solids concentration (Chavan et al. 2023).

Several research studies have highlighted the reduction of respiration rate by edible coating. Alginate coating of sweet cherries reduced the respiration rate. It has been inferred that barrier property of the coating aids in the reduction of selective permeability of fruit surface to CO₂ and O₂. This leads to an elevated concentration of CO₂ and a reduction in concentration of O₂. Therefore, a lower respiration rate was observed in the coated fruits (especially at higher concentrations of alginate) compared to the uncoated ones. No significant difference was seen in respiration rate of both coated and uncoated in cold storage (Díaz‐Mula et al. 2012). Similarly, plum fruits coated using carboxymethylcellulose and pectin alone or in combination helped in the reduction of respiration rate that has a positive effect on various other quality parameters and reduction in decay (Panahirad, Naghshiband‐Hassani, Bergin et al. 2020).

In another study, plums treated with CH stored were able to reduce the respiration rate. CH coating through partial blocking of the pores on plum surface suppressed and delayed the onset of respiratory peak (Kumar et al. 2017). Similarly, Liu et al. (2014) also observed that treatment of CH and ascorbic acid or a combination on plums decreased the respiration rate. The combined treatment was successful in delaying the onset of respiratory climacteric. In addition to this, another study using edible coating from rice starch reduced the rate of respiration in plums. The coating creates a modified atmosphere that aids in lowering concentration of CO₂ (Thakur et al. 2018).

In certain recent studies, composite coating developed utilizing CH incorporated with the extract of sea buckthorn leaf for application on peaches, it was observed that there was a reduction in weight loss as the CH formed a semipermeable barrier reducing gaseous exchange and lowering the respiration rate (Rather et al. 2024). Another recent study fabricated electrospinned polyvinyl alcohol (PVA) nanofiber films incorporated with cinnamon oil micelles (CEO‐micelles) to improve the sustained release of 1‐methylcyclopropene/α‐cyclodextrin (α‐CD) powder (1‐MCP/PVA films). The combination of 1‐MCP/PVA + CEO‐micelles was effective in reducing the respiration rate (Luo et al. 2024). Hence, in conclusion, lowering the respiration rate using edible coating will enhance the postharvest life of stone fruits.

5.5. Ethylene Production

In climacteric fruits, ethylene, the gaseous plant hormone, has the key role in ripening (Bapat 2010). An increase in ethylene production occurs upon an increase in respiration, which provides the energy for the methionine cycle. Therefore, O₂ serves as the critical factor for ethylene production, and its intake is reduced by the application of edible coating. Accordingly, edible coating helps in slowing down the ripening‐associated changes in stone fruits.

According to the research by Morsy and Rayan (2019), apricots coated with gellan gum, alginate, and CH helped in minimizing deterioration along with maintenance of quality and shelf life of the fruit stored at 4°C. CH and GA exhibit filmogenic properties that resulted in semipermeable film around the fruit. This property tailored the internal atmosphere by reducing O₂ or increasing CO₂ (reducing the respiration rate) level, thus suppressing ethylene production. Apricots coated with combination of Aloe vera enriched with BSM led to reduction of ethylene production (Nourozi and Sayyari 2020).

Aloe vera or A. arborescens gels coating of peach and plums stored at 20°C for 6 days exhibited 70% and 50% inhibition on ethylene production and respiration rate, respectively. The natural waxy skin of plum enabled better adhesion of coating compared to the pubescent and sinuous epidermis of peach (Guillén et al. 2013). Similarly, rice starch‐based coating of plum fruit also reduced the ethylene production compared to the uncoated fruits. The uncoated fruits demonstrated a significant surge in ethylene production during the first week (Thakur et al. 2018). The coating of sweet cherries using GA and almond gum; ethylene production decreased with a reduction in respiration rate (Mahfoudhi and Hamdi 2015). The hygroscopic property of these coatings forms a barrier in gaseous exchange between the fruit surface and surroundings, thus reducing respiration rate and ethylene production (Mahfoudhi and Hamdi 2015).

5.6. Chilling Injury

A physiological disorder occurring in stone fruits upon storage at low temperature is known as CI. This deteriorates the flavor and texture before the appearance of visual symptoms. Substantial economic loss of stone fruits occurs due to CI during storage and transportation (Palumbo et al. 2024). The details on this postharvest issue have been mentioned in Section 3.5 CI. Edible coating of stone fruits helps in minimizing the CI symptoms.

Some of the latest research addressing the impact of edible coating on CI is discussed. Peaches coated with gelatin films containing different concentrations of trans‐cinnamic acid were explored. The fruits coated were observed to be free from CI and shriveling and pathogenic soft rots (Sultan et al. 2024). In plums, the increase in the ripening rate increases the sensitivity of the fruit to CI. HPMC and GA composite edible coating of plums incorporated with geraniol helped in reduction of CI compared to uncoated fruits. In the uncoated fruits, over 50% of the flesh was affected by flesh bleeding after 8 weeks of storage. Coating with HPMC was more effective than GA. Addition of geraniol did not show any significant difference in CI (Asgarian et al. 2023). The information on mitigation of CI by edible coating is scarce.

CI symptoms appear immediately and intensely in stone fruits stored between 2°C and 7°C, in comparison to fruit stored at a temperature less than or equal to 0°C, but beyond the freezing point. During shipping, fruits must be cooled and stored near or below 0°C. If the CI susceptible fruits are held 5°C during transportation, it will reduce the postharvest life (Crisosto and Day 2012). Therefore, the maintenance of appropriate temperature during the handling is a crucial factor in minimizing CI.

5.7. Pigments and Color

Appearance, color, and firmness of the stone fruits are some key factors consumers consider for their quality and acceptability (Afonso et al. 2023; Hu et al. 2022). For instance, color changes during ripening and senescence alter the quality of plum fruits (More et al. 2022). Edible coating helps in the reduction of drastic color changes by reducing respiration rate that limits the oxygen availability for enzymatic action.

Research on coating based on taro starch and casein composite added with micellar pomegranate peel extract (MPPE) for plums indicated that fruit peel changed from red to dark red color with increase in storage days, but there was less change in the coated fruits. Cold storage helped in reducing the darkening. The coating developed successfully delayed ripening during the cold storage and reduced respiration, and this in turn inhibited the synthesis of anthocyanin (More et al. 2022). Similarly, sweet cherry treated with CH was effective in maintaining the color values compared to control. This study proved that 0.5% w/v CH coating successfully maintained the color and acceptability of sweet cherry (Hu et al. 2022).

5.8. Total Soluble Solids

The edible quality of fruits is attributed to their sweetness, the fundamental component responsible for being sugars. The sweetness of stone fruits is a major factor influencing consumer acceptance. It is represented as TSS and is measured from the extracted juice using a refractometer. The TSS is expressed as °Brix (1°Brix is equivalent to 1 g sucrose/100 g solution) (Scalisi and O'Connell 2021b). TSS of the stone fruits increases after harvesting due to the hydrolysis of complex carbohydrates like starch into their monomeric unit, simple sugars. This also occurs due to moisture loss during storage.

Several studies have shown that edible coating can minimize the rate of increase of TSS. Research by Bal (2019) reported that edible coating of alginate enriched with salicylic and oxalic acid considerably prolonged the rise of TSS in coated plums in contrast to uncoated counterparts. It is inferred that coating acted as a barrier to gases, lowering the respiration rate along with the reduction in moisture loss, further resulting in lowering TSS. But the study by Thakur et al. (2018) did not observe significant difference in the TSS content in both coated and control, and this indicates that the developed composite coating did not have any adverse effect on the fruit (Figure 12). However, coating apricots with alginate, CH, or gellan gum significantly reduced the rate of increase of TSS in contrast to the control fruits. The filmogenic property of the coating matrix created a semipermeable layer around the fruit, modifying gas concentrations and suppressing the rate of respiration and production of ethylene (Morsy and Rayan 2019).

FIGURE 12.

Development of edible coating based on rice starch to improve the self‐life of plum. These coatings delayed gas transmission and improved the quality of plum. Source: The figure is reproduced from Thakur et al. (2018) with permission from Elsevier, copyright 2018 (license number: 5927130363120).

The composite edible coating of sea buckthorn leaf extract and CH significantly increased the shelf life of peaches. TSS increase was highest in control (16.2%) compared to the coated fruits. The coated fruits exhibited a minimal increase in TSS (Rather et al. 2024). Similarly, composite coating of 30% Aloe vera and 1.5% CH demonstrated lower TSS values than control (Aboryia et al. 2022). This signifies the effectiveness of the composite coating in reducing the increase of TSS. Studies using a combination of 1‐methylcyclopropene and CMC on peaches also observed comparable results (Sortino et al. 2020). Edible coating of sweet cherry with CH or in combination with melatonin significantly reduced the rise in TSS. It was observed that control (17.6%) had the highest TSS at the end of storage study compared to CH (16.5%) and CH + melatonin (16.6%). This effect is due to the retardation of the catabolic processes and respiration rate (Bal 2024).

5.9. pH and Titratable Acidity

The two interrelated concepts that deal with acidity in food are pH and titratable acidity, or total acidity (TA) (Tyl and Sadler 2017). TA represents the total acid concentration in food and is measured by the titration of intrinsic acid with standard base. pH, also called active acidity (negative log [base 10] of the hydrogen ion concentration), is measured with a pH meter; the millivolt is converted to pH with the use of the Nernst equation (Tyl and Sadler 2017). TA is a better predictor of acid's impact on flavor than pH (Tyl and Sadler 2017). But the ability of a microorganism to grow in a specific food is more dependent on the concentration of free hydronium ions (H₃O⁺) than on titratable acidity that is measured by pH. Therefore, both factors determine the quality of food. TA and pH also play a key role in the organoleptic property of stone fruits (Riva et al. 2020).

As the fruit matures, acid gets converted to sugars (increase in sweetness) along with its consumption by different enzymatic activities, thus causing an increase in pH, which leads to a decrease in sourness of fruit (Morsy and Rayan 2019). Edible coating creates a gas and moisture barrier layer, thus causing changes in pH. In the study by Nourozi and Sayyari (2020), they observed that coating apricots with BSM was efficient in retaining the pH and controlled its variation compared to uncoated fruits. Research by Morsy and Rayan (2019) observed that coating apricots with alginate, CH, and gellan gum increased the pH of all the samples, but the control showed the highest increase. pH in control increased from 4.27 to 4.49. Samples coated with CH represented the highest increase in pH (4.45); thereby, the sourness of the fruit was reduced.

Generally, the TA decreases during postharvest storage, but TA losses have also been minimized by the application of edible coating. The main organic acid in stone fruits used is malic acid, which is utilized for respiration, metabolic activities, and ripening (Ali, Akbar Anjum et al. 2021; Riva et al. 2020). Coating apricot with GA, the authors observed that TA decreased during the storage for 8 days. But TA was higher (51%) in the coated fruits compared to control (Ali, Akbar Anjum et al. 2021). The research by Nourozi and Sayyari (2020) observed that coating apricots with BSM and its combination with AVG increased the TA levels from Day 14 to 29. Plums coated with alginate maintained highest TA after the cold storage in comparison with control and fruits with GA, gellan gum, and CH coating (Fawole et al. 2020). The CH–alginate LBL edible coating of plums stored demonstrated a decrease in TA upon increase in storage time. The TA of double layer coated samples was 1.5 times control. The coating helped reduce the loss of TA by plums (Li et al. 2022). During the edible coating of sweet cherry with carboxymethyl CH–gelatin in combination with CaCl₂ or ascorbic acid (AA), the researchers observed that TA reduced during storage in all the samples (Zhang et al. 2021).

5.10. Phytochemical and Antioxidant Activity

Phytochemicals are the secondary metabolites present in fruits that contribute to their nutritional and organoleptic properties. Stone fruits are highly packed with phytochemicals (Lara, Bonghi et al. 2020). These compounds contribute to strong antioxidant activity in stone fruits. During ripening and maturation, the phenol content and antioxidant activity of both the peel and flesh increase (four to five times higher in peel than flesh) (Riva et al. 2020). However, as the fruit reaches senescence (due to cell breakdown and activities of peroxidase and polyphenol oxidase), the content of these phytochemicals is found to be reduced. Edible coating has been explored to provide a reduction in the loss of phenolic compounds and maintain high antioxidant activity in stone fruits (Riva et al. 2020).

Thakur et al. (2018) observed that rice starch coating of plum fruit improved its retention of DPPH scavenging activity in contrast to the control fruits on 21st day of storage study. Additionally, the authors observed that the flavonoid content influenced the antioxidant activity. During edible coating of nectarines with CMC and GA, the researchers noted that fruits coated with 1% CMC had the highest activity, whereas uncoated fruits had the lowest value. The coating helped in retention of the activity (Jayarajan and Sharma 2020). From these studies, it can be concluded that the edible coating helps in lowering respiration rate, thus resulting in retention of phenolic compounds.

Carotenoids and ascorbic acid also possess antioxidant activity. Apart from its antioxidant property, ascorbic acid also has nutritional benefits. It helps in removal of reactive oxygen species (ROS) (Li et al. 2022). In peaches coated with sea buckthorn leaf extract and CH (Rather et al. 2024), plums coated with sodium alginate, CH, and its LBL addition (Li et al. 2022), apricots coated with CMC and GA (Jayarajan and Sharma 2020), and sweet cherries coated with CH, mucilage, and levan (Mujtaba et al. 2023), it was observed that the coated fruits maintained the ascorbic acid content in contrast with control fruits. The authors suggest that coating reduces the oxidation of ascorbic acid by limiting O₂ availability, which helps in maximizing the ascorbic acid content in the coated fruits compared to control. This restriction of oxygen not only prevents oxidative breakdown but also slows down fruit degradation and delays senescence.

Rather et al. (2024) observed that upon coating peaches with CH incorporated with sea buckthorn leaf extract, and there was a drop in the levels of total phenolic compounds (TPC) in the case of all samples. But the coating of CH incorporated with sea buckthorn leaf extract demonstrated maximum retention of the compounds. In a study on coating sweet cherry with xanthan, guar, and wild sage seed gum, it was observed that the TPCs of coated cherries were higher than the uncoated samples (Salehi et al. 2023). In another study on sweet cherries, the influence of the coating on TPC content was analyzed. The fruits were coated using alginate (3%) and CH (1%) incorporated with active ingredient olive leaves extract (OLE). It was observed that coated fruits had a lower rate of reduction of TPC compared to control fruits. About 90.98% (CH) and 90.79% (alginate) retention of TPC were observed in the samples enriched with OLE, which were comparatively lower without the extract. This was attributed to the lower permeability of O₂, which, in turn, caused a decrease of enzymatic activity (polyphenol oxidase and peroxidase) (Zam 2019).

LBL coating of alginate and CH in plums stored protected the fruits from depletion of TPC levels. TPC content of all samples was observed to increase gradually and then decrease. The breakdown of cell structure associated with aging may be the cause of the decrease in TPC at a later stage of storage. Specifically, over the course of storage, the TPC of the LBL CH–alginate‐coated samples was kept at a higher level than that of the other samples (Li et al. 2022). Similarly, the edible coatings of nectarines with carboxymethylcellulose and GA, stored under low‐temperature storage conditions, significantly influenced the TPC (Jayarajan and Sharma 2020).

In conclusion, the protective nature of the edible film or coating on the fruit surface acts as a barrier property against the exchange of CO₂ and O₂; lowers the oxidation of the phenolic compounds and respiration rate. Moreover, it is noteworthy that fruit varieties and coating materials affect how protective an edible coating is in preserving or maintaining the TPC of fruits.

5.11. Microbial Decay

Fruits are infected with pathogens during postharvest handling and storage, which leads to fruit deterioration. Consumers prefer treatments that minimize fruit deterioration (Sowmyashree et al. 2021). Common microbes for stone fruit spoilage include fungi, such as P. expansum, R. stolonifer, M. fructicola, and B. cinerea, which are usually responsible for the microbial degradation of stone fruit, resulting in green/blue mold rot, soft rot, brown rot, and grey mold rot, respectively. Not only fungi but also bacteria are responsible for fruit degradation such as Escherichia coli O157:H7 and Salmonella typhimurium (Riva et al. 2020) (Figure 13).

FIGURE 13.

Plums inoculated with different cultures: (A and B) Rhizopus stolonifer, (C–E): Monilinia fructicola, where (A) and (C) are control fruits, (B) is coated with 4.5% wax, and (D) and (E) are coated with 9% wax. Source: The figure is reproduced from Gonçalves et al. (2010) with permission from Elsevier, copyright 2010 (license number: 5927130597975).

Navarro et al. (2011) demonstrated that coating of AVG on nectarines reduced the decay from Penicillium digitatum, B. cinerea, and R. stolonifer, although the addition of thymol to AVG did not improve its effectiveness. Sowmyashree et al. (2021) reported an ≈81% decay reduction in nectarines using an LBL coating composed of CH and CMC, alone or incorporated with mixed plant extract (MPE). Mendes‐Oliveira et al. (2022) observed that nisin addition to zein‐based coating successfully prevented the growth of Listeria monocytogenes on nectarines. CH‐coated cherries also demonstrated a significant reduction in bacterial load. The findings of this investigation show that CH has antibacterial properties. This is because negatively charged carboxyl groups on the bacterial cell membrane attach to amino groups on the CH, which are positively charged, altering charge distribution on cell surface and impairing membrane stability.

Alginate‐based coatings with rhubarb improved the microbiological quality of the peaches, extending the shelf life and delaying the onset until fourth day of storage. The decay index of treated peaches was 65% lower than the control. Rhubarb extracts effectively controlled the growth of P. expansum. The antifungal effect is primarily due to rhein, aloe‐emodin, and emodin, with emodin being the most potent agent (Li et al. 2019). Numerous studies show that coatings act as barriers to the entry of pathogens responsible for fruit decay. Furthermore, the addition of EO, plant extracts, or any bioactive agent results in restriction of microbial growth.

Ali et al. (2024) developed a coating solution for peaches comprising BW, CH, and tannic acid. The antibacterial efficacy of the coating matrix was higher than that of the standard antibiotic kanamycin. It inhibited the growth of Bacillus subtilis and E. coli. The coating matrices were applied on the fruit by cotton swabs. It is well known about the antibacterial effect of CH; similarly, tannic acid causes microbial cell death by the following methods: (i) inhibition of the activity of microbial extracellular enzymes, (ii) cutting the microbe off from essential nutrients, and (iii) hindering oxidative phosphorylation. BW is reported to have antibacterial effects against Gram‐negative and ‐positive bacteria and fungi. This coating matrix was effective in delaying the microbial decay and extending the shelf life. The authors Bansal et al. (2024) observed an increase in antibacterial effect on incorporating lemongrass oil into buckwheat starch and xanthan gum matrix. It disrupted the phospholipid membrane of the bacteria; the permeability of bacterial cell increased, leading to an imbalance and eventually death, increasing the shelf life of plums. Thus, the treatment with ECFs has a positive effect on shelf life by reducing microbial growth.

5.12. Organoleptic Properties

The changes in quality attributes in the fruits and vegetables can be best demonstrated by sensory scores. Commercial value of stone fruit such as peaches depends on its appearance, juiciness, texture, aroma, flavor, and sweetness during the storage period (Li et al. 2019). The acceptability of any postharvest treatment is determined by how well‐accepted the treated fruits are. In this circumstance, if the acceptance score falls below 5.0, then those fruits are deemed unfit for commercialization and human consumption (Sowmyashree et al. 2021).

In the plums coated with lac based, Semperfresh and Niprofresh edible coatings, the organoleptic properties were analyzed. As per the results, coated plums had more consumer acceptance than uncoated counterparts on the 35th day of storage. There was no negative impact of coating on consumer acceptance. Higher sensory scores for appearance were attained by plums coated with Semperfresh and lac‐based coatings, which gave the fruits a glossy look. Softening in the control fruits has caused a reduction in acceptance (Kumar et al. 2018). Similarly, the edible coating of nectarines with CMC, CH alone, or incorporated with MPE improved the overall acceptability of the coated fruits compared to control. The highest acceptability for CMC–CH–MPE‐coated fruits in contrast to control (Sowmyashree et al. 2021). The research by Li et al. (2019) also observed the same results. Coating peaches with rhubarb and sodium alginate improved the overall acceptability of the coated fruits in comparison to control. The appearance of the coated fruits was maintained compared to alginate alone and control. During the fourth and seventh days of storage, the aroma, sweetness, and juiciness of the control peaches displayed considerably lower scores (p < 0.05) than the alginate‐coated peaches. When compared to peaches coated with alginate, the texture, and flavor characteristics of the control samples clearly declined with storage. After 4 days of storage, a superior trend was seen for all sensory qualities in the rhubarb–alginate‐coated samples compared to the 1.0% alginate‐coated samples.

Therefore, edible coating has the potential to improve the sensory characteristics of stone fruits, enhancing their marketability and consumer acceptance.

6. Nanotechnology in Edible Coating

Fruit postharvest management can be innovatively addressed with nanotechnology, which involves the manipulation of materials at the nanoscale. The term “nanoparticles” (NPs) refers to spherical substrates that have sizes ranging from 1 to 100 nm in the laboratory and 1–1000 nm in industrial settings. NPs are a new aspect of nanotechnology that provide improved and unique characteristics over their bigger counterparts, including nanosize, unique morphological features and surface area‐to‐volume ratio, and. Being nanosize, the particles can easily fit into the epidermal pores of fruit; it can also control mass transfer, increase coating wettability, improve biocompatibility, guarantee uniform distribution, suppress activity of microbes, and lower the cost of postharvest management (Olunusi et al. 2024). Furthermore, this technology helps in observation of fruit freshness in real time, preserving optimal quality during storage and transportation, in addition to retaining its freshness and protecting pericarp of fruit.

6.1. Nanoparticles

Silver (Ag) (Bizymis et al. 2023; Shahat et al. 2020), titanium dioxide (TiO₂) (Khan et al. 2023), zinc oxide (ZnO) (Batool et al. 2022; Ouzakar et al. 2023), and Zn‐doped TiO₂ NPs (Mann and Sooch 2023) are the primary NPs utilized in the edible coating of stone fruits. In addition to the metal origin foundation, food‐grade polysaccharide biopolymers such as CH (Algarni et al. 2022; Mahmoudi, Razavi, Rabiei, Gohari et al. 2022; Mahmoudi, Razavi, Rabiei, Palou, et al. 2022) can also be used to create NPs. In addition to serving as an encapsulating carrier for the delivery of bioactive compounds, NPs enhance the coating's mechanical, physical, and barrier qualities. Table 4 tabulates all the studies on nanotechnological approach.

TABLE 4.

Potential applications of nano‐based edible material for enhancing postharvest quality of stone fruits.

Polymer matrix	Type of stone fruit	Nanoparticles/active ingredients	Type of formulations	Mode of synthesis	Key findings	References
a) Chitosan (CH), cellulose nanocrystals (CNC), and beta‐cyclodextrin (CD) (CH‐CNC‐CD) b) Hydroxypropyl methylcellulose (HPMC), cellulose nanocrystals (CNC), and beta‐cyclodextrin (CD) (HPMC‐CNC‐CD)	Cherry	Silver nanoparticle (AgNP)	Nanocomposite	High speed homogenization and ultrasonication	–The incorporation of 10% v/v AgNP led to the reduction of 99.99% microbial growth in both films –It was found to be effective against Escherichia coli –Addition of AgNP leads to a reduction in barrier property –It was effective on coated cherries	Bizymis et al. (2023)
Maize starch	Apricots	Silver nanoparticle (AgNP)	Nanoparticle	High speed homogenization	–Improved the shelf life of apricots for 8 days, stored at 25°C ± 3°C, or for 24 days at 6°C ± 2°C	Shahat et al. (2020)
—	Sweet Cherry	Zinc oxide nanoparticle (ZnONPs)	Nanoparticle	Biosynthesis using Phaeodactylum tricornutum	–The coated fruits exhibited reduced decay –Inhibited growth of Mucor rot in sweet cherry –Demonstrated inhibitory effect against E. coli, Staphylococcus aureus, and Candida albicans	Ouzakar et al. (2023)
—	Plum	Glycine betaine‐coated chitosan nanoparticle (CTS‐GB‐NPs)	Nanoparticle	—	–Helped reduce CI in fruits –Improved quality of coated fruits –Preserves nutritional quality and shelf life –Increase storage life up to 40 days at 1°C	Mahmoudi et al. (2022)
—	Plum	Chitosan‐arginine NPs (CTS‐Arg NPs)	Nanoparticle	—	–Improved the physiochemical quality attributes of coated fruits –Reduced CI	Mahmoudi, Razavi, Rabiei, Palou, et al. (2022)
—	Apricot	Chitosan NPs (CHNPs)	Nanoparticle	Ionic gelation method	–Improved quality attributes and shelf life up to 9 and 30 days in room temperature and cold storage, respectively	Algarni et al. (2022)
Chitosan	Sweet cherry	Natamycin nanoparticles	Nanoparticle	Anti‐solvent method	–Incorporation of the NPs improves the mechanical properties and reduced the WVP –Improved the quality, prevented decay –Up to 35 days of storage life	Shao et al. (2025)
Sodium alginate	Peach	TiO2 nanoparticles	Nanoparticle and nanoemulsion coating	–NPs: Green synthesis using Citrus limetta peel extract –Nanoemulsion: homogenization and probe sonication	–Improved quality parameters in coated fruits –Reduced microbial growth –Extended peach shelf life at room temperature conditions	Khan et al. (2023)
Chitosan	Plum	Ginger essential oil	Nanoemulsion	Homogenization and ultrasonication	–Incorporation of nanoemulsion significantly improved the quality parameters –It is effective in extending the shelf life up to 35 days	Showkat et al. (2025)
Chitosan	Apricot	Pomegranate peel extract	Nanoemulsion	Homogenization and ultrasonication	–Reduction in decay, improved quality attributes –Reduced microbial load –Extends the shelf life of apricots	Gull et al. (2021)
Chitosan	Apricots	Oregano essential oil	Nanoemulsion	Homogenization and sonication	–Enhanced antifungal activity against Alternaria alternata –The zebrafish model confirmed the safety of the films	Guo et al. (2022)
Carnauba wax	Plum	Lemongrass oil	Nanoemulsion	—	–Inhibited growth of E. coli and Salmonella typhimurium –Improved the quality attributes without affecting the sensory characteristics –Enhance storage life of fruits	Kim et al. (2013)

Recently, Bizymis et al. (2023) worked on improving the antibacterial property of edible films for cherry preservation. The addition of AgNPs resulted in excellent antimicrobial activity of both the compositions. About 96% reduction in Gram‐negative bacteria (E. coli) was observed. But this addition reduced the thickness and barrier properties, while improving the transparency. The color of the cherries was significantly improved, along with a reduction in the microbial load being observed. In another research, the physicochemical and antibacterial properties of ZnONPs created from Phaeodactylum tricornutum cultures inhibited the growth of Mucor hiemalis’ mycelia, which is the cause of Mucor rot in sweet cherry. According to a study, the fruits coated with ZnONPs had an improvement in antioxidant activity and flavonoid content at the end of storage. All these facts point to ZnONPs‐based coating (green coating) as safest and most efficient method for keeping commercial fruits fresh for extended periods of time (Ouzakar et al. 2023). Similarly, AgNPs coated apricots demonstrated improved shelf life. The fruits may be stored for 24 days at 6°C and 8 days at 25°C without losing quality (Shahat et al. 2020).

The application of glycine betaine‐coated CH NPs (CTS‐GB NPs) on plum fruits helped reduce CI and caused decreased electrolyte leakage, malondialdehyde (MDA), and hydrogen peroxide (H₂O₂) concentration. Considering the industrial/large‐scale application, it can mitigate CI and improve nutritional quality and shelf life of plums (Mahmoudi, Razavi, Rabiei, Gohari et al. 2022). Similarly, in another study, the same authors studied the effect of coating arginine (Arg) and CH (CTS) on plum. In contrast to uncoated plum, weight loss was delayed, and the coating maintained the ascorbic acid content and firmness of fruits. Overall, it improved the physiochemical properties of plums (Mahmoudi, Razavi, Rabiei, Palou, et al. 2022). In another study, the authors aimed to ascertain how coatings, including CH and NPs (CHNPs), as thin films affect the quality and shelf life of apricots. Ultimately, it was discovered that CHNP coatings enhanced the qualitative characteristics, and they improved their shelf life for up to 9 days at room temperature and 30 days in cold storage, (Algarni et al. 2022). Research by Khan et al. (2023) observed that coating peaches with sodium alginate enriched with TiO₂ NPs lowered the activity of polyphenol oxidase and reduced the microbial load. It, in addition, maintained the natural color of the fruit. The NPs helped in maintaining the cell wall integrity and slowed down softening of fruit by lowering respiration rate; that's enhancing the shelf life. From this research, it was concluded that TiO₂ NPs were successful in improving the storage life of peaches kept in ambient condition.

6.2. Nanoemulsions

Emulsions are the dispersion of two immiscible liquids. The immiscible liquids form the two components of emulsion (dispersed phase and dispersion medium). Basically, water and oil form an emulsion. An oil‐in‐water (O/W) emulsion is composed of oil droplets dispersed in aqueous phase (used for delivery of hydrophobic substances), and vice versa for the water‐in‐oil (W/O) (used for delivery of hydrophilic compounds). Coarse emulsion (conventional/macroemulsion), microemulsions, and nanoemulsions are the categories of emulsion based on the size and stability of droplets (Aswathanarayan and Vittal 2019).

Nanoemulsions have a mean droplet diameter of less than 500 nm, as a result, they have a clear or hazy appearance (Mushtaq et al. 2023; Singh et al. 2017). Encapsulation of bioactives, such as EO, antioxidants, and antimicrobials, is efficiently done by nanoemulsion. This improves bioactivity, efficacy, and controlled release of these compounds. This can lower the concentration of EOs required to produce the same effect (Shen et al. 2023; Yadav et al. 2022). Several research studies have demonstrated the beneficial effects of nanoemulsified EO in an edible polymeric matrix on enhancing the storage life of stone fruits along with reducing strong aroma of EO.

Recently, Khan et al. (2023) showed that peach fruit can have its quality preserved and its shelf life extended for up to 7 days at room temperature when coated with nanoemulsion. The influence of nanochitosan coating enriched with pomegranate peel extract (PPE) on apricots was studied by Gull et al. (2021). A significant reduction in the decay percentage and weight loss was observed. The antibacterial effect of PPE inhibited the overall psychrophilic bacteria, yeast, and mold growth. Thus, the coating maintained apricot quality. The research by Guo et al. (2022) reported that nanoemulsion of OEO incorporated into CH‐based edible coating was successful in inhibiting the growth of Alternaria alternata, causing black spot rot in apricots. A reduction in particle size by sonication treatment improved the antifungal activity and the emulsion stability.

In an earlier study, Kim et al. (2013) developed nanoemulsion coating containing lemongrass oil (LO) for preserving plums’ shelf life. Edible coating was developed by combining nanoemulsion with carnauba wax. The coatings inhibited the development of E. coli O57:H7 and S. typhimurium. The flavor as well as the glossiness of plum were unaffected by the application of coating. These findings indicate that applying an LO‐containing nanoemulsion coating to plums is a successful postharvest technique that can extend their shelf life, maintain physiochemical attributes, and improve microbiological safety.

7. Safety and Regulatory Aspects

The coatings for stone fruit or any category of fruits and vegetables must only be made with materials that are recognized as GRAS. It is also important to strictly adhere to safety standards because not all GRAS compounds are thought to be safe for consumers. The edible coatings or films must satisfy requirements that include being non‐toxic, easily accessible, biodegradable, and eco‐friendly. These coatings need to maintain the fruits’ nutritional value and not have a negative effect on the fruit's surface while being stored (Olunusi et al. 2024).

Commercial use of edible coating is contingent upon getting certification and approval from pertinent regulatory organizations, such as the Food and Drug Administration (FDA) and the EU. Transparency is essential for all ingredients used in coating formulations, especially for allergic reactions (proteins). The application of protein‐based materials is limited due to the risk of allergens. Ethical or religious beliefs regarding animal‐based protein sources are also a limitation to this (Yadav et al. 2022). Edible coatings that are applied to fresh fruit fall under one of four regulatory categories: food coating ingredients, food additives, food contact materials, and food packaging materials. Ensuring the safe use of edible coating requires strict compliance with laws, including the US FDA, Plastics Directive EU No. 10/2011 (PIM), Good Manufacturing Practice (GMP) Regulation (EC) No. 2023/2006, Swiss Ordinance (SR 817.023.21), and framework regulation EU No. 1935/2004 (Olunusi et al. 2024).

A crucial part of coating is the addition of NPs, which act as antioxidant and antibacterial agents. The packaging of food using nanomaterials is carefully assessed, resulting in the need for international surveillance. EU Regulation 10/2011 specifies the appropriate NPs for plastic food contact materials, highlighting the importance of adhering to set food industry standards and safe usage. To verify the edible nature of the coating, it is also crucial to perform comprehensive characterizations and analytical testing in accordance with regulatory requirements and literature guidelines (Olunusi et al. 2024). Composition, morphological, rheological, physical, barrier characteristics, thermal stability, optical, antioxidant capacity, mechanical, structural, and antibacterial activity are a few of the variables that are tested (Cloete et al. 2023).

Although commercialization of fruit ECFs is still in developmental stage, edible coatings for specific food products have already been developed and commercialized, and large‐scale implementations of non‐edible intelligent fruit coatings, like packaging systems, freshness sensors, and indicators, have been made. Furthermore, thorough toxicity studies carried out over a range of periods are essential for ensuring the safety of the environment and people. It is important to consider several factors that affect the toxicity of NPs, such as composition, form, surface charge, scale, and stability. The primary reason for concern is that the fruit product may contain NPs that have migrated in. This has prompted research to be done to create regulatory frameworks and receive consumer acceptance (Cloete et al. 2023).

8. Challenges, Economic Benefits, and Future Aspects

8.1. Technical and Economic Challenges

The preservation of physiological and physiochemical qualities, prolonging shelf life, and lowering postharvest losses are how edible coatings provide economic benefits. Numerous studies have shown that applying edible coatings to stone fruits can significantly increase their shelf life when compared to samples without any coating. Furthermore, because of its edible nature and biodegradability, it provides an alternative to packaging made of plastic and leaves no environmental residue. Additionally, the edible coatings may serve as a vehicle for bioactive substances like antioxidants to enhance the nutritional benefits of fresh produce (Yadav et al. 2022).

Few challenges associated with edible coating are that certain materials used for production can cause hypersensitive responses in consumers (proteins e.g.). One solution to this problem is that, be it a minute quantity, the material should be properly labeled for the consumers to be aware of its composition. So, it is desired to label for any allergenicity caused by the respective material used. Another key factor to be considered during the development of the coating is its toxicity (Matloob et al. 2023). The material should only be used if it is GRAS, and it should be used within the permissible limits. The acceptable daily intake (ADI) must be taken into consideration. But it will be difficult to measure the intake of the materials in edible coating, as several parameters influences it, like number of fruits consumed, if skin is consumed or not, and coating thickness (Gammage and Marangoni 2025).

Another challenge in edible coating is associated with the growing interest in the vegan diet among the consumers. The selection of materials for coating must also favor the dietary restrictions of vegan individuals. Considering this aspect, the coating cannot be made from chitin, gelatin, wax, and CH (from animal sources). Therefore, proteins from vegetable sources are an alternative. These sources offer a wide variety, sustainable, and nutritionally rich active ingredients. Plant‐based proteins can be sourced from cereals, legumes, quinoa, amaranth, oilseeds, mushrooms, chia seeds, nuts, and green leaves. Besides proteins, carbohydrates, such as alginate, glucan, and carrageenan, obtained from algae; pectin, cellulose, and starch from plants; and CH, chitin from fungal sources (excluding crustaceans like shrimps and crabs), can be utilized to improve the shelf life of produce while satisfying dietary restrictions of vegan consumers. Thus, they find a variety of applications (Ribeiro et al. 2024).

The cost of some ingredients required to produce coating or requirement of novel equipment or processing techniques may create an economic hurdle for commercialization. To minimize the cost of production, various research studies have focused on using by‐products of industries to develop edible coatings for stone fruits. Edible films and coatings created from mango by‐products have been implemented to enhance the shelf life of peaches (Torres‐León et al. 2018) (Figure 14); the incorporation of PPE can reduce the cost of the coating or film (Gull et al. 2021; More et al. 2022) and promotes a sustainable and circular economic approach.

FIGURE 14.

(i) Edible films developed from mango by‐products: (A) film from peel; (B) film from peel with antioxidants of mango seed; (ii) peaches coated: (A) control; (B) peel‐based coating with antioxidants; (C) peel‐based coating. Source: The figures are reproduced from Torres‐León et al. (2018), with permission from Elsevier, copyright 2018 (license number: 5927130977139).

Acceptance of edible coating requires generating awareness among people related to this postharvest preservation method. In a study, the team led by Bucher analyzed the consumer acceptance of edible coated apples among consumers. The fear of consumers about the food produced by novel technologies is known as Food Technology Neophobia (or FTN), and this FTN level indicates the inhibition in people to accept food products developed by novel methods. According to this method, a high FTN means the people have a lower liking of novel foods and vice versa. But the study revealed that if proper information and awareness among the consumers about the relevant technology and proper labeling of the coating and its ingredients will lead to an increase in consumer acceptance and reduce the risk perception (Bucher et al. 2023). Therefore, research in this field must consider gaining consumer trust by providing the essential information for its successful implementation.

8.2. Future Directions and Innovations

Even though the area of edible coating is of growing interest, the commercial application of the edible coating needs to be strengthened. From an industrial point of view, the research could focus on scaling up and commercialization of the edible coating of the stone fruits. The challenges that might be experienced include protection of fruits from damage during the application of the coating and prevention of moisture loss during the process of drying post application. Spraying or dipping process is an easier method when considering industrial processing. When the fruits are passing through the conveyor before final packaging, the edible coating matrix could be applied either by spraying or dipping and provide time for drying it out. This necessitates the need for a better feasible method for uniform distribution of coating material and development of efficient drying systems on a large scale, minimizing product damage during processing.

Future work must focus on development of more sustainable and economical approaches to increase storage life of stone fruits. Selection of ideal coating material, storage conditions, and coating method needs to be optimized to get optimum results. The requirement for a high moisture barrier property in coating material needs to be optimized along with providing good adhesion on the fruit surface by optimizing the contact angle based on the fruit surface as mentioned in Section 4.1. By‐product utilization could serve as a better source and help minimize the cost; this can lead to a more sustainable approach, especially when using bioactive components. To increase awareness among consumers, proper information on edible coating and its purpose needs to be provided to consumers along with proper labeling. This will help reduce the risk of acceptance. Forthcoming research could also focus on coupling non‐thermal methods to edible coating to provide a hurdle environment, which could increase quality, safety, and shelf life.

To assess the impact of different coating materials and their concentration on the physiochemical, phytochemical, and sensory attributes of coated fruits, various statistical analyses can be employed. The relationship among different quality characteristics can be identified through cluster analysis (CA) (Ayub et al. 2021). Both principal component analysis (PCA) and CA are key multivariate tools for evaluating the physical and chemical attributes of food (Moldao‐Martins et al. 2003). These techniques can be applied in future research on edible coating to evaluate the influence of each parameter on fruit quality. To evaluate the environmental and economic risks of a novel coating material before commercialization, techno‐economic analysis (TEA) and life cycle assessment (LCA) could be carried out. In a latest study, Rajendran et al. (2024) analyzed this aspect of the bionanocomposite developed from cellulose nanocrystals and soy protein isolate for the coating of avocado. The estimated cost and carbon footprint of the coating matrix were found to be $0.59/kg and 0.33 kg CO₂ eq/kg, respectively (cradle to gate LCA). Even though edible coating materials do not generate waste, LCA and TEA studies are recommended to improve the environmental impact of these food packaging materials to achieve the SDGs by 2030.

9. Conclusion

Stone fruits are climacteric and highly perishable produces. It undergoes rapid deterioration after harvesting. Application of edible coating is a growing area of interest to improve the shelf life of stone fruits. Various edible coatings alone or incorporated with bioactive agents have been found to improve the organoleptic properties and reduce the postharvest losses in these fruits to a significant degree compared to the uncoated counterparts. The barrier property provided by the coating helps reduce respiration rate, weight loss, and activity of ethylene, which enhances the shelf life.

Additionally, novel nanotechnological approaches in edible coating, such as nanoemulsions and inclusion of NPs, act as a game changer. Consumer acceptance, cost, and economic viability are the issues currently faced by this technique. Safety assessment of the coating materials and considering their daily intake requirement could help address these concerns, although clinical trials are not necessarily required for the approval of food contact treatment. Edible coating has a significant role in the extension of stone fruits shelf life and holds a great scope in the near future.

Author Contributions

Reshma Krishnan: methodology, investigation, visualization, writing–original draft, data curation. Manjusri Misra: conceptualization, investigation, validation, resources, funding acquisition, project administration, supervision, writing–review and editing. Jayasankar Subramanian: conceptualization, methodology, investigation, validation, supervision, funding acquisition, writing–review and editing. Amar Mohanty: conceptualization, methodology, investigation, validation, resources, project administration, supervision, writing–review and editing.

Conflicts of Interest

The authors declare no conflicts of interest.