In recent decades, consumers have become more worried about their food habits, rejecting products with additives and giving preference to fresh ones [1]. Furthermore, society has increased its concern about the environment, leading to an increased interest in reducing plastic consumption and food waste. The food industry has been struggling with the loss of food quality and quantity, especially of perishable products, between the harvest and consumption steps of the chain ^[1][2][1,2]. The losses are mainly related to food spoilage caused by microbial contamination, molecules oxidation, and sensory characteristics deterioration ^[3][4][3,4]. These effects affect the safety of food products, threaten human health, and have a negative impact on consumer acceptance [4]. Considering the demands of both consumers and industry, edible coatings have been introduced as one alternative food packaging to replace plastic packaging and the synthetic preservatives traditionally incorporated to prolong the shelf life of different food products.

Edible coatings are thin layers applied directly on the food material’s surface. Food packaging is qualified as “edible” if it is an integral part of a food that may be eaten with it [5]. This material preserves and maximizes food quality, being widely used as a postharvest practice, especially in perishable products such as fruits and vegetables (F&V). Edible coatings protect food products from microbial contaminants, increase shelf life, decrease deterioration effects, and reduce lipid oxidation and moisture loss [1]. As with any other food-film production, edible coating formulation must consider different parameters, such as barrier properties (oxygen and carbon dioxide permeability), optical properties (they must be transparent and colorless), and sensory characteristics (they must be flavorless, tasteless, and odorless) [6]. Edible coatings can also enhance the sensory product attributes, like appearance and biochemical, physicochemical, and microbial stability. The nontoxicity and safety of this material and the low processing cost and the feasibility make edible coatings a good plastic-packaging alternative [5]. It must be noted that coatings do not always provide the proper attributes. Sometimes, the mechanical characteristics, poor transparency, or the lack of antimicrobial and oxidation resistance leads to the production of unsuitable films. Nevertheless, coatings are carriers for food additives like antimicrobials and antioxidants to improve both functional and physicochemical properties ^[3][4][3,4]. Moreover, edible coatings are considered environmentally friendly since they replace plastic packaging and reduce food waste by increasing the shelf-life storage of food products ^[1][6][1,6]. To produce edible coatings, various formulations can be used by engaging different structural compounds [6]. Thus, edible coatings can be classified into three groups, considering the nature of their elements: hydrocolloids (polysaccharides and comprising proteins), lipids, and blends of these compounds [7]. Furthermore, the usage of food industry by-products to produce biopolymers for edible coatings has already been considered [5]. This circular economy thinking strategy leads to reducing food waste, lowering the environmental impact of the food industry.

Fruits and vegetables (F&Vs) are products composed of vitamins, dietary fiber, phytochemicals, antioxidants, and minerals, whose consumption is linked to different health benefits such as the maintenance of human body immunity and the reduction in the risk of cardiovascular and cancer diseases, being fundamental for human nutrition ^{[8][9][10][11]}[8,9,10,11]. F&Vs are widely consumed but problematic to manage along the supply chain since they are living tissues whose metabolic processes, such as CO₂ production and O₂ consumption during respiration, continue after harvest. Moreover, F&Vs have a high water content, so they are considered highly perishable products ^{[8][9][10][11][12]}[8,9,10,11,12]. Postharvest deterioration can be minimized by controlling respiration rate, ethylene production, moisture loss, and microbial load. Both optimal storage conditions and postharvest technologies are needed to guarantee their storage stability and shelf-life extension [8]. F&Vs are products likely to be infected by Gram+ and Gram− bacteria, fungi, yeast, and molds because of the physiological and compositional changes occurring in the supply chain, making these products suitable substrates for microbial growth [10]. According to data, the main physico-chemical parameters affecting microbial spoilage of F&Vs are pH, temperature, and water activity (a_w). Fruit pH is under 4.5, which promotes fungi growth (pH range between 3 and 8). Instead, vegetables have a pH range of between 4.8 and 6.5, allowing both fungi and bacteria growth [10]. The storage temperature recommended for F&Vs is between 0 and 5 °C since high temperatures accelerate the respiration process while low temperatures inhibit or delay microbial growth [10]. Nevertheless, psychotropic bacteria and fungi and chilling injuries must also be considered [10]. Finally, the liquid water available is a crucial factor for microbial growth (a_w between 0.97 and 1.00), even when harsh environmental conditions are applied. F&Vs have an a_w between 0.95 and 0.99 and are susceptible to microbial spoilage; however, reducing the water content is not an option [10].

F&V physicochemical characteristics lead to high product losses in the supply chain. Different studies have been carried out recently about food loss and waste (FLW). Food loss is the reduction in the quality or quantity of food that takes place in the chain, excluding retail, food service providers, and consumers, because of the decisions and actions of food suppliers. Food waste is the reduction in the quality or quantity of food resulting from decisions and actions by retailers, food services, and consumers [12]. According to different data, more than 20% of F&V production is lost or wasted [13], and 3–18% of the F&V loss occurs in the processing steps because of human errors, poor management, and technical failures [12]. In developing economies, food loss is linked to the postharvest and processing level, while developed economies are characterized by losing food at the retail and consumer level, being considered food waste [13]. Considering that the population is expected to reach 9.1 billion people by 2050, F&V stability and shelf-life extension have become issues for the food industry and society since increasing production cannot be the only solution to fulfill the demand [13]. Both stability and shelf life are linked to food quality and safety, being essential parameters for the food industry that affect the sensorial quality of the products [8]. Thus, food packaging is one key factor to prevent F&V waste, which takes place during the supply chain and once F&Vs are stored by consumers. Edible coatings may be a suitable alternative to traditional plastic food packaging since they can enhance the shelf life of F&Vs by reducing their respiration rate and loss of water and protecting them from physical damage and microbial spoilage, preventing postharvest loss [14].

Nowadays, edible coatings are studied for perishable food products, such as F&Vs, meat and poultry, and fresh fish. On the one hand, microbial contamination is common in these products because of their high water content. F&Vs are prone to water loss, mechanical damage, and sensory changes during storage, leading to economic loss [3]. Mechanical injury, environmental stress, and pathological breakdown are also situations that reduce these perishable food products’ shelf life ^[15][59]. These effects also impact the consumers’ acceptance and health [3]. Different studies have applied biopolymers with bioactive compounds (such as EOs), inorganic NPs, or bio-nanocomposites as edible coatings to prolong these products’ shelf life. In this section, the current application of edible coatings (Table 1) is discussed, providing several examples where F&V shelf life is improved.

Product	Subproduct	Extraction	Conditions	Compound	Formulation	Application	Product	Ref.
Mango	Mango peel flour	Drying pretreatment	60 °C; 48 h	-	1.09% MPF 0.33% Gly	Casting	Peach	[16][25]
	Mango seed kernel	Solvent extraction	EtOH 90%; 75 °C	Antioxidant compounds	1.09% MPF 0.33% Gly 0.078 g/L EMS
Onion	Leaves, stems, flowers	UAE	Acetone	Phenolic compounds	1% SA 0.3 g/g Gly/SA 0.04 g/g CaCO3/SA 5.4 g/g GDL/CaCO3	-	-	[17][22]
Artichoke
Thistle
Mango	Kernel	Solvent extraction	Sodium metabisulphite 0.16%	Amylose; amylopectin	Gly:Sorbitol 1:1 Starch 50%	Dipping	Tomato	[18][62]
Olive leaf	Leaves	Solvent extraction	EtOH 40%; 60 °C; 120 min	Olive leaf extract	3% SA 10% Gly 2% CaCl2 0.01 g/mL Chitosan 0.02 g/mL OLE	Dipping	Sweet cherries	[19][28]
Loquat leaf	Leaves	Reflux extraction	EtOH 50%; 196 °C	Loquat leaf extract	10 g/L SA 0.7 g/L CA 10 g/L SE 0.5 g/L AsA 0.5 g/L PS	Dipping	Tangerines	[20][26]
Jackfruit leaf	Leaves	MAE	EtOH:H2O 4:1; 840 W; 2 min	Jackfruit leaf extract	1.5% pectin (w/v) 30% (w/w) Gly 10% (w/w) Beeswax JLE 5 mg/mL	Wounded	Tomatoes	[21][27]
Moringa leaf	Leaves	NS	-	Moringa leaf extract	MLE 2% Chitosan 0.5% CMC 0.5%	Dipping	Avocado	[22][63]
Haskap leaf	Leaves	ATPE	Sodium phosphate 10%, EtOH 37%, H2O 53%; 5 min	Haskap leaf bioactive compounds	PPC 10% 0.91% Gly 10% SPHLE/ASHLE 1.7 g CA/MA	Filming	Grape tomatoes	[23][64]
						Dipping	Bananas

Several studies have been carried out using edible coatings as shelf-life extenders. Polysaccharides are the most common macromolecules used in EC production. Sucheta et al. studied the tomato’s changes during 30 days of storage at 25 °C using a pectin-based edible coating mixed with corn flour and beetroot powder in different proportions. Results showed how the coating produced with 50% pectin and 50% corn flour (PCF) achieved the best weight loss, decay percentage, respiration rate, and biochemical quality. Moreover, PCF and P (100% pectin) coating could maintain maximum glossiness and minimum shrinkage of the tomato’s pericarp without causing off-flavors ^[24][30]. Rodriguez-Garcia et al. also studied the tomato changes that took place during 12 days of storage at 25 °C. The edible coating was prepared using citrus peel pectin as the main macromolecule, mixed with oregano EO. Results showed the antifungal effect of the EC on inoculated tomatoes because of the EO addition. Moreover, the total phenol content and the antioxidant activity were increased without affecting the sensory acceptability of the tomatoes ^[25][31]. Another study explored the tomato’s variations after being coated with alginate mixed with aloe vera, and ZnO-NPs were measured during 16 days of storage at room temperature. Results showed the applicability of this edible coating since the UV shielding and water barrier and the thermal, mechanical, and antimicrobial properties were excellent. The authors demonstrated that the improved properties resulted from the synergic action of the alginate mixed with ZnO-NPs and aloe vera ^[26][36]. Strawberries were also among the focus fruits for the shelf-life extension. Khodaei et al. applied an edible coating made of CMC, Persian gum (PG), low methoxyl pectin (LMP), or tragacanth gum (TG) in strawberries stored at fridge temperature (4 °C) for 16 days. To analyze the effect of the different coating treatments on the strawberries’ shelf-life, the TOPSIS method was applied, showing that the CMC coating has the best results in reducing weight loss and spoilage and preserving nutritional ingredients ^[27][33]. The shelf-life prolongation of coated strawberries was also studied. The coatings were made of pullulan (a water-soluble polysaccharide), and cinnamon EO was incorporated in a nanoemulsion structure. The edible coating addition led to different improvements in the mass loss delay, firmness, total soluble solids, and titratable acidity during the 6 days of storage at room temperature ^[28][39]. In the same way as strawberries, cherry fruits are highly perishable. Sweet cherries were coated with a polysaccharide-based coat of alginate and chitosan and mixed with olive leaf extract. After 20 days of storage at 25 °C, coated cherries showed retardation of the ripening process and maximum retention of phenolic compounds. Furthermore, the authors determined the correlation between antioxidant activity and the retention of phenolic compounds ^[19][28]. Coated grapes have been studied using a polysaccharide-based coating of chitosan (1%) and a combination of chitosan (1%) and gum ghatti (1%) applied to the grapes’ surface before their storage at fridge temperature (1 °C) for 60 days. After comparing the results, the chitosan and gum ghatti showed better antifungal activity. This coat also gave good results regarding nutritional properties, phenolic compounds, and antioxidant activity maintenance ^[29][35].

Regarding protein-based coatings, fewer studies have been conducted. Protein-based coatings mixed with transglutaminase were applied to apples, potatoes, and carrots cut in slices and stored at fresh temperatures for 10 days. positive results were shown when the transglutaminase was incorporated into the edible coating, reducing weight loss, preventing microbial growth, and maintaining antioxidant activity during the 10-day storage. Furthermore, apples, carrots, and potatoes showed no significant changes in their hardness and chewiness ^[30][32]. Another study compared the addition of lemon oil, lemongrass EO, and non-incorporated oils in whey-protein edible coatings applied onto the surface of pears. Results showed how the coating with lemon oil (1%) and lemongrass EO (0.5%) reduced weight loss, WVP, oxygen, and carbon dioxide. However, those pears coated with lemon oil had a reduction in firmness after 28 days at fresh storage with 80% humidity, while those coated with lemongrass EO showed higher brownness because of the nature of the oil and its natural yellow color. Regarding acceptability, both coatings showed a slight reduction in acceptability compared with the EC without the oils ^[31][34]. Walnut flour protein was applied to the kernel surface of walnuts to improve their storage for 40 days at 84 °C. Edible coatings preserved the sensory characteristics, especially those regarding lipid deterioration (e.g., lipidic peroxidation that leads to rancid flavor) ^[32][41].

Edible coatings seem a suitable pathway for the shelf-life extension of F&Vs, producing some improvements such as retardation of maturation, inhibition of enzymatic brown reactions, or reduction in respiration rates, among others. However, the impact of the edible coating application on the acceptance of the product, depending on firmness, color, flavor, taste, smell, hardness, and overall acceptability, should be considered. Basaglia et al. studied the changes in color and firmness of coated pineapples, and results showed no significant variations in color until day 7, with a lower decrease in brightness compared to uncoated pineapples. No significant changes were measured in firmness until day 9. Moreover, 12 trained judges analyzed aroma and overall evaluation, finding no significant difference until day 5 ^[33][37]. Manzoor et al. determined the firmness of fresh-cut kiwifruit coated with sodium alginate, ascorbic acid, and vanillin, showing slower changes in those coated slices than in the uncoated ones ^[34][40]. However, Tabassum et al. determined the changes in color and firmness when guava leaf and lemon extract were applied to bananas using a scale ranging from 1 to 7 and 1 to 5, respectively. Results showed that coated bananas maintained firmness and color for 2 and 5 days more than those uncoated, respectively ^[35][29]. In a different study, 15 semi-trained judges evaluated coated tomatoes’ taste, firmness, and visual appearance. After a 15-day storage period, the acceptance rate was higher than for the uncoated. Nevertheless, a distinct but pleasant difference in the coated tomatoes was detected. Regarding firmness and color, results showed higher visual brightness of coated tomatoes compared with those uncoated. Finally, firmness of coated tomatoes was reduced by 28%, while uncoated tomatoes showed a reduction in firmness of 61% ^[36][38]. The sensory changes of tomatoes coated with whey protein, xanthan gum, and clove oil were also analyzed by a trained panelist. Color, texture, taste, flavor, and overall acceptability were evaluated. After 15 days of storage, the coated tomatoes were found acceptable, whereas the uncoated tomatoes showed a desiccated appearance. The coated tomatoes showed no adverse effect on color, texture, taste, and flavor ^[37][44]. Regarding the data available considering sensory characteristics of the F&Vs coated, positive results are found. Overall, there is an improvement in the firmness, color, flavor, smell, and taste of the samples coated, guaranteeing the consumers’ acceptability of F&Vs.

When EC are added onto F&V surfaces, the materials of these coatings are in direct contact with the food product. Therefore, the safety approval of the corresponding authorities is necessary for the commercialization of these products ^[38][65]. In this way, the Food and Drug Administration (FDA) and the European Food Safety Authority (EFSA) have developed codes regarding the proper application of packaging and food contact materials (FCM) ^[38][65], guaranteeing the consumer’s health ^[39][66]. Thus, three different categories have been described: FCM, defined as the materials and articles that are in direct contact with food, such as nanoparticles and antimicrobial and antioxidant compounds, that in the case of the European Union are legislated by Regulation (EC) 1935/2004; food contact substances (FCS), which are the components of the main material, and food contact articles (FCA), which are the final product (whether they are coatings or films) ^[38][39][65,66]. It is important to remark that the edible coatings added to the surfaces of F&Vs must be a recognized GRAS or food additive by the FDA, and the main compounds used in the production of EC are generally in the additives list made by the European authorities included in Regulation (EC) 1333/2008 ^[38][65].

In conclusion, when edible coatings are developed, it is important to use compounds that are considered safe or are included in the additive lists of the different authorities so consumer health is not compromised. In this way, it would be interesting for the European authorities to develop a more specific legislation for EC, since it seems to be an alternative with potential for the improvement of the shelf life and quality of perishable products such as F&Vs.