## 4 The Role of Edible Coatings in the Enhancement of the Postharvest Quality of Apples  
The basic idea about the edible active coating on the surface of apples is presented in Figure 3, which indicates that the main purpose is to maintain moisture inside the fruit while letting it respirate. Microbial contamination present in minimally processed food products can arise at various stages of production, e.g., in the orchard, at harvest, storage, processing, or distribution. In addition, improper storage temperature, too high humidity, and mechanical damage also have an impact [161]. One of the basic conditions for the proper preservation of fresh fruit immediately after harvesting is the use of reduced storage temperature throughout the cold chain, which reduces the appearance of the two most common moulds caused by _Penicillium expansum_ and _Botrytis cinerea_. Chemical fungicides have been used to reduce postharvest spoilage of fresh fruit and vegetables, but their use has been restricted due to emerging consumer concerns and their adverse health and environmental impacts. Currently, edible coatings and films containing the addition of natural antimicrobial compounds are of great interest [162]. Figure 3: The mechanism of active coating for apples. The results of the study showed that the mixture of _Bifidobacterium lactis_ and _Lactobacillus rhamn_, which was on the surface of apples with an alginate coating, sufficiently reaches the human small intestine, exerting a beneficial effect on health. Fresh apples retained their microbiological and nutritional properties, making the alginate-based solution a good probiotic carrier, which is important in the aspect of developing new functional food products [163] Also, according to [PERSON] et al. [164], adding probiotics to edible films, in addition to ensuring their good stability, reduces the growth of microorganisms, and thus food spoilage. Thanks to the consumption of fresh fruit covered with a probiotic film, it becomes possible to supply beneficial bacteria to the human body, which are protected by the cellulose contained in the fruit. Recent studies show that probiotic bacteria contained in edible membranes help maintain physicochemical parameters and nutritional and sensory factors during storage. The use of an edible coating based on pullulan and basil on the \"Jonagored\" apples resulted in antifungal activity against _Rhizopus arrhizus_, while edible films based on potassium sorbate, pullulan, and gelatin showed effectiveness in terms of antibacterial properties against _E. coli_, _K. apiculate_, and _B. cinerea_[100]. To prevent contamination and enhance the visual appeal by adding a gloss, the coating is increasingly used before marketing fruit. Composite edible coatings are most effective because single ingredients are ineffective enough to improve fruit shelf life and quality (Table 1). The most commonly used additives that provide additional gloss to fresh apples are shellac wax and carnauba wax, which primarily prevent weight loss. These substances, alone or as components of an emulsion, simultaneously control water loss and thus preserve the quality of fresh fruit and delay their ripening, which can be observed visually. The example of uncoated and coated apples with apple pectin-based edible coatings before and after 1 week of storage are presented in Figure 4. Consumers judge fresh fruit by changes in the surface of the skin, firmness, and greasiness. Failure to meet these standards by producers reduces the acceptance of the product by the consumer or its complete rejection and thus reduces the financial return [165]. In a study on the use of zinc nanoparticles for coating climacteric fruits, it was proven that they effectively delay ripening, reduce weight and moisture loss, and preserve fruit firmness. Due to its excellent mechanical, barrier, and biocompatibility properties, zinc oxide has gained a lot of interest in the scientific community [160].