# Edible Packaging: A Technological Update for the Sustainable Future of the Food Industry
## 3 Results
### Production of Edible Films and Coatings
#### 3.3.3 Production of Edible Coatings  
The film-forming solution can be directly applied to food surfaces as coatings in the form of liquid suspension, emulsion, or powder. Methods like dipping, spraying, brushing, fluidized bed processing, and the panning method are used to apply edible coatings to food products, followed by drying. Figure 1 is a schematic representation of the process used to produce edible coatings.  
The dipping method is the oldest and most common method used to coat edible coatings on foods such as meat products, fruit, and vegetables [13]. This method is one of the ideal choices for coating irregular food surfaces [15]. The surface tension, density, and viscosity of the coating solution are significant in estimating the thickness of the film. The dipping method involves dipping a product directly into an aqueous coating solution,  
Figure 2: Schematic representation of the production of edible films via the extrusion method.  
removing it, and subsequently subjecting it to air drying to produce a delicate membranous film that envelops the product's surface. Another method for coating formation is the foam application method. Emulsions are typically used in this method. The foam breaks through a lot of tumbling so that the coating solution can be uniformly applied throughout the product's surface [19].  
The spraying method is preferred when only one surface needs to be coated and a thin layer of coating is necessary. Compared to pan or fluidized bed coating, it is a more precise form of coating application, wherein the solution is applied to the food surface using pressure (60-80 psi) [18]. However, in this method, after coating and drying one/the upper surface of the product, the product needs to be rotated or spun to cover the other lower surface. This method is mostly preferred for products with large surfaces. In this coating process, the spray nozzle plays a crucial role as it can influence factors like droplet size, surface tension, spray distance and angle, flow rate, overlap speed, viscosity, temperature, and pressure of the coating fluid [15; 19].  
Fluidized bed processing is a process that involves applying a very thin coating to dry particles of extremely low size and/or density. In this method, the small particles that are to be coated are added to a rotating fluidized bed. A centrifugal force pushes the coated particles towards the equipment's wall. Also, the equipment is designed to allow for airflow; thus, the combined effects of airflow and centrifugal force effectively counter the total force acting on the food particles [15; 19].  
The pan-coating method is used to cover hard, almost-spherical particles in thin or thick layers [13]. This coating can prevent the loss of moisture and lipids and can provide additional flavors to the coated product. The pharmaceutical and confectionery industries both use the pan-coating method to cover the products with this coating material. In this method, the pan is a large, rotating bowl in which the item to be coated is placed. A ladle or spray is used to add the coating solution to a rotating pan. To apply the coating solution throughout the food's surface, the product is rotated in the pan [19].