## 4 Discussion
### Study on Red Fruits and the Implementation of Cutting-Edge Edible Coating
#### 4.3.3 Application Technique for Applying an Edible Coating on Red Fruits
There are several types of spraying, such as air spray atomization, which involves low speed and cylindrical spray flow, air-assisted airless atomization, used for highly viscous coatings, and pressure atomization spraying, where coatings are applied using pressure instead of air [105; 157; 160]. The biopolymer is dissolved into a suitable solvent in order to generate a solution. The solution is then atomized into a fine mist using a spray nozzle, which is sprayed onto the surface of the fruit or vegetable [171; 175]. When spraying, the pressure, viscosity, surface temperature, and coating tension are critical elements that greatly determine the final coating performance [157; 160; 176]. The benefit of spraying is that it is a rapid and effective approach that can be readily scaled up for commercial production [171] and to have the capacity to apply two or more distinct coatings, thus generating a multi-layered coating [160]. Additionally, the thickness of the coating layer may be adjusted with this process [157]. Adding antibacterial agents or antioxidants to the biopolymer solution may help to increase the coated produce's shelf life [171]. The spraying method permits multi-layer applications such as interlayer solutions, as well as uniform coatings with homogenous thicknesses [177]. Additionally, the coating thickness is larger than that when using the dipping technique, owing to the low viscosity of the solution [105; 160]. However, the spraying approach also has significant disadvantages [178]. Pan coating technique  
The pan coating process comprises putting the food products within a revolving container, where the coating is subsequently sprayed or sprinkled, thus guaranteeing a homogenous integration onto the food surface [157]. Subsequently, the coating is cured [179]. The pan coating process is used to manufacture thin or thick layers of coatings onto hard surfaces, enabling for the simultaneous coating of many food items, even with size variability, thus providing a clear, flexible, and shiny coating material [157]. The primary drawback of this technology is that it takes some time to achieve, considering the necessity for water evaporation throughout the process [157]. Moreover, the coating must be applied gradually; otherwise, it may cause the food items to cling together within the revolving container [157; 165]. Electro-spraying  
Electro-spraying is a process in which a liquid is atomized into small droplets using an electric field. The electro-spraying method utilizes a strong electric field to produce charged droplets that have a precise and limited size distribution. These droplets are of micrometric and sub-micrometric dimensions [180]. The electro-spraying approach may modify droplet characteristics, such as size and layer thickness, by adjusting the flow velocity and solution viscosity [105; 181]. Vacuum infusion is used for fresh fruits and vegetables that have a porous structure [112; 171]. The biopolymer solution is injected into the vacuum chamber, where it permeates the pores of the fruits [182]. Implementing this technique on food items like carrots has the potential to enhance their sensory properties and nutritional content, while also prolonging their shelf life and maintaining their firmness. This might be particularly advantageous for the preservation of fruits with robust skins or membranes that need a more substantial coating [183]. Vacuum infusion is not suitable for fruits with delicate structures as they may be damaged during the vacuum process [171; 184]. Layer by Layer (Multilayer Coating)  
The layer-by-layer deposition technique relies on the electrostatic interactions between the food surface and the charged polyelectrolytes. The electrostatic interactions enhance the attachment of the coating to the food surface and may be used to produce coatings which consist of several thin layers that are chemically or physically interconnected [105].