Food coating

Coating is an industrial process that consists of applying a liquid or a powder onto the surface of an edible product to convey new (usually sensory) properties. Coating designates an operation as much as the result of it: the application of a layer and the layer itself. Coating takes different meanings depending on the industry concerned.Sugar-coated rice.IQF vegetables coated with cream.Sugar-coated dragees. Coating is an industrial process that consists of applying a liquid or a powder onto the surface of an edible product to convey new (usually sensory) properties. Coating designates an operation as much as the result of it: the application of a layer and the layer itself. Coating takes different meanings depending on the industry concerned. This article concerns coating applications in the food industry. There are many similarities between coating processes and numerous examples of technology transfer to and from the food industry. Coating in the food industry is the application of a layer of liquids or solids onto a product. The operation essentially relies on mechanical energy. It consists mostly in setting the product particles in motion and simultaneously applying the coating ingredient in a certain pattern to expose one to the other. It involves such phenomena as adhesion, friction, viscosity, surface tension and crystallisation. Food coating is not a “hard” science such as drying or cooling, which can be described by equations and are predictable. Food coating is rather a “soft” knowledge derived from the accumulation of know-how. One reason is that the product and the ingredients considered have complex characteristics, variations and interactions. Encapsulation is the application of a liquid layer to very small particles. It relies on an array of principles: entrapping a molecule inside a matrix, chemical bonding, and polymerisation. Encapsulation aims at the protection and controlled release of active molecules when immersed in an environment. As a rule of thumb, particle size can discriminate between “encapsulation” (below 300 µm to 1000 µm) and “food coating” (above this limit). Mere mechanical movement is not adequate and sufficient to fulfill the proper coating of minute particles. Pictures Coatings can be added for the enhancement of organoleptic properties of a food product.Appearance and palatability can be improved by adding color (white dragee, brown chocolate), changing the surface aspect (glazed sweets or rough, crispy nuggets); changing or adding tastes (sweet dragee, salted snack) or flavours (fruit-glazed sweet goods), or texture (breaded crispy nuggets).