**6. Edible coatings for food applications**

#### **6.1 Characteristics of edible films and coatings**

Any substance with a thickness of less than 0.3 mm [34] that is created from a blend of biopolymers and other additives is considered to be an edible film or coating, in watery media, scattered [10, 35, 36]. Although some authors use the terms "edible film" and "coating" interchangeably, others contend that there is a distinction to be made because of how they are absorbed into the food product [37]. The edible coating is created directly on the food, as opposed to the edible film, which is manufactured in advance and then attaches to the product [37, 38]. However, in both cases, rigid matrices with similar properties are produced [39].

The primary traits edible films and coatings can exhibit:


#### **6.2 The components of edible films and coatings**

Edible films and coatings are frequently assessed for their mechanical properties, such as their elasticity and rigidity, as well as the force required to break them, using terms like elongation at break (E), tensile strength (TS), and elasticity *Flavoring and Coating Technologies for Processing Methods, Packaging Materials… DOI: http://dx.doi.org/10.5772/intechopen.109542*

modulus (EM) [44, 45]. These terms also refer to similar characteristics, such as their elasticity and rigidity. Permeation, adsorption, and diffusion, which are associated with the flow of solutes between food and the atmosphere, are other mass transfer mechanisms they share [44, 46]. However, both mechanical properties and mass transfer phenomena are influenced by the type of material and manufacturing method that enables the formation of different biopolymeric matrix topologies [41–45]. The top biopolymers and additives used to make edible films and coatings are listed in **Table 3**, along with details on their properties and packing potential.

Starch is recognized as the universal biopolymer for bio-packaging and has been used extensively for decades [47] because of its characteristics and gelatinization abilities. Alginate is an important biopolymer that can also be used to make hydrogels and encapsulation barriers [48, 49]. However, chitosan has lately gained interest for the creation of edible films and coatings due to its capabilities as a gelling agent, chemical (it may establish hydrogen bonds and hydrophobic interactions), and biological (its biocompatibility, biodegradability, and bioactivity) [50–52]. While some writers have opted to use organic packaging materials such as proteins (such as collagen and protein isolates) [53, 54], lipids, and carbohydrates (such as canola oil and cinnamon bark oil) [55, 56], as well as other unusual materials (such as smooth-hound protein and papaya puree) [57, 58], to create bio-packaging with specific properties.


**Table 3.**

*Main materials used and functionality in the manufacture of edible films and coatings.*

However, the purpose of additives (such as plasticizers or stabilizers) in the formulation of edible films and coatings is to alter the mechanical characteristics (preferably increasing E and decreasing TS and EM) as well as mass transfer phenomena [37]. Additionally, adding anti-oxidant, fungicidal, or anti-microbial chemicals enables the creation of bioactive biopackaging [50, 59].
