Sources, Origin and Characterization of Edible Packaging

Abstract

Edible packaging is generally available commercially as edible films or edible coatings depending upon their structural composition and end utilization or function towards food preservation. Edible coatings comprise those materials that are applied directly on food surfaces, either on the outer surface or between layers, and are generally consumed directly as a part of the food that they protect. On the other hand, edible films are usually manufactured separately and applied on the food surface for packaging, and can be removed from or peeled off the food before consumption. Edible packaging should be, as the name suggests, edible and easy to digest. They should be non-toxic to human beings while also being biodegradable. Depending on the function of the end product, a wide range of biodegradable components such as hydrocolloids/ polysaccharides, lipids and proteins are extracted from plant sources, animal sources and microorganisms for the process of anufacturing various edible coatings and films. The materials, thus, sourced can be categorized into three broad types as those originating from natural sources, such as agro sources, meaning the biopolymers are extracted directly from the natural biomass; those extracted from biomass developed by action of microorganisms or fermentation or those that are chemically synthesized from biomass. Apart from the characteristics that ensure edible packaging to be used as a food component, the packaging material should also possess various other properties that will allow it to effectively protect food materials from various external factors, while also preserving the structural integrity of the food materials. Edible biopolymers that make up edible coats and films inherently possess the property to form multiple layers or films, which is the most vital property for the development of any packaging material. This is in most part due to their ability to form a structural matrix that is both continuous and adequately cohesive. This property of forming a continuous structural matrix enables the resulting packaging film or coating to exhibit a myriad of essential characteristics like the ability to limit or prevent the transfer of moisture, gases (viz. oxygen and carbon dioxide), aroma, lipids, etc. that may affect the shelf life or important organoleptic properties of the food material. Such functionalities aid in the preservation of mechanical integrity of the food being packed. In order to optimize the functionality of edible packaging, their quality is inspected and characterized with regard to various properties including water vapour permeability (WVP), thickness, water solubility, oxygen permeability (OP) and mechanical properties (elongation, tensile strength, etc.). Sensory properties such as appearance (whether transparent/coloured/opaque), odour, taste and texture of the packaging material are also some of the important determinants of quality. As edible packaging is, in its essence, organic and biodegradable, care needs to be taken to ensure that the resulting edible films or coatings do not degrade easily when exposed to various external factors such as moisture, heat and light, among others. The various sources of edible biopolymers required for the development of edible packaging, their origin and characterization have been discussed in detail in this chapter.