Suman Bishnoi1, Gauri Jairath2 and Neha Thakur1*
Natural biopolymers have recently become more popular as packaging ingredients since they are safe, biodegradable, and multifunctional.The pollution that plastic-based packaging materials produce in the environment calls for strong environmental protection and the promotion of newer, sustainable, and natural raw material substitutes for fossil-based raw materials in packaging technologies.
Edible films and coatings are natural polymers obtained from agricultural productions such as animal and vegetable proteins, gums, and lipids and are totally biodegradable, and therefore perfectly safe for the environment.They are the thin films used to cover any type of food product. These can be employed to increase the shelf life of the product and are edible with or without additional removal from the food. Films can be used to create pouches, wraps, capsules, bags, or casings, depending on the extent of the fabrication processes; coatings are a specific type of film that are applied directly onto the surface of materials. The only fundamental difference in the material composition between films and coatings is their thickness.These thin coatings can act as a barrier against moisture, microbial contamination, oxygen, and other factors that are crucial for extending the shelf life of the products. In order to formulate edible coatings and films with the appropriate structural characteristics, numerous components are needed. Extruding mixtures of polysaccharides, proteins, and/or lipids, laminating two or more edible films, or emulsion creation can all be used to create composite films.
Raw materials for edible packaging
The type, characteristics, and intended use of the food that is to be packaged determine precisely what materials are needed for edible coatings and edible films. Biopolymers such proteins, polysaccharides (pectin, starch, carrageenan, alginate, and xanthan), gums, resins, and lipids can all be employed alone or in combination to produce films.
Renewable-source proteins are large molecules with specific amino acid sequences connected together by amide linkages. Casein and whey protein from milk, soy protein, maize zein, wheat gluten, pea protein, rice bran protein collagen, egg albumin from eggs, myofibrillar protein of fish, and keratin are among the most frequently utilised proteins in edible film and coating compositions.
Simple monosaccharide units make up polysaccharides, which have more complex and unpredictably changing conformational structural changes but heavier molecular weights. You can get polysaccharides from either plant or animal sources (Chitin and chitosan,). The several forms of starch, modified cellulose (Carboxymethyle cellulose, Methylcellulose, and Hydroxypropyl cellulose, as well as Hydroxypropyl methylcellulose), non-starch carbohydrates, gellan gums, and fibres are all examples of polysaccharides.
The vast majority of lipids and resins have good film-forming characteristics, are edible, and are biodegradable. Lipids are composed of a variety of biopolymers, such as oils, free fatty acids, bee waxes, carnuba wax, paraffin wax, shellac resin, terpene resin, and actetogylcerides.
In order to prevent brittleness, the formation of protein-based films typically necessitates the integration of a limited content of some structural agents, such as plasticizers. When polysaccharides or proteins are utilised as the primary ingredient in the production of edible films and coatings, plasticizers are usually necessary since these film structures are frequently brittle and stiff due to significant interactions between their polymer molecules.By lowering the ratio of the crystalline to the amorphous area, which is somewhat related to lowering the glass transition temperature of the polymers, plasticizers are low molecular weight agents added to the polymeric film forming materials. There are two main categories of plasticizers: I substances that can form a lot of hydrogen bonds and interact with polymers by breaking up polymer-polymer bonds and maintaining the proper distances between polymer chains (such as glycerol, polyethylene glycol, sorbitol, and water); and (ii) substances that can interact with a lot of water and retain a lot of water molecules, resulting in a higher moisture content and a bigger hydrodynamic radius (e.g., sucrose).
The various physical, chemical, and mechanical properties of coatings and films can be maintained while adding additives to edible films in sufficient quantities to produce desired results. The edible films can include active ingredients such as antioxidants, nutraceuticals, emulsifiers, antimicrobials, flavours, pigments, light absorbers, and colourants. These additives actively contribute to preserving, enhancing, and safeguarding food quality and safety.
Challenges and opportunities
- Lack of knowledge: The researchers have studied the about various film forming substances, plasticizer concentration and about the properties of formed films but, inadequate data is available on the practical applications of the same.
- Appealing the masses: In order to gain acceptance among the consumers, safe, locally available and completely biodegradableingredients need to be focused upon.
- Higher cost: edible films cost higher than the corresponding traditional plastics,so cost has also been a major constraint in adoption of these
- The opportunities of edible films and coatings lie with benefits of addition of numerous functional agents like antioxidants, nutraceuticals, antimicrobial agents, vitamins, probiotics, flavouring and colouring agents.
- The replacement of the synthetic plastics with edible films offer a great solution to waste generated because of non biodegradable nature of these petrochemical films. The use of polysaccharides to form edible films offer newer prospects to develop biodegradable films.
- The different antioxidant compounds can be nano encapsulated on edible films as lipophilic particles which offers to be an appealing strategy.
Food, pharmaceutical, and biotech industries have recognised edible packaging as a superior alternative to synthetic packaging for minimising waste and creating unique applications with desirable attributes for enhancing a product, such as safety, stability, quality, diversity, and customer convenience. These materials offer the advantages of becoming new, all-natural, secure, and environmentally friendly with the added benefit that they could be produced using renewable resources.