Edible packaging has traditionally been used to improve food appearance and preservation and it has sparked significant interest in recent decades, owing to the prospect of partially substituting non-biodegradable synthetic packaging materials. Food packaging serves three primary functions: protection, communication and convenience. As industrialization progresses, the usage of plastic for food packaging increases dramatically. Plastic output in the globe has reached 380 million tonnes, producing significant growth during the past two decades, with 40% of the plastic produced being utilized in packaging applications.
Read: June 2023 Issue of Food InfoTech Magazine.
Consumers have been more aware of the environmental impact of plastic in recent decades. As a result, usage of alternative packaging materials with a longer shelf life, higher quality and a lower environmental impact have become crucial in the food packaging sector.
The main purpose of the edible film is to regulate moisture loss and reduce undesirable chemical reaction rates, in order to improve the quality and safety of a wide variety of processed and fresh meals. Natural polymers derived from polysaccharides, proteins (animal or vegetable), lipids or mixtures of these components are used to make edible packaging materials.
MATERIALS USED FOR EDIBLE FILM FORMATION
• Protein-based Edible Film
Corn zein, wheat gluten, soy protein, peanut protein, quinoa protein and sesame protein are examples of edible packaging made from plant proteins. Keratin, egg white protein, myofibrillar protein, collagen, gelatine, casein and milk whey protein, on the other hand, are animal-derived film formers. Protein-based materials appear to be more appealing among edible film sources since they also provide nutritional value. Furthermore, protein-based edible films have superior mechanical and gas barrier capabilities, while having low moisture barrier properties.
Protein-based films outperform lipid and polysaccharide-based films. Due to their tightly packed and organized hydrogen-bonded network structure, they exhibit superior physical properties and gas-blocking effects. Because of the globular structured proteins, maize zein, wheat gluten, soy protein and whey protein-based edible films have higher oxygen permeability as compared to collagen-based films.
Protein-based edible films can also be used for individual packaging of small pieces of food, especially for products where individual packaging is impractical, such as beans, almonds and cashew nuts. The protein-based film can be made using both wet and dry processes. Individual packaging is impractical, such as beans, almonds and cashew nuts. The protein-based film can be made using both wet and dry processes.
• Polysaccharide-based Edible Film
Polysaccharides viz cellulose, hemicellulose, starch, pectin and derivatives of all these alginates, pullulan, chitin and chitosan are intensively used for edible film and coating materials preparation. Edible films based on polysaccharides have a well-ordered hydrogen-bonded network, making them effective oxygen blockers. However, due to their hydrophilic nature, polysaccharide-based films are less effective as a moisture barrier. Polysaccharide coatings are oil-free, colourless and are used to enhance the shelf life of a product without producing anaerobic conditions.
• Lipids-based Edible Film
Lipids are naturally occurring chemicals found in plants, animals and insects. The lipid functional groups are composed of mono-, di- and triglycerides, phospholipids, phosphatides, terpenes, cerebrosides, fatty acids and fatty alcohols. Due to their low polarity, various plant and animal-based lipids (oils and fats) are included in film-forming solution (FFS) to the emulsion-based edible film to impart more hydrophobic qualities. Some lipid components, such as virgin coconut oil added to the FFS, lowered the edible film’s water vapour permeability (WVP). The compatibility of the lipid phase with the polymer matrix is critical for the film to have the appropriate characteristics. The use of various essential oils in the manufacture of edible films improves the WVP as well as functional qualities, such as anti-bacterial and antioxidant properties. The lipid-based self-supporting edible film is typically made using the solvent casting process with an FFS containing any of the high molecular weight polymers (protein or polysaccharide).
Methods for Edible Film Formulation
The wet and dry processes are the most common methods for producing edible film. In the wet process, biopolymers are solubilized or dispersed in an aqueous solution, either water-based or alcohol-based to produce FFS, which is then dried. Biopolymers were turned into a film in the dry method by utilizing the thermoplastic behaviour of some proteins and polysaccharides at low moisture levels. The wet procedure, also known as solvent casting is the most often employed approach in the creation of edible films. The solvent casting process includes dissolving the base biopolymer in a suitable solvent, such as water or ethanol to generate an FFS; casting the FFS into suitable moulds or Teflon coated plates; drying the casted film formulation solution, peeling/removing the film and storing at an appropriate RH and temperature.
Application of Edible Film for Packaging of Foods
• Dairy Products
Cheese packaging is one of the edible film’s potential application areas. Packaging, particularly antimicrobial filming cheese has been found to have a significant impact on its shelf life. The effectiveness of chitosan-based film as a carrier of natamycin in improving the storage stability of Saloio cheese was investigated and the product was stable for seven days at ambient storage settings.
• Meat and Meat Products
Meat and meat products are popular among customers due to their distinct flavour and nutritional value. Meat, on the other hand is very sensitive to spoilage due to microbiological and chemical changes and thus is required to be preserved with care. Because of their antioxidant and antibacterial characteristics, essential oils have become more commonly used in edible films in recent years. It evaluated the antibacterial properties of zein-based films in combination with ZEO (3%), monolaurin (1%) and minced beef against E. coli O157:H7, L. monocytogenes and L. monocytogenes in vitro, which in turn enhanced antimicrobial activity of the film.
Recent Trends, Challenges & Future Perspectives in Edible Films
• Edible films made from byproducts of food processing have grown in popularity in recent years. By-products from the food processing of fruits, vegetables, seafood and edible oils showed great promise for the development of edible films with specialized features. Composite film formation and nanotechnology applications have been tested.
• The ability of films to be heat sealed is another essential quality. For bio-based films, the optimal sealing temperature range is constrained. Therefore, the likelihood of undersealing and charring as a result of overheating is increased for these films. This has a detrimental effect on how it is used to create pouches and coverings.
• To establish edible film’s suitability for food storage, it is also crucial to determine how its properties change with time, temperature and relative humidity.
• Programmes that raise consumer awareness and undertaking promotions for edible films may also help them in gaining higher acceptance.
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