Polysaccharides, Protein and Lipid -Based Natural Edible Films in Food Packaging: A Review

Food is a vital product for the survival of human beings and with passage of time quality concerns of consumers are rising. Edible films and coatings are thin layers applied on food products to protect them and improve their quality. Films/coatings are prepared from naturally occurring renewable sources (polysaccharides, proteins, lipids and composites) which we can eat without disposing them. These films are environment friendly and contain antioxidants, anti-browning agents and colorants. Various methods (spraying, brushing, electro-spraying) are used to apply a coating on food material to protect them from microbial growth, prolonging their shelf life and improving other quality aspects like sensory attributes, appearance, originality and freshness of ingredients. In addition to edible films, some special additives like glycerol, sorbitol etc. is used to improve the efficiency of edible films and coatings. Chemistry and nature of these films and coatings vary in the vast range of hydrophilic and hydrophobic boundaries to cover the whole range of food products. In recent times, herbal coatings are widely used for the coating purposes e.g. Aloe Vera, citral and eugenol essential oils. However, some challenges presented are focusing the scientific attention for viable solution.

Chitosan is a biodegradable biocompatible polymer derived from natural renewable resources with numerous applications in various fields, and one of which is the area of edible films and coatings. Chitosan has antibacterial and antifungal properties which qualify it for food protection, however, its weak mechanical properties, gas and water vapor permeability limit its uses. This review discusses the application of chitosan and its blends with other natural polymers such as starch and other ingredients for example essential oils, and clay in the field of edible films for food protection. The mechanical behavior and the gas and water vapor permeability of the films are also discussed. References dealing with the antimicrobial behavior of these films and their impact on food protection are explored.