The investigation of edible packaging films based on pullulan and alginate

The packaging industry is highly dependent on fossil resources and have serious environmental drawbacks. The largest part of the total volume of plastic waste is generated from food packaging, so new packaging strategies with green materials are required. Using the edible packaging films which are renewable, biodegradable and versatile, can reduce the amount of plastic waste. Also, there is an increasing demand of higher quality foods and a growing interest from consumers for minimally processed fresh-like foods with an extended shelf life. Edible films can be effective barriers which prevent unwanted mass transfers in foods. They can be green alternative to synthetic petroleum-based polymer packaging materials and nowadays this topic is a fast-growing area. Sodium alginate as a natural polysaccharide can be used for edible films with excellent properties such as transparency. But, sodium alginate practical applications in food packaging are limited as single-component because of poor mechanical and barrier properties. At the same time, pullulan is an extracellular and water-soluble microbial polysaccharide with good film-formation properties. The packaging materials made from pullulan and alginate may be better candidates for edible packaging films. The objective of this study was to formulate pullulan and sodium alginate based edible films for food packaging. For that purpose a series of pullulan/alginate films with different ratios were prepared. To improve film flexibility and processability, glycerol was added as plasticizers in the film formulation. Designed films were solvent cast from aqueous polymer solution. Understanding the film-forming mechanism during the drying process is crucial to predict properties of the obtained films, so rheological properties of prepared solutions were investigated. Formulated films have the potential to be used as inner primary packaging and can be manufactured by preparing a film-forming composition and enclosing a food product with the film. Using this kind of packaging material, no waste is generated contributing to the circular economy.