Agar-based packaging films produced by melt mixing: Study of their retrogradation upon storage

Abstract

[EN] The ability of agar with different purification degrees to produce packaging films has been evaluated and the stability of the obtained materials after prolonged storage has been investigated. The less purified agar resulted in films with higher water vapor permeability and lower mechanical performance than pure commercial agar. However, the commercial agar film required the addition of a plasticizer to produce films that could be manipulated. It has also been observed that prolonged storage at 53 % RH results in a change in the semi- crystalline structure of the agar and in water-polysaccharide interactions. As a result, pure agar films undergo a rigidizing effect resulting in unmanageable films after 7 days of storage. The presence of glycerol improved the stability of the films by limiting the structural changes up to 14 days of storage. In contrast, the films from the least purified agar extract, seemed to be less affected by moisture, showing a higher stability during storage. This points to the potential of the less purified extract to be used as an additive to reduce costs and improve the storage stability of pure agar films.