Gelatin films containing plant extracts

Abstract

Polymer films based on traditional synthetic polymers are widely used throughout the world. However, the impossibility of biodegradation of synthetic polymers in the environment and, as a result, the accumulation of polymeric waste stimulates using biodegradable bio-based polymers instead of traditional ones. One of them is gelatin. Gelatin is biodegradable, it has good mechanical and barrier properties, high film forming ability and widely distributed. Presented research includes results of a investigation of gelatin films based on aqueous extracts from the leaves of sea buckthorn leaves, plantain leaves, pine needles (film based on distilled water used as a control). The qualitative and quantitative composition of polyphenolic compounds (the sum of polyphenols, flavonoids and tannins) that make up the extracts was determined using physico-chemical methods of analysis. The antioxidant activity of plant extracts has been established. The highest amount of antioxidants (64 mg/100 сm 3 ) was found in extracts from sea buckthorn leaves. Using plant extracts in the composition of gelatin films did not cause significant changes in their thermal stability; it was confirmed by thermogravimetric analysis. Significant changes in properties compared to the control were noted for samples containing sea buckthorn leaf extract. Thus, the value of the stress at break was 11.6 MPa, and the elongation at break was 100% (11.4 MPa and 65% for control, respectively). For all the studied samples, there was a lower water absorption (200–223% after 60 minutes) compared to the control (254% after 60 minutes) and vapor permeability values comparable to the control. Such combination of film properties, with a high content of antioxidants in plant extracts, allows us to consider these materials as promising for the creation of biodegradable packaging films with antibacterial activity.