Characterization of antioxidant and antibacterial gelatin films incorporated with Ginkgo biloba extract

Abstract

Ginkgo biloba extract (GBE) contains Ginkgo biloba flavonoids, which are phenolic compounds. These compounds can be introduced into films for their functional properties (such as their antioxidant and antibacterial property), allowing this film to be used as food packaging. Thus, the aim of this study was to introduce the GBE into a gelatin solution to prepare gelatin films and evaluate the influence of the natural extract addition on the physicochemical and antimicrobial properties. The gelatin films were successfully prepared by casting technique, and GBE was incorporated at concentrations of 0, 0.5, 1.5, 2.5, 3, 4, and 5 g/100 g of gelatin. The mechanical properties, film solubility, moisture content, water vapor permeability, infrared spectroscopic characteristics, film microstructure, light barrier property, antioxidant property and antibacterial property of the films were investigated. The incorporation of gelatin films with GBE increased the UV-visible shielding performance of films. The antioxidant ability of the film was improved, which was supposed to be related to the active substances of the GBE. The GBE also exhibited potential antimicrobial activity against tested microorganisms. With the increase in the GBE concentration incorporated into the films, the antimicrobial activity of the gelatin film with GBE was also enhanced.

Fig. 1. FTIR spectra of the films. (a) C_GBE = 0 g, (b) C_GBE = 0.5 g/100 g gelatin, (c) C_GBE = 1.5 g/100 g gelatin, (d) C_GBE = 2.5 g/100 g gelatin, (e) C_GBE = 3.0 g/100 g gelatin, (f) C_GBE = 4.0 g/100 g gelatin, (g) C_GBE = 5.0 g/100 g gelatin.

Fig. 2. SEM micrographs of the surface of the films. (1) C_GBE = 0 g, (2) C_GBE = 0.5 g/100 g gelatin, (3) C_GBE = 1.5 g/100 g gelatin, (4) C_GBE = 2.5 g/100 g gelatin, (5) C_GBE = 3.0 g/100 g gelatin, (6) C_GBE = 4.0 g/100 g gelatin, (7) C_GBE = 5.0 g/100 g gelatin.

Fig. 3. Ultraviolet and visible light barrier properties of films. (1) C_GBE = 0 g, (2) C_GBE = 0.5 g/100 g gelatin, (3) C_GBE = 1.5 g/100 g gelatin, (4) C_GBE = 2.5 g/100 g gelatin, (5) C_GBE = 3.0 g/100 g gelatin, (6) C_GBE = 4.0 g/100 g gelatin, (7) C_GBE = 5.0 g/100 g gelatin.

Fig. 4. DPPH radical scavenging activity of films.

Fig. 5. Photographs of the antibacterial activity on two tested strains. (1) C_GBE = 0 g, (2) C_GBE = 0.5 g/100 g gelatin, (3) C_GBE = 1.5 g/100 g gelatin, (4) C_GBE = 2.5 g/100 g gelatin, (5) C_GBE = 3.0 g/100 g gelatin, (6) C_GBE = 4.0 g/100 g gelatin, (7) C_GBE = 5.0 g/100 g gelatin.