Effect of green propolis extract on functional properties of active pectin-based films

Green propolis is an attractive natural source of antioxidant and antimicrobial compounds. In this paper, pectin (P) films incorporated with green propolis extract (PE) (i.e., P/PE films) were prepared by casting. The effect of different PE concentrations (1–3% w/w) on films' physicochemical properties was investigated for the first time. Regardless of the PE concentration added, no significant morphological and structural changes of the P-based films were identified using scanning electron microscopy (SEM) and Fourier-transform infrared spectroscopy (FT-IR) analysis. However, a reduction in the crystallinity of the P films was observed through the X-ray diffraction (XRD) analysis, which was correlated to film tensile strength (TS) reduction from 19.0 (P film) to 14.8 MPa (P/PE3% film). The other mechanical and water vapor barrier properties did not change significantly. However, the incorporation of PE improved UV-light barrier properties of the P films. Additionally, antioxidant activity of the P films (12.6%) considerably increased to 54.8% (P/PE3% film), suggesting the potential of P/PE film to be used as active food packaging.