Development of antioxidant edible films based on mung bean protein enriched with pomegranate peel

In this study, mung bean protein films enriched with different concentrations (0, 2.5, 12.5, and 25% w/w based on protein content) of pomegranate peel as a rich source of bioactives were prepared and characterized. The incorporation of pomegranate peel increased the thickness, water vapor permeability, water contact angle, tensile strength, and flexibility of the films, but decreased their solubility and moisture content. The color parameters (L*, a*, and b*) of mung bean protein film were significantly affected by the addition of pomegranate peel. The surface and cross-section of films were further studied using scanning electron microscopy (SEM). In addition, observations made by Fourier transform infrared (FT-IR) spectroscopy suggested the formation of hydrogen bonds in the film matrix. X-ray diffraction (XRD) analysis confirmed that the amorphous nature of mung bean protein film was not affected by enriching with pomegranate peel. The films enriched with pomegranate peel also showed higher total phenolic content, antioxidant activity (measured by ABTS and DPPH radical scavenging and reducing power), and antibacterial capacity compared to the control mung bean protein film. Generally, the results emphasized the potential use of mung bean protein and pomegranate peel as by-products of food industry to develop bio-functional edible films intended for packaging of food products.