Biodegradable protein films from gallic acid and the cataractous eye protein isolate

Abstract

Films have been prepared from the natural antioxidant gallic acid and a proteinaceous source, the discarded emulsion obtained after cataract surgery referred to as the cataractous eye protein isolate (CEPI). Fourier transform spectroscopy (FTIR) and SDS PAGE studies confirmed the crosslinking of gallic acid with CEPI. The cross-section and surface of films were further characterized by scanning electron microscopy (SEM). The decrease in crystallinity of the films was confirmed by X-ray diffraction studies. The thermal property of the films is enhanced by the addition of gallic acid as evidenced from the Thermogravimetric analysis (TGA) studies. Films having 2% (w/w) gallic acid exhibited the maximum tensile strength of 2.88 ± 0.32 MPa comparable to other cross-linked films such as soy, casein, canola based protein films. The light barrier property of the films improved with incorporation of gallic acid. The cross-linked films were degraded by the application of the enzyme trypsin. The films also showed good antioxidant properties as determined from the 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay. The gallic acid incorporated nontoxic CEPI films are biodegradable and possess appreciable mechanical properties and could find use in diverse applications including pharmaceuticals.