Investigation of the structural and physical properties, antioxidant and antimicrobial activity of pectin-konjac glucomannan composite edible films incorporated with tea polyphenol

Composite edible films of pectin (PEC) and konjac glucomannan (KGM) were incorporated with tea polyphenol (TP) to develop active food packaging. The effects of 1%-5% TP (w/w, on a dry basis of the weight of PEC and KGM) on the structural and physical properties, antioxidant and antimicrobial activity of the resultant PEC/KGM films were systematically evaluated. Fourier transform infrared (FTIR) spectroscopy and scanning electron microscopy (SEM) suggested the good compatibility of the components and the well-dispersion of TP in the matrix, due to the occurrence of hydrogen-bonding among them. The incorporation of TP significantly improved the antioxidant and antimicrobial activity of the films, while induced decreases in the transmittance, moisture content and elongation at break. In particular, addition of TP at appropriate levels remarkably increased the mechanical and water-resistant properties of the films. For example, the tensile strength and contact angle value of the films with 2% TP increased by 5.28 MPa and 18.93 degrees, respectively. However, overloading of TP in the composite films might produce some aggregations and thus have negative effects on their performance. In sum, the developed PEC/KGM/TP films possessed the potential to be applied as bioactive materials in food packaging sectors.