Physical and antioxidant properties of an active film from chitosan incorporated with wheatgrass (Triticum aestivum L.) extract

Abstract

A new type of environmentally friendly active film from chitosan with the addition of glycerol 20% (w/w) and wheatgrass extract (WGE) with different concentrations of 3%, 6% and 9% was developed. The physical, antioxidant and mechanical properties of films were evaluated. The results suggested that the presence of WGE in chitosan films made the films denser due to the interaction between substances in WGE with chitosan. These changes resulted in the improvement of water vapor permeability properties (with the value of 1.03 g mm m-2 d-1 kPa-1 at 9% WGE). The addition of WGE into chitosan-based films also significantly affected the color and chlorophyll content (increase up to 8.87 mg chlorophyll/ g film). The mechanical properties of films showed that the films became more flexible when incorporated with WGE. In addition, the total phenolic content and antioxidant activity of WGE-embedded films significantly enhanced (p<0.05) approximately 18 times and 6 times, respectively, compared to the those of the control and 20%-glycerol films. Fourier transform infrared (FTIR) spectrometry and scanning electron microscopy (SEM) were carried out to observe the potential modifications in chemical structure and microstructure of the films. The changes in their FTIR spectra suggested that certain interactions between chitosan and the polyphenols from WGE occurred. SEM images showed that the incorporation of glycerol improved the smoothness of films and WGE was well dispersed in the film matrices. This study proved the benefits of WGE incorporation into chitosan films and its potential in the development of active packaging. Key word: active packaging, chitosan film, wheatgrass, antioxidant, phenolic