Chromophores modified porous clay heterostructures for smart packaging films

Abstract

Smart packagings for detecting fish and climacteric fruit freshness were prepared based on polypropylene/chromophores (methyl red) modified functionalized porous clay heterostructure (PCH) nanocomposite films and low-density polyethylene/chromophores (bromothymol blue) modified PCH nanocomposite films, respectively. The incorporation of chromophores in porous materials was investigated by N2 adsorption-desorption, XRD and SEM. The nanaocomposite was prepared by twin screw extruder and fabricated into nanocomposite film by compression molding. The color change of PP/APPCH-MR nanocomposite films from red to light orange corresponded to the total volatile basic nitrogen releasing during fish spoilage. The color change of LDPE/PCH-BTB nanocomposite films from green to yellow correlated with standard CO2 levels, which can be compared to CO2 levels from respiration during fruit ripening. Porous clay improved the barrier properties of nanocomposite indicated by the reduction of oxygen transmission rate. Thus, PP/APPCH-MR nanocomposite films could be used to determine fish freshness and LDPE/PCH-BTB nanocomposite films can be applied for detecting the quality of climacteric fruit by color change. Moreover, both pH indicators can prolong the shelf-life of product by incorporated porous materials into the films.