Effect of pH on functional, gas sensing and antimicrobial properties of bio-nanocomposite gelatin film for food packaging application

A bio-nanocomposite film is a polymer blend with nanofiller dispersed in a biopolymer matrix. The aim of this study is to investigate the functional, gas sensing and antimicrobial properties of bio-nanocomposite films incorporated with chicken skin gelatin/ tapioca starch/zinc oxide at different pH levels (pH 4, 6, 7 and 8). Bio-nanocomposite films were prepared using a casting technique followed by the characterization of their functional, gas sensing and antimicrobial properties. Film formulations with pH at different levels showed increased thickness, colour and water vapour permeability (WVP) (p < 0.05). In addition, the increase of pH in films in chicken skin gelatin bio-nanocomposite films increased the tensile strength (TS), while decreasing the elongation at break (EAB). The highest response for ammonia gas in chicken skin gelatin bio-nanocomposite films was obtained at pH 7, with quick response time (τres) within 10 s. The inhibition zone of Staphylococcus aureus in chicken skin gelatin bio-nanocomposite films increased with increasing pH levels. Overall, chicken skin gelatin bio-nanocomposite films with a pH level of 8 were found to have the optimal formulation, with the highest values in thickness, and TS, with the lowest values for WVP and EAB. In conclusion, bio-nanocomposite chicken skin gelatin films with an alkaline pH are a superior packaging material.