Extrusion of gelatin-based composite films: Effects of processing temperature and pH of film forming solution on mechanical and barrier properties of manufactured films

The composite films, gelatin incorporated with corn oil were manufactured using a twin-screw co-rotating extruder. The effect of extrusion temperature (90, 105, 120 and 130 degrees C) and film forming pH values (5.7-8.7) on the mechanical and barrier properties of gelatin-based composite films were investigated. Increasing the temperature from 90 to 130 degrees C improved (P < 0.05) the tensile strength (TS) of films. Increasing temperature to 120 degrees C improved (P < 0.05) water vapour permeability (WVP) values of gelatin-based composite films; however, this was accompanied by a decrease (P < 0.05) in gas barrier properties. Additionally the use of film forming solutions possessing high pH values improved the mechanical properties of films and caused a decrease (P < 0.05) in oxygen permeability. Neither temperature nor pH had any significant effect on the seal strength for any of the gelatin-based composite films manufactured. Confocal laser scanning microscopy (CLSM) results showed a corresponding increase in the number of oil droplets when processing temperature increased. (C) 2014 Elsevier Ltd. All rights reserved.