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

• Gelatin films incorporated with corn oil were manufactured using a twin-screw co-rotating extruder.
• The effect of extrusion temperature and film forming pH values on the properties of composite films were investigated.
• Both barrel temperature and pH values of film forming solutions played major roles in determining the final properties of 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 °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 °C improved (P < 0.05) the tensile strength (TS) of films. Increasing temperature to 120 °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.