Film Casting Formulation and method: Heat 7g absolute ethanol (70 °C), add 1.6g (90%w/w) protein, stir until dissolved. Add 2g distilled water, stir, then add 0.6g plasticizer mixture (1 PEG: 1 glycerol: 1 lactic acid), stir for a further 4 minutes (makes 2 films). Method of casting: 4g casting solution is placed in a petri dish and left overnight on a level surface to set. Final film weight = approx 0.8g.
Film Quality Attributes Tensile properties Water Vapour Transmission
Tensile properties Measure force at break Calculate stress Measure extended distance at break Calculate strain Plot stress against strain Zein 95 Zein 70
Water Vapour Transmission Measure water loss (g) through film with time over a period of 5 days (no control of temperature and Relative Humidity) Calculate Water Vapour Transmission