Edible film fabrication modified by freeze drying from whey protein isolate and sunflower oil: Functional property evaluation

The objective of the study was to simplify the composite film fabrication process. Different sunflower oil (SO) concentrations, 0.05, 0.10 and 0.15 (g/100 mL) were incorporated into whey protein isolate (WPI) matrix. The obtained WPI-SO solutions were dried using a freeze dryer to get a new composite powder. The powder was just mixed with water and glycerol; then it was cast to form WPI-SO based edible films. The effects of freeze drying and SO concentration on the optical, physical, thermal, barrier, mechanical and morphological properties of the novel WPI films were investigated. It was observed that films formed from reconstituted powder had enhanced barrier properties. Oil incorporation into the film matrix resulted in decreased lipid droplet size and increased opacity. In conclusion, edible films were produced successfully with improved functional properties. This situation proved that film production method, modified with freeze drying, has promising potential for biodegradable packaging industry.