Effect of drying rate on the physicochemical properties of soy protein isolate-soy oil emulsion films

The effect of drying rate on physicochemical properties of emulsion films prepared from soy protein isolate (SPI) and soy oil was investigated. No changes were observed in emulsion micromorphology during 60 min of drying at a rate of 0.05 g s-1 m- 2, whereas the emulsion droplet size increased with the drying rate. Phase separation was formed in emulsion films prepared at drying rate of 0.05 g s-1 m- 2, but it vanished with increased drying rate. Tensile strength (TS) and elongation at break (EAB) of films prepared at drying rate of 0.05 g s-1 m- 2 were 7.95 MPa and 47.58%, respectively. No change was observed in TS with increased drying rate, whereas EAB increased first and then decreased. When the drying rate increased, the water vapor permeability, contact angle, and thermal stability of films increased, whereas the opacity value and infrared peak intensities that represent oil on film's upper surfaces decreased.