Heat curing of soy protein films at atmospheric and sub-atmospheric conditions

The effect of heat curing at atmospheric or subatmospheric conditions on selected properties (moisture content, water vapor permeability (WVP), color, tensile strength (TS), elongation (E), and total soluble matter (TSM) content) of cast soy protein isolate films was investigated. Films were heat cured at 85degreesC for 6, 12, 18, or 24 h at absolute pressures of 101.3, 81.32, or 61.32 kPa. Heat-cured films had increased (P < 0.05) TS and decreased (P < 0.05) WVP and E compared to control, unheated films. Heat treatment under vacuum reduced the WVP of films faster than heat curing at atmospheric pressure. High TS values, low E values, and low TSM values were also reached within short heating time tinder vacuum. However, vacuum treatment increased the size and number of cavities in cured films as evidenced by scanning electron micrographs.