Abstract: This study was conducted to determine the effect of ferulic acid on selected properties of glycerol-plasticized soyprotein isolate (SPI) films. Films were plate casted from heated (80℃ for 30 min) neutral or alkaline aqueous solutions of SPI(5g/100 ml water) , glycerol (2.5g), and ferulic acid (0, 100, 200, 300mg), and dried in an oven at 50℃. Tensile strength (TS),percent of elongation at break (E) , color values ( L, a, and b) , and water vapor permeability (WVP) were examined afterconditioning film specimens at 25℃ and 52% relative humidity (RH) for 2d. The use of ferulic acid resulted in the increase inboth E and TS to different extents at different pHs. The addition of ferulic acid made it possible to prepare SPI films from neutralfilm-forming solutions: compared with control films without ferulic acid, the addition of 100～300mg ferulic acid resulted in anincrease of TS from 62.5% to 94.3%, and an increase of E from 24.2% to 54.4%. Increased darkness, redness and yellowness asevidenced by smaller L values and greater +a and +b values were noted for films with high amounts of ferulic acid. Nodistinguished positive effect of ferulic acid on the WVP of the films was found.

Key words: soy protein isolate (SPI), ferulic acid, film, mechanical properties, water vapor permeability (WVP), colour