Abstract: Monoglyceride and glucose were added to the film-forming solution respectively while making soy protein isolate (SPI) film. The mechanical properties were tested after the films were stored at room temperature for 2 d or under frozen condition for 7 d. Both tensile strength (TS) and percent of elongation at break (E) were affected as the substances were added. Compared with the SPI film control, the TS of monoglyceride-containing SPI film increased more than 25%, while the E changed very little. The TS of glucose-containing SPI film increased 35% and the E increased 55%. Freeze storage has different effects on these SPI films. The mechanical properties of glucose-containing SPI film were impaired by frozen, with an average decrease of 50% in TS, while in other cases, freeze storage had no significant influence, which implied that such SPI films would have potential application in food packaging for frozen products.

Key words: soy protein isolate film, monoglyceride, glucose, freeze storage