Soy protein isolate (SPI) plastic extrudates (Figure) were made by extrusion. The effect of methyl cellulose on the mechanical property and water absorption was investigation. SPI (10 parts), H₂O (4-8 parts), glycerol (2 parts) and methylcellulose (0 or 2 parts) were thoroughly mixed. After 12 hours, the compounding was extruded with a twin - screw co-rotating extruder (American UNIAX CORPORTION І). With the moisture contents increasing, SPI plastic extrudates displayed properties from rigid to soft. After being submerged in water for 24 hours, the SPI plastic extrudate without methylcellulose (sample 1) absorbed up to 180% water. With the presence of two parts of methylcellulose, water absorption of the SPI plastic extrudates (samples) decreased by 30%. And the Tensile strength (TS) of samples increased 3 times, simultaneously, the percent of elongation at break decreased by 28%.

Figure  The samples of SPI plastic extrudates with methylcellulose

 Acknowledgment

We gratefully acknowledge the financial support from the NSFC (project 50573025 and 20436020)