The objective of this study was to determine the effect of moisture contents (40, 50, 60%) and CO2 gas injection (0 and 800 mL/min) on physicochemical properties of extruded soy protein isolate (SPI). The expansion ratio and specific length at 40 and 50% moisture contents with CO2 gas injection increased while piece density decreased. On the contrary, the expansion ratio and specific length of extruded SPI at 60% moisture content with CO₂ gas injection decreased while piece density increased. Extruded SPI with CO2 gas injection had small cell size and higher amount of cell than extruded SPI without CO2 gas injection. The water holding capacity and nitrogen solubility index increased with CO2 gas injection increased while the integrity index and the springiness and cohesiveness decreased. In conclusion, extruded SPI with CO2 gas injection showed better expansion properties and cell formation than extruded SPI without CO2 gas injection.

• Gihyung Ryu(Department of Food Science and Technology, Kongju National University, Korea)
• Nayeong Kim(Department of Food Science and Technology, Kongju National University, Korea)