2014 Volume 20 Issue 3 Pages 517-527
In this study, hairtail surimi (HS) and soy protein isolate (SPI) blends were extruded using a co-rotating twin-screw extruder. The effects of feed moisture, screw speed, and barrel temperature on the texture and water-holding capacity of the extrudates were investigated using response surface methodology. HS and SPI were mixed at a ratio of 1:4; the screw speed was tested at three levels between 80 and 120 rpm; the barrel temperature was set between 140°C and 160°C, and the feed moisture was set between 30% and 50%. The digestibility and microstructure of the extrudate produced by optimum condutions were also studied. The results demonstrated that the physical properties were significantly (p < 0.05) affected by the three process variables. Water-holding capacity and extrudate texture were found to mainly depend on barrel temperature and feed moisture, respectively. In vitro protein digestibility of the blends was improved by the extruding process.