Mechanical properties of protein-stabilized starch-based supercritical fluid extrudates.

Mechanical properties of starch-based supercritical fluid extrusion (SCFX) extrudates were correlated to their structure. Thermosetting ingredients were added to the feed and the extrudate was dried to set the expanded structure. Compared to whey protein concentrate with 34% protein (WPC-34), addition of egg white (EW) gave a softer skin and a fragile but well formed cellular structure. For drying between 70 and 100 degrees C, the overall structure was more homogenous for EW added. A higher modulus was associated with a larger number average of sides in a cell face and higher percentage of closed cells. Ashby's model (1983) for non-food cellular solids gave a good fit to our data for relating relative compressive modulus to relative bulk density. A linear regression model indicated that bulk density alone was a good predictor of mechanical strength.