Single screw extrusion of apple pomace

Response surface methodology was used to investigate the single screw extrusion of apple pomace–defatted soy flour–corn grits blends and the product properties. Five different blends at a level of 0–20% w/w apple pomace were extrusion cooked with varied barrel and die temperature (100–140℃), screw speed (100–200？rpm), and feed moisture content (14–20% wet basis). Increasing apple pomace content in the blends significantly (P？<？0.05) increased the bulk density, the total phenolic content, and the antioxidant activity of the extrudates. The expansion ratio increased with pomace inclusion level of 5% but decreased significantly (P？<？0.05) at higher levels of pomace inclusion (10–20%). Moisture content had quadratic influence on water absorption and solubility indices. Optimal extrusion cooking conditions most likely to produce apple pomace-enriched extruded snack products were at 140℃ barrel and die temperature, 20% feed moisture content, and 200？rpm screw speed. The results indicated active interaction between apple pomace and starch during expansion process