Tapioca-fish and tapioca-peanut snacks by twin-screw extrusion and deep-fat frying

Two half-products were prepared from tapioca starch/catfish fillet-belly fl ap mince (60:40) and tapioca starch/partially defatted peanut flour (PDPF) (60:40) by twin-screw extrusion. The process variables were temperature in the last two zones of the extruder (90, 95, 100 degrees C) and screw speeds (100, 250, 400 rpm). Moisture content (40%, wet basis) and feed rate (27 g /min) were held constant. Simultaneously increasing temperature and screw s peed resulted in increased expansion, and decreased bulk density and shear strength. Degree of starch gelatinization in half-products ranged from 87 t o 95%, Optimum conditions predicted by response surface methodology were: f or fish half-products 94-100 degrees C and 220-400 rpm and for peanut half- products, 95-100 degrees C and 230-400 rpm.