Cassava flour was extruded by varying parameters of feed moisture; temperature; screw speed and feed rate. We investigated significance of each variable and interactions between variables on each extrudate characteristic. Optimum expansion (2.82) was at 11% feed moisture 120-125 "C; screw speed, 520rpm; feed rate, 250g/min. Effect of feed moisture was most significant on expansion, bulk density and extrudate moisture. Increasing temperature, increased expansion and water solubility, but decreased bulk density, extrudate moisture and water absorption. Screw speed most influenced water absorption and solubility. Extrudate moisture correlated negatively (PcO.01) with extmdate expansion. Water solubility index of extrudate negatively correlated (PcO.05) with extrudate moisture and water absorption index but correlated positively (pcO.05) with expansion.

Cassava flour (Man&r esculenta Crantz) was texturized by singlescrew extrusion processing. Relationships between texture and microstructure as a function of extrusion variables were examined. The effect of feed moisture or screw speed was significant (P < 0.01) on all textural parameters except springiness and energy first bite. Hardness, gumminess (P < 0.05) fracturability and cohesiveness (P < 0.01) decreased with increasing temperature. Hardness, fracturability and firmness were lowest at screw speed 520 rpm with feed rate fOOg/min, 120-125'C and 11% feed moisture. Scanning electron micrographs showed structural change from a coarse cell mass at high feed moisture to a porous, thin-walled structure with decreased feed moisture.

Adding soybean flour, soybean oil and wheat bran to cassava flour increased the percentage of crude protein/fat and crude fiber respectively in the blends. Crude protein or extrudate correlated negatively (P

Blends of cassava flour with cassava starch or amylose were processed on a Wenger X-5 laboratory extruder. Cassava starch added to cassava flour increased total carbohydrate in feed, reducing yellow color, water absorption and extrudate bulk density but increased expansion, product moisture, water solubility and total reducing sugars. Amylose addition increased extrudate surface regularity with reduced water solubility, total reducing sugars, and bulk density. Expansion was highest in mixtures containing 60% amylose. Textural properties of extrudate increased on addition of amylose or cassava starch. Differences in microstructures existed between cassava flour and cassava starch extrudate.

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