Effects of extrusion variables and starch modification on the puffing characteristics of yam (Dioscorea alata) flour

Abstract

The viability of extruding yam flour and the effects of extrusion temperature, feed moisture content, particle size and added amylose or amylopectin on the puffing characteristics were investigated. Extrusion temperature <1OO°C, feed moisture content > 10% and any level of added amylose depressed product expansion. Product firmness and density decreased with increasing extrusion temperatures but increased with increasing feed moisture content above a critical limit of 9%. In general, feed particle size and addition of amylopectin did not affect the characteristics of yam flour extrudates. Yam flour can be successfully extruded with maximum expansion at a feed moisture range of 8-10% using extrusion temperatures of 100-115°C