Properties of extrudates from sorghum varieties

Abstract

Extrusion cooking is a modern high-temperature short-time (HTST) processing technology, which is becoming popular in certain industries because it offers several advantages over other types of cooking processes. The objective of this study was to evaluate the extrusion performance of sorghum (Sorghum bicolor) varieties commonly grown in Uganda. Four varieties of sorghum namely, Seso1, Epuripur, Seso3 and Eyera were extruded with and without defatted soy-flour. Physical-chemical properties of the extrudates including, lateral expansion, bulk density, hardness, water absorption index, water solubility index, as well as proximate composition were determined. The extrudates exhibited 240-300% lateral expansion and 0.067-0.095 g cm-3 bulk density. The water absorption index was 6.4-7.9 g g-1 compared to 1.9-2.3 g g-1 of the control; while the water solubility index was 6.5-13% compared to 3.4-5.0%% of the control. Extrusion of all the varieties reduced the peak and final viscosity of the extrudates. There were no varietal differences with respect to lateral expansion, bulk density and hardness. However, the water absorption index for the varieties increased in the order, Eyera, Seso 3, Seso 1 and Epuripur; while the water solubility index for the varieties increased in the order, Seso 1, Seso 3, Eyera and Epuripur. Defatted soybean flour had no effect on the extrudate properties. The results suggest that the four sorghum varieties in this study can be used in the production of extruded puffed snacks, breakfast cereals and other food
products.

Key Words: Bulk density, extrusion cooking, sorghum, soy-flour