ENERGY CONSIDERATIONS ON EXTRUSION OF TARHANA, A WHEAT FLOUR BASED PRODUCT
Tarhana, a traditional Turkish cereal food, was extruded using a twin-screw extruder. The effect of the changes in barrel temperature (60–120C), feed rate (10–20 kg/h, wet basis) and screw speed (100–300 rpm) on the mechanical and thermal energy inputs was investigated. Energy balances showed that increasing barrel temperature tends to reduce the contribution of heat energy converted from the mechanical energy (ME) to the total heat energy absorbed by tarhana. The use of high-screw speeds at relatively high barrel temperatures and at low feed rates is not suitable from an energy point of view because only a small portion of the ME introduced into the system is absorbed by tarhana. It is concluded that higher barrel temperatures, lower screw speeds and higher feed rates are more suitable for economic tarhana extrusion. PRACTICAL APPLICATIONS
Traditional batch method of tarhana production is not automated with manufacturing capacities being low and highly labor extensive. Developing tarhana using extrusion cooking would allow tarhana to be produced at a lower cost because of more efficient use of energy and greater process control; production capacity would be greater, and quality control could be more easily monitored, leading to a standard product. Moreover, an easier preparation of instant tarhana soup would facilitate its usage at home for households and in school, hospital and military canteens. Investigating the energy changes during tarhana extrusion could lead to a clearer understanding of tarhana extrusion from an engineering point of view.
Document Type: Research Article
Affiliations: Department of Food TechnologyThe Manchester Metropolitan UniversityManchester, U.K.
Publication date: June 1, 2010