Process Parameters Optimization and Development of Extruded Teff Based Snacks
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Date
2015-03
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Addis Ababa University
Abstract
Protein-energy malnutrition has been identified as one of the problems in East Africa. Attempts have been made to combat this nutritional problem by developing nutritious foods of high protein and energy value from cereal-legume combinations. This study aimed to develop nutritious and sensorial acceptable teff based expanded product using twin screw extruder through optimization of extrusion process variables. Experimental design with barrel temperature (120,140,160°C), feed moisture content (14, 17, 20%) and blend ratio BR1 (70T:20M:10L), BR2 (60T:25M:15L) and BR3 (50T:30M:20L) as independent variables which were three factors at three levels produced 20 different runs. The experimental study was performed using response surface methodology face centred central composite design to investigate the effect of independent variables such as barrel temperature, feed moisture content and blend ratio on products functional properties (water absorption index and water solubility index),physical properties (expansion ratio, specific length),textural property (hardness) and sensory quality. Proximate composition, mineral content, anti-nutritional content and functional properties values for raw materials, blended flour were evaluated and the blended flour was extruded then extrudate proximate composition, mineral and anti-nutritional content, physical, textural, functional properties and sensory quality evaluation were investigated. The maximum expansion ratio (4.85mm/mm), maximum water absorption index (7.80 g/g),minimum bulk density(0.108 g/cm3) and minimum hardness (13.49N) values of the extrudates were observed at 1400C, 14% feed moisture content and 60T:25M:15L blend ratio. Sensory quality evaluation of extrudate produced at 140ºC barrel temperature, 14% feed moisture content and 60T:25M:15L blend ratios with added vanilla powder were significantly (P<0.05) better in colour (8.33 ± 21), flavour (8.35 ±0.76), crispiness (8.33±0.64) and overall acceptability (8.56 ± 0.79).The model developed could be used for designing of extrusion conditions for getting extrudates with desirable physical characteristics.
Keywords: Blend ratio, Extrusion process, Extrudates, Process optimization, Response Surface Methodology, Teff, Twin screw extruder
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Keywords
Blend ratio, Extrusion process, Extrudates, Process optimization, Response Surface Methodology, Teff, Twin screw extruder