Development and Evaluation of Ready-to-Eat Extruded Snack from Teff Rye and Sorghum
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Date
2014-02
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Addis Ababa University
Abstract
The aim of the research was to investigate the effect of extrusion variables including temperature, screw speed and feed moisture on functional and sensory properties ready-to-eat (RTE) expanded snack from Teff, Rye and Sorghum was investigated. The blends of teff, rye and sorghum flours were extruded in a laboratory scale twin-screw extruder. Experimental design with range of temperature (130 to 180°C), screw speed (130 to 190 rpm) and moisture content (12 to 18%) were taken as independent variables. The combinations were studied using response surface methodology to investigate the effect of variables on product responses (expansion ratio, bulk density, specific length, color (a*, b* and L* values), Water absorption and water solubility index characteristics). Multiple regression equations were obtained to describe the effects of each variable on product responses. When the temperature was increased from 130 to 180 0C expansion ratio increased from (0.80-1.36), water solubility index from (10.68-25.78), a* value from (2.56-4.51) and b* value from (8.06-19.64), but lower bulk density, specific length, water absorption index and L*values was observed at a temperature range of 130-1800C. As the screw speed increases from 130 to 190 rpm; bulk density, specific length, and water absorption index were decreased whereas higher water solubility index was observed and no significant effect on expansion ratio and color values. Increasing feed moisture content resulted in higher a*value (2.56) and b* values (8.06), bulk density, water absorption index and lower expansion ratio, water solubility index, specific length and L*value. Analysis of the sensory data showed significant difference (P<0.05) in the sensory attributes; appearance, flavor and crispness. The color and overall acceptability of the extruded products processed at different temperature and feed moisture were not significantly different. The product processed at 130 0C, 15% feed moisture and 160 rpm showed the highest score in terms of overall acceptability. The outcome of optimization study revealed that at a temperature (180°C), screw speed (190 rpm) and feed moisture (12%) acceptable ready-to-eat extruded snack was produced.
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Keywords
Ready to Eat snack, Rye, Sorghum, Response surface methodology, Twin screw extrusion, Teff