Effect of Processing Conditions and Optimization of Gluten Free Lentil-Corn Blend Extrudates

No Thumbnail Available



Journal Title

Journal ISSN

Volume Title


Addis Ababa University


An expanded food product was obtained from lentil -corn flour mixtures by extrusion cooking. Effects of cooking temperature; blend ratio and moisture contents of the feed mixture were investigated. Effects of these functional properties on expansion ratio, WAI, WSI, WHC, sensory properties and bulk density were assessed. Specific blends of Lentil and corn were subjected to twin screw extrusion process with the objective of enriching the protein and mineral content of corn and produce a range of extruded products. The proportions of lentil and corn were selected using a unique 15-run, three-factor, and three-level using Response Surface Methodology (RSM). The lentil flour addition was maintained at 10%, 30% and 50% to test the effect of protein addition to the cereal or (corn) maintained at 50%, 70% and 90% on the physical properties of the extruded products. Extruded products were obtained using a co-rotating twin screw extruder under operating conditions optimized in a previous study. In general, proportion of ingredients induced significant changes in the product quality attributes evaluated. Blends with higher proportion of lentil and lower proportions of corn showed a significantly (p < 0.01) lower specific length value. It was demonstrated that lentil has good potential for making good extruded products with rich in protein and fiber. 47.8% lentil flour, 52.2% corn flour (db) processed at 15.82% moisture content and 181.97°C temperature was selected as the best formulation to yield a protein rich extruded product with desirable physical and functional attributes. The product was fully expanded and well cooked with almost uniform in sizes and shapes at these optimum conditions. The extruded snacks were evaluated and determined for its quality attributes such as chemical composition, physical and functional properties, sensory qualities and textural properties. Values of physical properties of extrudates obtained: expansion ratio were in the range of 1.08- 1.43 and bulk density were 0.36-0.54 gm/cm3 and specific length 1.09-3.90 cm/gm and of functional properties obtained:WAI were 4.11-8.23%, WSI were 6.41-11.74% and WHC were 2.64-8.83%. Over all acceptability is in the range of 4.7-8.24.The textural data were evaluated by breaking strength test with the help of cylindrical probe TA-XT whose values indicates between 0.4 to 0.80 N/mm2. The sensory scores of the extruded products had a mean value greater than 5, and rated acceptable by sensory panels. Keywords: Extrusion physical properties, Optimization, Response Surface Methodology, lentil, corn.



Extrusion physical properties, Optimization, Response Surface Methodology, lentil, Corn