Development and sensory properties of extruded sorghum-based gluten-free pasta

Pasta is one of the most consumed staples worldwide. New formulations incorporating novel nutritious ingredients are now common in its production. The purpose of this study was to formulate, optimise and evaluate the sensory properties of sorghum-based extruded gluten-free pasta. Sorghum flour, pearl millet flour, high-iron bean flour (Biofortified NUA 45 beans) and Hermes potato flour were evaluated for proximate and micronutrient composition, formulated to produce pasta through the extrusion process. Three sorghum-based pastas, namely sorghum high bean pasta (SHBP), sorghum bean pasta (SBP) and sorghum high potato pasta (SHPP) were produced and evaluated for sensorial properties (visual, palpatory and gustatory qualities). The Box-Benhken Design (BBD) in conjunction with Response Surface Methodology (RSM) was used to select the best formulation by evaluating cooking quality parameters and sensory parameters. The protein content in the four flours ranged from 10.52% to 22.00%. NUA 45 bean flour had significantly (p<0.05) higher protein content than the other flours. Potato flour had significantly higher carbohydrate content (73.82%) than other flours. SHPP had a significantly (p<0.001) higher optimum cooking time (7 minutes) than SHBP (5 minutes) and SBP (6.2 minutes). SHPP had significantly (p<0.001) higher water absorption (WA) capacity (238%) than pasta SHBP (190%) and SBP (210%). A significant (p<0.001) difference in the swelling index (SI) of the three pasta samples was observed, with pasta SHBP having a significantly lower SI (1.02%) than pasta SBP (1.15%) and pasta SHPP (1.24%). The cooking loss (CL) for pasta SHPP (11%) was significantly higher (P<0.001) than for pastas SHBP and SBP, with pasta SHBP having the lowest CL. There was no significant (p>0.05) difference in the cross-sectional area, surface appearance and surface property of the three cooked pastas. A significant (p<0.05) difference in shape between SHBP and SBP samples was noted. The gluten-free pasta was developed and produced successfully. Sorghum high bean pasta treatment (SHBP) was found to be superior in terms of sensory, nutritional and physical properties as compared to the other pasta samples, making it good for commercialisation.