Abstract

The effect of process variables (feed composition, feed moisture, and exit barrel temperature) on the vitamins, antinutrients, and sensory profile of extruded snacks produced from sorghum and charamenya flour blends using response surface methodology were investigated in this study. Feed composition (FC, 10-30%), feed moisture content (FMC, 25-30%) and exit barrel temperature (EBT, 110-130°C) were the independent process variables considered while vitamins, anti-nutrients and sensory evaluation were the response variables. Flour produced from sorghum (SF) and charamenya (CF) seeds were blended in the ratio of 3.2:96.8, 10:90, 20:80, 30:70 and 36.8:63.2%. The blends were conditioned to desired moisture content and allowed to equilibrate overnight in a refrigerator (4°C). Feeding temperature, cooking temperature, screw speed, and pressure of the extruder were set at 90 and 100°C, 250 rpm, and >300 psi, respectively. Extruded snacks from each run were collected when steady state extrusion conditions were attained and dried overnight at 40°C in a cabinet dryer. The vitamins (A, B₁, B₂, B₆, B₁₂, C, and D) and antinutrients (phytate, oxalate and tannin) content reduced post extrusion when compared with the flour blends prior to extrusion. They were significantly (p<0.05) affected by FC, FMC, and EBT.  There were also observed significant (p<0.05) differences in the sensory scores of all the attributes tested except flavor (p>0.05), indicating the extrusion process’s ability to reduce the beany flavor associated with legumes.

Key words: Extrusion, snacks, micronutrient, antinutrients, sensory, cereal-legume.