Physico-chemical and sensory quality of extruded light red kidney bean (Phaseolus vulgaris L.) porridge

A laboratory co-rotating twin-screw extruder was used to study the effect of extrusion conditions on physical, chemical, and sensory characteristics of extruded light red kidney beans (Phaseolus vulgaris L). Raw bean flour was extruded at 25 g/100g and 36 g/100g moisture content. Other extrusion parameters were: barrel temperatures, 120 °C/105 °C (BT-1) and 130/115 °C (BT-2); screw speeds, 118 rpm (SS-1), 194 rpm (SS-2), and 253 rpm (SS-3); and feed rates of 80 and 120 g/min (FR-1 and FR-2, respectively). Extrudates were analyzed for expansion ratio (ER), bulk density (BD), water absorption index (WAI), water solubility index (WSI), and lectins, as phytohemagglutinin (PHA) activity. Sensory evaluation of bean porridge, obtained after coarsely grinding extrudates, was done to compare it to Sosuma, a traditional Rwandan porridge. Feed rate significantly influenced average ER, which was determined to be 1.22 and 1.30 for FR-1 and FR-2, respectively. Increasing moisture content from 25 g/100g to 36 g/100g significantly increased average BD. The WAI and WSI values did not show a clear trend under extrusion conditions used in this study. For all extruded samples, lectin was reduced to less than one-tenth of that in the raw beans. Sensory evaluation of bean porridge, on a 1-9 hedonic scale (1 = dislike extremely and 9 = like extremely), exhibited scores of 7.65, 7.69, 6.25, and 6.94 for color, texture, flavor, and overall acceptability, respectively.