Moisture dependent physical properties of dehusked unsplitted pigeon pea

Abstract

Pigeon pea (Cajanus cajan, L.) is an important legume crop in semiarid tropics generally consumed as dried peas for making dhal, flour or green vegetable peas. Dehusked unsplitted pigeon pea also called gota are obtained during the primary processing for making dhal. Hence, the knowledge about the physical properties of gota is important for designing processing machineries. In this regard, the study of the physical properties of gota (dehusked unsplitted pigeon pea) in the moisture content range of 10.2–28.2% d.b. was conducted. Five different levels of moisture content in the above range were selected. The average length, width, thickness, arithmetic mean diameter, geometric mean diameter, sphericity surface area, volume, thousand seed weight, bulk density, true density, porosity, angle of repose and coefficient of friction on plywood, mild steel and galvanized iron were determined in this moisture range. The values of average length, width, thickness, arithmetic mean diameter, geometric mean diameter, sphericity and surface area varied from 5.33 to 5.43mm, 4.39 to 4.45mm, 3.93 to 3.77mm, 4.51 to 4.55mm, 4.88 to 4.5mm, 0.858 to 0.828 and 63.29 to 63.73mm2 respectively. At the given moisture levels, volume, thousand seeds weight ranged from 38.41 to 40.77mm3, 61.94g to 68.93g in the same moisture range, the bulk density and true density decreased linearly from 859.5 to 781.7 kg/m3 and 1306.6 to 1128 kg/m3 respectively and porosity decreased non linearly from 34.22 to 30.2%. The static coefficient of friction of gota over different materials, namely plywood, mild steel and galvanized iron increased linearly from 0.4491 to 0.8405, 0.4789 to 0.7882 and 0.2851 to 0.6775 respectively. In the selected moisture range, the angle of repose increased from 28.35° to 36.72°.