Physical and Engineering Properties of Some Nigerian Sweet Potato Roots [Ipomoea Batatas (L.) Lam

Abstract

Several varieties of sweet potato are being cultivated by many countries of the world including Nigeria. Data on physical and engineering properties required for the design and fabrication of handling and processing equipment for these important horticultural produce are either few or non-available. In this study the proximate composition and several physical and engineering properties of four popular varieties of Nigerian sweet potato (size, shape, mass, weight, volume, surface area, density, sphericity, latent heat, specific heat, thermal conductivity, thermal diffusivity) were determined using standard procedures. The surface areas for orange fleshed sweet potato (OFSP), yellow fleshed sweet potato (YFSP), purple fleshed sweet potato (PFSP) and white fleshed sweet potato (WFSP) are 2.36±0.30, 2.92±0.29, 2.43±0.41 and 1.97±0.19 (×104 mm2 ) respectively. The geometric mean diameter obtained are 82.02±5.43, 95.17±4.61, 84.33±8.27 and 77.03±4.02 mm for OFSP, YFSP, PFSP and WFSP respectively. The values for sphericity were OFSP, 54.15±3.00; YFSP, 55.82±4.55; PFSP, 59.31±4.15 and WFSP, 54.75±1.58 %. The latent heat ranged between 198.08±0.71 and 272.10±0.33 KJKg-1. Orange fleshed sweet potato had the highest thermal conductivity of 0.55±0.001 Wm-1K-1.while purple fleshed and white fleshed sweet potato had the lowest value of 0.44±0.001 Wm-1K-1. The specific heat capacity values were OFSP, 3.69±0.03; YFSP, 3.18±0.01; PFSP, 3.11±0.01 and WFSP, 3.11±0.02 KJ Kg-1K-1. Properties such as major diameters, intermediate diameters, sphericities, aspect ratio, unit volume, unit mass and unit weight were found not to be statistically different at P ≤ 0.05 ±SD.