Biosystems Engineering (2005) 92 (3), 325–334 doi:10.1016/j.biosystemseng.2005.07.011 PH—Postharvest Technology Some Physical Properties of Balanites Aegyptiaca Nuts N.A. Aviara; E. Mamman; B. Umar Department of Agricultural Engineering, University of Maiduguri, Maiduguri, Nigeria; e-mail of corresponding author: nddyaviara@yahoo.com (Received 21 September 2004; accepted in revised form 21 July 2005; published online 3 October 2005) The physical properties of Balanites Aegyptiaca nuts were determined as a function of moisture content. Two varieties of the nut, namely one end tapered oblong variety A and spheroidal variety B, were identified. At the moisture content of 472% (d.b.) for the oblong nuts, measurements yielded an average maximum diameter of 150mm, and length of 289mm. The corresponding values for the kernels were 101 and 182mm, respectively. For the spheroidal nuts, the major and minor semi-axial dimensions averaged 136 and 80mm, respectively. The corresponding values for the kernels were 82 and 53mm, respectively. The kernels constituted about 2263% of the oblong nuts and 24% of the spheroidal nuts by mass. In the moisture range of 472–2635% (d.b.) the one thousand nut mass of the oblong nuts, the particle density and porosity increased from 239 to 333kg, 92248 to 99274kgm 3 and 4186% to 4746%, respectively. The bulk density decreased from 53635 to 52160kgm 3 , while the static coefficient of friction on different structural surfaces and angle of repose increased from 0194 to 0577 and from 22361 to 33661, respectively. For the spheroidal nuts in the moisture range of 471–2418% the one thousand nut mass, particle density, porosity, static coefficient of friction on different structural surfaces and angle of repose increased from 226 to 311 kg, 964 to 105201kgm 3 , 4410% to 4937%, 0194 to 0504 and 22841 to 32971, respectively. The bulk density decreased from 54690 to 53266kgm 3 . r 2005 Silsoe Research Institute. All rights reserved Published by Elsevier Ltd 1. Introduction Balanites Aegyptiaca also known as desert date in English, and ‘adua’ in Hausa (Hall & Walker, 1991), is an important tree crop of the Sudan savannah zone and semi arid tropical region of Africa. The leaves are used as food, the bark as a substance for fishing and the wood as yoke for draught animals and hand implements. Two varieties of the tree with fruit, nut and kernel shapes that corroborate the findings of Launert (1963) are common in North Eastern Nigeria. The flesh of the ripe fruit, which is very rich in carbohydrate and vitamins, is eaten, but the tree is mainly important for its nut that is also known as stone (Shanks & Shanks, 1991). The nut is obtained after the removal of the flesh and pulp of the fruit and it contains a kernel with oil content and protein contents ranging from 30% to 60% and from 20% to 30%, respectively. The oil is good for cooking as it has an acceptable scent and taste (Hall & Walker, 1991), and does not smoke excessively when heated (Shanks & Shanks, 1991). It has been found to have potential for industrial applications as raw material in the manufacture of soap, candle, chemicals and cosmetics as well as pharmaceu- tical products. The kernel meal remaining after oil extraction can be used as livestock feed (Abu-Al-Futuh, 1983). The processing of Balanites Aegyptiaca fruit involves soaking it in water for 3 days and washing off the pulp to obtain the nut. The nut is sun-dried for several hours and the kernel is obtained from it by cracking with stone on top of another stone or a hard flat surface. Oil is extracted from the kernel by heating its meal in a pan over an open fire or boiling it in a pot containing water. Of all the operations involved, the cracking of nuts presents the most onerous task and risk. Improved methods of handling and processing the nuts using suitable machines and equipment can be developed if the physical properties are known. Aviara et al. (1999) noted that the moisture-dependent char- acteristics of the physical properties of agricultural ARTICLE IN PRESS 1537-5110/$30.00 325 r 2005 Silsoe Research Institute. All rights reserved Published by Elsevier Ltd