International Journal of Research in Engineering and Science (IJRES) ISSN (Online): 2320-9364, ISSN (Print): 2320-9356 www.ijres.org Volume 3 Issue 1 ǁ Jan. 2015 ǁ PP.07-14 www.ijres.org 7 | Page Investigation into the Energy Demand for Palm Nut Cracking Using the Static Impact Method *O. J. Esua 1 , D. N. Onwe 1 , V. E. Etuk 2 , J. U. Okoko 1 , 1 Department of Agricultural and Food Engineering, University of Uyo. P.M.B. 1017, Uyo, Akwa Ibom State, Nigeria. 2 Department of Chemical and Petroleum Engineering, University of Uyo. P.M.B. 1017, Uyo, Akwa Ibom State, Nigeria. Abstract: Investigation into the energy demand for cracking of palm nuts using static impact method was carried out. A nut cracking energy equipment was designed and constructed for the analysis. Fresh palm kernel nuts already dried to a moisture content of 10.42%wb ready for cracking were obtained from an oil mill and characterized into five categories based on their nominal diameter as follows d<12mm; 12mm≤d<15mm; 15mm≤d<17mm; 17mm≤d<19mm; 19mm≤d20mm. The nuts were subjected to cracking using the equipment developed and visual observation was used to assess the level of cracking as follows; completely cracked (CC), completely cracked with slight damage (CCD), cracked without nut separation (CWS), unable to crack (UC) and smashed (SM). The results show that efficiency for complete cracking of nuts without defects increased with increase in drop height to a peak (80 – 100%) and then decreased. Statistical analysis show that the cracking energy determined and cracking percentage have high linear correlation at (0.91, 0.82, 0.94, 0.81 and 0.74) and corresponding high coefficient of determination (0.836, 0.671, 0.889, 0.659, 0.5407) for the various size ranges with their t test showing high significance at 5% level of probability. It was also observed that cracking energies of 0.514; 0.709; 0.904; 1.294 and 1.787 J respectively were adequate to sufficiently crack palm nuts of the five size ranges respectively and release whole kernel. The results suggests the need to grade palm kernel nuts before cracking and the design of a nut cracker with a grading component before cracking to actualize minimal breakage of kernels. Key Words: cracking energy, palm kernel nuts, nut cracker, grading. I. Introduction Palm kernel is a by-product of the oil palm (Elaeis guineensis Jacq.) which is acclaimed to be the richest vegetable oil plant. Two major species of the oil palm are being cultivated; Dura and Pisifera. Whereas the Dura is thick shelled with thin mesocarp, the Pisifera species is thin shelled with thicker mesocarp (Okoroigwe and Saffron, 2012). In Nigeria, it is abundantly grown in the southern part in mostly three varieties namely dura, tenera, and pisifera (Antia, 2014). The palm fruit is drupe oval in shape and contains kernel which is the seed (nut). The kernel is surrounded by the fruit wall made up of hard shell (endocarp), fibrous fruit pulp or oil bearing tissue (mesocarp) and the skin as shown in Fig.1 (Hamdan et al, 2000). The nuts of oil palm is dried and cracked into palm kernel and shell, and the kernel is separated into palm kernel oil (PKO), palm kernel meal (PKM), and water (Akinoso et al, 2009). The kernels are usually processed in to obtain oil and cake. The oil is used for making soap, cosmetics, glycerol, margarine, explosives, refined edible vegetable oil, etc (Antia et al, 2012). Figure 1. Cross Section of the Oil Palm fruit (Hamdan et al, 2000)