Effects of heating temperature and time on some mechanical properties of Balanites Aegyptiaca nut

Abstract

Balanites aegyptiaca nuts were pretreated by heating at different temperatures in the range of 30 – 90^oC for time durations in the range of 30 – 120 mins. Moisture content of the nuts prior to pretreatment was 4.7 % (d.b.). Some strength properties of the pretreated nuts namely, bioyield, yield and rupture points; bioyield, compressive and rupture strengths; and moduli of elasticity, resilience, stiffness and toughness were determined at lateral and longitudinal axial loading, using a Universal Testing Machine (UTM). Results showed that all the strength properties of the nut decreased with increase in temperature and varied significantly with heating time at different loading orientations. Temperature and heating time range existed within which the nuts exhibited the typical behavior of biomaterials when heated and subjected to compression. After these ranges were exceeded, the nuts’ behavior deviated.         The study suggests that in addition to conditioning balanites aegyptiaca nuts to a moisture level at which they could easily be cracked, further treatment by exposure to heat at a level and for a duration that would not compromise product quality, could be used to enhance energy efficiency. Loading along the longitudinal axis should be applied if the cracking of nut is to be carried out using uniaxial compression.