Effect of Moisture Content on the Mechanical Properties of Dika (Irvingia gabonensis) Fruit and Nut

Abstract

Aims: The effect of varying moisture content on the mechanical properties of Dika (Irvingia gabonensis) fruits and nuts was carried out. Some of the mechanical properties investigated were deformation at peak, energy at peak, deformation at break, energy to break, force at peak, force at break and Young’s modulus. Study Design: Dika nut and dika fruit samples were each separated into six different portions named F, E, D, C, B and A, analysis carried out were in duplicate Place and Duration of Study: Federal University of Technology, Akure, Nigeria, where preliminary analyses were carried out and Federal Institute of Industrial research, Oshodi (FIIRO), Lagos Nigeria where the mechanical properties were analyzed using Testrometric AX type DBBMTCL – 2500Kg Equipment. The research was carried out between March and September, 2012. Methodology: Each sample was oven dried until required moisture content (5%, 8%, 11%, 14%, 17% and 20% d.b. respectively) were attained the samples were separated into six portions and oven dried until required moisture content (5%, 8%, 11%, 14%, 17% and 20% d.b. respectively were attained). Each sample of the treated dika nuts and fruits was placed between the compression plates of the testing equipment. The samples were compressed at a constant deformation rate of 40.00mm min-1. The procedure was repeated for the all the samples. The data logger attached to the machine recorded the parameters. Results: There was no significant (p=0.05) difference on the effect of moisture (8 % to 20 % d.b) on the force at peak of dika fruit except at moisture content (5% d.b). The effect of moisture on deformation at peak, energy at peak, deformation at break, energy to break, force at break and Young’s modulus were significantly (p = 0.05) different at 8% and 5% b.d while there was no significant (p = 0.05) difference at moisture content 11% to 20%. The effect of moisture on the dika nut mechanical properties also showed similar behavior as that of dika fruit. Lower moisture (5% and 8% d.b.) significantly (p=0.05) affected the mechanical properties while higher moisture (11% to 20 % d.b) did not significantly affect the properties Conclusion: As the moisture content reduces, the better the mechanical properties of dika nut and fruit, hence, improvement in their postharvest handlings.