Development and Testing of Macadamia (Macadamia integrifolia Maiden & Betche) Nutshell Cracker

Abstract

Macadamia was not only a new plant in Thailand but also lack of physical properties data. Major problem of the production process is high percentage of broken kernels from macadamia crackers breakage. This study in this experiment was analyzed the physical fracture and physical characteristic of macadamia nut cracking under compressive force which was exerted between two solid plates. Results of this study were manipulated in the design and construction of manually operated macadamia nut, cracker. Examination of the macadamia nut was found average moisture content of 3-5%wb, spherical ratio of 0.96, average thickness of nutshell 3.5±1.5 mm, proportion of kernels per nut 32%. According to the compressive force applied to macadamia nut showed that the cracking started from the points where compressive force applied and the shell was broken along circumference of the nut. This cracking behaviour was due to maximum tension stress exerted at the plane perpendicular to the applied force(2,230 n). In this study the nut cracker used two slotted steel plates mounted or frame having linkage mechanism for applying compressive force on macadamia nut. The force of 101.67N was applied on handle bar of the cracker for cracking the nut. Out put of the cracker was 3.1 kg per hour per man having, 69% perfect kernels, 31% fractured kernels.