Development of a Walnut (Tetracarpidium conophorum) Cracker

Abstract

The emerging knowledge of the use and importance of African walnut (Tetracarpidium conophorum) for different purposes has made the study for the development of walnut cracker imperative. A cracker for walnut was designed, constructed and evaluated. The major components of the machine are the cracking and cleaning units. The cracking of the walnuts to bring out the needed oily seeds is achieved through the compressive and shearing actions between the two abrasive drums when the nuts fell in between them, while the cleaning unit has a centrifugal fan that separates the seed from the cracked shells via air velocity. The performance evaluation of the machine was carried out using four levels of cracking drum speeds (280, 310,340, and 370 rpm) and fan speeds (1200, 1400, 1600, and 1800 rpm); also two levels of feed rates (32 and 42 kg/h) and moisture content (10.3 and 17.6%wb). The results obtained showed that; on the average, the machine had a cracking efficiency of 92.63%, cleaning efficiency of 95.48%, percentage seed loss of 5.93%, mechanical damage index of 11.06%, throughput of 21.05 kg/h and cracker performance index of 88.3%. The power requirement for operating the machine is 1.68 kW. With this newly developed walnut cracker, full exploitation of the nutritional, industrial and medicinal potential of the walnut seed will be enhanced.