Influence of Nut Cracking Methods on Kernel Quality and Separability of Product
In order to provide rational basis for design considerations to reduce kernel breakage in palm nut cracking using the conventional centrifugal nutcracker and enhance subsequent kernel and shell separation, comparison was made between the qualities of products from manually and mechanically cracked nuts. Furthermore, a 23 factorial experiment was conducted to determine the effects of the machine operational parameters and size of nut on nut cracking efficiency, quality of recovered kernels, and fragmentation of the nutshell. The nutcracker with a throughput capacity of 250 kg/h and a rotational of 1100 rpm gave a cracking efficiency of 97.2%, but kernel breakage was up to 9.7%; however, kernel breakage was 5.5% when the nutcracker was driven at a lower speed of 800 rpm and unbroken nuts were recycled. In contrast, cracking the nuts manually yielded 100% cracking efficiency and 2.0% kernel breakage, but the process was cumbersome and time consuming. In relation to the separation of the product, shell particles passing through a sieve with 10 mm aperture were 71.3% of the total shell produced using the nutcracker; compared with 58.3% from nuts broken manually.
ASAE “Standard S352. Moisture measurement – grains and seeds”. Agricultural Engineers Year Book, ASAE, St. Joseph MI, p. 345; 1982.
Barnes, J. W., “Statistical analysis for engineers and scientists; a computer-based approach”.McGraw-Hill, Inc., New York, 1994.
Box, G. E. P., Hunter, J. S. and Hunter, W. G., “Statistics for experimenters: design innovation and discovery, 2nd Edition”. John Wiley, New York, 1998.
Hartley, C. W. S., “The oil palm”. Longman Publishers, London, 1977.
Koya, O. A., “Studies of the mechanics of nut cracking and centrifugal separation of palm kernel and shell mixture”. Unpublished PhD thesis, Obafemi Awolowo University, Ile-Ife, Nigeria, 2004.
Koya, O. A. and Faborode, M. O., “Mathemetical modeling of palm nut cracking based on Hertz theory”. Biosystems Engineering. 91(4): 471 – 478, 2005.
Koya, O. A. and Faborode, M. O., “Separation theory for palm kernel and shell mixture on a spinning disc”. Biosystems Engineering. 95(3): 405 – 412, 2006.
Koya, O. A., Idowu, A. and Faborode, M. O., “Physical properties of palm kernel and shell relevant in nut cracking and product separation”. Journal of Agricultural Engineering and Technology, 12: 33 – 45, 2004.
Manuwa, S. I., “Design, fabrication and testing of a low cost palm nut cracker”. Paper presented at the 19th Annual Conference of the Nigerian Society of Agricultural Engineers, at the Federal University of Technology, Owerri, Nigeria, 1997.
Manuwa, S. I., “Fracture resistance of palm nuts to compressive loading”. Paper presented at the 20th Annual Conference of the Nigerian Society of Agricultural Engineers at Lagos Airport Hotel, Lagos, Nigeria, 1998.
Meriam, J. L. and Kraige, L. G., “Engineering mechanics, volume 2: dynamics, 4th edition”. John Wiley and Sons, Inc., New York, 1998.
Obiakor, S. I. and Babatunde, O. O., “Development and testing of the NCAM centrifugal palm nut cracker”. AGRIMECH Research and Information Bulletin of the National Centre for Agricultural Mechanization (NCAM), 1999.
Olie, J. J. and Tjeng, T. D., “Kernel recovery in the extraction of palm oil”, The Netherland Stork Amsterdam, Amstelveen, p. 63 – 72, 1974.
Owolarafe, O. K., Sanni, L. A., Edinowe, O. S., Ogunyomi, O. T., Faborode, M. O. and Ajibola, O. O., “Development of an oil palm fruit stripper”. Journal of Agricultural Engineering and Technology. 10: 59 – 64, 2002.