Effective conditions for extracting higher quality kernels from walnuts
Main Article Content
Keywords
cracker, cracking characteristics, impact energy, kernel, moisture content, walnut
Abstract
Samples of walnut at 9.25, 15.98, 23.36, and 29.72% (wet basis) moisture contents were subjected to impact energy ranged from 0.13 to 1.11 J using an impact test apparatus. Data obtained on the quantity of fully cracked and unbroken kernel, fully cracked but broken kernel and uncracked nuts were used in the computation of the nuts cracking characteristics. Results showed that impact energy, moisture content and the interaction effects of these two variables significantly influenced the cracking characteristics of walnuts (P<0.01). Full cracking of nuts increased with decreasing moisture content and increased impact energy. The optimum moisture content for cracking walnuts that gave the best result in combination with a high whole kernel yield and low kernel breakage was found to be about 16%. The optimum impact energy for cracking was found to be about 1.01 J. However, the result of the study shows that development of a centrifugal impact cracker, which uses impact to crack walnuts is possible. It suggests that the radius and speed of the cracker should be such that it will not allow the impact energy of 1.01 J and velocity of 11 m/s to be exceeded and walnuts should be conditioned at a moisture content of about 16% for optimal efficiency.
References
Akani, A.O., Ohanwe, C.N. and Omoniyi, I.O., 2000. Determination of optimum impact for decortication of bambara groundnut. Proceedings of the Nigerian Institution of Agricultural Engineers 22: 87-89.
Altuntas, E. and Erkol, M., 2009. The effects of moisture content, compression speeds and axes on mechanical properties of walnut cultivars. Food and Bioprocess Technology 4: 1288-1295.
Altuntas, E. and Özkan, Y., 2008. Physical and mechanical properties of some walnut (Juglans regia L.) cultivars. International Journal of Food Engineering 4: 1349.
Asoegwu, S.N., 1995. Some physical properties and cracking energy of conophor nuts at different moisture content. International Agrophysics 9: 131-142.
Aviara, N.A., Gwandzang, M.I. and Haque, M.A., 1999. Physical properties of guna seeds. Journal of Agricultural Engineering Research 73: 105-111.
Borghei, A.M., Tavakoli, T. and Khazaei, J., 2000. Design, construction, and testing of walnut cracker. Proceedings of European Agricultural Engineering Conference, Warwick University, UK.
Figiel, A. and Kita, A., 2008. Drying kinetic, water activity, shrinkage and texture of walnut kernels. Acta Agrophisica 11: 71-80.
Fluck, R.C. and Ahmed, E.M., 1973. Impact testing of fruits and vegetables. Transactions of the ASAE 16: 660-666.
Ghafari, A., Chegini, G.R., Khazaei, J. and Vahdati, K., 2011. Design, construction and performance evaluation of the walnut cracking machine. International Journal of Nuts and Related Science 2: 11-16.
Khazaei,J., Rasekh, M. and Borghei, A.M., 2002. Physical and mechanical properties of almond and its kernel related to cracking and peeling. ASAE, St. Joseph, MI, USA, pp. 353-356.
Kim, T.H., Opara, L.U., Hampton, J.G., Hardacre, A.K. and MacKay, B.R., 2002. The effects of grain temperature on breakage susceptibility in maize. Biosystem Engineering 82: 415-421.
Koyuncu, M.A.K., Ekinci, K. and Savran, E., 2004. Cracking characteristics of walnut. Biosystem Engineering 87: 305-311.
Laverdrine, F., Ravel, A., Villet, A., Ducros, V. and Alary, J., 2000. Mineral composition of two walnut cultivars originating in France and California. Food Chemistry 68: 347-351.
Makanjuola, G.A., 1975. An evaluation of some centrifugal impaction devices for shelling melon seeds. Journal of Agricultural Engineering Research 20: 71-77.
Odigbo, E.U., 1979. Impact egusi shelling machine. Transactions of the ASAE 22: 1264-1269.
Oluwole, F.A., Abdulrahi, A.T. and Olalere R.K., 2007a. Effect of moisture content on the crackability of bambara groundnut using a centrifugal cracker. International Agrophysics 21: 179-184.
Oluwole, F.A., Aviara, N.A. and Haque, M.A., 2004. Development and performance tests of a sheanut cracker. Journal Food Engineering 65: 117-123.
Oluwole, F.A., Aviara, N.A. and Haque, M.A., 2007b. Effect of moisture content and impact energy on the crackability of sheanut. International Agrophysics 21: 179-184.
SAS, 2001. SAS procedures guide. SAS Institute Inc., Cary, NC, USA.
Sharifian, F. and Derafshi, H.M., 2008. Mechanical behavior of walnut under cracking conditions. Journal of Applied Sciences 8: 886-890.
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