Convective Hot Air Drying of Different Varieties of Blanched Sweet Potato Slices
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Convective Hot Air Drying of Different Varieties of Blanched Sweet Potato Slices

Authors: M. O. Oke, T. S. Workneh

Abstract:

Drying behavior of blanched sweet potato in a cabinet dryer using different five air temperatures (40-80°C) and ten sweet potato varieties sliced to 5mm thickness were investigated. The drying data were fitted to eight models. The Modified Henderson and Pabis model gave the best fit to the experimental moisture ratio data obtained during the drying of all the varieties while Newton (Lewis) and Wang and Singh models gave the least fit. The values of Deff obtained for Bophelo variety (1.27 x 10-9 to 1.77 x 10-9 m2/s) was the least while that of S191 (1.93 x 10-9 to 2.47 x 10-9 m2/s) was the highest which indicates that moisture diffusivity in sweet potato is affected by the genetic factor. Activation energy values ranged from 0.27-6.54 kJ/mol. The lower activation energy indicates that drying of sweet potato slices requires less energy and is hence a cost and energy saving method. The drying behavior of blanched sweet potato was investigated in a cabinet dryer. Drying time decreased considerably with increase in hot air temperature. Out of the eight models fitted, the Modified Henderson and Pabis model gave the best fit to the experimental moisture ratio data on all the varieties while Newton, Wang and Singh models gave the least. The lower activation energy (0.27 - 6.54 kJ/mol) obtained indicates that drying of sweet potato slices requires less energy and is hence a cost and energy saving method.

Keywords: Sweet Potato Slice, Drying Models, Moisture Ratio, Moisture Diffusivity, Activation Energy.

Digital Object Identifier (DOI): doi.org/10.5281/zenodo.1097219

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References:


[1] T. Zhang, C.G. Oates, Relationship between amylose degradation and physico-chemical properties of sweet potato starches. Food Chem., 1999, vol. 65, pp. 157–163.
[2] V.C.K Silayo, H.S. Laswai, J. Mkuchu, J.J. Mpagalile, Effect of sundrying on some quality characteristics of sweet potato chips. Afri. J. Food, Agric. Nutr. Dev., 2003, vol. 3, no. 2, pp. 35-45.
[3] K.S. Jayaraman, and D.K. Gupta, Dehydration of fruits and vegetables— recent developments in principles and techniques. Drying Technol., 2006, vol. 24, no. 10, pp. 1487–1494.
[4] J.M. Babajide, A.O.Obadina, O.B.Oyewole, L.N.Ugbaka, Microbial quality of dry yam ‘‘gbodo’’ parboiled with ⁄ without adjuncts. Afri. J. Biotech., 2006, vol. 5, pp. 278–281.
[5] W. Senadeera, B. Bhandari, G .Young, B. Wijesinghe, Physical property changes of fruits and vegetables during hot air drying. In: Drying Technology in Agriculture and Food Sciences (edited by A.S. Mujumdar). Enfield: Science Publishers. 2000, pp. 159–161.
[6] E.K. Akpinar, Y. Bicer, Modelling of the drying of eggplants in thinlayers. Intl. J. Food Sci. Technol., 2005, vol. 40, pp. 273–281.
[7] T. Gunhan, V. Demir, E. Hancioglu, A. Hepbasli. Mathematical modeling of drying of bay leaves. Energy Conv Mgt 2005, vol. 46, pp.1667–1679.
[8] K. Sacilik, R. Keskin, A.K. Elicin, Mathematical modeling of solar tunnel drying of thin layer organic tomato. J. Food Eng., 2006, vol. 73, pp. 231- 238.
[9] A. Midilli, H. Kucuk, Z. Yapar, A new model for single layer drying. Drying Technol. 2002, vol. 20, pp. 1503–1513.
[10] I.T. Togrul, D. Pehlivan, Mathematical modeling of solar drying of apricots in thin layers. J. Food Eng., 2002, vol. 55, pp. 209–216.
[11] A. Midilli, H. Kucuk, Mathematical modeling of thin layer drying of pistachio by using solar energy. Energy Conv Mgt., 2003, vol. 44, pp. 1111–1122.
[12] I. Doymaz, Convective air drying characteristics of thin layer carrots. J. Food Eng., 2004, vol. 61, pp. 359–364.
[13] I. Doymaz, Thin layer drying behaviour of mint leaves. J. Food Eng., 2006, vol. 74, pp. 370–375.
[14] E.K. Akpinar, Y. Bicer, F. Cetinkaya, Modeling of thin layer drying of parsley leaves in a convective dryer and under open sun. J. Food Eng., 2006, vol. 75, pp. 308–315.
[15] I. Doymaz, The kinetics of forced convective air-drying of pumpkin slices. J. Food Eng. 2007, vol. 79, pp. 243–248.
[16] I. Doymaz, Effect of citric acid and blanching pre-treatments on drying and rehydration of Amasya red apples. Food Bioprod. Proc., 2010, vol. 88, pp. 124–132.
[17] K.O. Falade, E.S. Abbo, Air-drying and rehydration characteristics of date palm (Phoenix dactylifera L.) fruits. J. Food Eng., 2007, vol. 79, pp. 724–730.
[18] R.K. Goyal, O. Mujjeb, V.K. Bhargava.. Mathematical Modeling of Thin Layer Drying Kinetics of Apple in Tunnel Dryer. Intl. J. Food Eng., 2008, vol. 4, no. 8, pp. 1949-1968.
[19] T.Y. Tunde-Akintunde and M.O. Oke, Thin-layer drying characteristics of tiger nut (Cyperus Esculentus) seeds. J. Food Procss. Preserv., 2012, vol. 36, no. 5, pp. 457–464.
[20] T.S. Workneh, M.O. Oke, Thin Layer Modeling of Microwave- Convective Drying of Tomato Slices. Intl. J. Food Eng., 2013, vol. 9, no. 1, pp. 75-90.
[21] B. Baumann, E. Escher, Mass and heat transfer during deep fat frying of potato slices. Rate of drying and oil uptake. Lebensmittel- Wissenschaft und-Technol., 1995, 28, pp. 395–403.
[22] C.T. Akanbi, R.S. Adeyemi, A. Ojo, Drying characteristics and sorption isotherm of tomato slices. J. Food Eng., 2006, vol. 73, pp. 141–146.
[23] S.R. Hassan-Beygi, M. Aghbashlo, M.H. Kianmehr, J. Massah, Drying characteristics of walnut (Juglans regia L.) during convection drying. Intl. Agrophy., 2009, vol. 23, pp. 129–135
[24] T.Y.Tunde-Akintunde, Mathematical modeling of sun and solar drying of chilli pepper. Renew. Energy, 2011, vol. 36, pp. 2139-2145.
[25] C.Y. Wang, R.P. Singh, A single layer drying equation for rough rice. ASAE paper no. 3001. 1978
[26] V.T. Karathanos, Determination of water content of dried fruits by drying kinetics. J. Food Engi., 1999, vol. 39, pp. 337-344.
[27] G. Mazza and M.L. Maguer, Dehydration of onion: some theoretical and practical considerations. J. Food Technol., 1980, vol. 15, pp. 181–194.
[28] A. Lopez, A.E. Iguaz and P. Virseda, Thin-layer drying behaviour of vegetable wastes from wholesale market. Drying Technology: An Inter. J., 2000, vol. 18, pp. 4-5.
[29] A. Piga, I. Pinna, K.B. Ozer, M. Agabbio, U. Aksoy, Hot air dehydration of figs (Ficus carica L.): drying kinetics and quality loss. Intl. J. Food Sci. Technol., 2004, vol. 39, pp. 793–799.
[30] P.S. Madamba, R.H. Driscoll and K.A. Buckle, The thin layer drying characteristics of garlic slices. J. Food Eng. 1996, vol. 29, pp. 75–97.
[31] A. Kaleta and K. Górnicki, Some remarks on evaluation of drying models of red beet particles. Energy Conv. Mgt., 2010, vol. 51, pp. 2967–2978.
[32] Y. Lin, J. Tsen, V.A. King, Effects of far-infrared radiation on the freeze-drying of sweet potato. J. Food Eng., 2005, vol. 68, pp. 249–255.
[33] S. Singh, R. Sharma, A.S. Bawa, D.C. Saxena, Drying and rehydration characteristics of water chestnut (Trapanatans) as a function of drying air temperature. J. Food Eng., 2008, vol. 87, pp. 213–221
[34] J.H. Lee and H.J. Kim, Vacuum drying kinetics of Asian white radish (Raphanus sativus L.) slices. LWT - Food Sci. Technol., 2009, vol. 42, pp. 180–186.
[35] J. Crank, The mathematics of diffusion (2nd ed.). Clarendon Press. Oxford, UK, 1975.
[36] G. Mwithiga and J.O. Olwal, The drying kinetics of kale (Brassica oleracea) in a convective hot air dryer. J. Food Eng. 2005, vol. 71, pp. 373–378.
[37] S. Simal, A. Femenia, J.A. Carcel, C. Rossello, Mathematical modeling of the drying curves of kiwi fruits: influence of the ripening stage. J. Sci. Food Agric., 2005, vol. 85, pp. 425–432.
[38] O.P. Sobukola, O.U. Dairo, A.V. Odunew, Convective hot air drying of blanched yam slices. Intl J Food Sci Technol, 2008, vol. 43, pp. 1233– 1238.
[39] S. Arora, U.S. Shivhare, J. Ahmed, G.S.V. Raghavan,. Drying kinetics of Agaricus bisporus and Pleurotus florida mushrooms. Trans. Ame. Soc. Agric. Engr., 2003, vol. 46, pp. 721–724.