Convective Hot Air Drying of Different Varieties of Blanched Sweet Potato Slices
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.
[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.
[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.
@article{"International Journal of Biological, Life and Agricultural Sciences:68454", author = "M. O. Oke and T. S. Workneh", title = "Convective Hot Air Drying of Different Varieties of Blanched Sweet Potato Slices", 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.", volume = "8", number = "12", pages = "1349-7", }
