Evaluation and Characterization of Vacuum Drying of Date Paste

Authors
Z. Ashraf
Z. Hamidi
M. A. Sahari
M. A. Sahari
Department of Food Science and Technology, Tarbiat Modares University, P. O. Box: 14115-336, Tehran, Islamic Republic of Iran.
Abstract
The drying behavior and characteristics of date paste were studied at temperatures of 60, 70, and 80ºC as thin layer with sample thicknesses of 1, 1.5, and 2 cm in a laboratory scale vacuum chamber. Modeling of drying kinetics of date paste was investigated based on the specific temperatures and sample thicknesses. The experimental moisture loss data were fitted to eight thin layer drying models available in the literature. The modified Henderson-Pabis, Verma, and Jena-Das models showed better fitness to the experimental drying data compared to the other models. The effective moisture diffusivity ranged between 6.0854×10-8 and 4.868×10-7 m2 s-1. Effective diffusivity increased with the increase in temperature and sample thickness. The temperature dependence of effective moisture diffusivity was expressed by an Arrhenius type equation.

Keywords

1. Akgun, N. A. and Doymaz, I. 2005. Modeling of Olive Cake Thin-layer Drying Process. J. Food Eng., 68: 455–461.
2. Akpinar, E. K., Bicer, Y. and Yildiz, C. 2003. Thin Layer Drying of Red Pepper. J. Food Eng., 59: 99–104.
3. Belghit, A., Kouhila, M. and Boutaleb, B. C. 2000. Experimental Study of Drying Kinetics of Forced Convection of Aromatic Plants. Energy Convers. Manage., 41: 1303–1321.
4. Crank, J. 1975. The Mathematics of Diffusion. Second Edition, Clearendon Press, Oxford, UK, PP.44-68.
5. Doymaz, I. 2005. Drying Behavior of Green Beans. J. Food Eng., 69: 161–165.
6. Doymaz, I. 2007. The Kinetics of Forced Convective Air-drying of Pumpkin Slices. J. Food Eng., 79: 243–248.
7. Ertekin, C. and Yaldiz, O. 2004. Drying of Eggplant and Selection of a Suitable Thin Layer Drying Model. J. Food Eng., 63: 349–359.
8. Falade, K. O. and Abbo, E. S. 2007. Air-drying and Rehydration Characteristics of Date Palm (Phoenix dactylifera L.) Fruits. J. Food Eng., 79: 724–730.
9. Giri, S. K. and Prasad, S. 2007. Drying Kinetics and Rehydration Characteristics of Microwave-Vacuum and Convective Hot-Air Dried Mushrooms. J. Food Eng., 78: 512–521.
10. Glenn, T. L. 1978. Dynamic Analysis of Grain Drying System. Unpublished Ph.D. Thesis, Ohio State University, Ann Arbor, MI.
11. Gunhan, T., Demir, V., Hancioglu, E. and Hepbasli, A. 2005. Mathematical Modeling of Drying of Bay Leaves. J. Food Eng., 46: 1667–1679.
12. Heldman, D. R. and Lund, D. B. 2007. Handbook of Food Engineering. CRC Press, London, UK.
13. Jain, D. and Pathare, P. B. 2004. Selection and Evaluation of Thin Layer Drying Models for Infrared Radiative and Convective Drying of Onion Slices. Biosystems Eng., 89: 289–296.
14. Jena, S. and Das, H. 2007. Modeling for Vacuum Drying Characteristics of Coconut Presscake. J. Food Eng., 79: 92–99.
15. Kaleemullah, S. and Kailappan, R. 2007. Monolayer Moisture, Free Energy Change and Fractionation of Bound Water of Red Chilies. J. Stored Prod. Res., 43: 104–110.
16. Karathanos, V. T. 1999. Determination of Water Content of Dried Fruits by Drying Kinetics. J. Food Eng., 39: 337–344.
17. Kulkarni, S. G., Vijayanand, P., Aksha, M., Reena, P. and Ramana, K. V. R. 2008. Effect of Dehydration on the Quality and Storage Stability of Immature Dates (Pheonix dactylifera). Food Sci. Technol., 41: 278–283.
18. Kumar, D. G. P., Hebbar, H. U., Ramesh, M. N. 2006. Suitability of Thin Layer Models for Infrared-Hot Air-Drying of Onion Slices. LWT–Food Sci. Technol., 39: 700–705.
19. Lertworasirikul, S. 2008. Drying Kinetics of Semi-Finished Cassava Crackers: A Comparative Study. LWT–Food Sci. Technol., 41: 1360–1371.
20. Lewis, W. K. 1921. The Rate of Drying of Solid Materials. J. Ind. Eng. Chem., 13: 427–432.
21. Menges, O. H. and Ertekin, C. 2006. Mathematical Modeling of Thin Layer Drying of Golden Apples. J. Food Eng., 77: 119–125.
22. Midilli, A., Kucuk, H. and Yapar, Z. 2002. A New Model for Single Layer Drying. Dry. Technol., 20: 1503–1513.
23. Nguyen, M. and Price, W. E. 2007. Air-drying of Banana: Influence of Experimental Parameters, Slab Thickness, Banana Maturity and Harvesting Season. J. Food Eng., 79: 200–207.
24. Page, G. E. 1949. Factors Influencing the Maximum Rates of Air Drying Shelled Corn in Thin Layers. M.Sc. Thesis. Department of Mechanical Engineering, Purdue University, Purdue, USA.
25. Pathare, P. B. and Sharma, G. P. 2006. Effective Moisture Diffusivity of Onion Slices Undergoing Infrared Convective Drying. Biosystems Eng., 93: 285–291.
26. Sarsavadia, P. N., Sawhney, R. L., Pangavhane, D. R. and Singh, S. P. 1999. Drying Behavior of Brined Onion Slices. J. Food Eng., 40: 219–226.
27. Sharma, G. P., Verma, R. C. and Pathare, P. 2005. Mathematical Modeling of Infrared Radiation Thin Layer Drying of Onion Slices. J. Food Eng., 71: 282–286.
28. Togrul, I. T. and Pehlivan, D. 2002. Mathematical Modeling of Solar Drying of Apricots in Thin Layers. J. Food Eng., 55: 209–216.
29. Togrul, I. T. and Pehlivan, D. 2003. Modeling of Drying Kinetics of Single Apricot. J. Food Eng., 58: 23–32.
30. Verma, L. R., Bucklin, R. A., Endan, J. B., Wratten, F. T. 1985. Effects of Drying Air Parameters on Rice Drying Models. Trans. ASAE, 28: 296–301.
31. Wang, C. Y. and Singh, R. P. 1978. A Single Layer Drying Equation for Rough Rice. ASAE Paper No. 3001.
32. Wang, Z., Sun, J., Chen, F., Liao, X. and Hu, X. 2007. Mathematical Modeling on Thin Layer Microwave Drying of Apple Pomace with and without Hot Air Pre-Drying. J. Food Eng., 80: 536–544.
33. Wu, L., Orikasa, T., Ogawa, Y. and Tagawa, A. 2007. Vacuum Drying Characteristics of Eggplants. J. Food Eng., 83: 422–429.
Journal of Agricultural Science and Technology
Volume 14, Issue 3
May and June 2012
Pages 565-575