Commenced in January 2007
Frequency: Monthly
Edition: International
Paper Count: 30737
Performance of an Improved Fluidized System for Processing Green Tea

Authors: John Abraham, Nickson Kipng’etich Lang’at, Thomas Thoruwa, John Wanyoko

Abstract:

Green tea is made from the top two leaves and buds of a shrub, Camellia sinensis, of the family Theaceae and the order Theales. The green tea leaves are picked and immediately sent to be dried or steamed to prevent fermentation. Fluid bed drying technique is a common drying method used in drying green tea because of its ease in design and construction and fluidization of fine tea particles. Major problems in this method are significant loss of chemical content of the leaf and green appearance of tea, retention of high moisture content in the leaves and bed channeling and defluidization. The energy associated with the drying technology has been shown to be a vital factor in determining the quality of green tea. As part of the implementation, prototype dryer was built that facilitated sequence of operations involving steaming, cooling, pre-drying and final drying. The major findings of the project were in terms of quality characteristics of tea leaves and energy consumption during processing. The optimal design achieved a moisture content of 4.2 ± 0.84%. With the optimum drying temperature of 100 ºC, the specific energy consumption was 1697.8 kj.Kg-1 and evaporation rate of 4.272 x 10-4 Kg.m-2.s-1. The energy consumption in a fluidized system can be further reduced by focusing on energy saving designs.

Keywords: evaporation rate, maceration, fluid bed dryer, specific energy consumption

Digital Object Identifier (DOI): doi.org/10.5281/zenodo.1124901

Procedia APA BibTeX Chicago EndNote Harvard JSON MLA RIS XML ISO 690 PDF Downloads 1278

References:


[1] Sin H.L. 2005. Tea for Health F.R.C.P.
[2] Oguni, I. 2002. Green Tea and Human Health. University of Shizuoka, Japan Tea Exporters’ Association.
[3] Chang Kaison (2015). World Tea Production and Trade. Current and Future Development Food and Agricultural Organization of the United Nation.
[4] Vanecek V., Markvart M. &Drbohlav R. 1966. Fluidised Bed Drying. Leonard Hill Books: London
[5] Gibert, H., Baxerres, J. L., and Kim, H., 1980 “Blanching time in fluidized beds. In food processing Engineering”, Applied science publishers, London.
[6] Sadeghi, M., and M. H. Khoshtaghaza. 2012. Vibration effect on particle bed aerodynamic behavior and thermal performance of black tea in fluidized bed dryers. J. Agric.Sci. Technol. 14:781–788.
[7] Watano S., Imada Y., Hamada K., Wakamatsu Y., Tanabe Y., Dave R. and Pfeffer R., 2003. Microgranulation of fine powders by a novel rotating fluidized bed granulator. Department of Chemical Engineering, Osaka Prefecture University, 1-1 Gakuen-cho, Sakai, Osaka 599-8531, Japan.
[8] Langat, N. 2014. Development of an improved fluid bed dryer system for green tea drying in the industry, PhD Thesis, Kenyatta University.
[9] Vishal Singh, Deepak Kumar Verma and Gurupreet Singh, 2014. Processing Technology and Health Benefits of Green. Food Process Engineering, Agricultural and Food Engineering Department, Indian Institute of Technology, Kharagpur (West-Bengal)-721302, India.
[10] Cheng Shu-Jun & Chen Miao-Ian, 2002 Tea Bioactivity and Therapeutic Potential. Taylor and Francis, 11 new Fetter Lane, London EC4P 4EE
[11] Tomlins K. I., Mashingaidze A., 1996. Review of the Tea Withering in The Manufacture of Black Tea. TRF TNL 122, 12-20
[12] Hampton, M. G. (1992). Production of black tea. In Tea- Cultivation to Consumption, ed. K. C. Willson & M. N. Clifford. Chapman and Hall, London, pp. 459-511.
[13] Owuor, P. O., Tsushida, T., Ho&a, H. & Murai, T. (1987). Effects of artificial withering on the chemical composition and quality of black tea. Trop. Sci., 27, 159-166.