Legume Research

  • Chief EditorJ. S. Sandhu

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Legume Research, volume 40 issue 4 (august 2017) : 649-654

Convective and microwave drying characteristics, energy requirement and color retention of dehydrated nettle leaves (Urtica diocia L.) 

Fuat Lule, Turhan Koyuncu
1<p>Faculty of Technology,&nbsp;University of Adiyaman, 02040 Adiyaman, Turkey.</p>
Cite article:- Lule Fuat, Koyuncu Turhan (2017). Convective and microwave drying characteristics, energy requirementand color retention of dehydrated nettle leaves (Urtica diocia L.) . Legume Research. 40(4): 649-654. doi: DOI:10.18805/lr.v0i0.8409.

In this research, convective and microwave drying characteristics, energy requirement and color changes of nettle leaves (Urtica diocia L.) were reported. Samples of freshly harvested nettle leaves were dehydrated under three air temperatures of 50 °C, 60 °C and 70 °C and at three microwave power levels of PL-1, PL-2 and PL-3. Selected drying air velocity was 0.30 m/s for all temperatures. This is coming from the fact that it was understood from the preliminary studies that the temperature less than 50 °C and the air speed more than 0.30 ms-1 increase the drying time and energy requirement, extremely for these products. Nettle leaves were dehydrated from the initial moisture content of 320 (percentage dry basis) to a final moisture content of 7 % to 9 %. During convective drying experiments, product were weighted automatically by the balance per (5 to10) min. Data were transferred to the computer and processed by a software. During microwave drying, the product were weighted and data recorded manually per (15 to 60) min. The influence of drying method, drying air temperature and microwave power level have also been studied. Hunter L, a, b values system was also used to evaluate changes in total color difference (DE) on dried products. The results showed that convective drying air temperature and microwave oven power levels influenced the total drying time, total energy requirement, specific energy requirement and color difference for nettle leaves. The minimum specific energy requirement were determined as 6.95 kWhkg-1 and 23.63 kWhkg-1 for 70 °C and PL-2 respectively. 70 °C drying air temperature and PL-3 was found to yield better quality product in terms of color retention of Hunter L, a, b and  DE. As a result, to reduce drying energy consumption and to keep better color retention, convective drying can be recommended for this application.

  1. Alibas, Ý., (2007). Energy Consumption and Colour Characteristics of Nettle Leaves during Microwave, Vacuum and Convective Drying. Biosystems Engineering, 96: 495–502

  2. Alibas, Ý., (2010). Determination of drying parameters, ascorbic acid contents and color characteristics of nettle leaves during microwave-, air- and combined microwave-air-drying. Journal of Food Process Engineering, 33: 213-233

  3. AOAC. (1984). Official Methods of Analysis of the Association of Official Analytical Chemists. 14th Ed., Arlington : Virginia. 22.013, USA.

  4. Chrubasik, J. E., Roufogalis, B. D., Wagner, H., and Chrubasik, S. H., (2007). A comprehensive review on the stinging nettle effect and efficacy profiles. Part II: Urticae radix. Phytomedicine, 14: 568–579

  5. Chrubasik, J. E., Roufogalis, B. D., Wagner, H., and Chrubasik, S. H., (2007). A comprehensive review on nettle effect and efficacy profiles, Part I: Herba urticae. Phytomedicine, 14: 423–435

  6. Doymaz, I., Tugrul, N. and Pala, M. (2006). Drying characteristics of dill and parsley leaves. Jounal of Food Engineering, 77: 559-565.

  7. Ekechukwu, O.V. (1999). Review of solar-energy drying systems I : an overview of drying principles and theory. Energy Conversion and Management, 40: 593-613.

  8. Gigler, J.K., Loon, W.K.P.van, Seres, I., Meerdink, G., and Coumans, W.J. (2000). Drying characteristics of willow chips and stems. J. Agric. Engng. Res., 77: 391-400. 

  9. Guil-Guerrero, J.L., Rebolloso-Fuentes, M.M., and Torija Isasa, M.E., (2003). Fatty acids and carotenoids from Stinging Nettle (Urtica dioica L.). Journal of Food Composition and Analysis, 16: 111–119.

  10. Hojnik, M., Skerget, M., and Knez, Z., (2007). Isolation of chlorophylls from stinging nettle (Urtica dioica L.). Separation and Purification Technology, 57: 37–46.

  11. Holman, J.P. (1994). Experimental methods for engineers. McGraw-Hill, Inc; New York, USA.

  12. Jimenes, M., Mateo, J. J., Huerta, T., and Mateo, R. (1994). Influence of the Storage Conditions on Some Physiochemical and Mycological Parameters of Honey. Journal of the Science of Food and Agriculture, 64(1), 67-74. 

  13. Kadu, A.B., Phirkel , P.S., Khojare, A.S., Wasnik and M.P.G. (2005). Studies on drying behaviour of some selected fruit vegetables. J. Dairying, Foods and H.S 24: 1 – 5.

  14. Kaya, A., and Aydýn, O., (2009). An experimental study on drying kinetics of some. Energy Conversion and Management, 50: 118–124.

  15. Koyuncu, T., Tosun, Ý., and Üstün, N.S. (2003). Drying kinetics and color retention of dehydrated rosehips. Drying Technology, 21: 1369-1381. 

  16. Koyuncu, T., Serdar, U., and Tosun, Ý. (2004). Drying kinetics and energy requirement for dehydration of chestnuts (Castanea sativa Mill.). Jounal of Food Engineering, 62: 165-168.

  17. Lozano, J. E., Drudis, R., and Ibarz, A. (1994). Enzymatic Browning in Apple Pulps. Journal of Food Science, 59:    564-567.

  18. Ochoa M.R., Kesseler, A.G., Pirone, B.N., Marquez, C.A., and Michelis A. De. (2002). Shrinkage during convective drying of whole rose hip (Rosa Rubiginosa L.) fruits. Lebensm.- Wiss. U.-Technol., 35: 400-406. 

  19. Sengar, S.H., Kurchania, A.K. (2005). Experýmental performance analysýs of composýte solar dryer cum cooker. J. Dairying, Foods and H.S. 24: 123 - 129


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