International Scientific Journal


Konjac glucomannan (KGM) can be obtained from tubers (called corms) of various species within the Amorphophallus genus. Among the most popular species for use in food industry is Buk Nuea Sai (Amorphophallus muelleri), a native species in Thailand. Drying process can be helpful in preserving KGM during long storage periods. However, the existing drying systems are often slow and lead to drying delays and subsequently quality reduction of the dried product. Given the economic importance of KGM, new, more efficient drying systems, have to be developed. The present study focuses on the drying kinetics of konjac dices in a fluidized bed, operating at a constant air velocity of 2.5 m/s and air temperatures of 50, 60, and 70°C. Six empirical mathematical models were selected to describe and compare the drying characteristics of konjac dices subjected to these conditions. The model coefficients were determined by non-linear regression analysis. Among the tested models used to describe the drying kinetics of konjac dices, the two-term model was found as the best one. The moisture loss from the dice was described by the Fick’s diffusion equation, and based on the obtained results the effective moisture diffusivity was estimated, getting a value in the range between 9.60526 ⋅ 10–9 m2/s and 1.2006 ⋅ 10−7 m2/s. The relationship between the temperature and the effective moisture diffusivity was described adequately by means of Arrhenius-type equation. An activation energy value between 8.65 kJ/mol and 61.28 kJ/mol was obtained. The findings allow the successful simulation of konjac dice drying in a fluidized bed between 50 and 70°C, 30-60 mm bed height and 6-15 mm dice thickness.
PAPER REVISED: 2020-02-17
PAPER ACCEPTED: 2020-02-24
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  1. Tippawan Sukumanand, "Amorphophallus sp. in Thailand.," in Department of Agriculture, vol. 91, 2005, pp. 399-404.
  2. Z. Jianrong, Z. Donghua, G. Srzednicki, S. Kanlayanarat, and C. Borompichaichartkul, "Asexual reproduction of Amorphophallus bulbifer by low-cost artificial-induction technique," Acta Hortic., vol. 837, pp. 351-358, 2009.
  3. A. S. Mujumdar, Handbook of Industrial Drying, vol. 6, no. 3. 2014.
  4. M. Torki-Harchegani, D. Ghanbarian, A. Ghasemi Pirbalouti, and M. Sadeghi, "Dehydration behaviour, mathematical modelling, energy efficiency and essential oil yield of peppermint leaves undergoing microwave and hot air treatments," Renew. Sustain. Energy Rev., vol. 58, Figure 10. Influence of high drying air temperature on effective moisture diffusivity. pp. 407-418, 2016.
  5. D. Maisnam, P. Rasane, A. Dey, S. Kaur, and C. Sarma, "Recent advances in conventional drying of foods," J. Food Technol. Preserv., vol. 1, no. 1, pp. 25-34, 2015.
  6. H. T. Sabarez, "Mathematical Modeling of the Coupled Transport Phenomena and Color Development: Finish Drying of Trellis-Dried Sultanas," Dry. Technol., vol. 32, no. 5, pp. 578-589, 2014.
  7. S. Soponronnarit, T. Swasdisevi, S. Wetchacama, and W. Wutiwiwatchai, "Fluidised bed drying of soybeans," J. Stored Prod. Res., vol. 37, no. 2, pp. 133-151, 2001.
  8. A. Harish, M. Rashmi, T. P. Krishna Murthy, B. M. Blessy, and S. Ananda, "Mathematical modeling of thin layer microwave drying kinetics of elephant foot yam (Amorphophallus paeoniifolius)," Int. Food Res. J., 2014.
  9. S. Vijayan, T. V. Arjunan, and A. Kumar, "Mathematical modeling and performance analysis of thin layer drying of bitter gourd in sensible storage based indirect solar dryer," Innov. Food Sci. Emerg. Technol., vol. 36, pp. 59-67, 2016.
  10. O. R. Alara, N. H. Abdurahman, and O. A. Olalere, "Mathematical modelling and morphological properties of thin layer oven drying of Vernonia amygdalina leaves," J. Saudi Soc. Agric. Sci., vol. 18, no. 3, pp. 309-315, 2018.
  11. O. P. Sobukola, O. U. Dairo, L. O. Sanni, A. V. Odunewu, and B. O. Fafiolu, "Thin layer drying process of some leafy vegetables under open sun," Food Sci. Technol. Int., vol. 13, no. 1, pp. 35-40, 2007.
  12. O. A. Aregbesola, B. . Ogunsina, A. E. Sofolahan, and N. N. Chime, "Mathematical modeling of thin layer drying characteristics of dika (Irvingia gabonensis) nuts and kernels," Niger. Food J., vol. 33, no. 1, pp. 83-89, 2015.
  13. J. S. Roberts, D. R. Kidd, and O. Padilla-Zakour, "Drying kinetics of grape seeds," J. Food Eng., vol. 89, no. 4, pp. 460-465, 2008.
  14. V. Demir, T. Gunhan, and A. K. Yagcioglu, "Mathematical modelling of convection drying of green table olives," Biosyst. Eng., vol. 98, no. 1, pp. 47-53, 2007.
  15. S. Uma Maheswari, R. Kumaresan, and A. Janet, "Drying kinetics of canola in fluidised bed dryer," Int. J. Appl. Eng. Res., vol. 10, no. 2, pp. 5073-5090, 2015.
  16. M. J. Perea-Flores et al., "Mathematical modelling of castor oil seeds (Ricinus communis) drying kinetics in fluidized bed at high temperatures," Ind. Crops Prod., vol. 38, no. 1, pp. 64-71, 2012.
  17. Q. Shi, Y. Zheng, and Y. Zhao, "Mathematical modeling on thin-layer heat pump drying of yacon (Smallanthus sonchifolius) slices," Energy Convers. Manag., vol. 71, pp. 208-216, 2013.
  18. K. Fan, L. Chen, J. He, and F. Yan, "Characterization of Thin Layer Hot Air Drying of Sweet Potatoes (Ipomoea batatas L.) Slices," J. Food Process. Preserv., vol. 39, no. 6, pp. 1361-1371, 2015.
  19. J. W. Westwater and H. G. Drickamer, "The Mathematics of Diffusion," J. Am. Chem. Soc., vol. 79, no. 5, pp. 1267-1268, 1957.
  20. A. Benseddik, A. Azzi, M. N. Zidoune, R. Khanniche, and C. Besombes, "Empirical and diffusion models of rehydration process of differently dried pumpkin slices," J. Saudi Soc. Agric. Sci., vol. 18, no. 4, pp. 401-410, 2019.
  21. I. Zlatanovi, "Author ‟ s personal copy Low-temperature convective drying of apple cubes."
  22. R. Sadin, G. R. Chegini, and H. Sadin, "The effect of temperature and slice thickness on drying kinetics tomato in the infrared dryer," Heat Mass Transf. und Stoffuebertragung, vol. 50, no. 4, pp. 501-507, 2014.
  23. L. Ben Haj Said, H. Najjaa, A. Farhat, M. Neffati, and S. Bellagha, "Thin layer convective air drying of wild edible plant (Allium roseum) leaves: experimental kinetics, modeling and quality," J. Food Sci. Technol., vol. 52, no. 6, pp. 3739-3749, 2015.
  24. S. Mghazli, M. Ouhammou, N. Hidar, L. Lahnine, A. Idlimam, and M. Mahrouz, "Drying characteristics and kinetics solar drying of Moroccan rosemary leaves," Renew. Energy, vol. 108, pp. 303-310, 2017.
  25. I. Doymaz, "Evaluation of mathematical models for prediction of thin-layer drying of banana slices," Int. J. Food Prop., vol. 13, no. 3, pp. 486-497, 2010.
  26. M. Premi, H. K. Sharma, B. C. Sarkar, and C. Singh, "Kinetics of drumstick leaves(Moringa oleifera) during convective drying.," African J. Plant Sci., vol. 4, no. 10, pp. 391-400, 2010.
  27. I. Doymaz, "Evaluation of some thin-layer drying models of persimmon slices (Diospyros kaki L.)," Energy Conversion and Management, vol. 56. pp. 199-205, 2012.
  28. I. Doymaz and F. Kocayigit, "Drying and rehydration behaviors of convection drying of green peas," Dry. Technol., vol. 29, no. 11, pp. 1273-1282, 2011.
  29. H. W. Xiao, X. D. Yao, H. Lin, W. X. Yang, J. S. Meng, and Z. J. Gao, "Effect of SSB (Superheated Steam Blanching) time and drying temperature on hot air impingement drying kinetics and quality attributes of yam slices," J. Food Process Eng., vol. 35, no. 3, pp. 370-390, 2012.

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