Modelling of microwave assisted hot-air drying and microstructural study of oilseeds

Mohamed Hemis, Ruplal Choudhary, Nathalie Becerra-Mora, Punit Kohli, Vijaya Raghavan

Abstract


Abstract: A modelling study was performed to solve the heat and mass transfer problems between grain and the ambient air encountered during drying by microwave assisted hot-air dryer, under low microwave (MW) density of 0.2 W/g. Canola (Brassica napus), soybean (Glycine max) and corn (Zea mays) seeds were chosen due to their inherent high oil content. Scanning electron microscopy (SEM) was used to study the effect of drying conditions on the structural characteristics of these oilseeds. A mathematical model was adapted to simulate drying of one seed of canola, soybean and corn. The process of water transfer was modelled based on the effect of vapour pressure on the water molecules inside the seed. It was observed that when the difference between the vapour pressure inside the grain and the surrounding air was higher than, the drying rate increased which led to cracks in the grain. Results showed that the drying rate decreased when the temperature of air inside the cavity of the microwave increased for all the oilseeds studied, because of the reduced differential vapour pressure between the grain and the ambient air. On the other hand, the drying rate increased if the temperature of the inlet air was reduced because the difference between the two pressures increased. It was concluded that by controlling the ambient air, the grains could be protected against popping and cracking because of lower vapour pressure differential during MW assisted hot-air drying.
Keywords: mathematical modelling, oilseeds, MW assisted drying, drying rate, SEM images
DOI: 10.3965/j.ijabe.20160906.2442

Citation: Hemis M, Choudhary R, Becerra-Mora N, Kohli P, Raghavan V. Modelling of microwave assisted hot-air drying and microstructural study of oilseeds. Int J Agric & Biol Eng, 2016; 9(6): 167－177.

Keywords


mathematical modelling, oilseeds, MW assisted drying, drying rate, SEM images

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References


United States Department of Agriculture (USDA). Oilseeds: world markets and trade. 2015 (report December, 2015). Available:http://www.fas.usda.gov/data/oilseeds-world-markets-and-trade. Accessed on [2016]

Berrios J, Wood D F, Whitehand L W, Pan J. Sodium bicarbonate and the microstructure, expansion and color of extruded black beans. J Food Processing and Preservation, 2004; 28: 321–335.

Bdour Mohammed A, Al-Rabadi Ghaid J, Al-Ameiri Nofal S,

Mahadeen Atif Y, Aaludatt Muhammad H. Microscopic analysis of extruded and pelleted barley and sorghum grains. Jordan Journal of Biological Sciences, 2014; 7(3): 227–231.

Gazor H R, Mohsenimanesh A. Modelling the drying kinetics of canola in fluidised bed dryer. Czech Journal of Food Sciences, 2010; 6(6): 531–537.

Vicas S M, Palade P A. The drying processes of corn seeds in a microwave field. Analele Universităńii Din Oradea Fascicula: Ecotoxicologie, Zootehnie Si Tehnologii De Industrie Alimentară, 2010; 1278–1286.

Ranjbaran M, Zare D. A new Approach for modelling of hot air-microwave thin layer drying of soybean. Electronic Journal of Polish Agricultural Universities, 2012; 15(3): #01.

Association of Official Analytical Chemists (AOAC). Official methods of analysis. Washington, D.C.: AOAC. 2000.

Costa L M, Resende O, Sousa K A, Gonçalves D N. Effective diffusion coefficient and mathematical modelling of the drying of crambe seeds. Rev. Bras. Engenharia Agríc. Ambiental, 2011; 15(10): 1089–1096.

Gely M C, Giner S A. Diffusion coefficient relationships during drying of soya bean cultivars. Biosystems Engineering, 2007; 96(2): 213–222.

Hemis M, Choudhary R, Watson G D. A coupled mathematical model for simultaneous microwave and convective drying of wheat seeds. Biosystems engineering, 2012; 112(3): 202–209.

Hemis M, Raghavan G S V. Effect of convective air attributes with microwave drying of soybean: model prediction and experimental validation. Drying Technology 2014; 32(5): 543–549(7).

Hemis M, Choudhary R, Gariépy Y, Raghavan V G S. Experiments and modelling of the microwave assisted convective drying of canola seeds. Biosystems Engineering, 2015; 139(4): 121–127.

Chen A A, Singh R K, Haghighi K, Nelson P E. Finite element analysis of temperature distribution in microwave cylindrical potato tissue. Journal of Food Engineering, 1993; 18(4): 351–368.

Swami S. Microwave heating characteristics of simulated high moisture foods. M.Sc. thesis. Amherst, MA.: University of Massachusetts, 1982.

Nelson S O, Kraszewski A W, Trabelsi S, Lawrence K C. Using cereal grain permittivity for sensing moisture content. IEEE Transactions on Instrumentation and Measurement, 2000; 49(3): 470–475.

Nelson S O, Trabelsi S. Sensing grain and seed moisture and density from dielectric properties. Int J Agric & Biol Eng, 2011; 4(1): 1–7.

Salek J, Villota R. A comparative study of whirling and

conventional fluidized beds in their application to dehydration. I. Heat and mass transfer analysis. Journal of Food Processing and Preservation, 1984; 8(2): 73–98.

Aregba A W, Nadeau J P. Comparison of two non-equilibrium models for static grain deep bed drying by numerical simulation. Journal of Food Engineering 2007; 78(4): 1174–1187.

Muhlbauer W, Scherer R. The specific heat of cereals (in German). Grundlagen der Landtechnik, 1977; 27: 33–40.

ASAE D243.4 MAY 2003 (R2008). Thermal Properties of Grain and Grain Products. ASABE STANDARDS, 2008.

Uma Shanker Shivhare. Drying characteristics of corn in a microwave field with a surface-wave applicator. PhD dissertation. Macdonald campus McGill University, 1991. Site web: http://digitool.library.mcgill.ca/R?func=dbin-jump- full&object_id=70344

Chang C S. Measuring density and porosity of grain kernels using a gas pycnometer. Cereal Chemistry Journal, 1988; 65(1): 13–15.

Verboven P, Herremans E, Borisjuk L, Helfen L, Ho Q T, Tschiersch H, et al. Void space inside the developing seed of Brassica napus and the modelling of its function. New

Phytologist, 2013; 199(4): 936–947.

Yu D U, Shrestha B L, Baik O D. Thermal conductivity, specific heat, thermal diffusivity and emissivity of stored canola seeds with their temperature and moisture content. Journal of Food Engineering, 2015; 165: 156–165.

Campana L A, Sempe M E, Filgueira R R. Effect of microwave energy on drying wheat. Cereal Chemistry, 1986; 63(3): 271–273.

Stroshine R, Hamann D. Physical properties of agricultural materials and food products. West Lafayette, IN: Purdue University, 1993.

Deshpande S D, Bal S, Ojha T P. Bulk thermal conductivity and diffusivity of soybean. Journal of Food Processing and Preservation, 1996; 20(3):177–189.

Kazarian E A, Hall C W. The thermal properties of grain. Transactions of the ASAE, 1965; 8(1): 33–37.

Yu D U, Shrestha B L, Baik O D. Radio frequency dielectric properties of bulk canola seeds under different temperatures, moisture contents, and frequencies for feasibility of radio frequency disinfestation. International Journal of Food Properties, 2015; 18(12): 2746–2763.




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