Title: Effect of microwave and hot air drying on flax straw at controlled temperatures

Authors: Gopu Raveendran Nair; Pansa Liplap; Yvan Gariepy; G.S.V. Raghavan

Addresses: Department of Bioresource Engineering, Macdonald Campus of McGill University, Sainte-Anne-de-Bellevue, Quebec H9X 3V9, Canada. ' Department of Bioresource Engineering, Macdonald Campus of McGill University, Sainte-Anne-de-Bellevue, Quebec H9X 3V9, Canada. ' Department of Bioresource Engineering, Macdonald Campus of McGill University, Sainte-Anne-de-Bellevue, Quebec H9X 3V9, Canada. ' Department of Bioresource Engineering, Macdonald Campus of McGill University, Sainte-Anne-de-Bellevue, Quebec H9X 3V9, Canada

Abstract: Flax stems were subjected to microwave drying at controlled temperatures. The rate of drying was then compared with conventional hot air drying. The product temperature was maintained at 40°C, 60°C and 80°C for both microwave and hot air drying. The moisture content of flax stem was about 70% (wet basis). The microwave drying was conducted in a microwave apparatus which recorded mass, product temperature, incident microwave power, reflected microwave power and inlet/outlet air temperature. The final moisture content for experiment was set to 9% (wet basis). Microwaveconvective drying ensured about 30% to 70% reduction of drying time for drying flax straw as compared to hot air drying. Curve fitting with different mathematical models were carried out and all the models were fitted well for both hot air and microwave drying. The tensile strength of flax straw, measured with an Instron apparatus, increased with an increase in the processing temperature of both processes. Hot air dried flax straw showed the greatest tensile strength and modulus of elasticity at processing temperatures of 60°C and 80°C with a significant difference.

Keywords: microwave drying; flax straw; tensile strength; hot air drying; controlled temperatures; moisture content; curve fitting; mathematical modelling.

DOI: 10.1504/IJPTI.2012.050982

International Journal of Postharvest Technology and Innovation, 2012 Vol.2 No.4, pp.355 - 369

Received: 08 Mar 2011
Accepted: 04 Dec 2011

Published online: 12 Dec 2012 *

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