ARS | Publication request: Influence of moisture content and temperature on thermal conductivity and thermal diffusivity of rice flours

Submitted to: International Journal of Food Properties
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: January 12, 2011
Publication Date: March 15, 2011
Citation: Mahapatra, A.K., Lan, Y., Harris, D.L. 2011. Influence of moisture content and temperature on thermal conductivity and thermal diffusivity of rice flours. International Journal of Food Properties. 14:675-683.

Interpretive Summary: Determination of thermal properties of food materials is very useful for quantifying thermal processes and designing various processing systems. Although thermal properties of rough rice have been studies by several researchers, rice flour thermal properties have been studied very little to date. With the increasing quantity and variety of rice flours being produced by food industries, there is a need for information about their thermal properties. We found that thermal conductivity values increased and thermal diffusivity decreased, with increasing temperature, bulk density, and moisture content of rice flours. The results provide useful information for the rice industry to improve quality and consistency of rice flour, and for engineers to design the rice processing equipment involving heat transfer.

Technical Abstract: The thermal conductivity and thermal diffusivity of four types of rice flours and one type of rice protein were determine at temperatures ranging from 4.8 to 36.8 C, bulk densities 535 to 875.8 kg/m3, and moisture contents 2.6 to 16.7 percent (w.b.), using a KD2 Thermal Properties Analyzer. It was observed that thermal conductivity of rice flours and rice protein increased with the increase in temperature, moisture content as well as with increase in bulk density. However, thermal diffusivity decreased with increase in moisture content, increase in temperature and bulk density. The thermal conductivities values obtained were within the range of 0.045 to 0.124 W/m/K, whereas the thermal diffusivity values were in the range of 0.094 to 0.128 mm2/S.