NEW TECHNOLOGIES TO PROCESS VALUE-ADDED, HEALTHY FOODS FROM FRUITS AND VEGETABLES
Location: Processed Foods Research
Title: Drying characteristics and quality of rough rice under infrared radiation heating
Submitted to: Transactions of the ASABE
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: November 1, 2010
Publication Date: February 14, 2011
Citation: Pan, Z., Khir, R., Bett Garber, K.L., Champagne, E.T., Thompson, J.F., Salim, A., Mohamed, S. 2011. Drying characteristics and quality of rough rice under infrared radiation heating. Transactions of the ASABE. 54(1):203-210.
Interpretive Summary: This research investigated the drying rate and quality of rough rice under infrared heating. The dependence of drying rate on initial moisture, drying bed thickness, and grain temperature was determined. The results showed that infrared drying can be used to dry rough rice to achieve reduced drying time and high quality of milled rice.
Infrared (IR) radiation heating could provide high heating rate and rapid moisture removal for rough rice drying. The objective of this research was to investigate the effect of the drying bed thickness on drying characteristics and quality of rough rice subjected to IR heating. Samples of freshly harvested medium grain rice (M202 variety) with 20.5 % and 23.8% (wb) moisture contents were used for this study. They were dried with two different radiation intensities, 4685 and 5348 W/m2, and exposure times of 15, 30, 40, 60, 90 and 120s for each drying bed thickness. The tested three drying bed thicknesses were single layer, 5 mm and 10 mm. After IR drying, the samples were tempered for 4 hours followed by slow cooling. The drying rate, moisture removal, and temperature of rice were determined. The rice temperatures after the IR heating were in the range of 35.9 to 71.4 ºC. The heating and drying rates decreased with the increase of bed thickness. A significant amount of moisture was removed during slow cooling after tempering, without additional energy input. Sensory quality and milled rice quality, including total rice yield, head rice yield, and degree of milling of the dried rice were evaluated. IR heating under tested conditions had no adverse effects on rice sensory and milling quality. We concluded that a high heating rate, fast drying and good rice quality can be achieved by IR heating rough rice to about 60 ºC followed by tempering and slow cooling with a tested bed thickness up to 10 mm.