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United States Department of Agriculture

Agricultural Research Service

Research Project: NEW TECHNOLOGIES TO PROCESS VALUE-ADDED, HEALTHY FOODS FROM FRUITS AND VEGETABLES

Location: Healthy Processed Foods Research

Title: Comparison of Drying Characteristics and Quality of Rough Rice Dried with Infrared and Heated Air

Authors
item Amaratunga, K.S.P. - UC DAVIS, CA
item PAN, ZHONGLI
item Zheng, Xianzhe - NORTHEAST AG UNIV., CHINA
item Thompson, James - UC DAVIS, DAVIS, CA

Submitted to: American Society of Agricultural Engineers Meetings Papers
Publication Type: Proceedings
Publication Acceptance Date: May 20, 2005
Publication Date: July 17, 2005
Citation: Amaratunga, K., Pan, Z., Zheng, X., Thompson, J.F. 2005. Comparison of Drying Characteristics and Quality of Rough Rice Dried with Infrared and Heated Air. American Society of Agricultural Engineers Meetings Papers. ASAE Paper No. 056005. p. 1-10. St. Joseph, MI.

Interpretive Summary: Infrared for rice drying has been a great interest of rice farmers. However, the performance of the infrared dryer has not been compared with commercial rice drying practices. The objective of this study was to compare the drying process characteristics and quality of rice dried with an infrared dryer and a commercial hot air dyer. The drying rates, total rice yields and head rice yields were measured and compared for the rice dried with different methods. The multiple pass infrared drying showed a higher drying rate than heated air commercial drying.

Technical Abstract: The objective of this study was to study and compare the drying process characteristics and quality of rice dried with a laboratory catalytic infrared (CIR) dryer, a laboratory simulated forced air convention (FAC) column dryer, and a commercial column dryer. Medium grain rice of variety M202 was used for the study. The rice samples were dried by using both the CIR and simulated FAC dryers with single and double passes, at two different temperatures of 36°C and 45°C to remove from 1.5% and 4% moisture at each drying pass. The milling quality, including head rice yield (HRY), total rice yield (TRY) and whiteness of the dried rice were evaluated. The CIR dryer showed much faster heating rate and more uniform heating to rice kernels than the simulated FAC column dryer. It took 28 and 11 minutes, respectively, to remove 2% moisture at 36°C and 45°C. On average, the head rice yields of the CIR, FAC and commercially dried rice were 62.4%, 61.1% and 58%, respectively. Corresponding total rice yields for the different drying methods were 70.2%, 69.5%, and 70%. It was found that for CIR drying, high drying temperature, 45°C, single pass with at least 3% moisture removal can be used to produce dried rice with milling quality equal to or higher than 36°C FAC drying with 1.5% moisture removal by each drying pass. The energy efficiency of CIR dryer was improved when the ratio of rice loading to emitter surface area. It is expected a large scale CIR dryer could have much higher energy efficiency than commercial column dryers.

Last Modified: 9/10/2014
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