Effect of tempering approach following cross-flow drying on rice milling yields

Abstract

Three tempering approaches were followed after drying rough rice at 16.3% and 20.5% initial moisture contents (IMCs) using 57 °C/13% RH air at an airflow of 0.56 (m³/s)/m² for 30, 60, and 90 min in an experimentally simulated cross-flow drying column. For the longer drying durations, post-tempering head rice yields were consistently less when the interstitial air from rice from different cross sections of the drying column was allowed to “interact” during tempering than when the rice from these different cross sections was tempered separately; this effect was more prominent at the greater rice IMC. RH of the interstitial air during tempering was measured and used to estimate the minimum tempering durations required for the different tempering approaches.

Keywords:

• Rice drying
• cross-flow drying
• tempering
• glass transition temperature
• head rice yield
• milling yield

Acknowledgments

The authors express their gratitude to Bhagwati Prakash (PhD) of the University of Arkansas Rice Processing Program (UARPP) for his input in planning this study, as well as Redentor Mijares Burgos and Joanne Baltz-Gray of the UARPP, for their assistance with processing samples.

Disclosure statement

No potential conflict of interest was reported by the authors.