Author : Sakda Intaravichai

Summary : The experiment investigated the impact of humidified rice whitening on the performance of a rice mill in terms of milled-rice recovery and milled-rice quality. Results were derived from various milling system using an abrasive rice whitener as a single-pass whitener without air cooling prior to the second whitener and without adding water in the second-pass friction type humified whitener; a double-pass whitening system with air-cooling prior to the second whitener but adding water in the second-pass friction type humified whitener; a double pass whitening system without air-cooling prior to the second whitener, but adding water in the second-pass friction-type humified whitener; a double pass whitening system with air-cooling prior to the second whitener, and adding water in the second-pass friction-type humified whitener. Results showed that the application of humified whitening yielded significant improvements in head rice yield and whiteness degree through values of 37.21 percent and 48.23 percent, respectively. The results were slightly improved by the application of air-cooling prior to the humified whitening pass with values of 37.68 percent and 48.70 percent, respectively. The total milling recovery at uniform whiteness degree, as produced during the five milling tests, show that there were no increments over the recommended standard value (test 1) with values of 0.17 percent, 0.22 percent, 1.33 percent, and 1.48 percent derived from tests II, III, IV, and V, respectively. There was no significant difference in the moisture content of rice milled using the various milling systems. However, a significant difference was found in the moisture content of bran produced by the humified whitener with a maximum value of 16.44 percent. The average value of the moisture content of bran produced as a mixture by the abrasive whitener and by the humified whitener, however, was acceptable (14.50 percent). The moisture content of bran was slightly reduced through air cooling prior to the second pass humified.