Effect of the Temperature, Moisturing Time and Final Moisture Content on Broken Rice Grain Percentage at Some Rice Grain Varieties

The aim of this research was to investigate the effect of grain soaking time (at two levels in 2 and 4 days), grain soaking temperature (at two levels 10 and 25 °C) and grain final moisture content (at three levels 8, 11, 14%w.b.) on the percentage of broken grain during husking and whitening processes for three paddy rice varieties (Hashemi, Hasani and Khazar) which are common in Guilan Province. The results revealed that the effect of main factors and their intractions was significant on the broken grain percentage during husking and whitening processes. The Hashemi variety had the highest broken grain with values 42.99% and 38.48% at husking and whitening processes, respectively. By increasing grain soaking time from two to four days, broken grain mean values at husking and whitening processes decreased significantly from 20.23% to 15.59% and 29.53% to 27.19%, respectively. By increasing soaking temperature from 10 to 25 °C, broken grain mean values at husking and whitening processes decreased significantly from 19.26% to 16.57% and 29.64% to 27.38%, respectively. The increase of final grain moisture content from 8 to 14%w.b. caused a significant decrease of broken grain at husking from mean value 21.39% to 14.88% and a increase significant in broken grains at whitening from mean value 25.91% to 31.05%. Comparison of the mean results of quaternary interactions showed that the least broken grains percent of husking process (4.736%) was obtained at test with Hasani variety, soaking time of four days, soaking temperature of 10°C and grain moisture content of 14 (%w.b.). Also, the hightest broken grain percentage of husking process (56.8%) was obtained at test with Hashemi variety, the soaking time of two days, the soaking temperature of 10 °C and the grain moisture content of 8 w.b.%. The least broken grain percentage of whitening process (9.44 %) was obtained at test with Khazar variety, the soaking time of four days, the soaking temperature of 25 °C and the moisture content of 11 w.b.%. The highest broken grain percentage of whitening process (57.85%) was obtained at test with Hashemi, soaking time of 2 days, soaking temperature of 10 °C and grain moisture content of 14%(w.b.).