Effect of Hot Water Soaking on Hydration of Nadu Type Paddy Grains

Abstract

Sri Lanka is an agriculture based country where rice plays a key role in food industry. Parboiling is one of the processing methods of paddy, which involves soaking as one of its processing steps. Hot water soaking is commonly practiced in commercial mills for different paddy varieties. However, it has not yet got popularity in Jaffna. An attempt was made to check the effect of temperature on hydration of Nadu type long paddy grains during soaking and consequent steaming. The hypothesis of the experiment was that increase in temperature of soaking water would increase paddy hydration, which intern reduces soaking time. Nadu type long grains were selected for experiment. Different levels of temperature (4 0 ,5 0 ,6 0 ,7 0 and 80 °C) were used. Three replicates were used for each temperature and cold soaking was set as a control. Soaking was done for 2 hours and steaming was performed thereafter under uniform condition. Moisture content of grain samples was determined by oven-dry method. Results revealed that higher temperature increased the paddy hydration during soaking and subsequently in steaming. Hot water soaking was the best option for processing Nadu type long grains in Jaffna as it increased paddy hydration during soaking and steaming. However, milling yield analysis has to be performed to determine the effects on colour of paddy grains and to set the best temperature for hot water soaking without damaging milled rice quality.