DRYING
However, higher air temperature help reduce the drying time. If drying is done too fast, internal stresses develop in the grain and cause breakage during milling. After drying is completed, paddy should be allowed to stand for at least several hours preferably for one or two days before it is milled, to permit internal moisture differences and stresses to equalize. Moisture reduction takes place rapidly during the first part of drying from 36 to 18 per cent moisture level, but is slow from 18 to 14 per cent. The drying process should be stopped at about 18 per cent moisture to allow paddy to temper or equalize for several hours before continuing the drying to 14 per cent. Most parboiled paddy is sun-dried on large drying floors. A large number of workers are required to constantly turn and mix the paddy to achieve rapid, uniform drying. For best results, paddy is spreaded about 2.5 cm thick over the floor. In contrast with field paddy, parboiled paddy requires air temperatures of up to 100°C during the first drying period. During the second period air temperature should be kept below 75°C. Maintaining higher air temperature will not decrease the drying time but will result in increased drying cost and more damage to milled rice quality. The first drying period takes about three hours including dryer loading and unloading time. After tempering, the second drying period takes about two hours.