Milling of rice

The rice grain, as harvested from the plant, called paddy or rough rice, is not in an edible form. The grain has an external rough and inedible covering, husk (comprising of two boat-shaped halves, viz. lemma and palea), that has to be removed first. This yields ‘brown’ rice, called so due to its brownish external surface. It still has some outer layers (collectively termed as bran) which do not get ‘cooked’ during the normal cooking process. These layers also are to be removed, partially or fully, for rice to be properly cooked. The technology for obtaining edible rice from paddy, in a form that can be cooked, is perhaps as old as agriculture itself, presumably running into prehistoric times. The process of removing husk and the bran layers, which yields edible rice, is called rice milling. The technology presumably started with the use of mortar and pestle in its simplest form. Manual milling by hand pounding of paddy in a mortar and pestle was common for centuries. Further development of this system was the mechanised version of pestle and mortar, still operated by hand or leg. Some sort of hand pounding, in wooden or stone mortar and a wooden pestle, may still be in practice in very remote tribal areas and villages. Use of energy for milling of rice, other than human, started some 200 years ago in South Carolina, a British colony, then in colonial America, where the cultivation of rice was introduced during 1680s. Black slaves, brought from Africa, were put to use for hand-pounding of paddy to produce milled rice. Rice was then a commercial commodity, mainly for export to Britain and other European countries. A worker, using wooden mortar and pestle, could produce from one to one-and-half bushel of rice in a day (a bushel is 45 lbs. or 20.4 kg). However, milling of paddy in mortar and pestle was not just ‘pounding’ of the grain, since the goal was to obtain whole, not broken or pulverised, grains. To achieve minimum breakage during the pounding process, it was generally performed in two distinct operations. During the first pounding, majority of the hull or the husk was removed, representing a

relatively easy step. The second stage was polishing the rice. This was more difficult and involved detaching the bran without breakage. To achieve this required a skilled tapping and rolling motion. The accounts of that period (latter half of eighteenth century) of South Carolina mention that a skilled worker could produce 95% whole grains, while a less skilled, ‘careless’, or a fatigued worker could easily shatter half of the rice. Increased paddy production required more quantities to be milled. Manual labour became a limitation. Improvised pestle and mortar mills turned by farm animals were then invented in the later part of the eighteenth century. These included the ‘pecker machine’ in which the pestle was made to move like the stroke of a woodpecker, and a ‘cog mill’ in which an upright pestle was driven by a horizontal cog wheel. These machines could mill from three to six barrels a day (a barrel is 162 lbs., i.e. 73.5 kg of rice). A water-powered (tidal-powered) rice milling system was first developed and installed in 1793 by one Jonathan Lucas on paddy farms, on the river Cooper, north of Charleston in South Carolina, USA. This was the first ever water-powered rice mill, to replace manual pounding and threshing operations by mechanical machinery in USA. Around this time, the system of flooding rice fields by action of the tide was coming into general use, but a large crop was considered a dubious blessing because of the difficulty of removing the husk from the grain. The water-mill built by Lucas was driven by a very large undershot water wheel. It was an improved tide mill with many machinery units for continuous operation. It had rolling-screen paddy cleaner, elevators, mechanical pounding system for milling and the packing system. Three persons could manage such a mill. On a favourable tide beat, the mill could produce about sixteen to twenty barrels, and larger mills up to 100 barrels of rice, per day. It is interesting, however, to note that water-powered rice mills were also in operation on the other side of globe, in China, around the same period. A ‘British Embassy’, consisting of two large ships with more than 400 personnel, was sent by the King of Great Britain to the Emperor of China during 1793 which travelled through the ancient empire before returning. The account of this travel mentions, among other things, the way paddy was being cultivated and processed at that time in China. It has been mentioned that the cottagelevel mill was the foot-operated, vertical pounding system (similar to that of pecker machine of USA), or a set of two circular stones between which the grain was made to pass. The large-scale rice milling was being carried out in China by water-powered mills (also similar to the water-powered mills of USA). Jonathan Lucas subsequently installed his mills throughout the rice region of South Carolina. Figure 5.1 shows an illustration of a typical water

mill existing in South Carolina, USA, during 1790s; and Fig. 5.2 shows a typical large-scale, water-powered rice mill existing around the same period in China.