Rice Mill Set Up

Topics: Bran, Rice, Whole grain Pages: 8 (2262 words) Published: January 6, 2011
Description of Rice Milling Operation:
Paddy in its raw form cannot be consumed by human beings. It needs to be suitably processed for obtaining rice. Rice milling is the process which helps in removal of hulls and barns from paddy grains to produce polished rice. Rice forms the basic primary processed product obtained from paddy and this is further processed for obtaining various secondary and tertiary products. The basic rice milling processes consist of:

Process Definition
1. Pre Cleaning: Removing all impurities and unfilled grains from paddy 2. De-stoning: Separating small stones from paddy
3. Parboiling (Optional): Helps in improving the nutritional quality by gelatinization of starch inside the rice grain. It improves the milling recovery percent during deshelling and polishing / whitening operation 4. Husking: Removing husk from paddy

5. Husk Aspiration: Separating the husk from brown rice/ unhusked paddy 6. Paddy Separation: Separating the unhusked paddy from brown rice 7. Whitening: Removing all or part of the bran layer and germ from brown rice 8. Polishing: Improving the appearance of milled rice by removing the remaining bran particles and by polishing the exterior of the milled kernel 9. Length Grading: Separating small and large brokens from head rice 10. Blending: Mixing head rice with predetermined amount of brokens, as required by the customer 11. Weighing and bagging: Preparing the milled rice for transport to the customer The flow diagram of the various unit operations are as follows: Status of Rice Milling Units in India:

Rice milling is the oldest and the largest agro processing industry of the country. At present it has a turn over of more than 25,500/- core per annum. It processes about 85 million tones of paddy per year and provides staple food grain and other valuable products required by over 60% of the population. Paddy grain is milled either in raw condition or after par-boiling, mostly by single hullers of which over 82,000 are registered in the country. Apart from it there are also a large number of unregistered single hulling units in the country. A good number (60 %) of these are also linked with par-boiling units and sun -drying yards. Most of the tiny hullers of about 250-300 kg/hr capacities are employed for custom milling of paddy. Apart from it double hulling units number over 2,600 units, under run disc shellers cum cone polishers numbering 5,000 units and rubber roll shellers cum friction polishers numbering over 10,000 units are also present in the country. Further over the years there has been a steady growth of improved rice mills in the country. Most of these have capacities ranging from 2 tones /hr to 10 tones/ hr. Need for improved rice mills:

The recovery of whole grains in a traditional rice mill using steel hullers for dehusking is around 52-54%. There is excessive loss in the form of coarse and fine broken. Further loss of large portion of endosperm layers during the dehusking operation further accentuates the problem. Against it, the recovery percent of whole grains in modern rice mills using rubber roll shellers for dehusking operation is around 62-64%. The whole grain recovery percent further increases to 66-68% in case of milling of parboiled paddy. Thus it can be seen that there is an overall improvement of recovery of whole grains by about 10-14% if one uses rubber roll shellers for rice milling operations. The conversion ratio (i.e. recovery % of various final product and byproduct for every 100 kg feed of raw paddy) for these improved rice mills are can be as follows: 1. Percent of milled rice: 62-68%

2. Percent of rice bran: 4-5%
3. Percent of rice husk: 25%
4. Percent of germ wastages: 2%-8%
It has been observed that dehusking using rubber roll shellers reduces the risk of breaking the grain because husk is pulled off almost at once and pressure is applied by means of resilient surfaces across the width of the grain, where kernels, generally are much...
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