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Par boiling of rice involves the partial cooking of rice paddy and involves the process of soaking gelatinizing and drying prior to milling. The objective is to impart a required hardness on the grain (with husk intact) in order to withstand milling operations. Rice is parboiled in the hull, which softens the kernel, allowing the surface starch, bran and other components to commingle. The water is than drained and the rice is carefully steam dried. The dried parboiled rice is sent through machines, which remove the hull and polish the kernels.



1. Single stage parboiling system (For small grain boiled cream color rice)  

2. Two stage parboiling system( For small grain boiled and steam white color rice)

3. Three stage parboil system (For long grain rice like Basmati and other long rice)



Raw paddy intake through cleaning section and transferred to soaking tank paddy storage bin and then raw paddy steaming process 2 to 4 minutes (only for long grain and some of other medium grains) after above process paddy moved to soaking tanks. While in the paddy form, the rice soaked in water at ambient temperature (20-30 C) will take 36 to 48 hours to reach 30 per cent moisture content. In hot water (60-65 C), it will take only two to four hours. If soaking time is too long, part of rice dissolves in water, the seed begins to germinate, and starch fermentation occurs.

Water temperature and length of soaking time affect the solubility of substances in rice as well as color, smell, and taste. . During hot water soaking (60-65 C), the grain absorbs moisture faster and reaches a moisture level of 30-35 per cent in two to four hours depending on the variety. Hot soaking keeps the grain at a higher temperature, which will reduce the steaming time needed to complete the process. The moisture content of paddy increases to about 38 per cent during steaming. When heating paddy with non- pressurized small variations are found in color, quantity of soluble starch, and the amount of swelling of the milled parboiled rice. Heating has a considerable effect on color. When the steaming temperature exceeds 100 C, the color becomes considerably deeper and the grain becomes harder. Longer steaming times also cause rice to be harder and darker. The process also may change depends on paddy s well as required out put. 


Drying should be done 12 to 14 percent moisture for safe storage and milling.

Parboiled rice is more difficult to dry and requires energy than field paddy because its moisture content is much higher, however, higher air temperature help reduce the drying time. Most parboiled paddy is sun-dried on large drying floors by large number

of people who are required to constantly turn and mix the paddy to achieve rapid, uniform drying. In contrast with field paddy, Nagraj Driers helps to dry parboiled paddy,it 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. 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 temperatures also may varies depends upon the type of paddy.



The uses of rice worldwide is great; principal among them include; staple food (Nutrition) both human and animals. Countries also benefit from rice production by getting foreign exchange, and above all medicine. The grain products of rice ,include: flakes, rice flour, starch, rice milk, rice cakes, and the extended uses of rice include: rice husk for fuel, rice bran for oil and animals feed, broken rice used as

snacks,rice flour and rice beverage.

  • Parboiled rice has a higher vitamin content than raw milled rice.

  • Parboiled rice is quite nutritious, being an excellent source of niacin, a good source of thiamine and magnesium and a moderate source of protein, iron and zinc. Levels of vitamins and minerals fall between white rice and brown rice.

  • Parboiled rice is widely used in the catering industry, as it is less sticky when cooked.

  • It is good in salads and retains its flavour and quality when kept hot for serving large numbers of people.

  • All rice comes from the field with insect eggs in the germ of the rice. These eggs hatch when the temperature is warm and moisture is available. The high temperatures occurring during parboiling kill any insect eggs in the rice and essentially sterilise it.

  • Parboiling also mends the cracks in the rice, that is, it glues broken rice back together and dramatically improves the milling yield of whole kernels in the rice.

  • Parboiling changes the texture of the rice. It becomes firmer and less sticky.

  • It is a much more durable kernel.

  • It takes just as long to cook (actually a little longer) as white rice, but is much easier to cook.

  • It can be overcooked without being mushy or losing its grain shape.

  • It does not have to be steamed. It can be cooked by blanching only. It has a long steam table life, which is important for restaurants. It is the only type of rice that can withstand the harsh treatment of most industrial processes that involve cooking and then freezing, canning, or drying.

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