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April 27, 2020

Beyond the Ri’ichi Part 4: Processing long-grain rice – Milling

by Hiromi Saita, Senior Staff, International Management Office, Satake Corporation, Japan

The most important consideration in milling long-grain rice is proper control of the polishing pressure. If the pressure is too low, then rice milling will not progress correctly. If the pressure is too high, it will break the rice grain.

Milling long-grain using Japanese equipment for short-grain generates a large amount of broken rice. This is mainly due to the inner pressure of the frictional milling machine, which is specifically designed to be high for short-grain rice milling.
 


Long-grain rice cannot resist such high pressure and, thus, cracks. Moreover, high value varieties such as Basmati and Jasmine rice, mainly for exports, (and whose production yield impacts directly on profits), are even more likely to present a high broken rice rate, even compared to other long-grain rice varieties. For that reason, careful attention must be paid to the selection of equipment and the operation of these varieties of rice. In addition, the temperature rise of the rice grain during the milling process causes the loss of its natural aroma, hence a suppression of this temperature rise is fundamental.

Since it is rare to find overseas rice processing plants handling wide varieties of rice in small lots like those in Japan, it is more critical to maintain stable performance over time once a machine is installed. Having stable machine performance without using complicated mechanisms such as automatic weight control, like the kinds used in Japan, is desirable.

Some Parboil rice production plants may mix a small amount of calcium carbonate with the raw materials. Parboil rice bran is usually more viscous than brown rice's bran and tends to accumulate inside the machinery and, thus, gives rise to more frequent cleaning. However, adding calcium carbonate can remove the bran deposit from the outset, thereby improving the cleaning frequency of the rice milling machine.

However, the abrasion action of calcium carbonate also causes wear of the screen of the rice milling machine and the machine itself. For this reason, white pig iron cast iron with improved wear resistance is used in the casting part, and the plate thickness of the part where the consumption is severe is increased in advance.


Read more HERE.
 

The Global Miller
This blog is maintained by The Global Miller staff and is supported by the magazine Milling and Grain
which is published by Perendale Publishers Limited.


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