with soft-kernel sorghum, parboiling more than doubled the yield of decorticated grain.)

  • Inactivates enzymes and thereby greatly extends shelf life. (It even improves the storability of pearl-millet flour, a material notorious for turning smelly during storage.)

  • Kills insects and their eggs so that it reduces storage losses.

  • Improves the grain's cooking characteristics. (Boiling parboiled sorghum, for instance, doesn't produce mush; instead, the kernels remain separate, whole, and very much like pilaf or rice.)

  • Improves nutritional values. (This is notably because it helps retain water-soluble constituents—such as the B vitamins and certain minerals—that otherwise are thrown out with the cooking water.)

  • Upgrades certain grains that have poor processing characteristics (the soft endosperm in finger millet, for example).

Given its now widespread use in the rice industry, parboiling is a surprisingly recent newcomer to commerce. Until the 1930s, it was hardly known outside South Asia where it was a village technology employed by poor people in their cottages. In the last 60 years, however, parboiled rice has rocketed into extensive worldwide use, and parboiling is now done on a giant commercial scale in countries such as the United States.

Parboiling is still good for village-level use, however. For example, field trials in Mali, using local sorghum and pearl millet, showed that it was practical, satisfactory, and boosted the yields from milling. Malian families tested the parboiled grains in local dishes and condiments (such as peanut sauce) and rated them very acceptable.9

At first sight, the extra energy and effort needed to parboil grains would seem to be a major disadvantage. However, the increases in yield and quality provide both the processor and consumer with substantial benefits.10 Rice is already parboiled in the villages of some parts of Mali (not to mention half of India), which certainly suggests that the product is good enough so that people will find the fuel and put in the extra effort to prepare it.

Flaking

In this process, decorticated (pearled) grains are soaked, heated, partially dried (to about 18 percent moisture), pressed between rollers,

9  

These tests were run at Sotuba. The whole grain was washed, placed in cast-iron pots (covered) and heated in tap water over an open fire until the boiling point was reached. The pots were then taken from the fire and allowed to cool overnight. The next morning they were heated again and drained immediately after once more reaching the boil. The moist grain was next spread out in the shade to dry (24 hours for pearl millet and 48 hours for sorghum). The final product was decorticated with a mechanical mill.

10  

An increase of only 1-2 percent in the milled yield of commercially parboiled rice gives the processor enough profit to offset the extra energy costs.



The National Academies | 500 Fifth St. N.W. | Washington, D.C. 20001
Copyright © National Academy of Sciences. All rights reserved.
Terms of Use and Privacy Statement