News of Rice, An Ancient Staple

Ernest B. Kester, Jenkin W. Jones.

For hundreds of years rice has been a staple article of diet in many parts of the world. It is a major part of the daily fare of millions of people. We mean the familiar milled white rice, which is marketed and eaten in many populous countries. It is nourishing, but it is deficient in B vitamins and minerals.

Brown, or husked, rice contains more minerals, proteins, and vitamins than milled rice, but milled rice is more attractive in appearance, requires less time to cook, and is easier to digest. Also, it keeps much better in storage than does brown or undermilled rice, which soon become rancid in hot, humid climates, where most of the world's crop of rice is produced and consumed.

The Asiatic methods of rice storage and milling, based on ages of experience, are fundamentally sound. Much of the rough rice produced in Asia is stored after threshing and milled only as needed for local use. A mortar and pestle operated by hand or mechanically are extensively used for milling. With this primitive equipment, parts of the bran layer and germ of the kernel are left on the milled rice. Hence, the product is more nutritious than machine-milled rice. Much of the rice consumed in Asia is therefore under-milled, but in the larger cities and in some rural communities the use of machine-milled rice has increased. Beriberi, a deficiency disease, is apt to occur among people whose major food is machine-milled rice, which lacks thiamine.

Man has continually searched for ways of improving rice by transforming it into a more attractive food, and legion are the recipes for cooking rice with condiments and other foods to enhance its appeal and nutritional value. In the United States, we consume only 5 to 6 pounds of rice a person a year, compared to 200 pounds in the Orient. The American housewife uses it as an occasional substitute for potatoes, a side dish, the basis for a pudding, or an addition to soups. She does not usually rely on rice to any great extent in the daily diet of her family.

The large rice-producing areas of the United States are in Arkansas, California, Louisiana and Texas. Each of those States raises at least 20 percent of the total crop, which in 1950 was about 2 million tons.

Varieties of rice in the South and in the West are chosen for their adaptability to the soils and climate of each area. In the South, long-grain and medium-grain varieties predominate; but in California, almost the entire acreage is devoted to the Japan or Pearl rice, a short-grain type.

LET US LOOK at a whole grain of rice and see how it is constructed and what happens to it in milling. On the outside is the hull, a fairly rigid but loosely adhering protective covering, which constitutes about 20 percent of the grain and contains 20 percent of ash, mostly silica. Beneath the hull is the brown rice, which owes its color to layers of bran, or pericarp. The bran is rich in oil, protein, mineral salts, and vitamins. If it is not removed, the rice turns rancid. The bran is therefore rubbed off in special machines, and with it goes the embryo or germ. This is the costliest part of rice milling, because 20 to 30 percent of the kernels are broken and must be separated and sold at a discount. The different grades of broken rice are called second head, screenings, and brewer's rice, depending on the sizes.

Inside the outer brown bran layer is a finer, lighter-colored layer like the outside bran in composition. It is called polish and is also taken off. The bran and polish together constitute about 10 percent of the original brown rice and contain about 85 percent of the oil, 10 percent of the protein, 80 percent of the thiamine, 70 percent of the mineral matter and crude fiber, 50 percent of the riboflavin, and 65 percent of the niacin.

What is left is the highly milled white rice of commerce, which is 90 to 94 percent starch and 6 to 10 percent protein. It contains very small amounts of vitamins and minerals.

At our present low rate of rice consumption, however, the detrimental effect of over-milling on the human diet is a debatable point.

By a process of parboiling before the hull is removed, most of the B-vitamin content of rough rice is retained in milled rice.

How is rice parboiled? The variations in that treatment are many, but essentially it is performed as follows. Rough (unhulled) rice is steeped in warm or hot water, then drained, steamed (usually under pressure), dried, hulled, and milled in the usual way. Milling causes very little breakage, especially if steaming is done under pressure and the rice is carefully dried. The finished rice has a light; sometimes a very light, brown color. It is translucent because of the partial cooking and gelatinization of the starch.

In most of India, Burma, Ceylon, the Malayan Peninsula, and in British Guiana, the parboiling of rice before milling has been practiced for generations. In those areas, this form of rice is eaten almost exclusively. Its acceptance has not been so favorable in China. Originally, the natives of those other lands used a short boiling to make the hulls easier to remove, but in time they learned that they were healthier from eating parboiled rice instead of raw rice. The incidence of beriberi is indeed low in areas where parboiled rice is consumed. Chemical examination shows that parboiled rice contains much more of the antiberiberi vitamin (as well as other nutrients) than does highly milled white rice. The reason is that much of the vitamin content and mineral salts are driven or infused from the bran and germ into the endosperm by this treatment. Most of the oil remains in the bran, which is removed in milling.

Results of studies on the effect of parboiling on the milling and cooking quality of American rice, reported in 1935, in general bore out the claims made of the benefits of the process in Asia. Advantages of properly parboiled rice are higher mill yields of head rice (whole kernels), better retention of vitamins, improved cooking quality, resistance to insects, and suitability for use in canned products. Those advantages are of prime importance to rice millers, dealers, and' consumers.

Much work has been done in evaluating different parboiling procedures in the University of Arkansas, University of California, and the Bureau of Plant Industry, Soils, and Agricultural Engineering. What is desired in parboiled rice, or aimed at in technical studies, is a maximum infusion of vitamins and other nutrients from the bran and germ into the endosperm, a uniform and pleasing appearance of the rice grains, superior cooking qualities, minimum loss from breakage during milling, and a reasonably long storage life. Cooking without disintegration or formation of a pasty mass is a prime consideration. Modern methods of parboiling have attained many of the goals, but, as in most food processing, the road to improvement never reaches an end.

In the United States, parboiling has been modernized and adapted to large-scale manufacture. At least three plants are in operation that make converted, Malekized, or processed rice, although this long-known treatment of an age-old cereal was not introduced to our country until the Second World War. Indeed, the critical shortage of rice when Asiatic imports were shut off prompted the development here.

American parboiled rice was in great demand by our Armed Forces during the war. The sterilization it receives from the steam treatment under pressure helps preserve it against spoilage and insect infestations. It is an excellent ingredient of canned soups because the grains do not go to pieces under steam pressure. The housewife can cook parboiled rice more satisfactorily than raw rice without the bother of rinsing or steaming it. The grains do not readily become sticky and adhere to one another during cooking, and their brownish color becomes considerably lighter as cooking proceeds.

Parboiled rice has disadvantages, however. It lacks the perfect whiteness of well-milled raw rice, which by long association has become identified in people's minds with purity and cleanliness. Some nutrients are lost in the steeping liquors. In one mill, the liquors are recycled from batch to batch, but ultimately they become so highly colored that they must be discarded. Parboiled milled rice is costlier than raw milled rice. The oil in parboiled rice is more susceptible to rancidification than is oil of white rice, even though the amount is very small.

Nutritionally, however, the treated rice is superior to well-milled white rice. Let us compare data for three of the B vitamins in white and parboiled rice. Brown rice is included to show the maximum that could be attained if all the vitamins were captured in the parboiling. The figures are for micrograms per gram.

It must be understood that some variation may be observed in different samples, depending on varieties and the method of parboiling used, but the figures are at least illustrative.

ARTIFICIAL ENRICHMENT with mineral salts and synthetic vitamins also improves milled white rice. In the method currently used, batches of completely milled rice are fortified very heavily with strong solutions of vitamins and minerals applied layer-wise. Each layer is dried and protected from abrasion with a light soluble coating. The enriched rice is then blended with untreated rice in the proportions of about 1 to 200. The mixture is so uniform in appearance that without chemical tests it is almost impossible to distinguish the enriched from the unenriched grains.

A large-scale try-out of the product has been started in Bataan Province, Philippine Islands, where incidence of beriberi was high (1,500 cases among 12,000 natives examined). Of the B vitamins, only thiamine and niacin are being used in the fortification. Riboflavin is omitted because of its color, which might prevent general acceptance of the rice by the islanders. Natives of seven municipalities in Bataan are being fed the fortified rice; those in five others, for comparison, are being fed only plain milled rice. After 9 months of this experiment, a marked decline in mortality, as well as incidence of the disease, had taken place where the fortified rice was used.

The outcome of the study, which is being conducted jointly by the United States Public Health Service, the Philippine Department of Health, and the Williams-Waterman Fund of New York, will undoubtedly have a bearing on future remedial measures for nutritional problems in other parts of the Orient where vitamin B deficiency is prevalent.