The effects of various treatments of paddy rice on the aneurin and nicotinic acid content of the milled grain.

The first stage in the preparation of rice for food is the threshing of the harvested crop to yield paddy rice. This consists of the rice berry (or grain) enclosed in a rough, fibrous and silicious husk. Further preparation consists of hulling to remove this husk, followed by milling which removes the outer bran layer of the berry. For some time before beriberi was shown to result from a deficiency of vitamin B, it was known that the disease could be prevented and cured by a diet of parboiled rice. Aykroyd (1932) showed that a sample of milled parboiled rice contained a considerable amount of vitamin q, although most of the bran had been removed by milling, whereas milled grain that had not been treated by the process was deficient in the vitamin. Platt (1939) stressed the importance of parboiling as a method of conserving the vitamin % of rice. Parboiling originated centuries ago in India, and several procedures are now employed in different parts of the world. They involve soaking the paddy in water at various temperatures. The grain may also be steamed for a short period after the excess water has been drained off. The paddy is finally dried in the sun or by artificial means. Jones, Zeleny & Taylor (1946) investigated the effect of twelve different treatments on the aneurin content of the milled grain. Highly milled samples after treatment contained roughly four to five times as much aneurin as untreated samples milled to the same degree. A considerable range of treatments in which such conditions as soaking and steaming were varied has been studied by Kik (1946). The treated grain after milling has a higher aneurin content than untreated grain similarly milled. Kik & Williams (1945) have also shown that the nicotinic acid content of milled rice is more than doubled by parboiling. Hinton (1948-9) recently investigated the distribution of aneurin in the rice grain, and obtained direct evidence that during a parboiling process the vitamin moves from the germ and the pericarp-aleurone region into the endosperm (Hinton, 1948). The characteristics of parboiled rice which appear to have influenced populations that adopted the process include facilitation of hulling, reduction of breakage during hulling and milling and retention of shape by the cooked grain. The methods have been developed empirically. Many of them cause marked changes in the colour, odour and taste of the milled grain so that the product is only acceptable to limited sections of the consumers. I t has been shown, by the workers referred to above, that